nitrophenols and 4-nitrophenol

According to the 2008 US FDA (draft) and 2006 EMEA guidance documents for genotoxic impurities, an impurity that is positive in an in vitro genotoxicity study, in the absence of in vivo genotoxicity or carcinogenicity data, should be treated as genotoxic and typically controlled to 1.5 microg/day for chronic use. For p-nitrophenol (PNP), existing study results (i.e., positive in vitro clastogenicity in mammalian cells, no information on its in vivo genotoxicity, and negative with respect to carcinogenicity in a dermal mouse study with no confirmation of systemic exposure) indicated that it should be considered genotoxic and exposure as a drug impurity limited. Therefore, to more completely characterize the genotoxic potential of PNP (consistent with the guidance documents), in vivo mouse micronucleus and dermal pharmacokinetic bridging studies were conducted. In the micronucleus study, PNP was negative, demonstrating that the reported in vitro clastogenicity is not present in vivo. In the pharmacokinetic study, PNP was well absorbed dermally, validating the negative dermal carcinogenicity assessment. These results indicate that PNP should be considered a non-genotoxic impurity and, as a drug impurity, a threshold limit of 4 mg/day would be set (per ICH Q3C). This threshold limit is higher than the EPA reference dose (listed in the 2006 Edition of the Drinking Water Standards and Health Advisories), so if present at such levels, the specification limits for PNP should be determined on a case-by-case basis, based on risk-benefit.

Topics: Animals; Carcinogens; Dose-Response Relationship, Drug; Drug Contamination; Environmental Exposure; Female; Humans; Male; Maximum Tolerated Dose; Mice; Micronucleus Tests; Mutagens; Nitrophenols; Pharmaceutical Preparations; Risk Assessment; Skin; Threshold Limit Values

Topics: Acetylcholinesterase; Biomarkers; Cholinesterase Inhibitors; Chromatography, High Pressure Liquid; Environmental Exposure; Environmental Monitoring; Humans; Insecticides; Mass Spectrometry; Methyl Parathion; Nitrobenzenes; Nitrophenols; Parathion; Reference Values; Specimen Handling

Topics: Environmental Monitoring; Humans; Nitrophenols

Topics: Animals; Cytochrome P-450 Enzyme System; Humans; Hydroxylation; Isoenzymes; Nitrophenols; Substrate Specificity

The time-dependent loss of the 7-ethoxy-4-trifluoromethylcoumarin (EFC) O-deethylase activity of rat P450 2B1, rabbit P450 2B4, or dog P450 2B11 by 1-ethynylnaphthalene (1EN), 2-ethynylnaphthalene (2EN), 2-(1-propynyl)naphthalene (2PN), 1-ethynylanthracene (1EA), 2-ethynylanthracene, 2-ethynylphenanthrene, 3-ethynylphenanthrene, 9-ethynylphenanthrene (9EPh), 9-(1-propynyl)phenanthrene (9PPh), 4-ethynylpyrene (4EP), and 4-(1-propynyl)biphenyl (4PbP) was investigated. The rate constants for inactivation by the arylalkynes in descending order of effectiveness for the top five compounds were 9EPh>9PPh>1EN, 2EN, 2PN for 2B1, 9EPh>2EN>4EP>1EN, 1EA for 2B4, and 9EPh>1EA>4EP, 9PPh>2EN for 2B11. The size and the shape of the aromatic ring system and the placement of the alkyne functional group were important for inactivation. The most effective inactivator with all the isozymes was 9EPh. This compound also inactivated the EFC activity in microsomes from human lymphoblastoid cells expressing human P450 2B6. The specificity of 9EPh for the inhibition or inactivation of different P450 activities in microsomes from rats treated with various inducing agents was determined by measuring lidocaine, testosterone, p-nitrophenol, or erythromycin metabolism. The greatest effect was observed with the 2B-specific products from lidocaine and testosterone, whereas no effect was seen with p-nitrophenol or erythromycin. When the covalent binding of [3H]2EN to microsomal protein was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography, a radiolabeled protein band that corresponds to 2B1 was observed in the lanes containing microsomes from rats treated with phenobarbital and, to a lesser extent, pyridine and isosafrole after incubation with NADPH. When these microsomes were incubated with [3H]9EPh or [3H]1EP, two NADPH-dependent bands were radiolabeled. One corresponded to 2B1/2 and the other to a protein of approximately 59 kDa, which was observed in the lanes from phenobarbital-treated male and female rats and pyridine-treated male rats. No radiolabeled bands were observed with [3H,14C]4PbP with any of the microsomes.

Topics: Alkynes; Anesthetics, Local; Animals; Anti-Bacterial Agents; Autoradiography; Cytochrome P-450 Enzyme Inhibitors; Dogs; Electrophoresis, Polyacrylamide Gel; Enzyme Inhibitors; Erythromycin; Female; Humans; Lidocaine; Male; Mice; Microsomes, Liver; Nitrophenols; Rabbits; Rats; Rats, Inbred F344; Testosterone

Porous monolithic microreactors show great promise in catalytic applications, but are usually based on non-renewable materials. Herein, we demonstrate a Ni/Au nanoparticle-decorated carbonized wood (Ni/Au-CW) monolithic membrane microreactor for the efficient reduction of 4-nitrophenol. The hierarchical porous wood structure supports uniformly distributed heterobimetallic Ni/Au nanoparticles. As a consequence of these two factors, both mass diffusion and electron transfer are enhanced, resulting in a superior reduction efficiency of 99.5% as the liquor flows through the optimised Ni/Au-CW membrane. The reaction mechanism was investigated by electron paramagnetic resonance spectroscopy and density functional theory calculations. The proposed attraction-repulsion mechanism facilitated by the bimetallic nanoparticles has been ascribed to the different electronegativities of Ni and Au. The Ni/Au-CW membrane exhibits excellent catalytic performance and could be applicable to other catalytic transformations.

Topics: Gold; Metal Nanoparticles; Nitrophenols; Wood

Topics: Adsorption; Metal-Organic Frameworks; Nitrophenols; Triazines

P-nitrophenol (4-NP) is the most persistent and highly toxic species among nitrophenol. In this work, a novel fluorescent probe for the detection of 4-NP in aqueous environment was constructed by combining the carbon dots (CQDs) with excellent optical properties and the molecularly imprinted polymer (MIP) with favorable selectivity. The CQDs were synthesized by hydrothermal method using citric acid hydrate as carbon source and o-phenylenediamine as surface modifier, then the molecularly imprinted polymers coating on the CQDs (MIP@CQDs) were obtained by sol-gel imprinting process. The fluorescence quenching of MIP@CQDs is the results of internal filtration effect and dynamic quenching when they encounter with 4-NP. The probe is suitable for the quantitative detection of trace 4-NP in actual aqueous samples, such as tap water, wastewater and seawater, with satisfying recoveries from 95.1 % to 107.8 %, wide detection linear ranges between 0 and 144 μmol/L, low detection limit of 0.41 μmol/L and high selectivity. The detection results are consistent with those of the HPLC method. This work provides a simple, rapid and effective fluorescent detection method for trace 4-NP in aqueous environment.

Topics: Carbon; Limit of Detection; Molecular Imprinting; Nitrophenols; Quantum Dots; Water

Recently, p-nitrophenol (PNP), a common organic environmental pollutant, has been reported to be degraded by biochar. Although the degradation mechanism of PNP by biochar has been explored, the role of biochar-derived dissolved organic matter (BDOM) in PNP degradation remains unclear. Two BDOM samples were prepared in this study, and their PNP degradation performance was analyzed. BDOM5 (prepared at 500 °C) exhibited higher PNP degradation ratio than BDOM7 (prepared at 700 °C). The extent of PNP degradation per unit of BDOM5 and BDOM7 reached 9.54 and 4.19 mg/mg, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis showed that both oxidative and reductive processes contributed to the PNP degradation by BDOM. Compared with BDOM7, the higher PNP removal of BDOM5 was due to the higher electron exchange capacity. Furthermore, hydroxyl radicals (OH) played a critical role in the oxidative degradation process of PNP by BDOM. This study sheds light on the phenomenon of PNP degradation by BDOM and these results may be useful for accurately assessing the environmental impact of biochar application.

Topics: Charcoal; Dissolved Organic Matter; Environmental Pollutants; Nitrophenols

Per- and polyfluoroalkyl substances (PFASs) are a family of highly fluorinated aliphatic substances widely used in industrial and commercial applications. This study aims to determine the inhibition of PFASs towards sulfotransferases (SULTs) activity, and trying to explain the toxicity mechanism of PFASs. In vitro recombinant SULTs-catalyzed sulfation of p-nitrophenol (PNP) was utilized as a probe reaction. The incubation system was consisted of PFASs, SULTs, PNP, 3'-phosphoadenosine-5'-phosphosulfate, MgCl

Topics: Fluorocarbons; Humans; Nitrophenols; Structure-Activity Relationship; Sulfotransferases

The effective detection of environmental pollutants is very important to the sustainable development of human health and the environment. A luminescent Cd(II) coordination complex, {[Cd(dbtdb)(1,2,4-H

Topics: Cadmium; Fluorescence; Humans; Luminescence; Nitrophenols

The widely applied aromatic nitration in modern industry leads to toxic p-nitrophenol (PNP) in environment. Exploring its efficient degradation routes is of great interests. In this study, a novel four-step sequential modification procedure was developed to increase the specific surface area, functional group, hydrophilicity, and conductivity of carbon felt (CF). The implementation of the modified CF promoted reductive PNP biodegradation, attaining 95.2 ± 0.8% of removal efficiency with less accumulation of highly toxic organic intermediates (e.g., p-aminophenol), compared to carrier-free and CF-packed biosystems. The constructed anaerobic-aerobic process with modified CF in 219-d continuous operation achieved further removal of carbon and nitrogen containing intermediates and partial mineralization of PNP. The modified CF promoted the secretion of extracellular polymeric substances (EPS) and cytochrome c (Cyt c), which were essential components to facilitate direct interspecies electron transfer (DIET). Synergistic relationship was deduced that glucose was converted into volatile fatty acids by fermenters (e.g., Longilinea and Syntrophobacter), which donated electrons to the PNP degraders (e.g., Bacteroidetes_vadinHA17) through DIET channels (CF, Cyt c, EPS) to complete PNP removal. This study proposes a novel strategy using engineered conductive material to enhance the DIET process for efficient and sustainable PNP bioremediation.

Topics: Biodegradation, Environmental; Carbon; Carbon Fiber; Electrons; Nitrophenols

The detection and quantification of p-Nitrophenol in environmental samples are important for understanding the extent and impact of environmental pollution, protecting human health, ensuring regulatory compliance, and guiding remediation efforts. The main objective of this work was to investigate the electrochemical performance of a graphene oxide/cellulose nanofibril composite (GO/CNF) modified carbon paste electrode (GO/CNF/CPE) for the sensitive and reliable detection of p-nitrophenol in water samples. The transmission electron microscopy (TEM) technique was employed to enlighten the structure of nanocomposites. The electrochemical behavior of the fabricated electrochemical sensor was characterized via differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). Under optimized analytical conditions, the peak current of the analyte showed a wide linear relationship with its concentration in a range of 3.0 nM-210 μM with a low amount of the limit of detection (LOD) value of 0.8 nM determined by the DPV method. The proposed electrochemical sensor demonstrated excellent sensitivity, selectivity, and accuracy metrics in real sample analysis of p-nitrophenol.

Topics: Cellulose; Electrochemical Techniques; Electrodes; Graphite; Humans; Nitrophenols; Water Pollutants

Topics: 2,4-Dinitrophenol; Gases; Humans; Mercaptoethanol; Nitrophenols

Topics: Environmental Pollutants; Nitrophenols; Polyethylene Terephthalates

In the current study, we successfully used strychnos potatorum polysaccharide through autoclaving to synthesize palladium nanoparticles in a green, sustainable process. These polysaccharide act as a stabilizing, capping, and reducing agent. It also used various analytical characterizations, including UV-Visible spectroscopy, FT-IR spectroscopy, X-Ray diffraction (XRD), Scanning electron microscopy (FE-SEM), EDAX, and X-ray photoelectron spectroscopy (XPS), TEM and gel permeation chromatography (GPC) are used to analyze biosynthesized pallidum nanoparticles (PdNPs). The surface plasmon resonance (SPR) band at 276 nm and UV-visible spectroscopy revealed the presence of the generated PdNPs. The XRD data show that PdNPs have crystalline behavior and a pristine face-centered cubic (FCC) structure. The PdNPs were successfully developed by catalytic reduction of 4-nitrophenol (4-NP). The catalytic activity and reusability of the environmentally friendly PdNPs catalyst were demonstrated by achieving a remarkable transformation of 95 % nitrophenol to 4-aminophenol after five cycles. The reaction rate constant (k) for the degradation of 4-nitrophenol (4-NP) using SP-PdNPs as a catalyst is 0.1201 min

Topics: Catalysis; Hydrogenation; Metal Nanoparticles; Nitrophenols; Palladium; Polysaccharides; Spectroscopy, Fourier Transform Infrared; Strychnos

Three-dimensional (3D) printing technology has received remarkable attention in manufacturing catalysts with tailored shapes and high precision, particularly facilitating catalyst recovery, maximizing heat/mass transfer, as well as enhancing catalytic performance. Herein, an engineered recombinant Escherichia coli strain (denoted as e-E. coli) with overexpressing metallothionein (a metal-binding protein) was explored to synthesize Au nanoparticles serving as both reducing and stabilizing agents. Then, the mixed inks containing e-E. coli/Au composite and biocompatible polymers (sodium alginate and gelatin) were extruded based on a direct ink writing method followed by chemical crosslinking to form robust 3D grids with square symmetry. To boost the mass transfer and minimize pressure drop, the monolith catalysts were assembled into agitating paddles and used for liquid-phase batch reactions (volume: 1 L). As such, the reaction solutions were mixed internally via the powered "catalytic paddles" with high mechanical strength, excellent reactivity, and easy recyclability, which could be reused at least 7 cycles without performance loss. Our work provides a novel strategy for the fabrication of supported Au catalysts, and the proof-of-concept "catalytic paddles" by 3D printing technology can be applied to other industrial solution-based reactions.

Topics: Escherichia coli; Gold; Metal Nanoparticles; Nanocomposites; Nitrophenols; Printing, Three-Dimensional

Metal-free catalysts with environmental friendless, cost-competitiveness and less susceptibility to leaching and poisoning over metal-based catalysts, have revolutionized in the catalysis domain. In this respect, we herein report the first application of cheap and abundant pumpkin-derived N-doped porous carbon for the reduction of 2-methyl-4-nitrophenol assisted by NaBH

Topics: Carbon; Cucurbita; Nitrogen; Nitrophenols; Porosity

The aging effects of Polyethylene terephthalate (PET) microplastics were studied under Fenton process and Seawater. This research work mainly focuses on the aging mechanism of PET microplastics under two different conditions and their effect of aging on the adsorption of organic contaminants. The results of optical microscopic images, Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman Spectroscopy, carbonyl, carboxyl index, X-ray powder diffraction (XRD) and dissolved organic carbon (DOC) help to understand the aging mechanism of PET microplastics. Parallel factor analysis (PARAFAC) and two-dimensional correlation spectroscopy (2D-COS) were performed using 3D Excitation-Emission Matrix (3D-EEM) to understand the possible dissolved organic matter released during the Fenton process and seawater. The release of protein/phenol like components was observed in seawater whereas humic acid-like component was noted in the Fenton process. Later, the aged PET microplastics were tested for their adsorption capacity towards 4-nitrophenol at three different temperatures (15, 30 and 45 °C). The adsorption capacity of aged microplastics was found to be higher than the normal PET microplastics for all three different temperatures. Hydrogen bonding, n-pi interaction performed a significant role than pi-pi and hydrophobic interaction in the adsorption mechanism. A double layer with double energy model was found to be the best fit in the adsorption processes. The calculated adsorption energies (ΔE

Topics: Dissolved Organic Matter; Factor Analysis, Statistical; Microplastics; Nitrophenols; Physics; Plastics

In this paper, we proposed a dual-signal fluorometric and colorimetric system based on silicon quantum dots (SiQDs) and 4-nitrophenol (4-NP) for pH and urease sensing. SiQDs with fluorescence emission of 460 nm were prepared via aqueous-phase synthesis. As the pH of the system gradually increased, the absorption band of 4-NP at 400 nm increased and a color reaction from colorless to yellow occurred. The absorption of 4-NP overlapped quiet well with the fluorescence excitation spectrum of SiQDs, which can effectively quench the fluorescence of SiQDs. Therefore, the change of fluorescence and absorption intensities could be used to quantify pH value. The fluorometric and colorimetric pH-sensing systems both exhibited a linear respond to pH ranging from 6.0 to 7.8 with an interval of 0.2 pH unit. Urease could specifically hydrolyze urea to generate carbon dioxide and ammonia, causing an obvious increase of the pH value. Thus, urease could also be detected quantitatively by the above dual-signal pH sensing system. The linear ranges of the fluorometric and colorimetric methods for urease detection were both 2-40 U L-1. The limits of detection were 1.67 and 1.07 U L-1, respectively. More importantly, this established dual-signal system has been successfully exploited in the detection of urease in real samples with satisfactory recoveries. Compared with other traditional single-signal assay strategies, the results obtained by dual-signal methods are more accurate and reliable.

Topics: Colorimetry; Hydrogen-Ion Concentration; Limit of Detection; Nitrophenols; Quantum Dots; Silicon; Urease

P-nitrophenol (PNP), a widely used compound, is harmful to the environment and human health. In this study, four iron-based Prussian blue analogs (PBAs) were prepared by coprecipitation (Co-Fe PBA, Mn-Fe PBA, Cu-Fe PBA and Fe-Fe PBA). The Co-Fe PBA exhibited high peroxymonosulfate (PMS) activation performance for PNP degradation, removing over 90% of PNP in 60 min at an optimal pH of 7, temperature at 30 ℃, initial concentration of 20 mg/L, PBA dose of 0.2 g/L and PMS dose of 1 g/L. The physicochemical properties of the Co-Fe PBA were investigated by various characterization methods. The catalytic activity of PBA and the influence of various process parameters and water quality on the catalytic reaction were investigated to elucidate the mechanism of p-nitrophenol degradation by PBA-activated persulfate. Moreover, the mechanism of accelerated degradation of PNP under HCO

Topics: Bicarbonates; Ferrocyanides; Humans; Iron; Nitrophenols; Peroxides

The present investigation demonstrates an enhancement of the visible photocatalytic activities by C ion implantation in ZnO nanorod arrays (NRAs). Vertically aligned ZnO NRAs were prepared by seed layer assisted solution-phase growth and implanted with 70 keV carbon ions at various fluencies: 1E15, 5E15, 1E16, and 3E16 ions/cm

Topics: Carbon; Catalysis; Ions; Light; Methylene Blue; Nitrophenols; Zinc Oxide

A dual-response ratiometric fluorescence imprinted sensor based on visible/near-infrared emission was established for ultrasensitive, selective and visual detection 4-nitrophenol (4-NP). The molecularly imprinted polymer was incorporated in the ratiometric sensing system consisting of visible emission carbon dots@zeolitic imidazolate framework-8 (CDs@ZIF-8) and near-infrared emission cadmium telluride (CdTe) quantum dots. The CDs@ZIF-8 enhanced the emission of CDs and the fluorescence sensing performance. Compared to short wavelength of fluorophore, the near-infrared emission CdTe is less interference caused by auto-fluorescence of sample. The ratiometric fluorescence imprinted sensor exhibited dual response for 4-NP at 420 nm and 703 nm and a wide concentration response range. Moreover, a good linear response was existed in the two concentration ranges of 0.1 pM-3.0 pM and 0.05 μM-30 μM with the detection limit of 0.08 pM and 0.05 μΜ, respectively. Significantly, the fluorescence color changes can be observed from purple to pink to red with the naked eye. The fluorescence quenching mechanism of the ratimetric fluorescence imprinted sensor was discussed in detail. The ratiometric fluorescence imprinted sensor was used to detect 4-NP in various real samples with satisfactory recoveries of 97.5-106.3%, which provided an interesting avenue for the rapid detection of pollutant with high sensitivity, high selectivity and visualization in real environment.

Topics: Biosensing Techniques; Cadmium Compounds; Limit of Detection; Metal-Organic Frameworks; Molecular Imprinting; Nitrophenols; Quantum Dots; Spectrometry, Fluorescence; Tellurium

In order to overcome the sluggish kinetics of the redox conversion between Fe

Topics: Electrodes; Ferric Compounds; Hydrogen Peroxide; Nitrophenols; Oxidation-Reduction; Tannins; Water Pollutants, Chemical

Vertical baffled biofilm reactors (VBBR) equipped with Plastic-carriers and Fe-carriers were employed to explore the effect of biofilm carriers on biofilm formation and p-nitrophenol (PNP) degradation. The results showed that Fe-carriers enhanced biofilm formation and PNP degradation. The maximum thickness of biofilm grown on the Fe-carriers was 1.5-fold higher than that on the Plastic-carriers. The Fe-VBBR reached a maximum rate of PNP removal at 13.02 μM L

Topics: Biofilms; Iron; Nitrophenols; Water Pollutants, Chemical

A simple and highly selective fluorescence biosensor has been exploited for p-nitrophenol (p-NP) and alkaline phosphatase (ALP) activity detection based on the glutathione-stabilized copper nanoclusters (GSH-CuNCs) mediated-inner filter effect (IFE). The GSH-CuNCs were prepared by employing GSH as stabilizer and ascorbic acid (AA) as reductant. The obtained GSH-CuNCs exhibited a strong blue fluorescence emission at 420 nm with an excitation wavelength of 365 nm, which overlapped largely with the absorption spectra of p-nitrophenol (p-NP). Therefore, the luminescence of GSH-CuNCs could be quenched by p-NP through inner filter effect. In addition, ALP catalyzed the substrate p-nitrophenyl phosphate (p-NPP) to form p-nitrophenol (p-NP), which also leading to the fluorescence quenching of GSH-CuNCs. The fluorescent strategy was realized for the sensitive determination of p-NP and ALP activity with the promising limit of detection of 20 nM (for p-NP) and 0.003 mU⋅mL

Topics: Alkaline Phosphatase; Copper; Fluorescent Dyes; Glutathione; Humans; Limit of Detection; Metal Nanoparticles; Nitrophenols; Spectrometry, Fluorescence

Topics: Atmospheric Pressure; Chromium; Hydrogen Peroxide; Microwaves; Nitrophenols; Oxidation-Reduction

Topics: Arginine; Chlorophenols; Mixed Function Oxygenases; Molecular Docking Simulation; Nitrophenols; Phenols

A very simple, as well as sensitive and selective, sensing protocol was developed on a pre-anodized graphite pencil electrode surface coated using poly(thionine) (APGE/PTH). The poly(thionine) coated graphite pencil was then used for simultaneous sensing of 3-nitrophenol (3-NP) and 4-nitrophenol (4-NP). The poly(thionine) coated electrode exhibited an enhanced electrocatalytic property towards nitrophenol (3-NP and 4-NP) reduction. Redox peak potential and current of both nitrophenols were found well resolved and their simultaneous analysis was studied. Under optimized experimental conditions, APGE/PTH showed a long linear concentration range from 20 to 230 nM and 15 nM to 280 nM with a calculated limit of detection (LOD) of 4.5 and 4 nM and a sensitivity of 22.45 µA/nM and 27.12 µA/nM for 3-NP and 4-NP, respectively. Real sample analysis using the prepared sensor was tested with different environmental water samples and the sensors exhibited excellent recovery results in the range from 98.16 to 103.43%. Finally, the sensor exposed an promising selectivity, stability, and reproducibility towards sensing of 3-NP and 4-NP.

Topics: Electrochemical Techniques; Electrodes; Graphite; Nitrophenols; Phenothiazines; Reproducibility of Results; Water

New quinoline based fluorescent sensors 4 and 5 were rationally synthesized that exhibited excellent aggregation induced emission (AIE) in an aqueous medium. High fluorescence emission of sensors was accompanied by a noticeable redshift in their absorption and emission spectra that corresponds to the formation of J-aggregates. An AIE feature of sensors 4 and 5 was used for selective detection of Fe

Topics: Colorimetry; Fluorescent Dyes; Humans; Nitrophenols; Quinolines; Water

An aggregation-induced emission monomer-based fluorescent molecularly imprinted poly(ionic liquid) (AIE-FMIPIL) was synthesized for the first time with an AIE probe 4-(1,2,2-triphenylvinyl)phenyl acrylate (TPE), and an ionic liquid as dual functional monomers, and an ionic liquid as cross-linker. AIE-FMIPIL displayed a sphere-like shape and its average diameter was 410 nm. The absolute quantum yields of TPE and AIE-FMIPIL were 9.23% and 12.61%, respectively. The synergetic effect of TPE in the AIE-FMIPIL framework contributed to the higher quantum yield of AIE-FMIPIL. 4-Nitrophenol (4-NP) efficiently quenched AIE-FMIPIL with high fluorescence based on the Förster resonance energy transfer mechanism. The synthesized AIE-FMIPIL sensor was highly sensitive for 4-NP detection (linear range, 0.02-1.5 μM) in the optimal detection condition, with a low detection limit of 10 nM (S/N = 3). AIE-FMIPIL showed increased sensitivity and quenching efficiency compared with AIE-FMIP comprising a traditional monomer and cross-linker. AIE-FMIPIL exhibited selective binding to 4-NP because of the imprinted sites. AIE-FMIPIL was adopted to detect 4-NP in environmental samples.

Topics: Coloring Agents; Fluorescence Resonance Energy Transfer; Ionic Liquids; Nitrophenols

Topics: Luminescent Measurements; Nitrophenols; Polymers; Quantum Dots

Generally, the catalytic transformation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at heterogeneous metal surfaces follows a Langmuir-Hinshelwood (L-H) mechanism when sodium borohydride (NaBH

Topics: Electrons; Nitrophenols; Protons; Water

Herein, luminescent metal-organic framework (LMOF) is modified with molecularly imprinted polymer (MIP) and employed as an efficient and cost-effective nanoprobe for the determination of 4-nitrophenol (4-NP). Amine-UiO-66 support with unique luminescence property is chosen for creating the template of 4-NP using MIP to construct a highly selective LMOF-based sensor (amine-UiO-66/MIP nanocomposite). The imprinted sites formed at the surface of LMOF significantly enhance the selectivity of the probe for 4-NP over its analogs. 4-NP can effectively quench the fluorescent intensity of the optical sensor via the Förster resonance energy transfer (FRET) mechanism. Amine-UiO-66/MIP sensor provided the linear range of 0.05-50 μM and low limit of detection of 0.009 μM for sensing of 4-NP. The application of probe for the fluorometric analysis of real samples, including drinking and environmental water, provided satisfactory recovery results with low relative standard deviation (RSD).

Topics: Amines; Fluorescence Resonance Energy Transfer; Metal-Organic Frameworks; Molecular Imprinting; Molecularly Imprinted Polymers; Nanocomposites; Nitrophenols; Phthalic Acids

In the present work, plasma remediation of p-nitrophenol (PNP) contaminated soil was performed in a novel spray-type coaxial cylindrical dielectric barrier discharge (DBD) system at ambient temperature. This system is capable of generating large-size nonthermal plasma (NTP) and improving the diffusion and transfer of chemical active species around the dispersed soil particles. Several key parameters including plasma treatment time, discharge voltage, soil granular size, the entry speed of soil, PNP initial concentration, gas variety, and gas flow rate were investigated in terms of PNP degradation and energy efficiencies. Under the optimized experimental conditions, 54.2% of PNP was degraded after only 50 s discharge treatment, indicating that the spray-type coaxial cylindrical DBD system can degrade organic pollutants in soil more quickly compared to other plasma systems due to its efficient transfer of reactive oxygen and nitrogen species (RONS) into the contaminated soil. The possible PNP degradation pathways were proposed based on intermediates identification results and the role of reactive species analysis. The toxicological assessment of the PNP decomposition products was conducted by quantitative structure-activity relationship (QASR) analysis. This work is expected to provide a potential plasma technology for rapid and efficient processing of industrial organic pollutants contamination soil.

Topics: Environmental Restoration and Remediation; Nitrophenols; Reactive Nitrogen Species; Soil; Soil Pollutants

We report an effective facile immobilization of noble nanoparticles (M

Topics: Catalysis; Environmental Pollutants; Graphite; Metal Nanoparticles; Nitrogen Compounds; Nitrophenols; Silver; Spectroscopy, Fourier Transform Infrared

Manipulating the elemental composition is one major strategy to tune the properties of biochars to endow different functions to meet various application requirements. Compared with the widely reported plants- and manure-based precursors for biochars, microbes-based precursors take the lead in regional independency, rapid growth, morphology uniformity and abundant species with different adjustable elemental composition. In this work, fungal hyphae with massive microtubule structure were selected as a typical microbe precursor to prepare biochars whose catalysis capability was further evaluated by a representative reduction reaction of 4-nitrophenol (4-NP) using sodium borohydride as reductant. By simply increasing the nitrogen concentration in the culturing medium, the fungal hyphae derived biochars with increased nitrogen contents (2.1 wt% → 4.3 wt%) were successfully obtained after pyrolysis, showing almost two times higher catalysis ability (4.75 × 10

Topics: Adsorption; Catalysis; Charcoal; Hyphae; Nitrogen; Nitrophenols; Pyrolysis; Temperature

Catalytic reduction of nitroaromatic compounds using low-cost non-precious metal containing catalyst remains an essential topic in wastewater treatment. Herein, copper hexacyanoferrate nanospheres decorated copper foams (CF) were prepared by a facile method, and it was used as structured catalysts for the reduction of p-nitrophenol (p-NP) and azo dyes. The catalyst obtained by calcination at 200 °C shows the highest catalytic activity, with an almost complete reduction of p-NP within 3 min with a rate of 2.057 min

Topics: Azo Compounds; Copper; Ferrocyanides; Nanospheres; Nitrophenols

p-Nitrophenol is usually present in ammonia-rich wastewaters produced by some chemical plants. In this work, the response of anammox process to long-term p-nitrophenol stress was investigated. The changes in the efficiency, sludge characteristics, and microorganisms of the anammox system under different levels of p-nitrophenol stress were examined, and the potential stress mechanisms of p-nitrophenol on anammox were further speculated. The results showed that 10-50 mg/L p-nitrophenol had no obvious impact on nitrogen removal efficiency, but stimulated the secretion of more extracellular polymeric substances. 60 mg/L p-nitrophenol caused the nitrogen removal efficiency to decrease by 64.5% in 5 days. Long-term exposure to p-nitrophenol led to 8.6% reduction in Candidatus_Kuenenia abundance and 18.4%-35.9% decrease in the expression level of anammox bacterial functional genes. Molecular simulation indicated that p-nitrophenol could bind to key enzymes of anammox. This study provides new insights into the treatment of wastewater containing p-nitrophenol or phenol by anammox.

Topics: Anaerobic Ammonia Oxidation; Anaerobiosis; Bioreactors; Denitrification; Nitrogen; Nitrophenols; Oxidation-Reduction; Sewage; Wastewater

The steel slag was investigated for the removal of p-nitrophenol (4-NP) from simulated sewage by batch adsorption and fixed-bed column absorption experiments. The results showed that the maximum adsorption capacity was 109.66 mg/g at 298 K, pH of 7, initial concentration 100 mg/L, and dose 0.8 g/L. The adsorption process fitted the Langmuir isothermal adsorption model and followed pseudo-second-order kinetic models, the activation energy of adsorption (Ea) was 10.78 kJ/mol, which indicated that the adsorption was single-molecule layer physical adsorption. The regeneration efficiency was still maintained at 84.20% after five adsorption-desorption cycles. The column adsorption experiments showed that the adsorption capacity of the Thomas model reached 13.69 mg/g and the semi-penetrating time of the Yoon-Nelson model was 205 min at 298 K. Fe

Topics: Adsorption; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Sewage; Spectroscopy, Fourier Transform Infrared; Steel; Water Pollutants, Chemical

Very few aqueous medium experimental studies focus on the molecular interaction mechanism between the adsorbent and the adsorbate. Herein, we investigate the adsorption of two organic pollutants, phenol and p-nitrophenol (PNP) in dilute aqueous solution conditions on kaolinite (001) surface through classical molecular dynamics (MD) simulations. The present investigation addresses both adsorption isotherms and mechanistic issues. MD simulations at different solute concentrations generated density profiles and, thereby, adsorption isotherms. The data generated for phenol adsorption fitted both Langmuir and Freundlich isotherm models equally well. Alternatively, PNP adsorption data on the kaolinite surface followed the Langmuir model better. Overall, phenol exhibits a higher adsorption capacity on kaolinite than PNP. These results support the experimental observations made in earlier publications in the literature. Radial distribution functions (RDF) between various atom types on the adsorbent and molecules in the solution phase point toward hydrogen bond-dominated interaction mechanisms for organic pollutants.

Topics: Adsorption; Hydrogen-Ion Concentration; Kaolin; Kinetics; Molecular Dynamics Simulation; Nitrophenols; Phenol; Phenols; Thermodynamics; Water; Water Pollutants, Chemical

Topics: Carbon; Nanocomposites; Nickel; Nitrogen; Nitrophenols

Vehicle emissions are an important source of nitrated aromatic compounds (NACs) in particulate size smaller 2.5 μm (PM

Topics: 2,4-Dinitrophenol; Air Pollutants; Benzo(a)pyrene; Carbon; Chrysenes; Environmental Monitoring; Gasoline; Humans; Methanol; Nitrates; Nitro Compounds; Nitrophenols; Particulate Matter; Polycyclic Aromatic Hydrocarbons; Vehicle Emissions

Urinary para-nitrophenol (PNP), an exposure biomarker of ethyl parathion (EP) and methyl parathion (MP) pesticides, was still pervasively detected in the general population even after global restriction for years. And the concern whether there is an association of PNP level with child development of the nervous system is increasing. The current study aimed to evaluate the maternal urinary PNP concentrations during late pregnancy and the associations of PNP levels with cognitive and motor function of their children at the age of 2 years.. 323 mother-child pairs from the Sheyang Mini Birth Cohort Study were included in the current study. Gas chromatography-tandem mass spectrometry was used to measure concentrations of PNP, the specific metabolite of EP and MP, in maternal urine samples during pregnancy. Developmental quotients (DQs) scores measured with Gesell Developmental Scales were employed to evaluate cognitive and motor function of children aged 2 years. Generalized linear models were performed to analyze the associations of PNP concentrations in pregnant women's urine samples with cognitive and motor function of their children.. Maternal PNP was detected in all urine samples with a median of 4.11 μg/L and a range from 0.57 μg/L to 109.13 μg/L, respectively. Maternal urinary PNP concentrations showed a negative trend with DQ of motor area [regression coefficient (β) = - 1.35; 95 % confidence interval (95 %CI): - 2.37, - 0.33; P < 0.01], and the children whose mothers were in the fourth quartile exposure group performed significantly worse compared to the reference group (β = - 1.11; 95 %CI: - 1.80, - 0.42; P < 0.01). As for average DQ score, children with their mothers' urinary PNP concentrations in the third quartile group had higher scores than those in the first quartile group (β = 0.39; 95 %CI: 0.03, 0.75; P = 0.04). In sex-stratified analyses, a negative trend between maternal urinary PNP concentrations and DQ scores in motor area of children was only observed in boys (β = - 1.62; 95 %CI: - 2.80, - 0.43; P < 0.01). Boys in the third quartile group had higher DQ average scores than those in the lowest quartile as reference (β = 0.53; 95 %CI: 0.02, 1.04; P = 0.04).. The mothers from SMBCS may be widely exposed to EP and/or MP, which were associated with the cognitive and motor function of their children aged 2 years in a sex-specific manner. Our results might provide epidemiology evidence on the potential effects of prenatal exposure to EP and/or MP on children's cognitive and motor function.

Topics: Biomarkers; China; Cognition; Cohort Studies; Female; Gas Chromatography-Mass Spectrometry; Humans; Male; Methyl Parathion; Nitrophenols; Pesticides; Pregnancy; Pregnant Women

The reduction of

Topics: Carbon; Catalysis; Nickel; Nitrophenols; Oxidation-Reduction

Nitrite can be transformed to nitrophenolic byproducts in sulfate radical oxidation processes (SR-AOPs). These nitrophenols are highly mobile in subsurface and can potentially contaminate drinking water sources. However, their fate in a drinking water treatment remains ambiguous. Herein, the removal and transformation of four nitrophenolic byproducts formed during a heat activated peroxydisulfate oxidation process, i.e., 4-nitrophenol, 2,4-dinitrophenol, 5-nitrosalicylic acid, and 3,5-dinitrosalicylic acid, in a simulated drinking water treatment train were comprehensively examined. The removal of these nitrophenolic compounds in coagulation by either aluminum sulfate or ferric chloride ranged from 3.8% to 13.4%. In the chlorination process, 4-nitrophenol was removed only by 45.4% in 24 h at a chlorine dose of 5.0 mg/L. The removal of the other three nitrophenolic byproducts were less than 20%. Reaction between nitrophenolic byproducts and chlorine via electrophilic substitution gave rise to their chlorinated derivatives. Chlorinated nitrophenolic byproducts were more recalcitrant and toxic than their parent compounds, but still a tiny fraction of them could undergo further oxidation to form trichloronitromethane. This work implied that once nitrophenolic byproducts enter water source, they can penetrate the drinking water treatment train and react with the residual chlorine in distribution pipelines to form more hazardous byproducts. The findings raised additional concerns to the potential risk of the nitrophenolic byproducts formed in SR-AOPs.

Topics: 2,4-Dinitrophenol; Chlorine; Disinfection; Drinking Water; Halogenation; Nitrites; Nitrophenols; Sulfates; Water Pollutants, Chemical; Water Purification

Methyl parathion is an organophosphorus pesticide widely employed worldwide to control pests in agricultural and domestic environments. However, due to its intensive use, high toxicity, and environmental persistence, methyl parathion is recognized as an important ecosystem and human health threat, causing severe environmental pollution events and numerous human poisoning and deaths each year. Therefore, identifying and characterizing microorganisms capable of fully degrading methyl parathion and its degradation metabolites is a crucial environmental task for the bioremediation of pesticide-polluted sites. Burkholderia zhejiangensis CEIB S4-3 is a bacterial strain isolated from agricultural soils capable of immediately hydrolyzing methyl parathion at a concentration of 50 mg/L and degrading the 100% of the released p-nitrophenol in a 12-hour lapse when cultured in minimal salt medium. In this study, a comparative proteomic analysis was conducted in the presence and absence of methyl parathion to evaluate the biological mechanisms implicated in the methyl parathion biodegradation and resistance by the strain B. zhejiangensis CEIB S4-3. In each treatment, the changes in the protein expression patterns were evaluated at three sampling times, zero, three, and nine hours through the use of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and the differentially expressed proteins were identified by mass spectrometry (MALDI-TOF). The proteomic analysis allowed the identification of 72 proteins with differential expression, 35 proteins in the absence of the pesticide, and 37 proteins in the experimental condition in the presence of methyl parathion. The identified proteins are involved in different metabolic processes such as the carbohydrate and amino acids metabolism, carbon metabolism and energy production, fatty acids β-oxidation, and the aromatic compounds catabolism, including enzymes of the both p-nitrophenol degradation pathways (Hydroquinone dioxygenase and Hydroxyquinol 1,2 dioxygenase), as well as the overexpression of proteins implicated in cellular damage defense mechanisms such as the response and protection of the oxidative stress, reactive oxygen species defense, detoxification of xenobiotics, and DNA repair processes. According to these data, B. zhejiangensis CEIB S4-3 overexpress different proteins related to aromatic compounds catabolism and with the p-nitrophenol  degradation pathways, the higher expression levels observed in the t

Topics: Amino Acids; Burkholderiaceae; Carbohydrates; Carbon; Dioxygenases; Ecosystem; Fatty Acids; Hydroquinones; Methyl Parathion; Nitrophenols; Organophosphorus Compounds; Pesticides; Proteomics; Reactive Oxygen Species; Soil

Cr-MOF nanoparticles were synthesized by a simple hydrothermal method, and their morphology and structure were characterized by SEM, TEM, and XRD techniques. The Cr-MOF modified glassy carbon electrode (Cr-MOF/GCE) was well constructed and served as an efficient electrochemical sensor for the detection of p-nitrophenol (p-NP). It was found that the Cr-MOF nanoparticles had significant electrocatalytic activity toward the reduction of p-NP. The Cr-MOF-based electrochemical sensor exhibited a low detection limit of 0.7 μM for p-NP in a wide range of 2~500 μM and could maintain excellent detection stability in a series of interfering media. The electrochemical sensor was also practically applied to detect p-NP in a local river and confirmed its validity, showing potential application prospects.

Topics: Carbon; Electrochemical Techniques; Electrodes; Nanoparticles; Nitrophenols

Five yeast fungi strains (i.e., two Cryptococcus albidus, one Candida guillermondii, and two Candida tropicalis) were isolated from sugarcane and tested for their use of lignin as sole carbon source and their potential to grow in the presence of phenol and phenol derivatives (i.e., pentachlorophenol and p-nitrophenol). The full set of isolated yeasts showed ligninolytic activity, achieving at least 36% lignin degradation after 25 days. The C. albidus JS-B1 strain had the highest ligninolytic activity, achieving 27% lignin degradation within 4 days. This increased activity was associated with the production of ligninolytic laccase enzymes. All the tested yeast fungi strains showed growth in the presence of high concentrations of phenolic compounds (i.e., 900 mg/L phenol, 200 mg/L p-nitrophenol, 50 mg/L pentachlorophenol) and showed significant potential for lignin and lignin by-product degradation. Each of these five strains has the potential to be used in biological treatment processes for contaminated effluents from paper pulping and bleaching or phenol and phenol-derivative biodegradation processes for other industrial wastewater effluents.

Topics: Biodegradation, Environmental; Lignin; Nitrophenols; Pentachlorophenol; Phenol; Phenols; Yeasts

Three new triazine compounds [Co

Topics: Carbon Dioxide; Catalysis; Nitrophenols; Triazines

Catalytic hydrogenation reduction based on sodium borohydride (NaBH

Topics: Catalysis; Kinetics; Nitrophenols; Porosity

Potassium birnessites were prepared using two methods, sol-gel or oxidation. The solids were characterised by element chemical analysis, powder X-ray diffraction, FT-IR spectroscopy, thermal analyses, and nitrogen adsorption. The evolution of the properties as a function of the preparation method was discussed. The photocatalytic performance of these solids was preliminarily tested for the degradation of 4-nitrophenol. The degradation pathway and the nature of the by-products were investigated by mass spectrometry. The solids showed good catalytic behaviour, although their preparation must be improved, mainly concerning the calcination step involved in sol-gel synthesis, which led to the formation of Mn

Topics: Catalysis; Gas Chromatography-Mass Spectrometry; Nitrophenols; Oxides; Spectroscopy, Fourier Transform Infrared; Titanium

Para-Nitrophenol (p-nitrophenol) is a common industrial pollutant occurring widely in water bodies, yet actual monitoring methods are limited. Herein we proposed a fully electrochemically in situ synthesized graphene-polyarginine composite functionalized screen printed electrode, as a novel p-nitrophenol sensing platform. The electrode was characterized by morphologic, spectrometric and electrochemical techniques. p-nitrophenol in both pure aqueous solution and real water samples was tested. Results show a detection limit as low as the nanomolar level, and display a linear response and high selectivity in the range of 0.5-1250 μM. Molecular simulation reveals a detailed synergy between graphene and poly-arginine. The preferable orientation of nitrophenol molecules on the graphene interface in the presence of poly-arginine induces H- and ionic binding. This sensor is an ideal prototype for p-nitrophenol quantification in real waters.

Topics: Arginine; Electrochemical Techniques; Electrodes; Graphite; Nitrophenols

In this study, a simple and environment-friendly method has been successfully applied for the production of silver nanoparticles (AgNPs) using Poria cocos extract. The reaction time of 60 min, the temperature of 90 °C, and silver ion concentration of 2.0 mM were identified as the best condition for the PC-AgNPs fabrication. The XRD analysis confirmed a highly crystalline face-centered cubic structure of the biosynthesized material. The PC-AgNPs were presented separately in a spherical shape with an average crystal size of 20 nm, as endorsed by the TEM and FE-SEM measurements. The presence and crucial role of biomolecules in stabilizing the nanoparticles were elucidated by FTIR, EDX, and DLS techniques. The prepared biogenic nanoparticles were further applied for the reduction of 4-nitrophenol (4-NP) and colorimetric detection of Fe

Topics: Ferric Compounds; Ions; Metal Nanoparticles; Nitrophenols; Plant Extracts; Silver; Wolfiporia

Biodegradation mechanisms and microbial functional diversity during coupled p-nitrophenol (PNP) and p-aminophenol (PAP) degradation were studied in a bioelectrochemical system. PNP in the biocathode and PAP in the bioanode were almost completely removed within 28hr and 68hr respectively. The degradation followed the steps including hydrating hydroxyalkylation, dehydrogenating carbonylation, and hydrolating ring cleavage, etc. Metagemomic analysis based on the KEGG and eggNOG database annotations revealed the microbial composition and functional genes/enzymes related to phenol degradation in the system. The predominant bacteria genera were Lautropia, Pandoraea, Thiobacillus, Ignavibacterium, Truepera and Hyphomicrobium. The recognized biodegradation genes/enzymes related to pollutant degradation were as follows: pmo, hbd, & ppo for phenol degradation, nzba, amie, & badh for aromatic degradation, and CYP & p450 for xenobiotics degradation, etc. The co-occurrence of ARGs (antibiotic resistant genes), such as adeF, MexJ, ErmF, PDC-93 and Escherichia_coli_mdfA, etc., were annotated in CARD database during the biodegradation process. The Proteobacteria & Actinobacteria phylum was the primary host of both the biodegradation genes & ARGs in this system. The microbial functional diversity ensured the effective biodegradation of the phenol pollutants in the bioelectrochemical system.

Topics: Aminophenols; Biodegradation, Environmental; Nitrophenols

A simple method is reported for the preparation of silver nanoparticle (AgNP) embedded pH-responsive hydrogel microparticle catalyst via Michael addition gelation and in-situ silver nitrate (AgNO

Topics: Azo Compounds; Catalysis; Hydrogels; Metal Nanoparticles; Microspheres; Nitrophenols; Silver

Among the various organic pollutants and industrial chemicals, 4-nitrophenol has been one of the most monitored substances in aqueous environments, due to its enhanced solubility in such systems. This research reports for the first time the microwave-assisted synthesis of CdS/carbon/MoS

Topics: Carbon; Catalysis; Nanostructures; Nitrophenols

Phenolic compounds (like 4-nitrophenol) and dyes (like methyl orange) are common by-products discharged by many industries as wastes; they are toxic and may induce discomfort and irritation in humans when ingested. Most of these compounds can be made less toxic through catalytic degradation. Metal oxide nanoparticles are found to have high catalytic activity and can degrade toxic phenolic compounds and dyes. In the current study, pomegranate rind extract was used for the green synthesis of iron oxide nanoparticles that exhibited an octahedron morphology revealed by scanning electron microscopy analysis. Energy dispersive x-ray analysis showed 47.96% content of Fe (by weight); high resolution-transmission electron microscopy analysis confirmed that the nanoparticles had a particle size of 22.54 ± 4.13 nm. The particles were further characterized by x-ray diffraction, fourier transform-infrared spectroscopy, vibrating sample magnetometer, and thermogravimetric analysis. The nanoparticle proved to be efficient in reducing 4-nitrophenol and methyl orange. It was also found to be non-toxic towards murine macrophages, RAW 264.7 with good ROS-scavenging potential compared to control.

Topics: Animals; Cell Survival; Coloring Agents; Free Radical Scavengers; Green Chemistry Technology; Magnetite Nanoparticles; Mice; Nitrophenols; Plant Extracts; Pomegranate; RAW 264.7 Cells; Reactive Oxygen Species

A functional material integrated with a variety of functions is highly desired in wastewater treatment. In this research, a mussel-inspired method of immobilizing silver nanoparticles on the skeleton of a melamine sponge is proposed and applied for water remediation. Ag NPs were reduced in situ and grown on a polydopamine-modified melamine sponge. The catalytic reduction of 4-nitrophenol (4-NP) in the presence of the obtained MS-PDA-Ag was evaluated, and the results demonstrated that the MS-PDA-Ag presented high catalytic reduction activity. In addition, the monolithic MS-PDA-Ag presents excellent reusability with no remarkable decrease in catalytic efficiency after multiple reuses. Owing to the immobilized Ag NPs, the MS-PDA-Ag can also effectively inhibit the growth of bacteria against both gram-positive and gram-negative species, making it possible for bacteria elimination in polluted water. To further explore the possibility of utilizing the MS-PDA-Ag for versatile applications, a superhydrophobic derivative (S-MS-PDA-Ag) was prepared by coating a low-surface-energy substance (octadecanethiol) on the surface of MS-PDA-Ag. The obtained S-MS-PDA-Ag presents the capacities of oil/organics adsorption and water repellence, which can separate the insoluble oil/organics from water. The melamine sponge immobilized with Ag NPs demonstrates prominent catalytic reduction of 4-NP, antibacterial activity and the superhydrophobic derivative presents the capacity of insoluble oil/organics separation from oil-water mixtures, exhibiting high potential in the remediation of polluted water.

Topics: Animals; Anti-Bacterial Agents; Biomimetic Materials; Bivalvia; Gram-Negative Bacteria; Gram-Positive Bacteria; Hydrophobic and Hydrophilic Interactions; Metal Nanoparticles; Microbial Sensitivity Tests; Nitrophenols; Oils; Oxidation-Reduction; Silver; Triazines; Water; Water Purification

4-Nitrophenol (PNP) has been extensively used in manufacturing for several decades. Its toxic effects on the male reproductive system have been reported, but the underlying mechanisms remain unclear. In this study, we utilized two testicular somatic cell lines (TM3 and TM4 cells) to explore the possible toxic effects of PNP on the male reproductive system. The activity of the cells after exposure to different doses of PNP (0.01, 0.1, 1, 10 and 100 μM) was evaluated. PNP treatment at 10 μM significantly inhibited cell viability, and 10 μM PNP was thus selected for subsequent experiments. Although PNP (10 μM) inhibited cell proliferation, promoted cell apoptosis, and changed the cell cycle distribution and ultrastructure in both types of cells, these effects were more significant in the TM4 cells. In addition, an Agilent mouse mRNA array was used to identify the gene expression differences between the control and PNP (10 μM) exposed TM3 and TM4 cells. The microarray analysis identified 67 and 1372 differentially expressed genes mainly concentrated in endothelial cell morphogenesis and anatomical structure development in TM3 cells and associated with cardiovascular system development and circulatory system development in TM4 cells. Moreover, a pathway analysis revealed that PNP not only predominately affected meiotic recombination and meiosis in TM3 cells, but also influenced axon guidance and developmental biology in TM4 cells. These results suggest that TM3 and TM4 cells exhibit different responses to PNP, which might mediate different toxic mechanisms.

Topics: Animals; Apoptosis; Axon Guidance; Cell Line; Cell Survival; Dose-Response Relationship, Drug; Gene Expression Regulation; Leydig Cells; Male; Meiosis; Mice; Nitrophenols; Reproduction; Sertoli Cells; Testis

In this work, an alkaline phosphatase (ALP) biosensor was established based on G-quadruplex/N-methylmesoporphyrin IX (G4/NMM) and p-nitrophenol (PNP). Because the absorption of PNP was close to the excitation wavelength of G4/NMM, PNP could reduce the fluorescence of G4/NMM. Meanwhile, PNP was the hydrolysis product of p-nitrophenylphosphate (PNPP) by ALP. Therefore, ALP could be detected. This ALP biosensor had a linear analytical range from 2.5 to 25 U/L a the detection limit of 0.81 U/L. Moreover, it showed a satisfactory selectivity and recovery rates.

Topics: Alkaline Phosphatase; Biosensing Techniques; Limit of Detection; Mesoporphyrins; Nitrophenols

Topics: Aminophenols; Catalysis; Hydroxides; Kinetics; Metal Nanoparticles; Nanocomposites; Nitrophenols; Polysaccharides, Bacterial; Silver; Succinates

A highly effective fluorescent molecularly imprinted sensor (F-PDA-MIS) based on fluorescent polydopamine (F-PDA) was successfully synthesized for selective and ultrafast detection of p-nitrophenol (P-NP) in drinking water. F-PDA with abundant surface functional groups has been artfully modified to firstly serve as both fluorescent monomer and functional monomer in the synthesis of a uniform luminous F-PDA-MIS, which can greatly improve the detection efficiency. As expected, F-PDA-MIS had an obvious emission wavelength of 535 nm with the optimal excitation wavelength at 400 nm. Specially, F-PDA-MIS could detect P-NP in the range 100 to 1100 nM with much lower detection limit of 24.2 nM within 120 s compared with other conventional imprinted fluorescent sensors based on pure quantum dots (QDs) or dyes. This excellent test phenomenon is mainly ascribed to the rapid electron transfer between F-PDA and P-NP. Satisfactory recovery of 98.0-104% for mineral water and 98.6-106% for boiling water were obtained with relative standard deviations (RSDs) of 2.7-3.4% and 2.6-3.5% respectively. The detection reliability of F-PDA-MIS was verified by the comparison with high-performance liquid chromatography (HPLC-UV). Consequently, F-PDA as a fluorescence functional monomer has been shown to be a possible strategy to effectively improve the detection limit and shorten response time of the target determination in water..

Topics: Drinking Water; Fluorescent Dyes; Indoles; Limit of Detection; Molecularly Imprinted Polymers; Nitrophenols; Polymers; Spectrometry, Fluorescence; Water Pollutants, Chemical

The present work deals with the photocatalytic degradation of p-nitrophenol as it is a United States Environmental Protection Agency-listed priority pollutant and has adverse environmental and health effects. To eradicate the detrimental environmental impact of p-nitrophenol, the biologically synthesized ZnO nanoparticles were used as a photocatalyst. The degradation of p-nitrophenol was confirmed by decreasing the absorbance value at a characteristic wavelength of 317 nm using the UV-vis spectrophotometer. Reaction parameters such as ZnO photocatalyst concentration of 0.1 g/L at pH 11 in the presence of H

Topics: Catalysis; Hydrogen Peroxide; Nitrophenols; Zinc Oxide

Carbon dots (CDs) with excellent optical properties are widely used in biomedicine, fluorescence sensing, and light-emitting diodes (LEDs). However, it is still a challenge to prepare CDs that can stably emit red fluorescence in the water environment. In this study, polydopamine-encapsulated luminescent carbon dots (CDs@PDA) with an encapsulating structure were synthesized at room temperature from p-phenylenediamine-derived red-light CDs as the core and using mussel-inspired chemical properties of polydopamine (PDA). In the binary system of water:ethanol = 1: 3 (volume ratio), the as-prepared CDs@PDA had a dual emission of ultraviolet light (330 nm) and red light (640 nm) with the fluorescence quantum yields of 8.0 and 15.5%, respectively, at the same time under 285 nm light excitation. The as-prepared CDs@PDA could be directly used for fluorescence selective sensing of 4-nitrophenol (4-NP) and Fe

Topics: Carbon; Indoles; Nitrophenols; Polymers; Quantum Dots

A facile and cost-effective preparation of silver nanoparticles decorated magnetic composite for the effective catalytic degradation of 4-nitrophenol (4-NP) and Methylene blue (MB) and Rhodamine B (RhB) was investigated. Fe

Topics: Catalysis; Coloring Agents; Magnetic Phenomena; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Polymers; Silver

Silver nanoparticles (AgNPs) are widely sought after for a variety of biomedical and environmental applications due to their antimicrobial and catalytic properties. We present here a green and simple synthesis of AgNPs utilizing traditional Chinese medicinal herbs. The screening of 20 aqueous herb extracts shows that Sheng Di Huang (Rehmannia glutinosa) had the most promising potential in producing AgNPs of 30±6 nm, with narrow size distribution and high crystallinity. The antimicrobial activities of these AgNPs conducted on E. coli cells were found to be superior in comparison to poly(vinylpyrrolidone)-capped AgNPs synthesized using common chemical method. Additionally, the AgNPs obtained possess excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol. We compared the phytochemical and FTIR spectral analyses of the herb extract before and after synthesis, in order to elucidate the phytochemicals responsible for the reduction of Ag

Topics: Aminophenols; Anti-Infective Agents; Catalysis; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Plant Extracts; Plants, Medicinal; Rehmannia; Silver

Topics: Animals; Chickens; Hydrogen Peroxide; Male; Nitrophenols; Semen; Semen Analysis; Sperm Motility; Spermatozoa; Testis; Testosterone

The important role of reactive chlorine species (RCS) in electrochemical system has been widely concerned for water disinfection recently. In this study, we built an electrochemical system using carbon nanotube as cathode and oxide precursor (Ti/SnO

Topics: Catalysis; Chlorine; Electrochemical Techniques; Electrodes; Models, Theoretical; Nitrates; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical; Water Purification

Discharge of heavy metals from various sources of industrial wastewater poses significant environmental and health concerns. Thus, efficient recovery of precious metals from wastewater employing sustainable, rapid, and cost-effective treatment methods is highly desirable. In this work, palladium nanoparticles (Pd NPs) were successfully recovered from industrial wastewater using a pulsed laser process in the absence of additives or reducing agents. Notably, the developed approach is faster and more environmentally friendly than other conventional recovery methods. The recovered Pd NPs were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and inductively coupled plasma optical emission spectroscopy (ICP-OES). Various pulsed laser parameters (i.e., laser wavelength, power, and irradiation time) were optimized to obtain ideal conditions for the pulsed laser ablation process. Effective recovery of the Pd metal from industrial wastewater was achieved at a laser wavelength of 355 nm, power of 40 mJ/pulse, and irradiation time of 30 min. The Pd NPs exhibited excellent catalytic activity toward the reduction of 4-nitrophenol. Thus, the recovered materials showed remarkable potential for application in degradation of toxic aromatic nitro compounds in the environment.

Topics: Catalysis; Lasers; Metal Nanoparticles; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Palladium; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical; X-Ray Diffraction

We investigate the effect of the alcohol-induced increase in the content of CYP2E1 in human liver microsomes (HLM) on the function of CYP3A4. Membrane incorporation of the purified CYP2E1 into HLM considerably increases the rate of metabolism of 7-benzyloxyquinoline (BQ) and attenuates the homotropic cooperativity observed with this CYP3A4-specific substrate. It also eliminates the activating effect of α-naphthoflavone (ANF) seen in some HLM samples. To probe the physiological relevance of these effects, we compared three pooled preparations of HLM from normal donors (HLM-N) with a pooled preparation from ten heavy alcohol consumers (HLM-A). The composition of the P450 pool in all samples was characterized by the mass-spectrometric determination of 11 cytochrome P450 species. The fractional content of CYP2E1 in HLM-A was from 2.0 to 3.4 times higher than in HLM-N. In contrast, the content of CYP3A4 in HLM-A was the lowest among all samples. Despite that, HLM-A exhibited a much higher metabolism rate and a lower homotropic cooperativity with BQ, similar to CYP2E1-enriched HLM-N. To substantiate the involvement of interactions between CYP2E1 and CYP3A4 in these effects, we probed hetero-association of these proteins in CYP3A4-containing Supersomes™ with a technique employing CYP2E1 labeled with BODIPY-618 maleimide. These experiments evinced the interactions between the two enzymes and revealed an inhibitory effect of ANF on their association. Our results demonstrate that the functional properties of CYP3A4 are fundamentally dependent on the composition of the cytochrome P450 ensemble and suggest a possible impact of chronic alcohol exposure on the pharmacokinetics of drugs metabolized by CYP3A4.

Topics: Amino Acid Sequence; Amitriptyline; Benzoflavones; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP3A; Enzyme Activators; Ethanol; Female; Humans; Ivermectin; Male; Microsomes, Liver; Midazolam; Nitrophenols; Quinolines

Carbon dots (CDs) have excellent application prospects in various fields such as fluorescent dyes, but expanding their application, especially in bioimaging and the detection of organic pollutants, is still a major research objective. In this study, fluorescent CDs were successfully synthesized via the hydrothermal method using Serratia marcescens KMR-3. The platform based on CDs-KMR3 exhibited excellent stability, good biocompatibility, and low biotoxicity, and can be effectively applied to the imaging of bacteria, fungi, plant cells, protozoa and mammalian cells, and can specifically stain the membranes of all tested cells. In this study, for the first time, bacteria-derived CDs were used to image the representative species of organisms ranging from lower-order to higher-order organisms, thereby proving the feasibility of the application of CDs in the fluorescence imaging of Paramecium caudatum. Additionally, CDs-KMR3 can rapidly diffuse into all the parts of the leaf through diffusion into the veins and intercellular interstitium in response to the induction of transpiration. Moreover, the data illustrate that CDs-KMR3 are likely to enter the digestive tracts of microworms by ingestion through the oral cavity and pharynx, and spread to the pseudocoelom and somatic cells, and finally to be excreted from microworms through the anus. Furthermore, this platform can be utilized as fluorescent probes for the rapid and highly selective detection of p-nitrophenol (p-NP). Moreover, this study contributed to the increased application of bacteria-derived CDs in bioimaging and detection of p-NP.

Topics: Carbon; Fluorescent Dyes; HeLa Cells; Humans; Limit of Detection; Molecular Imaging; Nanoparticles; Nitrophenols; Optical Imaging; Serratia marcescens

Two chromatographic methods were validated for the determination of the widely prescribed analgesic and antipyretic drug combination of paracetamol (PC) (recently integrated into the supportive treatment of COVID-19), propyphenazone (PZ) and caffeine (CF) in the presence of two PC impurities, namely 4-aminophenol and 4-nitrophenol. A "dual-mode" gradient high-performance liquid chromatography method was developed, where the separation was achieved via "dual-mode" gradient by changing both the ternary mobile phase composition (acetonitrile: methanol: water) and the flow rate. This enables a good resolution within a relatively shorter analysis time. The analysis was realized using Zorbax Eclipse XDB column C18, 5 μm (250 × 4.6 mm) and the UV detector was set at 220 nm. The other method is a thin-layer chromatography densitometry method, where the separation was achieved using a mobile phase composed of chloroform: toluene: ethyl acetate: methanol: acetic acid (6: 6: 1: 2: 0.1, by volume). Densitometric detection was performed at 220 nm on silica gel 60 F254 plates. The developed methods were fully validated as per the ICH guidelines and proved to be accurate, robust, specific and suitable for application as purity indicating methods for routine analysis of PC in pure form or in pharmaceuticals with PZ and CF in quality control laboratories.

Topics: Acetaminophen; Aminophenols; Antipyrine; Caffeine; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Codeine; Densitometry; Drug Combinations; Drug Contamination; Limit of Detection; Meprobamate; Nitrophenols; Reproducibility of Results; Sensitivity and Specificity; Solvents; Tablets

Herein, we report cost effective and body compatible CuS nanoparticles (NPs) derived from a single source precursor as photothermal agent for healing deep cancer and photocatalytic remediation of organic carcinogens. These NPs efficiently kill MCF7 cells (both in vivo and in vitro) under NIR irradiation by raising the temperature of tumor cells. Such materials can be used for the treatment of deep cancer as they can produce a heating effect using high wavelength and deeply penetrating NIR radiation. Furthermore, CuS NPs under solar light irradiation efficiently convert p-nitrophenol (PNP), an environmental carcinogen, to p-aminophenol (PAP) of pharmaceutical implication. In a nutshell, CuS can be used for the treatment of deep cancer and for the remediation of carcinogenic pollutants. There seems an intrinsic connection between the two functions of CuS NPs that need to be explored in length.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinogens; Catalysis; Copper; Humans; Infrared Rays; MCF-7 Cells; Metal Nanoparticles; Mice, SCID; Neoplasms, Experimental; Nitrophenols; Photolysis; Phototherapy; Povidone

The catalytic performance of gold (Au) decorated cerium oxide nanoparticles (nanoceria) can be potentially crucial because such a defined arrangement of multiple materials may provide improved chemical and biological catalytic activities. In this work, we have utilized a highly localized approach to reduce Au nanoparticles (AuNPs) on the nanoceria-phosphotungstate composite's surface. Phosphotungstic acid (PTA) bound on nanoceria's surface acts as a UV-light dependent redox molecule that specifically reduces AuNPs. The mechanistic study demonstrates that PTA* molecules outstanding electron transfer ability leads to an excellent improvement in the catalytic performance of nanoceria-PTA*-AuNPs composite. Nanoceria-PTA*-AuNPs showed better and faster degradation of 4-nitrophenol than either nanoceria or PTA*-AuNPs. The developed nanoceria-PTA*-AuNPs exhibited efficient (>80 % in 5 min) conversion of 4-NP into 4-AP at room temperature and neutral pH. Additionally, the nanoceria-PTA*-AuNPs also showed improved peroxidase enzyme-like activity than the corresponding control samples. The observed catalytic activity could be due to the rapid electron transfer from nanoceria to AuNPs, where the metal nanoparticle acts as an electron sink, mediated by PTA*. Nanoceria-PTA*-AuNPs showed ∼ 2-fold better catalytic oxidation of peroxidase substrate than PTA*-AuNPs. The reported nanoceria-PTA*-AuNPs nanocomposites are expected to display improved biological enzyme-like activities, photocatalysis, and other biomedical applications.

Topics: Cerium; Gold; Metal Nanoparticles; Nanoparticles; Nitrophenols; Oxidation-Reduction; Peroxidase; Peroxidases

Because of the abundance of transition metals, their enhanced electrochemical/chemical efficiency on par with the benchmark catalysts, long-term stability, etc., the expansion of transition metal/metal oxide-based electrocatalysts for oxygen evolution, urea oxidation reactions and 4-nitrophenol reduction becomes indispensable. In particular, the abundant availability along with improved electrochemical performance is crucial for fuel cell applications when it comes to large scale commercialization. In this work, we report the synthesis of a trimetallic metal-organic framework based on Ni, Co and Zn using BTC as a linker and the preparation of its metal oxide - carbon composites at different temperatures, 600, 700 and 800 °C (TM-MOF-600, TM-MOF-700, and TM-MOF-800) by carbonization under an inert atmosphere. The PXRD pattern of TM-MOF complemented well with the simulated XRD patterns of Co-Ni-BTC MOF as well as Zn-BTC MOF, whereas the PXRD pattern of the carbonized samples indicated the presence of three types of metal oxides i.e., CoO, NiO, and ZnO. TEM indicated spherical morphology of TM-MOF, upon calcination, an irregular agglomeration occurred and the average particle size was found to be 60-110 nm. The as-prepared TM-MOF and its carbon composites were tested for their electrocatalytic as well as catalytic activities towards oxygen evolution, urea oxidation and 4-nitrophenol reduction reactions. Electrochemical results indicate the better performance of TM-MOF-800 in both OER and UOR reactions with an onset potential of 1.66 V (OER) and 1.37 V (UOR) at a current density of 10 mA cm

Topics: Carbon; Catalysis; Metals; Nitrophenols; Urea

Topics: Biopolymers; Catalysis; Chitosan; Ferric Compounds; Green Chemistry Technology; Magnetics; Nanocomposites; Nanoparticles; Nitrophenols; Palladium; Starch; Ultrasonic Waves

It is challenging to develop highly stable lanthanide luminescent sensors for detecting heavy metal ions and nitroaromatics in view of the human health and environmental security. To this end, two water stable Ln-MOFs with the chemical constitution of {[Ln(HL)]·3DMF·3H2O}n (Ln = Eu, LZG-Eu and Ln = Tb, LZG-Tb) have been developed solvothermally using a multidentate ligand (H4L) with the central phenyl backbone bisubstituted by 2,6-pyridine-dicarboxylic acid at the para-position, H4L = 1,4-bis(2',2'',6',6''-tetracarboxy-1,4':4,4''-pyridyl)benzene. Single crystal analysis demonstrates that two novel Ln-MOFs feature 4,4,4-connected nets with an unprecedented topology symbol of {42·6·83}2{42·62·82}{42·84} and contain two kinds of one-dimensional channels. Powder X-ray diffraction as well as the luminescence determination results indicate that they retain their crystallinity and structural integrity in harsh acidic and basic conditions with pH in the range of 4-11. Moreover, they are highly luminescent, which makes them excellent chemical sensors for detecting Cu2+ and 4-NP (4-nitrophenol) with high selectivity and sensitivity in aqueous media such as deionized water, tap water, and river water based on distinct quenching effects. To the best of our knowledge, their detection limits are lower than those documented so far. In addition, the quenching efficiency of 4-NP was retained in the presence of interfering ions even after the compounds were used for five cycles, which makes them attractive, reliable, visual, and recyclable luminescent Ln-MOF sensor materials for 4-NP. The recognition mechanism for Cu2+ could be attributed to the dissociation of the main framework induced by Cu2+ and the subsequent formation of a Cu2+ coordination species and that for 4-NP is considered to be multi-quenching mechanisms dominated by competition absorption.

Topics: Copper; Lanthanoid Series Elements; Ligands; Luminescent Agents; Models, Molecular; Molecular Conformation; Nitrophenols; Water

In this study, surface imprinting, magnetic separation, and fluorescent detection were integrated to develop a dual-recognition sensor (MF-MIPs), which was used for highly selective and sensitive detection of 4-nitrophenol (4-NP) in food samples. Silane-functionalized carbon dots (Si-CDs) participated in the imprinting process and were uniformly distributed into the MIPs layers. MF-MIPs sensor exhibited a high fluorescence response and selectivity based on the dual-recognition mechanism of imprinting recognition and fluorescence identification. The relative fluorescence intensity of MF-MIPs sensor presented a good linear relationship in the range of 0.08-10 μmol·L

Topics: Carbon; Food Analysis; Limit of Detection; Magnetics; Molecular Imprinting; Nitrophenols; Polymers; Quantum Dots; Reproducibility of Results; Silanes; Spectrometry, Fluorescence

Sulfidated zerovalent iron (S-ZVI) has been extensively used for reducing pollutants. In this study, the oxidation process in the reductive removal of

Topics: Anaerobiosis; Hydrogen Peroxide; Hydroxyl Radical; Iron; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical

Nitrobenzene compounds are highly toxic pollutants with good stability, and they have a major negative impact on both human health and the ecological environment. Herein, it was found for the first time that fluorescent DNA-silver nanoclusters (DNA-AgNCs) can catalyze the reduction of toxic and harmful nitro compounds into less toxic amino compounds with excellent tolerance to high temperature and organic solvents. In this study, the reduction of p-nitrophenol (4-NP) as a model was systematically investigated, followed by expending the substrate to disclose the versatility of this reaction. This report not only expanded the conditions for utilizing catalytic reduction conditions of DNA-AgNCs as an efficient catalyst in the control of hazardous chemicals but also widened the substrate range of DNA-AgNCs reduction, providing a new angle for the application of noble metal nanoclusters.

Topics: Catalysis; DNA; Hot Temperature; Metal Nanoparticles; Nitrobenzenes; Nitrophenols; Silver

Topics: Hydroxides; Metal Nanoparticles; Nitrogen; Nitrophenols; Palladium; Spectroscopy, Fourier Transform Infrared

Psychrobacter is one important typical strain in the Antarctic environment. In our previous study, Psychrobacter sp. ANT206 from Antarctica with novel cold-adapted nitroreductase (PsNTR) could biodegrade nitrobenzene and p-nitrophenol in low temperature environment. In this study, the in-frame deletion mutant of psntr (Δpsntr-ANT206) that displayed well genetic stability and kanamycin resistance stability was constructed using allelic replacement method. Additionally, Δpsntr-ANT206 was more sensitive to nitrobenzene and p-nitrophenol in the comparison of heat and hyperosmolarity, suggesting that psntr gene participated in the regulation of the tolerance against nitro-aromatic compounds (NACs). Further analysis was conducted by integrated gas chromatography-mass spectrometry (GC-MS), and several metabolites were identified. Among them, ethylbenzene, L-Alanine, citric acid, aniline, 4-aminophenol and other metabolites were different between the wild-type strain and Δpsntr-ANT206 under nitrobenzene and p-nitrophenol stress at different time periods under low temperature, respectively. These data could increase the knowledge of the construction of deletion mutant strains and biodegradation mechanism of NACs of typical strains Psychrobacter from Antarctica, which would also provide the basis of the molecular technique on the regulation of bioremediation of the contaminants under low temperature in the future.

Topics: Antarctic Regions; Biodegradation, Environmental; Nitrobenzenes; Nitrophenols; Nitroreductases; Psychrobacter; Temperature

Silver (Ag) nanocomposites were prepared via a facile and eco-friendly route using microbial extracellular polymer substances (EPSs) as green substrates for the catalytic reduction of 4-nitrophenol. Batch adsorption experiments demonstrated the binding of microbial EPSs to silver ions (Ag

Topics: Catalysis; Metal Nanoparticles; Nanocomposites; Nitrophenols; Polymers; Silver

Topics: Anaerobiosis; Biodegradation, Environmental; Biofilms; Bioreactors; Nitrophenols; RNA, Ribosomal, 16S; Waste Disposal, Fluid; Wastewater

4-Nitrophenol (4-NP) is an extensively utilized industrial chemical and one of major toxic water pollutant. Therefore, there is an urgent need to monitor the levels of 4-NP from environmental samples as well as its eradication are extremely important. Keeping this as a motivation, this research for the first-time reports microwave-assisted cost-effective synthesis of silver oxide (Ag

Topics: Methylene Blue; Microwaves; Nitrophenols; Silver; Zinc Oxide

p-Nitrophenol (PNP) is the main end product of organophosphorus insecticides and a derivative of diesel exhaust particles. In addition to its unfavorable impact on reproductive functions in both genders, it also has various harmful physiological effects including lung cancer and allergic rhinitis. The identification of the cellular readout that functions in metabolic pathway perpetuation is still far from clear. This research aimed to study the impact of chronic PNP exposure on the health condition of the liver in Japanese quails. Quails were exposed to different concentrations of PNP as follows: 0.0 (control), 0.01mg (PNP/0.01), 0.1mg (PNP/0.1), and 1mg (PNP/1) per kg of body weight for 2.5 months through oral administration. Liver and plasma samples were collected at 1.5, 2, and 2.5 months post-treatment for biochemical, histopathology, and immunohistochemistry assessment. The plasma aspartate aminotransferase (AST) level was assessed enzymatically. The livers were collected for histopathology, glycogen accumulation, proliferating cell nuclear antigen (PCNA), and apoptosis assessment. Our results revealed an irregularity in body weight due to the long-term exposure of PNP with a significant reduction in liver weight. PNP treatment caused histopathological alterations in the hepatic tissues which increased in severity by the long-term exposure. The low dose led to mild degeneration with lymphocytic infiltration, while the moderate dose has a congestion effect with some necrosis; meanwhile severe hepatocyte degeneration and RBCs hemolysis were noticed due to high dose of PNP. Glycogen accumulation increased in hepatocytes by prolonged exposure to p-Nitrophenol with the highest intensity in the group treated by the high dose. Moderate and high doses of PNP resulted in a significant increase in apoptosis and hepatocytes' proliferation at the different time points after treatment. This increase is markedly notable and maximized at 2.5 months post-treatment. The damage occurred in a time-dependent manner. These changes reflected on the plasma hepatic enzyme AST that was clearly increased at 2.5 months of exposure. Therefore, it could be concluded that PNP has profound toxic effects on the liver in cellular level. Taking into consideration the time and dose factors, both have a synergistic effect on the accumulation of glycogen, apoptosis, and cellular proliferation, highlighting the power of cellular investigation which will potentially open the door for earl

Topics: Animals; Apoptosis; Chemical and Drug Induced Liver Injury; Coturnix; Female; Glycogen; Humans; Liver; Male; Nitrophenols

Doxorubicin is a chemotherapeutic drug widely utilized in cancer treatment. An enzyme critical to doxorubicin metabolism is the cytosolic sulfotransferase (SULT) SULT1C4. This study investigated the functional impact of SULT1C4 single nucleotide polymorphisms (SNPs) on the sulfation of doxorubicin by SULT1C4 allozymes. A comprehensive database search was performed to identify various SULT1C4 SNPs. Ten nonsynonymous SULT1C4 SNPs were selected, and the corresponding cDNAs, packaged in pGEX-2TK expression vector, were generated via site-directed mutagenesis. Respective SULT1C4 allozymes were bacterially expressed and purified by affinity chromatography. Purified SULT1C4 allozymes, in comparison with the wild-type enzyme, were analysed for sulphating activities towards doxorubicin and 4-nitrophenol, a prototype substrate. Results obtained showed clearly differential doxorubicin-sulphating activity of SULT1C4 allozymes, implying differential metabolism of doxorubicin through sulfation in individuals with distinct SULT1C4 genotypes.

Topics: Cytosol; Doxorubicin; Genotype; Humans; Isoenzymes; Kinetics; Mutagenesis, Site-Directed; Nitrophenols; Polymorphism, Single Nucleotide; Sulfates; Sulfotransferases

The environmental fates of chlorinated 4-nitrophenols, 2,6-dichloro-4-nitrophenol (2,6-DCNP) and 2-chloro-4-nitrophenol (2C4NP), mediated via microbial catabolism have attracted great attention due to their high toxicity and persistence in the environment. In this study, a strain of Ensifer sp. 22-1 that was capable of degrading both 2,6-DCNP and 2C4NP was isolated from a halogenated aromatic-contaminated soil sample. A gene cluster cnpBADCERM was predicted to be involved in the catabolism of 2,6-DCNP and 2C4NP based on genome sequence analysis. A two-component monooxygenase CnpAB, composed of an oxygenase component (CnpA) and a reductase component (CnpB), was confirmed to catalyze the continuous denitration and dechlorination of 2,6-DCNP and 2C4NP to 6-chlorohydroxyquinol (6-CHQ) and hydroxyquinol (HQ), respectively. Knockout of cnpA resulted in the complete loss of the capacity for strain 22-1 to degrade 2,6-DCNP and 2C4NP. Homologous modeling and docking showed that Val155~Ala159, Phe206~Pro209 and Phe446~Arg461 of CnpA participated in the formation of the FAD-binding pocket, and Arg101, Val155 and Asn447 formed hydrogen bonds with 2,6-DCNP/2C4NP in the substrate-binding pocket. This work characterized a new two-component monooxygenase for 2,6-DCNP and 2C4NP, and enriched our understanding of the degradation mechanism of chlorinated nitrophenols (CNPs) by microorganisms.

Topics: Biodegradation, Environmental; Mixed Function Oxygenases; Nitrophenols

A facile, friendly and one-step hydrothermal protocol was used to synthesize nitrogen-doped carbon dots (N-CDs) by utilizing hexamethylenetetramine and ethanediamine as the carbon and nitrogen sources. It demonstrated good water solubility and fluorescence properties were stable, whether in acidic or alkaline. Quantum yield (QY) of N-CDs was 8.3% at an excitation wavelength of 325 nm with maximum emission at 425 nm. The fluorescence of N-CDs achieved very high fluorescence quenching of 60% in the detection of p-nitrophenol (p-NP) in aqueous medium via fluorescence resonance energy transfer (FRET) mechanisms. Under optimum conditions, fluorescence probs of N-CDs had strong selectivity to p-NP, and the fluorescence intensity was linearly proportional to p-NP concentration from 0.5 to 70.0 μM with a detection limit of 0.201 μM. The corresponding cell experiments were also performed, indicating that the prepared N-CDs possessed low cytotoxicity and good biocompatibility. Meanwhile, the N-CDs can be used for the determination of p-NP in river water and industrial wastewater.

Topics: Carbon; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Nitrogen; Nitrophenols; Quantum Dots

4-Nitrophenol, a priority pollutant, is degraded by Gram-positive and Gram-negative bacteria via 1,2,4-benzenetriol (BT) and hydroquinone (HQ), respectively. All enzymes involved in the two pathways have been functionally identified. So far, all Gram-negative 4-nitrophenol utilizers are from the genera Pseudomonas and

Topics: Bacterial Proteins; Biotransformation; Burkholderia; Catechols; Dioxygenases; Hydroquinones; Nitrophenols; Pseudomonas

In the present study, two catalysts based-on copper and nickel nanoparticles anchored on agarose-coated sponge (Cu-AG-sponge and Ni-AG-sponge) were prepared, respectively. Both catalysts were characterized by analytical techniques of thermogravimetric analysis energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). Spherical Cu and Ni nanoparticles on struts of AG-coated sponge were observed by FESEM and the samples' elemental composition was confirmed by EDX technique. After characterization, the Cu-AG-sponge and Ni-AG-sponge catalysts were tested in 4-nitrophenol (4-NP) and methylene blue dye (MB) reduction in an aqueous medium. The reduction of the 4-NP to 4-aminophenol (4-AP) was achieved up to 95% using the NaBH

Topics: Catalysis; Copper; Environmental Pollutants; Metal Nanoparticles; Methylene Blue; Nickel; Nitrophenols; Polymers; Water

Three types of alkyl-ammonium with different branching chains and three complexants with different functional groups were used to prepare alkyl-ammonium or complexant intercalated montmorillonite nanocomposite (A-Mt or C-Mt). In addition, synergistic intercalated montmorillonite nanocomposites (A/C-Mt) with alkyl-ammonium along with complexant were also prepared. The adsorption performance of the various nanocomposites toward Zn

Topics: Adsorption; Ammonium Compounds; Bentonite; Hydrogen-Ion Concentration; Kinetics; Nanocomposites; Nitrophenols; Wastewater; Water Pollutants, Chemical; Zinc

In this study calcium alginate-multiwall carbon nanotube (CA/MWCNTs) was synthesized using (CA) calcium alginate and multiwall carbon nanotube (MWCNTs), and its efficiency in adsorption of 4-Nitrophenol (4-NP) in aqueous solution was studied. The structure and properties of the synthesized adsorbent were investigated using scanning electron microscope (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The experimental design was performed using Box-Behnken design (BBD) in which variables pH, CA/MWCNTs, and temperature were examined. The results of the effect of temperature on the removal efficiency of 4-NP showed that the adsorption efficiency decreases with increasing temperature. The results of nonlinear isotherm and kinetics models showed that Langmuir and pseudo-second-order models were more consistent than other models. The maximum adsorption capacity of 4-NP in this study by CA, MWCNTs, and CA/MWCNTs was 136, 168.4, and 58.8 mg/g, respectively, which indicates that the use of MWCNTs on CA could increase the adsorption capacity. The results of reuse of the synthesized adsorbent at 4-NP removal also showed that after 5 reuse of the adsorbent, the removal of 4-NP using CA/MWCNTs is reduced by about 10%, which shows that the synthesized adsorbent can be used several times to adsorb contaminants without significant reduction in the efficiency.

Topics: Adsorption; Alginates; Kinetics; Microscopy, Electron, Scanning; Nanotubes, Carbon; Nitrophenols; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction

p-Nitrophenol and its derivatives can cause serious harm to the health of mankind and the earth's ecosystem. Therefore, it is necessary to develop a novel and rapid detection technology for p-nitrophenol and its derivative. Herein, excellent water-soluble, large-size and dual-emissive neuron cell-analogous carbon-based probes (NCNPs) have been prepared via a solvothermal approach, using o-phenylenediamine as the only precursor, which exhibit two distinctive fluorescence (FL) peaks at 420 and 555 nm under 345 nm excitation. The NCNPs show a neuron cell-like branched structure, are cross-connected, and are in the range of 10-20 nm in skeleton diameter. Interestingly, their blue-green dual-colour fluorescence is quenched by p-nitrophenol or its derivative due to the specific mechanism of the ππ stacking interactions or internal filtration effect. Accordingly, a simple, rapid, direct and free-label ratiometric FL detection of p-nitrophenol is proposed. An excellent linear relationship shows linear regions over the range of 0.1-50 μM between the ratio of the FL intensity (FL555 nm/FL420 nm) and the concentrations of p-nitrophenol. The detection limit is as low as 43 nM (3σ). Importantly, the NCNP-based probe also shows acceptable repeatability and reproducibility for the detection of p-nitrophenol and its derivatives, and the recovery results for p-nitrophenol in real wastewater samples are favourable.

Topics: Ecosystem; Fluorescent Dyes; Neurons; Nitrophenols; Quantum Dots; Reproducibility of Results

Herein, we report the fabrication of a novel, well-defined core-double-shell-structured magnetic Fe

Topics: Chromatography, High Pressure Liquid; Hydrophobic and Hydrophilic Interactions; Indoles; Limit of Detection; Magnetic Phenomena; Nanospheres; Nitrophenols; Polycyclic Aromatic Hydrocarbons; Polymers; Porosity; Solid Phase Extraction; Wastewater

The nonlinear sorption of hydrophobic organic contaminants (HOCs) could be changed to linear sorption by the suppression of coexisting solutes in natural system, resulting in the enhancement of mobility, bioavailability and risks of HOCs in the environment. In previous study, inspired from the competitive adsorption on activated carbon (AC), the displaceable fraction of HOCs sorption to soot by competitor was attributed to the adsorption on elemental carbon fraction of soot (EC-Soot), while the linear and nondisplaceable fraction was attributed to the partition in authigenic organic matter of soot (OM-Soot). In this study, however, we observed that the linear and nondisplaceable fraction of HOC (naphthalene) to a diesel soot (D-Soot) by competitor (phenanthrene or p-nitrophenol) should be attributed to not only the linear partition in OM-Soot, but also the residual linear adsorption on EC-Soot. We also observed that the competition on the surface of soot dominated by external surface was different from that of AC dominated by micropore surface, i.e., complete displacement of HOCs by p-nitrophenol could occur for the micropore surface of AC, but not for the external surface of soot. These observations were obtained through the separation of EC-Soot and OM-Soot from D-Soot with organic-solvent extraction and the sorption comparisons of D-Soot with an AC (ACF300) and a multiwalled carbon nanotube (MWCNT30). The obtained results would give new insights to the sorption mechanisms of HOCs by soot and help to assess their environmental risks.

Topics: Adsorption; Naphthalenes; Nitrophenols; Phenanthrenes; Soot

A rapid and simple fluorescence probe based on CeO

Topics: Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Nitrophenols; Quantum Dots

Topics: Charcoal; Iron; Nitrophenols; Water Pollutants, Chemical

Due to the good electrical, optical, magnetic, catalytic properties, transition metal nanoparticles (TMNPs) have been becoming more and more interesting in the fileds of environment, material, biomedicine, catalysis, and so on. Here, tannic acid (TA) is used as a green and efficient stabilizer to fabricate all kinds of TMNPs including AuNPs, AgNPs, CuNPs and PdNPs. These TMNPs possess small sizes ranging from 1 nm to 6 nm, which is conducive to several catalytic reactions in aqueous solution, such as 4-nitrophenol (4-NP) reduction, CuAAC reactions and Suzuki-Miyaura coupling reactions. AuNPs and PdNPs are found to have distinctly higher catalytic activities than AgNPs and CuNPs in the 4-NP reduction process. Especially, PdNPs show the highest catalytic activities with TOF up to 7200 h

Topics: Catalysis; Gold; Metal Nanoparticles; Nitrophenols; Palladium; Tannins

Invited for this month's cover is the joint research group of Prof. Chan Beum Park at the Korea Advanced Institute of Science and Technology (KAIST) and Prof. Chul-Ho Yun at the Chonnam National University (CNU). The image shows how the use of a natural photosensitizer, flavin mononucleotide, and visible light can lead to a cost-effective, green, and sustainable process for P450-catalyzed reactions in a whole-cell system. The Communication itself is available at 10.1002/cssc.202100944.

Topics: Catalysis; Chlorzoxazone; Cytochrome P-450 Enzyme System; Escherichia coli; Flavin Mononucleotide; Hydroxylation; Light; Nitrophenols; Oxidation-Reduction; Photosensitizing Agents; Photosynthesis; Solar Energy

In this paper, the adsorptive performance of synthesized thiourea (TU) modified poly(acrylonitrile-co-acrylic acid) (TU-P(AN-co-AA)) polymeric adsorbent for capturing p-nitrophenol (PNP) from aqueous solution was investigated. TU-P(AN-co-AA) was synthesized via the redox polymerization method with acrylonitrile (AN) and acrylic acid (AA) as the monomers, then modified chemically with thiourea (TU). Characterization analysis with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental microanalysis for CHNS, zeta potential measurement, Brunauer-Emmett-Teller (BET) surface analysis and thermal analyses were carried out to determine the morphology and physico-chemical properties of the synthesized polymer. The characterization results indicated successful surface modification of polymer with TU. The performance of TU-P(AN-co-AA) for the removal of PNP was investigated under various experimental parameters (adsorbent dosage, initial adsorbate concentration, contact time and temperature). The results demonstrated that the Freundlich isotherm model and pseudo-second-order kinetic model best described the equilibrium and kinetic data, respectively. Thermodynamic studies showed that the uptake of PNP by TU-P(AN-co-AA) was spontaneous and exothermic in nature. The results of the regeneration studies suggested that the TU-P(AN-co-AA) polymer is a reusable adsorbent with great potential for removing PNP from wastewater.

Topics: Acrylates; Acrylonitrile; Adsorption; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Thioamides; Water Pollutants, Chemical

In this study, tin oxide‑cobalt oxide nanocatalyst was prepared by a simple method, which grew in spherical particles with an average diameter of 30 nm. Tin oxide-cobalt oxide was further wrapped in alginate polymer hydrogel (Alg@tin oxide-cobalt oxide), and both materials were utilized as nanocatalysts for the catalytic transformation of different pollutants. Tin oxide-cobalt oxide and Alg@tin oxide-cobalt oxide nanocatalysts were tested for the catalytic reduction of 4-nitrophenol, congo red, methyl orange, methylene blue (MB) and potassium ferricyanide in which sodium borohydride was used as a reducing agent. Tin oxide-cobalt oxide and Alg@tin oxide-cobalt oxide nanocatalysts synergistically reduced MB in shorter time (2.0 and 4.0 min) compared to other dyes. The reduction conditions were optimized by changing different parameters. The rate constants for MB reduction were calculated and found to be 1.5714 min

Topics: Alginates; Azo Compounds; Borohydrides; Catalysis; Cobalt; Congo Red; Ferricyanides; Kinetics; Methylene Blue; Nanocomposites; Nanotechnology; Nitrophenols; Oxidation-Reduction; Oxides; Tin Compounds; Wastewater; Water Pollutants, Chemical; Water Purification

Catalytic reduction of nitroaromatic compounds present in wastewater by nanostructured materials is a promising process for wastewater treatment. A multifunctional electrode based on ternary spinal nickel cobalt oxide is used in the catalytic reduction of a nitroaromatic compound and supercapacitor application. In this study, we designed nanoflakes- like nickel cobaltite (NiCo

Topics: Electrodes; Minerals; Nickel; Nitrophenols

4-Nitrophenol (4-NP) is a hazardous aromatic compound widely used for various industries. Catalytic reduction of 4-NP using metal nanoparticles (NPs) is a highly effective method to treat 4-NP from waste effluent. Even though lots of methods have investigated to prepare efficient metal NPs composites, the nano and/or micro size of composites makes it hard to recover after wastewater treatment, limiting its practical use. Here, we fabricate 3-dimensional polyethylene imine grafted cellulose nanofibril (CNF-PEI) aerogel as a porous support material for platinum (Pt) NPs to practically and effectively treat 4-NP from wastewater. The Pt NPs are formed in-situ mode on cylindrical CNF-PEI aerogel by adsorption reaction with amine groups of PEI and subsequently reduction with NaBH

Topics: Catalysis; Cellulose; Nitrophenols; Wastewater

The present study reports the development of an electrochemical sensor based on sulfobutylether-β-cyclodextrin modified reduced graphene oxide hybrid (SBCD-rGO) for simultaneous detection of nitrophenol isomers. First, SBCD-rGO hybrid was synthesized and detailed characterized. Afterwards, a sensor was fabricated via the modification of glassy carbon electrode (GCE) with SBCD-rGO, and its electrochemical detection performances were also investigated. Then, the constructed electrochemical sensor was applied to detect nitrophenol isomers by voltammetry analysis. The results suggested that the sensitivities were 389.26, 280.88 and 217.19 μA/mM for p-nitrophenol (p-NP), m-nitrophenol (m-NP), and o-nitrophenol (o-NP), respectively, and their corresponding detection limits were all about 0.05 μM. Significantly, the combination of voltammetry analysis with the constructed sensor and data analysis by multiple linear regression realized the simultaneous detection of nitrophenol isomers.

Topics: beta-Cyclodextrins; Carbon; Electrochemical Techniques; Electrodes; Graphite; Isomerism; Limit of Detection; Nanostructures; Nitrophenols; Reproducibility of Results

CeO

Topics: Catalysis; Cerium; Microspheres; Nitrophenols; Oxidoreductases

The heme domain of cytochrome P450 116B5 from Acinetobacter radioresistens (P450 116B5hd), a self-sufficient class VII P450, was functionally expressed in Escherichia coli, purified and characterised in active form. Its unusually high reduction potential (-144 ± 42 mV) and stability in the presence of hydrogen peroxide make this enzyme a good candidate for driving catalysis with the so-called peroxide shunt, avoiding the need for a reductase and the expensive cofactor NAD(P)H. The enzyme is able to carry out the peroxide-driven hydroxylation of aromatic compounds such as p-nitrophenol (K

Topics: Acinetobacter; Benzidines; Biocatalysis; Cytochrome P-450 Enzyme System; Escherichia coli; Heme; Molecular Structure; Nitrophenols; Oxazines; Oxidation-Reduction; Peroxides

Million tons of sewage sludge produced yearly creates a severe pollution problem to environment, and thus needs either to be properly disposed of, or recovered. Here, we demonstrate a value-added utilization of sewage sludge by converting its contained organics into nanosized carbon dots (CDs) with microwave irradiation. This synthetic method, using waste resources as precursors and avoiding the requirement of hazardous reagents and complex procedures, has the great advantage of low cost, environmental friendliness, and easy scalability. The resultant CDs exhibit excellent fluorescence properties with a large quantum yield (QY) of up to 21.7%, higher than the most values of waste-derived CDs. It is found that CDs can serve as a sensitive and selective sensor to detect para-Nitrophenol (p-NP), a toxic pollutant, through fluorescence quenching, giving a linear detection range of 0.2-20 μM and a detection limit of as low as 0.069 μM. Systematic investigations suggest that the inner filter effect (IFE) is the dominant sensing mechanism. Moreover, the practical applications of CDs for p-NP assay in real water samples achieve good results.

Topics: Carbon; Fluorescence; Microwaves; Nitrophenols; Sewage; Waste Disposal, Fluid; Water Pollutants, Chemical

A facile and effective method has been developed to prepare hierarchical porous carbon nanofibers (PCNFs), carbon nanofibers supported nickel nanoparticles (PCNFs-Ni) and carbon nanofibers encapsulating gold nanoparticles (PCNFs-Au). PCNFs or PCNFs-Au were obtained by embedding metal-organic frameworks (e.g. ZIF-8 or ZIF-8-Au) into polyacrylonitrile via electrospinning and subsequent carbonization. In addition, PCNFs-Ni were obtained by impregnating PAN/ZIF-8 nanofibers in Ni(NO

Topics: Acrylic Resins; Adsorption; Carbon; Catalysis; Congo Red; Metal Nanoparticles; Metal-Organic Frameworks; Methylene Blue; Nanofibers; Nitrophenols; Porosity; Water Pollutants, Chemical

A porous carbon aerogel (CA) was prepared to activate persulfate (PS) for the removal of phenol. The adsorption of phenol on CA and its removal in CA/PS system was fitted to a second-order model and first-order kinetic model, respectively. Influencing factors of CA/PS such as pH, CA dose, PS concentration, phenol concentration and temperature were investigated. CA/PS presented good performance on phenol removal over a pH range of 3-11 with the highest removal obtained at pH 7. Four kinds of organic pollutants including tetracycline, Rhodamine B, Safranine T and malachite green were investigated in the CA/PS system, proving that the adsorption of the contaminants benefitted their subsequent oxidation removal. The removal of aromatic compounds (phenol, p-diphenol, p-chlorophenol, and p-nitrophenol) in CA/PS system followed a decreasing order of hydroxyl > chlorine > nitro. The radical scavenging experiments suggested the removal of phenol was mainly through a non-radical pathway. The study presented the preparation and application of a green catalyst to activate PS, which is very promising for the development of the technology and the treatment of phenolic wastewater.

Topics: Adsorption; Carbon; Catalysis; Chlorophenols; Hydroxyl Radical; Kinetics; Nitrophenols; Oxidation-Reduction; Phenol; Porosity; Sulfates; Tetracycline; Wastewater; Water Pollutants, Chemical

Although health hazards of 4-nitrophenol (PNP) exposure have been reported, the adverse effects of PNP exposure on cancer biological features are still unknown. We investigated the effects of administration of PNP in T24 human bladder cancer cells. The results showed that PNP exposure promoted cellular proliferation, migration and invasion, inhibited adhesion and apoptosis in vitro. Using quantitative real-time PCR, we found that (1) the mRNA expression levels of cell-cycle regulators PCNA, cyclin D1 and COX-2 were increased in PNP-treated cells compared to controls, however, that of pro-apoptotic gene Bax was decreased; (2) the expression level of EMT-associated gene E-cadherin was decreased in PNP-treated cells, whereas those of N-cadherin, vimentin, snail, and slug were increased; (3) the expression levels of cancer-promoting genes HIF-1, IL-1β, VEGFα and K-Ras were enhanced, but those of tumor suppressors p53, PTEN and BRCA were decreased. There was a positive association between PNP exposure times and the promotion effects. Finally, we found that the expression level of PPARγ (γ1 isoform) was increased in PNP-treated T24 cells. GW9662, a specific PPARγ antagonist, attenuated PNP-induced cell migration and invasion. These findings indicate that PNP exposure may promote bladder cancer growth and progression involving PPARγ signaling. PPARγ is a potential target for development of novel intervention study on environment pollution. Environ. Mol. Mutagen. 61:316-328, 2020. © 2019 Wiley Periodicals, Inc.

Topics: Carcinogens, Environmental; Cell Line, Tumor; Cell Movement; Cell Proliferation; Disease Progression; Endocrine Disruptors; Epithelial-Mesenchymal Transition; Humans; Neoplasm Invasiveness; Nitrophenols; Urinary Bladder Neoplasms

p-Nitrophenol (PNP) is one type of environmental pollutant, which is difficult to degrade and soluble in water. To investigate the effects of PNP on economically important marine fish species, we subjected Larimichthys crocea juvenile to five different concentrations of PNP for 96 h, and the semi-lethal concentration (LC50) was 6.218 mg/L. Then we collected the liver, kidney, and gill tissues to determine enzyme activity and gene expression levels, and analyzed histological changes. In histological analysis, the gills showed curling of lamella, epithelial lifting and hyperplasia; the parenchymal structure of hepatocytes was significantly damaged, with severe vacuolation and loss of original structure. The renal cells were damaged too, with congestion and renal tubular necrosis. Catalase and superoxide dismutase both showed an up- and down-tendency with the rise of concentration in the three tissues, and GSH-px had similar trend in the kidney, which decreased at 8 mg/L in the liver but showed no significant differences in the gills. Malondialdehyde of three tissues was increased with an increase in PNP concentration. The expression of four detoxification (cyp450, gst, gpx, hsp70) and one immune-related (mhc II) genes was induced at low PNP concentrations but inhibited at high PNP concentrations in the kidney. In liver, cyp450, hsp70 and mhc II showed similar trend but gst and gpx didn't increase at low PNP concentrations. Our results indicate that the fish possesses the ability to detoxify PNP; however, at high concentrations, PNP still causes serious damage to them. Our data not only help in understanding the ability of L. crocea to detoxify PNP but also should serve as a basis for the study of toxic effects of nitrobenzenes on marine fish.

Topics: Animals; Catalase; Fish Proteins; Gills; Inactivation, Metabolic; Kidney; Liver; Malondialdehyde; Nitrophenols; Perciformes; Superoxide Dismutase; Water Pollutants, Chemical

As the second largest natural polymer in nature, lignin has a large amount of reserves and has important practical application value, which has attracted increasing attention. Ag@LPAH, a nanometer silver catalyst with a 3D structure, was successfully prepared in a simple operation. In batch experiment and fixed-bed experiment, it showed excellent catalytic degradation ability and stability of 4-NP. Thanks to the large number of carboxyl groups present in the lignin-polyacrylic acid hydrogel, the silver nanoparticles are well controlled to grow with no agglomeration. Ag@LPAH-20 exhibited optimal catalytic performance and stability, requiring only 123 s to complete the reaction and maintaining 99% catalytic efficiency after 10 cycles. In addition, the catalytic efficiency can be maintained over 90% for more than 120 min in fixed bed experiment.

Topics: Acrylic Resins; Borohydrides; Catalysis; Hydrogels; Lignin; Nitrophenols; Recycling; Silver

To improve catalytic performance and stability of Ag nanoparticles (Ag NPs), a facile ultrasonication-assisted chemical reduction method was developed to fabricate reduced graphene oxide (rGO) aerogels loaded with 1-3 nm Ag NPs under the normal temperature and pressure. The ultrasonication facilitated the dispersion of Ag(I) in the form of silver ammonia and anchored onto GO nanosheets. Ag(I) and GO were simultaneously reduced to Ag(0) immobilizing onto 3D rGO hydrogels within the heterogeneous liquid phase, and ultimately formed 3D rGO-Ag NPs aerogels. The 3D rGO-Ag NPs aerogels displayed superb catalytic performance for the reduction of nitrobenzene (NB), 1,3-dinitrobenzene (DNB) and 4-nitrophenol (NP) into aniline, 1,3-diaminobenzene and 4-aminophenol, respectively. The individual reduction rate K

Topics: Aminophenols; Carrier Proteins; Catalysis; Dipeptides; Graphite; Metal Nanoparticles; Neoplasm Proteins; Nitrobenzenes; Nitrophenols; Silver

This study aimed to examine the mRNA expression, activity, and immunolocalisation of apoptosis/proliferation regulating factors following in vitro exposure of the stroma, white (WFs), and yellowish (YFs) follicles of the chicken ovary to 4-nitrophenol (PNP) or 3-methyl-4-nitrophenol (PNMC). PNMC increased the mRNA expression of caspase-3, -8, Apaf-1, and cytochrome c in the ovarian stroma. The activity of caspase-3, -8, and -9 decreased in WFs in both nitrophenol-treated groups. PNP reduced the number of caspase-3-positive cells in the stromal connective tissue (CT) and the theca interna and externa layers of WFs. In the stroma, the proliferating index decreased in the wall of primary follicles in both nitrophenol-treated groups, however, in the CT, the effect of PNMC was opposite. In the theca interna of WFs, PNP diminished the proliferating index. These results suggest that nitrophenols might impact the development of chicken ovarian follicles by affecting cell death and proliferation.

Topics: Animals; Apoptosis; Avian Proteins; Cell Proliferation; Chickens; Cresols; Female; Gene Expression Regulation; Nitrophenols; Ovary

The present study reports the biosynthesis of silver nanoparticles (AgNPs) using Bacillus amyloliquefaciens MSR5. The cellfree supernatant of B. amyloliquefaciens acted as a stabilizing agent for the synthesis of AgNPs. The synthesized AgNPs were characterized using UV-vis spectrophotometer, PXRD, FTIR, SEM-EDX, DLS, and TEM. TEM image showed the spherical shape of the biosynthesized AgNPs and it was found to be 20-40 nm in range. In this study, the AgNPs were prepared by ultrasonic irradiation. The stability of the AgNPs was found to be -33.4 mV using zeta potential. The catalytic 4-nitrophenol (4-NP) degradation by AgNPs was examined under solar irradiation and furthermore, the effects of several degradation parameters were studied. The biosynthesized AgNPs exhibited a strong chemocatalytic action with a comprehensive degradation (98%) of 4-NP to 4-aminophenol (4-AP) using NaBH

Topics: A549 Cells; Bacillus amyloliquefaciens; Catalysis; Cell Survival; Green Chemistry Technology; Humans; Hydrogen Peroxide; Hydrogen-Ion Concentration; Metal Nanoparticles; Nitrophenols; Photolysis; Silver; Sunlight

The field of nanobiotechnology and nanomedicine paves way for the use of several nanoparticles. Especially, in biomedical applications, the silver nanoparticles (AgNPs), gold nanoparticles (AuNPs) and palladium nanoparticles (PdNPs) are found most vital and promising, among other nanoparticles. The biomedical activities of these particles mostly depend on their shape, size and distribution. Preparation of these particles in an eco-friendly method is an immediate need of the society. Herein, AuNPs, AgNPs and PdNPs (MNPS) were synthesized by Solanum nigrum Leaves (SNL) extract. The structural and morphological studies were carried out by using TEM, XRD and EDAX, while the optical and chemical properties were studied using UV-visible spectrum and FTIR spectroscopy. The particles obtained were found to possess a FCC (Face Centered Cubic) structure. TEM images of Ag, Au and PdNPs showed spherical well dispersed nanoparticles with average size of 3.46 nm, 9.39 nm and 21.55 nm respectively. The FTIR spectra confirmed polyphenols and antioxidants in SNL extract act as reducing and capping agents respectively in the synthesis of MNPs. The EDX technique confirmed the presence of silver, gold and palladium nanoparticles. Antimicrobial studies noted that the AgNPs have effective inhibition against E. coli. The complete reduction of 4-Nitrophenol and the formation of 4-Aminophenol with the presence of NaBH

Topics: Anti-Bacterial Agents; Catalysis; Disk Diffusion Antimicrobial Tests; Escherichia coli; Gold; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Palladium; Particle Size; Plant Extracts; Plant Leaves; Silver; Solanum nigrum

Topics: Azo Compounds; Biomass; Catalysis; Congo Red; Environmental Pollutants; Lignin; Metal Nanoparticles; Methylene Blue; Models, Chemical; Nitrophenols

Catalytic properties and high adsorption affinity of nucleic acids and proteins to silver amalgam electrode surface make this kind of electrified interface perspective for bioanalytical and biomedical applications. For the first time, a basal-plane pyrolytic graphite electrode (bPGE) has been used as a substrate for electrodeposition of silver amalgam particles (AgAPs). Optimization of the resulting composition, surface morphology and electrochemical properties of the AgAPs was done by scanning electron microscopy with energy disperse X-ray spectroscopy, image processing software and voltammetric detection of electrochemically reducible model organic nitro compound, 4-nitrophenol. Spectro-electrochemical applicability of bPGE-AgAP has been demonstrated by electrolysis of 4-nitrophenol. Simultaneous UV-Vis-chronoamperometry provided information on the number of exchange electrons and the reduction rate constants. Preferential adsorption of the fluorescently labelled calf thymus DNA and the green fluorescent protein (GFP) on the surface of AgAPs was observed by fluorescence microscopy. In contrast to previously studied indium-tin oxide and vapour-deposited gold decorated by AgAPs, herein the presented bPGE-AgAP has provided sufficiently wide negative potential window allowing direct electroanalysis of non-labelled DNA and GFP using intrinsic electrochemical signals independently of the fluorescent labelling. The bPGE-AgAP can thus be expected to find application opportunities in protein electrochemistry, (bio)sensor development or in-situ spectro-electrochemical studies.

Topics: Adsorption; DNA; Electrochemical Techniques; Electroplating; Green Fluorescent Proteins; Microscopy, Electron, Scanning; Nitrophenols; Silver

The degradation of p-nitrophenol (p-NP) based on OH radicals (HO

Topics: Models, Theoretical; Nitrophenols; Oxidants; Reactive Oxygen Species; Solutions; Water Pollutants, Chemical; Water Purification

Topics: Carbon; Catalysis; Chromium; Congo Red; Lasers; Metal Nanoparticles; Methylene Blue; Nitrophenols; Palladium; Spectrometry, X-Ray Emission; Spectroscopy, Fourier Transform Infrared; Textiles; Water Pollutants, Chemical

Quantitative analysis of organic pollutants in environmental water is an important issue for ecological environment and human health. In this paper, the quantitative analysis of rhodamine 6G (R6G) and p-nitrophenol (PNP) is performed by the surface enhanced Raman scattering (SERS) technology. The enhancement of Raman signals is achieved on the surface of an electrochemically roughened nano-Au film. The SERS performance depends on the microstructure of roughened nano-Au films, which is affected by the thickness of Au films and electrochemical roughening parameters. The structure-dependence of SERS performance is validated by finite element simulation of local electromagnetic field distribution. An obvious SERS effect of R6G with an enhancement factor of 10

Topics: Electrochemical Techniques; Gold; Metal Nanoparticles; Nitrophenols; Particle Size; Rhodamines; Spectrum Analysis, Raman; Surface Properties

Herein, we have reported the synthesis, characterization and catalytic activity of highly stable gold nanoparticles (Au NPs) using red cabbage extract (RCE) under UV irradiation. The anthocyanin groups predominantly existing in RCE play an essential role for biosynthesis of stable Au NPs. The reasons for using anthocyanins: 1) they act as chelating agents for preferentially reacting with gold ions (Au

Topics: Anthocyanins; Brassica; Catalysis; Gold; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Plant Extracts; Salts; Ultraviolet Rays

Topics: Adsorption; Carbon; Methacrylates; Molecular Imprinting; Nanospheres; Nitrophenols; Phenol; Polymerization; Polymers; Silanes; Waste Disposal, Fluid; Wastewater

The cellulose, which is one of the most abundant solid by-products of agriculture and forestry industry, has been successfully tested for the synthesis of nitrogen and phosphorus co-doped carbon-based metal-free catalysts (NPC) via freeze-drying the mixture of cellulose crystallite and ammonium phosphate, followed by annealing of the hydrogel under nitrogen atmosphere at 800 °C for 2 h. Different techniques including TEM, SEM, FTIR and XPS spectroscopy have been applied to characterize the as-prepared NPC, which presents flake-like morphology with N and P doping levels of 4.3 atom% and 10.66 atom%, respectively. The NPC exhibits excellent catalytic activity for the reduction of p-nitrophenol (p-NP). The turnover frequency (TOF) of the reduction of p-NP is as high as 2 × 10

Topics: Carbon; Catalysis; Cellulose; Density Functional Theory; Nitrogen; Nitrophenols; Oxidation-Reduction; Particle Size; Phosphorus; Surface Properties

Topics: Bacteria; Bacterial Physiological Phenomena; Biodegradation, Environmental; Biofilms; Bioreactors; Hydroquinones; Membranes, Artificial; Nitrophenols; Phenol; RNA, Ribosomal, 16S; Salinity; Wastewater; Water Pollutants, Chemical

To improve the electrocatalytic efficiency of the cathode and provide a wider pH range in the electro-Fenton process, N-doped multi-walled carbon nanotubes (NCNTs) and ferrous ion complexed with carboxylated carbon nanotubes (CNT-COOFe

Topics: Electrodes; Hydrogen Peroxide; Nanotubes, Carbon; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical

Central-radial bi-porous nanocatalysts were synthesized by derivation from dendritic porous supports with hierarchical inorganic functional layers. The nanostructure exhibited a high unit loading capacity, accessible internal catalytic sites and protective mesoporous shell encapsulation. The nanocatalysts were utilized for efficient and stable heterogeneous catalytic reduction of 4-nitrophenol to 4-aminophenol with robust magnetic recyclability.

Topics: Aminophenols; Catalysis; Ferric Compounds; Gold; Magnetic Phenomena; Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Porosity; Silicon Dioxide; Surface Properties

Topics: Bioreactors; Microbiota; Nitrification; Nitrogen; Nitrophenols; Sewage

A luminescent metal-organic framework Eu

Topics: Cresols; Europium; Fluorescent Dyes; Humans; Metal-Organic Frameworks; Nitrophenols; Pesticides; Spectrometry, Fluorescence

Topics: Acacia; Anti-Infective Agents; Candida albicans; Catalysis; Coloring Agents; Dynamic Light Scattering; Environmental Pollutants; Kinetics; Metal Nanoparticles; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Nitrogen; Nitrophenols; Organic Chemicals; Photoelectron Spectroscopy; Plant Extracts; Secondary Metabolism; Silver; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Static Electricity; Temperature; Thermogravimetry; X-Ray Diffraction

Chromophore-appended cyclodextrins combine the supramolecular loading capabilities of cyclodextrins (CDs) with the optical properties of the affixed chromophores. Among fluorescent materials, carbon dots (CNDs) are attractive and the feasibility of CND-appended CDs as sensors has been demonstrated by different authors. However, CNDs are intrinsically heterogeneous materials and their ulterior functionalization yields hybrid composites that are not well defined in terms of structure and composition. Inspired by the fluorescence properties of 5-oxo-1,2,3,5-tetrahydroimidazo[1,2-a]pyridine-7-carboxylic acid (IPCA), the most paradigmatic of the molecular fluorophores detected in CNDs, herein we report two highly efficient synthetic chemical strategies for the preparation of IPCA-appended CDs that behave as CND-based CD "turn off-on" biosensors suitable for the analysis of cholesterol and β-galactosidase activity. We have deconstructed the CND-CD systems to demonstrate that (i) the role of CNDs is limited to acting as a support for the molecular fluorophores produced during their synthesis and (ii) the molecular fluorophores suffice for the determination of the enzymatic activity based on the quenching by p-nitrophenol as a sacrificial quencher.

Topics: beta-Galactosidase; Biosensing Techniques; Carbon; Cholesterol; Cyclodextrins; Fluorescence; Fluorescent Dyes; Humans; Nitrophenols; Quantum Dots

To evaluate the ability of the haloarchaeon Haloferax volcanii to produce Ag and Au nanoparticles (NPs) and to characterize the obtained material in order to find relevant properties for future potential applications.. Nanoparticles were produced by incubating H. volcanii cells with the corresponding metal salt. In the presence of precursor salts, cultures evidenced a colour change associated to the formation of metallic nanostructures with plasmonic bands located in the visible range of the spectrum. X-ray fluorescence analysis confirmed the presence of Ag and Au in the NPs which were spherical, with average sizes of 25 nmol l. Haloferax volcanii is able to synthesize metallic NPs with interesting properties for technological applications.. Our data demonstrate the ability of H. volcanii to synthesize metal NPs and constitutes a solid starting point to deepen the study and explore novel applications.

Topics: Anti-Bacterial Agents; Borohydrides; Gold; Haloferax volcanii; Metal Nanoparticles; Nitrophenols; Particle Size; Silver

Topics: Animals; Anti-Bacterial Agents; Catalysis; Egg Shell; Microbial Sensitivity Tests; Nanocomposites; Nitrophenols; Plant Extracts; Plants; Reactive Oxygen Species; Silver

Topics: Coumarins; Ionic Liquids; Molecular Imprinting; Nitrophenols

In the present work, we demonstrated the biosynthesis of silver nanoparticles (AgNPs) by highly stable, economic and eco-friendly method using leaf extract of Terminalia arjuna (T. arjuna) and employing as a catalyst for the degradation of methyl orange (MO), methylene blue (MB), congo red (CR) and 4- nitrophenol (4-NP). The biosynthesis of AgNPs was visually validated through the appearance of reddish-brown color and further confirmed by the UV-spectra at 418 nm. The TEM and FE-SEM studies revealed the spherical shape of particles with size ranged between 10-50 nm. Face centered cubic crystalline nature of AgNPs was proved by XRD analysis. The negative value of zeta potential (-21.7) indicated the stability of AgNPs and elemental composition was confirmed by EDS. FT-IR analysis revealed the functional groups present in the plant extract trigger the biosynthesis of AgNPs. The AgNPs exhibited strong degradation of MO (86.68%), MB (93.60%), CR (92.20%) and 4NP (88.80%) by completing the reduction reaction within 20 min. The reaction kinetics followed the pseudo-first-order and displayed k-values (rate constant) 0.166 min

Topics: Azo Compounds; Catalysis; Coloring Agents; Congo Red; Methylene Blue; Nanoparticles; Nitrophenols; Plant Extracts; Plant Leaves; Silver; Terminalia

Biochar can both adsorb and degrade p-nitrophenol (PNP); however, the PNP degradation mechanism has not been well investigated. We prepared two biochars at pyrolysis temperatures of 500 °C (B500) and 700 °C (B700). Although B500 showed much stronger free radical signals (which are associated with organic degradation, according to previous studies), the apparent PNP degradation was approximately 3 times higher in the B700 system. The degradation increased significantly after the biochars were washed with water. According to a quantitative analysis of the sorption and degradation and two-compartment first-order kinetics modeling of the apparent removal kinetics, sorption occurred mainly in the initial period, whereas degradation continued throughout the removal process. The PNP degradation rate constant depended mainly on the external surface area at a relatively low concentration (200 mg/L) and was controlled by the microporous surface area at a relatively high concentration (800 mg/L). In addition, the apparent degradation did not depend on the biochar particle size. Therefore, PNP degradation may be related to the three-dimensional structure of the biochar in addition to the exposed external surface. The well-developed pore structure, more accessible surface, and larger electron exchange capacity of B700 may promote electron transfer between the biochar and PNP, and thus accelerate PNP degradation. This study demonstrates that various properties of the biochar may contribute to PNP degradation.

Topics: Adsorption; Charcoal; Nitrophenols; Oxidation-Reduction; Pinus

Reaction mechanisms between sulfide and iron (hydr)oxides are well-documented; however, the effect of sulfidation of iron (hydr)oxides on the fate of contaminants in dynamic anoxic/oxic environments is largely overlooked. Taking p-nitrophenol (p-NP) as a targeted contaminant, we studied its fate during the sulfidation of goethite in dynamic anoxic/oxic environments. In anoxic environments, the adsorbed p-NP on goethite was sharply released in the presence of S(-II) at two different concentrations (denoted as G1 and G2, respectively) due to lower affinity of p-NP on ═Fe-SH than ═Fe-OH. Then, the desorbed p-NP in the G1 system was completely reduced to

Topics: Ferric Compounds; Iron Compounds; Minerals; Nitrophenols; Oxidation-Reduction; Sulfides

In this study, cobalt oxide nanoparticles (Co

Topics: Agar; Catalysis; Chemical Precipitation; Cobalt; Congo Red; Environmental Pollutants; Hydrogels; Methylene Blue; Nanocomposites; Nitrophenols; Oxides

In this study, the reduction of iron-carbon internal electrolysis was reinforced by persulfate for p-nitrophenol removal. The effects of persulfate dosage, initial pH and iron-carbon mass ratio were comprehensively studied in batch experiments. In the system of iron-carbon internal electrolysis coupled with persulfate, the iron-carbon internal electrolysis and persulfate had a significant mutual influence, exhibiting a wide range of pH in the treatment process. Moreover, the coupled system also showed the remarkable removal and degradation efficiency of p-nitrophenol according to the contrast experiments. The satisfactory results should be attributed to the potential reduction of iron-carbon internal electrolysis, which was stimulated by persulfate to transform the nitro group to the amine group, accompanying the subsequent oxidation. Furthermore, persulfate possessed the ability that the dynamically destructive effect on external and internal of Fe

Topics: Charcoal; Electrolysis; Iron; Models, Theoretical; Nitrophenols; Oxidation-Reduction; Sulfates; Wastewater; Water Pollutants, Chemical; Water Purification

In this study, biochar R550, obtained from rice husk charred at 550 °C, was used to detoxify Cr(VI) and organic pollutant p-nitrophenol (PNP) with the cooperation of sulfite, simultaneously. Cr(VI) was mainly reduced by sulfite, and the reduction was accelerated by biochar. Also, the reactive oxygen species formed in-situ as a result of enhanced oxidation of sulfite with Cr(VI)/R550 system and the activation of O

Topics: Adsorption; Charcoal; Chromium; Nitrophenols; Oryza; Oxidation-Reduction; Water Pollutants, Chemical

A simple and fast vortex-assisted liquid-liquid microextraction (VA-LLME) combining with fluorescent carbon dots have been developed for the determination 4-nitrophenol (4-NP). The high fluorescent quantum yield (58.9%) fluorine doped carbon dots (F-CDs) were synthesized using tetrafluoroterephthalic acid as a fluorine source and using citric acid as a fluorine source and using ethylenediamine as a nitrogen source via a one-step hydrothermal method. F-CDs fluorescence was effectively quenched by 4-NP due to inner filter effect (IFE) and the strong interactions between functional groups (-COOH,-OH, -NH

Topics: Carbon; Fluorine; Fluorometry; Liquid Phase Microextraction; Nitrophenols; Quantum Dots; Water Pollutants, Chemical

This study investigates an environmentally benign approach to generate platinum nanoparticles (Pt NP) supported on the reduced graphene oxide (RGO) by non-edible gum waste of gum kondagogu (GK). The reaction adheres to the green chemistry approach by using an aqueous medium and a nontoxic natural reductant-GK-whose abundant hydroxyl groups facilitate in the reduction process of platinum salt and helps as well in the homogenous distribution of ensued Pt NP on RGO sheets. Scanning Electron Microscopy (SEM) confirmed the formation of kondagogu gum/reduced graphene oxide framed spherical platinum nanoparticles (RGO-Pt) with an average particle size of 3.3 ± 0.6 nm, as affirmed by Transmission Electron Microscopy (TEM). X-ray Diffraction (XRD) results indicated that the Pt NPs formed are crystalline with a face-centered cubic structure, while morphological analysis by XRD and Raman spectroscopy revealed a simultaneous reduction of GO and Pt. The hydrogenation of 4-nitrophenol could be accomplished in the superior catalytic performance of RGO-Pt. The current strategy emphasizes a simple, fast and environmentally benign technique to generate low-cost gum waste supported nanoparticles with a commendable catalytic activity that can be exploited in environmental applications.

Topics: Bixaceae; Catalysis; Graphite; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Platinum; X-Ray Diffraction

Topics: Curcumin; Electrochemical Techniques; Food Contamination; Fruit and Vegetable Juices; Graphite; Insecticides; Limit of Detection; Malus; Methyl Parathion; Nanoparticles; Nickel; Nitrophenols; Reproducibility of Results; Rivers; Solanum lycopersicum; Water Pollutants, Chemical

Carbon dots (CDs) have broad prospective applications in various fields, and expanding the applications of fluorescent CDs, especially for CDs derived from bacteria, is a major research goal. In this study, novel CDs derived from Escherichia coli BW25113 (WT) were successfully synthesized via a one-step hydrothermal method. Unlike previously developed CDs-E. coli, CDs-WT can be used for microbial imaging of both live and dead cells. We demonstrated the biocompatibility, excellent penetrability, and nontoxic characteristics of CDs-WT for use as fluorescent probes for bioimaging both in vitro and in vivo. Importantly, we provide the first demonstration of CDs-WT distribution in various organs of mice, including the ability to cross the blood-brain barrier and the potential for rapid excretion through the intestines. Additionally, CDs-WT can be instantly utilized as a fluorescent probe for the highly selective and rapid detection of p-nitrophenol (p-NP) by the inner filter effect, with a limit of detection for p-NP of 11 nM, the lowest value reported to date. Hence, our results demonstrate the feasibility of p-NP detection and extend the bio-imaging applications of CDs prepared from bacteria.

Topics: Animals; Bacillus cereus; Carbon; Cell Line, Tumor; Escherichia coli; Fluorescent Dyes; Humans; Limit of Detection; Male; Mice, Inbred BALB C; Microscopy, Confocal; Microscopy, Fluorescence; Nitrophenols; Quantum Dots; Saccharomyces cerevisiae; Tissue Distribution

In this paper, the modified multi-walled carbon nanotubes were prepared by β-cyclodextrin denoted as β-CD-MWNTs. The structure and morphology of β-CD-MWNTs was characterized by TEM and the dynamic adsorption of p-nitrophenol on β-CD-MWNTs was studied by the Thomas model. Some affecting factors of dynamic adsorption and the adsorbent regeneration process such as the sewage concentration, the amount of absorbent in column, including the type of reagent, solid-liquid ratio, regeneration time, and regeneration times were investigated and optimized. The results indicated that the p-nitrophenol removal rate could reach 84% under stuffing 2 g β-CD-MWNTs. The curves of p-nitrophenol's dynamic adsorption conformed to the Thomas model. Moreover, the adsorption capacity of regenerated β-CD-MWNTs was similar to the fresh β-CD-MWNT column. The optimal conditions of regenerations of β-CD-MWNTs were shown as follows: the type of reagent is anhydrous ethanol, the solid-liquid ratio is 200:40 (mg/mL) and the regeneration time is 120 min.

Topics: Adsorption; beta-Cyclodextrins; Cyclodextrins; Models, Chemical; Nanotubes, Carbon; Nitrophenols

The chemical p-nitrophenol (PNP) is a priority pollutant, and PNP wastewater is highly toxic and resistant to biodegradation. The traditional physical and chemical methods (adsorption, extraction, and oxidation) for treating PNP wastewater have the disadvantages of complicated processes, high costs and secondary pollution generation. In this study, two integrated membrane-aerated bioreactor systems (RA and RB) with anoxic and aerated zones were constructed to enhance PNP biodegradation. The results showed that a helical silicone rubber membrane module displayed a high oxygen supply rate under a low membrane aeration pressure, and the hydraulic flow state of the reactor approached ideal mixing. At an influent PNP concentration of 500 mg/L, the average removal rates of PNP, chemical oxygen demand (COD) and total nitrogen (TN) reached 95.86%, 89.77%, and 94.81%, respectively, for RA and 89.48%, 74.26% and 64.78%, respectively, for RB, indicating efficient simultaneous PNP and nitrogen removal. Compared with that of RB, the pre-anoxic zone in RA not only performed detoxification pretreatment but also enhanced PNP degradation and denitrification effects, which relieved the biological treatment burden of the subsequent aerated zone. Based on these comprehensive analyses of reactor performance, the hydroquinone pathway might be the main route in the aerobic degradation of PNP.

Topics: Bioreactors; Membranes, Artificial; Nitrogen; Nitrophenols; Water Purification

CYP2E1 is a mammalian cytochrome P450 enzyme, which oxidizes a structurally diverse class of endogenous and exogenous (xenobiotic) compounds. Best studied is the role of CYP2E1 in phase I metabolism of xenobiotics including alcohol. CYP2E1 metabolizes ethanol and is active in generating reactive oxygen species (ROS) and subsequent oxidative stress in the hepatic tissues. Several studies have shown and discussed the importance of CYP2E1 in the hepatotoxic actions of alcohol. However, the vast majority assessed the CYP2E1 activity only in isolated microsomes. Here, we aimed to develop and optimize a fast and easy method to assess alcohol-induced CYP2E1 activity in hepatocytes in vitro applying oxidation of para-nitrophenol to para-nitrocatechol as specific substrate probe. Using hepatoma cells with and without stable CYP2E1 expression and primary human hepatocytes, we established specific methodology to assess CYP2E1 catalytic activity and its induction by ethanol in a small number of cells and in a very short time.

Topics: Biological Assay; Cytochrome P-450 CYP2E1; Dose-Response Relationship, Drug; Ethanol; Hep G2 Cells; Hepatocytes; Humans; Nitrophenols; Oxidation-Reduction; Primary Cell Culture

Topics: Catalysis; Congo Red; Dynamic Light Scattering; Gold; Laccase; Macromolecular Substances; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Polymers; Spectrophotometry, Ultraviolet; Time Factors

Citrate-capped gold nanoparticles (AuNPs) modified with thrombin-binding aptamer are often implemented for colorimetric, fluorescent, and electrochemical detection of thrombin in an aqueous solution. However, researchers have rarely explored the application of fibrinogen-modified AuNPs (F-AuNPs) for thrombin sensing. We present a simple, inexpensive, sensitive, and selective probe for colorimetric assay of thrombin through combining thrombin-induced inclusion of F-AuNPs into Fibrin and F-AuNPs-catalyzed reduction of 4-nitrophenol with an excess amount of NaBH

Topics: Colorimetry; Female; Fibrin; Fibrinogen; Gold; Humans; Metal Nanoparticles; Nitrophenols; Sensitivity and Specificity; Thrombin; Young Adult

Herein, we report the excellent catalytic activity of DNA-AgNCs toward 4-nitrophenol reduction and a strategy for improving their catalytic performance by forming bimetallic clusters (Ag-Pd, Ag-Au and Ag-Pt). The analogous influence of sequences on the catalytic activity of these nanoclusters is disclosed, which is quite different from their erratic fluorescence properties.

Topics: Catalysis; DNA; Fluorescence; Gold; Nitrophenols; Oxidation-Reduction; Palladium; Platinum; Silver

Topics: Alkaline Phosphatase; Cadmium Compounds; Energy Transfer; Fluorescence; Fluorescent Dyes; Humans; Limit of Detection; Nitrophenols; Organophosphorus Compounds; Quantum Dots; Spectrometry, Fluorescence; Sulfides; Tellurium

The hepatic cytochrome p450 enzymes 1 A, 2A19 and 2E1 is very important for the elimination of skatole from the body of pigs. Impaired skatole metabolism, results in skatole accumulation, which give rise to off flavor of the meat. Several metabolites of skatole has been identified, however the role of these metabolites in the inhibition of the skatole metabolizing enzymes are not documented. Using microsomes from pigs and fish, we determined the ability of several skatole metabolites to inhibit CYP1 A, CYP2A19 and CYP2E1 dependent activity. Our results show that 2-aminoacetophenone is an inhibitor of porcine CYP2A19 and CYP2E1 activity, but not the piscine orthologues. In conclusion, there is species specific differences in the inhibition of CYP1 A and CYP2A19 dependent metabolism of probe substrates. This is relevant to the evaluation of different model systems and to the reduction of off flavor of meat.

Topics: Acetophenones; Animals; Coumarins; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Cytochrome P-450 Enzyme System; Fishes; Liver; Male; Microsomes, Liver; Nitrophenols; Oxazines; Red Meat; Seafood; Skatole; Species Specificity; Swine

Geobacter sulfurreducens and anthraquinone-2-sulfonate (AQS) were used suspended and immobilized in barium alginate during the biotransformation of 4-nitrophenol (4-NP). The assays were conducted at different concentrations of 4-NP (50-400 mg/L) and AQS, either in suspended (0-400 μM) or immobilized form (0 or 760 μM), and under different pH values (5-9). G. sulfurreducens showed low capacity to reduce 4-NP in absence of AQS, especially at the highest concentrations of the contaminant. AQS improved the reduction rates from 0.0086 h

Topics: Alginates; Anthraquinones; Biotransformation; Geobacter; Hydrogen-Ion Concentration; Nitrophenols; Oxidation-Reduction

A microorganism template approach has been explored for the fabrication of various well-defined three-dimensional (3D) structures. However, most of these templates suffer from small size (few μm), difficulty to remove the template, or low surface area, which affect their potential use in different applications or makes industrial scale-up difficult. Conversely, foraminifer's microorganisms are large (up to 200 mm), consist of CaCO

Topics: Coloring Agents; Ethanol; Foraminifera; Metals; Nanostructures; Nitrophenols; Oxidation-Reduction; Oxides; Sulfides; Water Purification

Stearyl trimethyl ammonium chloride (STAC) and ethylenediamine (En) were successfully implanted into montmorillonite (MMt) interlayer to fabricate the novel adsorbent STAC-En-MMt for the simultaneous adsorption of Cu

Topics: Adsorption; Bentonite; Ethylenediamines; Ions; Kinetics; Metals, Heavy; Models, Chemical; Nitrophenols; Spectroscopy, Fourier Transform Infrared; Temperature; Water Pollutants, Chemical; X-Ray Diffraction

Gold nanoparticles (AuNPs) were prepared by a solvothermal method using sodium alginate (SA) as both, the reductant and stabilizer. The formation of SA-AuNPs was confirmed by UV-Vis spectroscopy, transmission electron microscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy. SA-AuNPs were functionalized with fluorescent 3-(dansylamino)phenylboronic acid (DAPB) moieties, through interactions between boronic acids and diol groups. The fluorescence resonance energy transfer from DAPB to AuNPs quenched the fluorescence of DAPB. In the presence of glucose, the competitive binding of DAPB with glucose resulted in the release of assembled DAPB from the surface of SA-AuNPs, resulting in the increase in fluorescence intensity. Furthermore, catalytic reduction of 4-nitrophenol was monitored via spectrophotometry using DAPB functionalized SA-AuNPs probes as catalyst. Compared to SA-AuNPs, the nanoprobes exhibited higher catalytic rates.

Topics: Alginates; Boronic Acids; Dansyl Compounds; Glucose; Gold; Metal Nanoparticles; Nitrophenols; Particle Size; Surface Properties

Palladium (Pd)-catalyzed reactions mostly show structure sensitivity: i.e., the selectivity and activity of the reactions are highly dependent on the arrangement of Pd atoms. In this regard, branched Pd nanoparticles show enhanced catalytic performance owing to the presence of low coordinated Pd atoms. In this paper, a novel solution-phase synthesis of flower-like Pd nanodendrites using ribonucleic acid (RNA) as a capping agent and ascorbic acid as a reducing agent was described. On the other hand, the co-use of polyvinylpyrrolidone (PVP) and potassium bromide (KBr) instead of RNA at the same synthesis conditions led to cuboid nanoparticles, while the sole use of ascorbic acid resulted in faceted nanoparticles. The formation of nanodendritic morphology was attributed to the RNA-assisted growth through particle attachment. This scenario was supported by TEM analysis that demonstrated the aggregation of small particles to form larger nanoparticles at the onset of the reaction. The shape and size of the nanoparticles could be readily tuned by the RNA content used. XPS confirmed the formation of metallic Pd nanoparticles. The presence of crystalline planes of {1 1 1}, {2 0 0}, {2 2 0}, {3 1 1} and {2 2 2} was demonstrated by XRD and SAED analyses. The Pd nanodendrites were used for the reduction of p-nitrophenol (PNP) and 2,4,6-trinitrotoluene (TNT), and reduction rate constants (k) were calculated as 1.078 min

Topics: Bromides; Catalysis; Dendrites; Kinetics; Metal Nanoparticles; Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Particle Size; Potassium Compounds; Povidone; RNA; Surface Properties; Trinitrotoluene

The glycosyltransferases (GTs) are an important subclass of enzymes that catalyze the biosynthesis of glycosidic bonds in oligosaccharides, polysaccharides and glycoconjugates by transferring a sugar residue from a donor substrate to an acceptor substrate. The membrane-associated GTs play a vital role in the biosynthesis of bacterial cell-wall polysaccharides. Characterization and quantification of GT activities is important for studies of biosynthesis of polysaccharides, drug target development, and production of bacterial products. In this chapter, colorimetric assays for the measurement of GT activities will be presented. Assays for GTs acting on monosaccharide-derivatives are based on the cleavage of unreacted glycosyl-p-nitrophenol acceptors followed by detection of p-nitrophenolate. GT reactions coupled with phosphatases and detection of inorganic phosphate are suitable for most GTs. These assays permit convenient quantification of GT activities and kinetics without the use of radioactive sugars.

Topics: Bacterial Proteins; Colorimetry; Enzyme Assays; Glycosyltransferases; Humans; Kinetics; Meningococcal Infections; Monosaccharides; Neisseria meningitidis; Nitrophenols; Substrate Specificity

The adsorption properties of alfalfa biochar, which is produced via high-temperature pyrolysis for 3 h, were improved by activating it with acid pickling and reheating for 2 h (named AB). The alfalfa biochar prepared under various conditions, such as ultrapure water washing (named AWB3), acid pickling (named APB3) without reheating and cracking, and pyrolyzing of alfalfa for 5 h before ultrapure water washing (named AWB5) or acid pickling (named APB5), were used as controls. The adsorption capacity of biochars was detected by using p-nitrophenol (PNP) as a model pollutant. The corresponding results showed that the specific surface area (SSA) of AB (119.99 m

Topics: Adsorption; Charcoal; Kinetics; Medicago sativa; Nitrophenols; Photoelectron Spectroscopy; Pyrolysis; Spectroscopy, Fourier Transform Infrared; Temperature

Biodegradation of recalcitrant organic compounds in microbial fuel cell (MFC) is limited, due to its strong electron affinity and persisted in anaerobic condition. In this study, Pseudomonas monteilii LZU-3 degraded p-nitrophenol (PNP) and generated current at 100 mg L

Topics: Bioelectric Energy Sources; Electricity; Electrodes; Nitrophenols

A novel dual-mode analytical method by employing nanozyme was developed for the detection of organophosphorus pesticides (OPP) for the first time. The detection principle is that the pesticide could be hydrolyzed to para-nitrophenol (p-NP) in the presence of nanoceria as nanozyme. p-NP exhibits the bright yellow color, and its color intensity has a positive correlation with the pesticide concentration. Meanwhile, the characteristic absorption peak at 400 nm of p-NP increases gradually with the raised concentration of pesticide. Therefore, a dual-mode method including smartphone-based colorimetric and spectroscopic strategies was rationally developed. Herein, methyl-paraoxon was selected as the representative compound. Under the optimum conditions, the detection limits of both two strategies were calculated to be 0.42 μmol L

Topics: Cerium; Colorimetry; Environmental Pollutants; Limit of Detection; Nanoparticles; Nitrophenols; Organophosphorus Compounds; Paraoxon; Pesticides; Plants, Medicinal; Spectrophotometry

Topics: Adsorption; Aluminum Silicates; Anions; Arsenic; Carbon; Catalysis; Charcoal; Chromium; Hydrocarbons; Iron; Lead; Lignin; Metals, Heavy; Methylene Blue; Nickel; Nitrogen; Nitrophenols; Porosity; Pyrolysis; Soil; Soil Pollutants; Wastewater; Water Pollutants, Chemical

The activities of heterogeneous Fenton and Photo-Fenton processes using pyrite (FeS

Topics: Catalysis; Hydrogen Peroxide; Hydroxyl Radical; Iron; Light; Nitrophenols; Oxidation-Reduction; Spectrum Analysis; Sulfides; Superoxides

Silver nanoparticle was synthesized using D-glucosamine chitosan base as green reducing agent at elevated temperature in alkaline pH ranges. The excess of D-glucosamine chitosan base was used as it is both stabilizing and reducing agent at different pHs, regulates the shape and size of the silver nanoparticles. The progressive growth of silver nanoparticles was monitored by UV-Visible spectral studies. A sharp peak at 420 nm indicates the formation of spherical silver nanoparticles. The size and shape of silver nanoparticles were observed from Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) methods. The anisotropically grown nanoparticles were used as probe for Surface Enhanced Raman Studies (SERS) using ATP (4-aminothiophenol) as a model system. The catalytic behavior of silver nanoparticles was exploited for 4-nitrophenol reduction and observed that the reduction reaction follows pseudo first order kinetics with a rate constant 0.65 min. The antibacterial activity of silver nanoparticles was also tested for both gram-positive and -negative microorganisms, in which higher zone of inhibition was observed for gram negative microorganism.

Topics: Anti-Bacterial Agents; Catalysis; Chitosan; Escherichia coli; Glucosamine; Green Chemistry Technology; Metal Nanoparticles; Microbial Sensitivity Tests; Nanotechnology; Nitrophenols; Oxidation-Reduction; Particle Size; Silver

Lignin, as the second largest natural polymer in nature, has great practical application value. Three-dimensional silver/lignin/PAM hydrogels have been successfully prepared via a rapid and convenient assembly process, showing good catalytic hydrogenation ability and stability in batch and dynamic catalytic processes of p-nitrophenol. It can be seen from the characterization results that abundant amino groups in the catalyst carrier can disperse silver ions homogeneously and limit the growth of silver nanoparticles in the reduction process with sodium borohydride. At room temperature, the catalytic process can be completed in about 5 min by using this catalyst and can maintain about 100 min of efficient catalysis in the dynamic catalytic experiment, the conversion rate can reach about 80%. After 10 times use, the catalyst still maintained good catalytic performance and the conversion rate could be kept at 97%.

Topics: Acrylic Resins; Catalysis; Hydrogels; Lignin; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Silver

The present research highlights the use of a montmorillonite clay to remove p-nitrophenol (PNP) from aqueous solution. The montmorillonite clay was characterized using powder X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, X-ray fluorescence, Brunauer-Emmett-Teller analyses, and zero point charge in order to establish the adsorption behavior-properties relationship. The physiochemical parameters like pH, initial PNP concentration, and adsorbent dose as well as their binary interaction effects on the PNP adsorption yield were statistically optimized using response surface methodology. As a result, 99.5% removal of PNP was obtained under the optimal conditions of pH 2, adsorbent dose of 2 g/l, and PNP concentration of 20 mg/l. The interaction between adsorbent dose and initial concentration was the most influencing interaction on the PNP removal efficiency. The mass transfer of PNP at the solution/adsorbent interface was described using pseudo-first-order and intraparticle diffusion. Langmuir isotherm well fitted the experimental equilibrium data with a satisfactory maximum adsorption capacity of 122.09 mg/g. The PNP adsorption process was thermodynamically spontaneous and endothermic. The regeneration study showed that the montmorillonite clay exhibited an excellent recycling capability. Overall, the montmorillonite clay is very attractive as an efficient, low-cost, eco-friendly, and recyclable adsorbent for the remediation of hazardous phenolic compounds in industrial effluents.

Topics: Adsorption; Bentonite; Clay; Diffusion; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Surface Properties; Thermodynamics; Water Pollutants, Chemical; Water Purification

To evaluate Pseudomonas monteilii strain PN1 for the removal efficiency of P-nitrophenol (PNP) in soils and its growth promotion of maize (Zea mays L.) seedlings under drought and saline-alkali stress.. PN1 can survive in soils contaminated with PNP dosage between 90 and 155 mg/kg and considerably improved the removal PNP efficiency in soils. Drought and saline-alkali stress reduced maize seedling growth (root length, shoot height and dry or fresh weight) and improved the antioxidant enzyme activities and malondialdehyde (MDA) and proline (PRO) contents. However, maize seedlings treated with PN1 remarkably promoted their growth compared with the control. The reduction in antioxidant enzyme activities and MDA and PRO contents was significant. This result may be correlated to the increased tolerance of maize seedlings to drought and saline-alkali stress.. Application of P. monteilii PN1 can be an extremely useful approach for the development of bioinoculants in improving plant tolerance to several abiotic stresses and removing PNP in soils to ensure secure crop production.

Topics: Alkalies; Biotransformation; Droughts; Nitrophenols; Pseudomonas; Salinity; Seedlings; Stress, Physiological; Zea mays

A fully mechanized Arduino-controlled multi-pumping flow analysis system and procedure for the determination of β-galactosidase activity are proposed. The applied bioanalytical method is based on the determination of p-nitrophenol formed in the course of enzyme-catalyzed hydrolysis of p-nitrophenyl-galactopyranosides. The photometric detection is performed using dedicated flow-through optoelectronic detector made of paired light emitting diodes. The developed bioanalytical system was applied for evaluation of optimal enzyme detection conditions (pH, temperature and reaction time), selection of appropriate substrate for the assays, comparison of enzymes of different origins (isoenzymes), detection of β-galactosidase inhibitor and finally to the determination of enzyme activity in some dietary supplements dedicated for people suffering from lactose intolerance. Depending on measurements conditions the developed bioanalytical system allows determination of β-galactosidase in the wide range of activity (up to 15 U/mL at detection limit ca 0.01 U/mL) with high sample flowthroughput (up to 30 detections per hour). Additionally, the potential utility of the developed analytical system for amyloglucosidase activity assays has been demonstrated.

Topics: beta-Galactosidase; Biocatalysis; Enzyme Assays; Galactose; Hydrogen-Ion Concentration; Isoenzymes; Nitrophenols; Temperature

A facile and economical hydrothermal approach is reported for preparing fluorescent nitrogen-doped carbon dots (N-CDs) via using o-phenylenediamine and dicyandiamine. Herein, the bright-yellow-emissive N-CDs are uniformly dispersed spherical nanoparticles with favorable solubility, superior photoluminescence and photobleaching resistance. The fluorescence intensity of N-CDs is linearly quenched by 4-nitrophenol (4-NP) over a concentration range of 0.1-39 μM, corresponding to a detection limit (LOD) of 0.05 μM. Based on this phenomenon, a 4-NP-detection method is exploited and applied to real samples analysis. The synthesized N-CDs are highly biocompatible and capable of biological imaging. Therefore, they are excellent candidates for live biological imaging.

Topics: Animals; Caenorhabditis elegans; Escherichia coli; Fluorescent Dyes; Hydrogen-Ion Concentration; Limit of Detection; Molecular Imaging; Nitrogen; Nitrophenols; Phenylenediamines; Photobleaching; Quantum Dots; Solubility; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Water Pollutants, Chemical; X-Ray Diffraction

Chicken feather-derived high-surface-area porous activated carbon (CFAC) material was prepared using chemical activation. A new composite composed of Ru-Pd nanoparticles supported on CFAC (Ru-Pd@CFAC) has been prepared by microwave-thermal reduction in the presence of the support. Characterization by XRD, Raman, BET, FE-SEM/TEM, FT-IR, TGA, XPS, HAADF-STEM-EDS, H

Topics: Alloys; Aniline Compounds; Animals; Carbon; Catalysis; Chickens; Chromium; Ferricyanides; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Porosity; Recycling; Ruthenium; Spectrophotometry; Spectroscopy, Fourier Transform Infrared; Temperature; Waste Disposal, Fluid

Activated carbon cloths (ACCs) were used as biofilms supports in the anaerobic biotransformation of 4-nitrophenol (4NP). As received ACC material (AW) was oxidized with HNO

Topics: Biodegradation, Environmental; Biofilms; Bioreactors; Biotransformation; Charcoal; Nitrophenols; RNA, Ribosomal, 16S; Sewage; Waste Disposal, Fluid

In this study, waste corn husk was used for the synthesis of an effective adsorbent (cornhusk activated carbon, CHAC) and by treating at two different temperatures, 250 °C (CHAC-250) and 500 °C (CHAC-500) to check adsorption efficiency. The synthesized adsorbents were characterized with the help of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy, Particle size analysis and x-ray diffraction (XRD), which revealed the different properties of the two adsorbents. The synthesized adsorbents were applied for the removal of phenol and p-nitrophenol (PNP) from aqueous solution. CHAC-500 was more efficient than the CHAC-250. The maximum adsorptions of phenol and PNP by CHAC-500 were ∼96% and ∼94%, respectively, while the maximum adsorptions of phenol and PNP by CHAC-250 were ∼81% and ∼84%, respectively. The adsorption processes were best fitted with the Langmuir adsorption isotherm and the pseudo-second-order kinetic model. The adsorption of phenol was an exothermic process, while that of PNP was an endothermic process, on both adsorbents.

Topics: Adsorption; Charcoal; Kinetics; Nitrophenols; Phenol; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Water Pollutants, Chemical; Zea mays

The toxicity of an organophosphorus (OP) insecticide, methyl parathion (MP), and its hydrolysis product, p-nitrophenol (PNP), to the native Australian cladoceran species, Daphnia carinata, was assessed. Both MP and PNP were stable in cladoceran water during the test period. D. carinata was sensitive to both MP and PNP; however, the parent compound was more toxic than its metabolite. This is the first study that demonstrated the acute toxicity of MP and PNP towards an Australian daphnid species. The present investigation emphasizes the need for including the native taxa as non-target test organisms while evaluating the toxicity of environmental pollutants.

Topics: Animals; Australia; Daphnia; Dose-Response Relationship, Drug; Insecticides; Methyl Parathion; Nitrophenols; Toxicity Tests, Acute

p-Nitrophenol (p-NP) pollutants are widely present in soil and aquatic environments and can seriously impair the health of living beings. Hence, a rapid, sensitive, and selective method for p-NP detection is urgently needed. Herein, for the first time, we successfully synthesized fluorescent carbon dots (CDs) from Bacillus cereus (BC) via a one-step hydrothermal process. The obtained CDs-BC can be applied as a rapid, highly selective, and sensitive sensor for p-NP detection. The fluorescence quenching efficiency of the CD-BC sensor exhibited excellent linear responses with p-NP concentrations at both 0.3-6.5 μM and 6.5-30 μM, with a detection limit of 0.11 μM. The mechanism of p-NP detection is based on the inner filter effect (IFE). Preliminary bacteria, cell, and animal studies showed that the as-prepared CDs-BC possess high photostability, excellent biocompatibility, low or no biotoxicity, and multicolor fluorescence emission properties; furthermore, they can be rapidly excreted from the body of mice, which suggests their potential for applications in the biomedical field.

Topics: Animals; Bacillus cereus; Carbon; Fluorescent Dyes; HeLa Cells; Humans; Limit of Detection; Mice; Microscopy, Confocal; Nitrophenols; Quantum Dots; Serratia marcescens; Tissue Distribution

In this study, a horizontally rotating disc recirculated (HRDR) photoreactor equipped with two UV lamps (6 W) was designed and fabricated for photocatalytic removal of p-nitrophenol (PNP). Photocatalyst (TiO

Topics: Catalysis; Nanoparticles; Nitrophenols; Photolysis; Polyethylene; Titanium; Ultraviolet Rays; Water Purification

Aqueous solutions of p-nitrophenol (PNP) were treated with UV-activated potassium periodate (UV/KPI) in an efficient photo-reactor. Either periodate or UV alone had little effect; however, their combination led to a significant degradation and mineralization. The response surface methodology was employed for design of experiments and optimization. The optimum conditions for treatment of 30 mg/L of the substrate were determined as [KPI] = 386.3 mg/L, pH = 6.2 and T = 34.6°C, under which 79.5% degradation was achieved after 60 min. Use of 25 and 40 kHz ultrasound waves caused the degradation to enhance to 88.3% and 92.3%, respectively. The intermediates were identified by gas chromatography-mass spectroscopy analysis, leading to propose the reaction pathway. The presence of water conventional bicarbonate, chloride, sulfate and nitrate anions caused unfavorable effects in efficiency. Meanwhile, the kinetic study showed that PNP degradation follows a pseudo-first-order reaction and the activation energy was determined. The irradiation energy consumption required for one order of magnitude degradation was estimated as 11.18 kWh/m

Topics: Nitrophenols; Oxidation-Reduction; Periodic Acid; Solutions; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification

This work was conducted in order to evaluate an instance of bioaugmentation, namely, the addition of a novel p-nitrophenol (PNP)-degrading bacterium Methylobacterium sp. C1 coaggregated with two other broad-spectrum coaggregating strains (Bacillus megaterium T1 and Bacillus cereus G5) within sequence batch biofilm reactors (SBBRs). Results showed that biofilms consisting of C1 and coaggregating bacteria were resistant to shock loads and were more efficient at PNP removal. High-throughput sequencing data revealed that biofilms formed in the presence of the coaggregating bacteria demonstrated greater microbial diversity. These results suggest that broad-spectrum coaggregating bacteria may be capable of mediating the immobilization of exogenous degrading bacteria into biofilms, rendering them more resistant to toxic compounds and environmental stresses. This represents the first attempt to assess the bioaugmentation of PNP-contaminated wastewater treatment through the utilization of broad-spectrum coaggregating bacteria.

Topics: Bacteria; Biofilms; Bioreactors; Nitrophenols; RNA, Ribosomal, 16S; Water Pollutants, Chemical

This study reports a one-pot and eco-friendly method for the synthesis of spherical ibuprofen derived silver nanoparticles (IBU-AgNPs) in aqueous media using ibuprofen analgesics drug as capping as well as reducing agent. Formation of AgNPs occurred within a few min (less than 5 min) at room temperature without resorting to any harsh conditions and hazardous organic solvents. Synthesized AgNPs were characterized with common analytical techniques. Transmission electron microscope (TEM) images confirmed the formation of spherical particles having a size distribution in the range of 12.5 ± 1.5 nm. Employment of IBU analgesic aided the control of better size distribution and prevented agglomeration of particles. Such AgNPs solution was highly stable for more than two months when stored at ambient temperature. The IBU-AgNPs solution showed excellent ultra-rapid catalytic activity for the complete degradation of toxic 4-nitrophenol (4-NPh) into non-toxic 4-aminophenol (4-APh) within 40 s. AgNPs were recovered with the help of water insoluble-room temperature ionic liquid and reused with enhanced catalytic potential. This method provides a novel, rapid and economical alternative for the treatment of toxic organic pollutants to maintain water quality and environmental safety against water pollution. It is extendable for the control of other reducible contaminants in water as well. Furthermore, this catalytic activity for an effective degradation of organic toxins is expected to play a crucial role for achieving the Sustainable Development Goal 6 set by United Nations.

Topics: Catalysis; Ibuprofen; Ionic Liquids; Ions; Metal Nanoparticles; Models, Chemical; Nitrophenols; Silver

Light-assisted in vivo synthesis of gold nanoparticles (NPs) from aqueous solutions of dilute Au

Topics: Catalysis; Gold; Green Chemistry Technology; Kinetics; Light; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Photosynthesis; Seaweed; Surface Properties; Ulva

Electrolysis was applied to enhance the efficiency of micron-size zero valent iron (mFe

Topics: Corrosion; Electrolysis; Iron; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical

The performance of a microbial fuel cell (MFC) to degrade oxyfluorfen was investigated. Approximately 77% of 50 mg/L oxyfluorfen was degraded within 24 h by anodic biofilm. The temperature, pH, and initial oxyfluorfen concentration had a significant effect on oxyfluorfen degrading, and a maximum degradation rate of 94.95% could theoretically be achieved at 31.96 °C, a pH of 7.65, and an initial oxyfluorfen concentration of 120.05 mg/L. Oxyfluorfen was further catabolized through various microbial metabolism pathways. Moreover, the anodic biofilm exhibited multiple catabolic capacities to 4-nitrophenol, chloramphenicol, pyraclostrobin, and sulfamethoxazole. Microbial community analysis indicated that functional bacteria Arcobacter, Acinetobacter, Azospirillum, Azonexus, and Comamonas were the predominant genera in the anodic biofilm. In terms of the efficient removal of various organic compounds and energy recovery, the MFC seemed to be a promising approach for the treatment of environmental contaminants.

Topics: Bioelectric Energy Sources; Electricity; Electrodes; Halogenated Diphenyl Ethers; Nitrophenols

Silver nanoparticles (AgNPs) have been synthesized via green route using an aqueous extract of Palm date fruit pericarp extract. The appearance of the yellow color and the surface resonance plasmon (SRP) band at around 400-450nm in UV-Visible spectroscopy initially reveals the formation of AgNPs. The particle size, crystalline nature, and size distribution was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) ring patterns, energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) techniques. The particles size ranged ca. 3nm to 30nm and are spherical in shape. The microbial activity of biogenic AgNPs was tested on clinical multiple drug resistance Staphylococcus aureus, Escherichia coli and Candida albicans reference strain. Zones of inhibition growth increases with [AgNPs]. The results suggest that the particle tested in this study certainly mediate the inhibition of bacterial and fungus growth. To overcome the serious problems related to environment like discharge of hazardous chemicals to water bodies, AgNPs have been found to be very important in the catalytic degradation of 4-nitrophenol. The rate of degradation strongly depends on the sun light exposure. Based on the chemical and kinetic studies, an attempt has been made to elucidate the mechanism of AgNPs formation.

Topics: Anti-Infective Agents; Candida albicans; Catalysis; Dynamic Light Scattering; Escherichia coli; Fruit; Green Chemistry Technology; Metal Nanoparticles; Microscopy, Electron, Scanning; Nitrophenols; Particle Size; Phoeniceae; Photolysis; Plant Extracts; Silver; Spectrometry, X-Ray Emission; Spectrophotometry; Staphylococcus aureus; Sunlight; Surface Plasmon Resonance

Carbon spherules from ginkgo seed starch were prepared through stabilization and carbonization processes. The ginkgo seed starch was first stabilized at 195 °C for 18 h, then carbonized at 500 °C for 2 h under an N₂ atmosphere. The characterization results confirmed that carbon spherules were in the size range of 10-20 μm. Experimental data were also evaluated to find out the kinetic characteristics of phenols on the carbon spherules during the adsorption process. Adsorption processes for phenol,

Topics: Carbon; Chlorophenols; Environmental Pollutants; Ginkgo biloba; Microscopy, Electron, Scanning; Nitrophenols; Phenols; Seeds; Spectroscopy, Fourier Transform Infrared; Starch; Thermodynamics; X-Ray Diffraction

A Gram-positive bacterium, Rhodococcus wratislaviensis strain 9, was isolated from groundwater contaminated with nitrophenolics and trichloroethene following enrichment culture technique. The cells of strain 9 grown on LB broth (uninduced) degraded 720 μM p-nitrophenol (PNP) within 12 h, and utilized as a source of carbon and energy. Orthogonal experimental design analysis to determine optimal conditions for biodegradation of PNP showed that pH had a significant positive effect (P ≤ .05) on bacterial degradation of PNP, while glucose, di- and tri-nitrophenols exhibited significant negative effect. Cell-free extracts obtained from PNP-grown culture that contained 20 μg mL

Topics: Biodegradation, Environmental; Groundwater; Hydrogen-Ion Concentration; Nitrophenols; Rhodococcus; Wastewater; Water Pollutants, Chemical

There is an increasing need to explore effective and clean approaches for hazardous contamination removal from wastewaters. In this work, a novel bead adsorbent, polyvinyl alcohol-graphene oxide (PVA-GO) macroporous hydrogel bead was prepared as filter media for p-nitrophenol (PNP), dye methylene blue (MB), and heavy metal U(VI) removal from aqueous solution. Batch and fixed-bed column experiments were carried out to evaluate the adsorption capacities of PNP, MB, and U(VI) on this bead. From batch experiments, the maximum adsorption capacities of PNP, MB, and U(VI) reached 347.87, 422.90, and 327.55 mg/g. From the fixed-bed column experiments, the adsorption capacities of PNP, MB, and U(VI) decreased with initial concentration increasing from 100 to 400 mg/L. The adsorption capacities of PNP, MB, and U(VI) decreased with increasing flow rate. Also, the maximum adsorption capacity of PNP decreased as pH increased from 3 to 9, while MB and U(VI) presented opposite tendencies. Furthermore, the bed depth service Time (BDST) model showed good linear relationships for the three ions' adsorption processes in this fixed-bed column, which indicated that the BDST model effectively evaluated and optimized the adsorption process of PVA-GO macroporous hydrogel bead in fixed-bed columns for hazardous contaminant removal from wastewaters.

Topics: Adsorption; Graphite; Hazardous Substances; Methylene Blue; Models, Theoretical; Nitrophenols; Oxides; Polyvinyl Alcohol; Porosity; Surface Properties; Uranium Compounds; Wastewater; Water Purification

Topics: Alkaline Phosphatase; alpha-Fetoproteins; Enzyme Assays; Enzyme-Linked Immunosorbent Assay; Fluorescent Antibody Technique; Humans; Limit of Detection; Models, Molecular; Nitrophenols; Phosphates; Spectrometry, Fluorescence

Biosynthesis of gold nanoparticles (AuNPs) by microbes has received much attention as an efficient and eco-friendly process. However, the characteristics of AuNPs biosynthesized by different microbial cell-free extracts are rarely comparatively studied. In this study, three locally isolated strains, i.e., bacteria Labrys sp. WJW, yeast Trichosporon montevideense WIN, and filamentous fungus Aspergillus sp. WL-Au, were selected for AuNPs biosynthesis. UV-Vis absorption bands at 538, 539, and 543 nm confirmed the formation of AuNPs by these strains. Transmission electron microscopy and selected area electron diffraction analyses revealed that the as-synthesized AuNPs were crystalline with spherical or pseudo-spherical shapes. However, the average sizes of these AuNPs were diverse, which were 18.8, 22.2 and 9.5 nm, respectively. The biomolecules involved in nanoparticles stabilization were demonstrated by Fourier transform infrared spectroscopy analysis. Four common functional groups such as -N-H, -C=C, -N=O, and -S=O groups were detected in these AuNPs, while a distinct -C=O group was involved in WL-Au-AuNPs. The catalytic rate of WL-Au-AuNPs toward 4-nitrophenol reduction (0.37 min

Topics: Aspergillus; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Spectroscopy, Fourier Transform Infrared; Trichosporon

The use of industrial waste to synthesize materials of technological interest is a rational way to minimize or solve environmental pollution problems. This work investigates the adsorption of cadmium and lead ions by magnetic hybrid adsorbents synthesized using the in natura biomasses coconut mesocarp (CCFe), sawdust (SAFe), and termite nest (TEFe) for the organic phases and magnetic cobalt ferrite as the inorganic phase. The formation of a cobalt ferrite phase was confirmed by XRD. The use of XRD and FTIR analyses revealed the presence of organic matter in the structure of the material. Removal assays performed at different pH values (2.0-8.0) showed the effectiveness of the adsorbent for the removal of Pb

Topics: Adsorption; Biomass; Cadmium; Hydrogen-Ion Concentration; Ions; Kinetics; Lead; Nitrophenols; Water Pollutants, Chemical

Recovery of noble metals using marine bacteria is becoming an attractive research area because the marine microbes can better adapt to unfavorable environment than terrestrial microorganisms. In this study, we first reported that a marine Bacillus sp. GP was capable of producing Pd and Au NPs in the presence of sodium lactate. Ultraviolet visible spectrometer (UV-vis), transmission electron microscopy (TEM), X-ray diffraction patterns (XRD), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FTIR) analyses were employed to explain the process and mechanism of Pd(II)/Au(III) reduction through GP. Additionally, we also found that bio-Pd/Au NPs could be used as catalysts in chemical reduction of 4-nitrophenol (4-NP). Moreover, the catalytic activity of bio-Pd NPs could be enhanced by Fe

Topics: Bacillus; Catalysis; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Oxides; Palladium; Photoelectron Spectroscopy; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared

The catalytic reduction of p-nitrophenol (p-NP) by coal fly ash (FA) washed with water was investigated in this study. A significant increase in pH (from 7.0 to 10.1) was observed in the suspension of raw fly ash (RFA), while water-washed fly ash (WFA) showed a relatively lower increase in pH (7.2), which was caused by the dissolution of Ca species during the water-washing process. Almost 33.4% of p-NP reduction was observed in the RFA suspension with NaBH

Topics: Coal Ash; Incineration; Iron; Metal Nanoparticles; Nitrophenols; Particulate Matter; Water

In the present study, a series of Ce2Zr2O7@rGO nanocomposites were synthesized using a simple solution combustion method followed by a photoreduction technique. The as-prepared samples were well characterised using various analytical techniques to determine the morphological, optical, structural, electrochemical and compositional properties. The presence of oxygen defects was observed from Raman and photoluminescence spectra. The photoreduction of GO to rGO was determined from Raman and Fourier-transform infrared (FTIR) spectroscopy results. The role of rGO proved to be quite significant for the enhanced photocatalytic activity of the nanocomposites. The synergistic communication between Ce2Zr2O7 and rGO accelerates the photoreduction of 4-nitrophenol along with the degradation of ciprofloxacin under visible light irradiation. Of the rGO nanocomposites, 3 wt% GO loaded Ce2Zr2O7 reduces 99% of 20 ppm of 4-nitrophenol to 4-aminophenol in 120 min and decomposes 10 ppm of ciprofloxacin by up to 89% in 60 min. The significant enhancement in the activity of the Ce2Zr2O7@rGO nanocomposite was ascribed to the effective charge separation of excitons through π-conjugation of graphene at the interface, which is well supported by the impedance, photoluminescence and photocatalytic results.

Topics: Chemistry Techniques, Analytical; Ciprofloxacin; Graphite; Light; Nanocomposites; Niobium; Nitrophenols; Oxidation-Reduction; Photochemistry

The eco-friendly biosynthesis of silver nanoparticles (AgNps) from bark extract of Albizia chevalier are reported here for their anti-proliferative, antibacterial and pollutant degradation potentials. The synthesized AgNps were characterized by FTIR spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-rays spectrometry (EDS) and X-ray diffraction studies. The TEM and FESEM images show a monodispersed spherical shaped particles of approximately 30 nm. Crystalline peaks were obtained for the synthesized AgNps in XRD spectrum. The AgNps were investigated for in vitro anticancer and antibacterial activities and its potential to degrade 4-nitrophenol (4-NP) and congo red dye (CR). The MTT results shows a significant dose-dependent antiproliferation effect of the AgNps on the cell lines HepG2, MDA-MB-231 and MFC7. The effect was found more pronounced in MDA-MB-231 as compared to MFC-7 cell lines. The antibacterial results indicated 99 and 95% killing of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) respectively, after 24 h of incubation with the AgNps. The AgNps were found to speed up the reductive degradation of 4-NP and CR dye, which give an alternative route for the removal of toxic organic pollutants from the wastewater. The synthesized AgNps were not only used as a bactericidal and anticancer agent, but also effectively used for the reductive degradation of carcinogenic compounds which are listed as the priority pollutants. Therefore, AgNps have the potential for the treatment of various cancers, bacterial infections and for industrial detoxification of wastewater.

Topics: Albizzia; Anti-Bacterial Agents; Antineoplastic Agents; Cell Line, Tumor; Congo Red; Humans; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Plant Bark; Plant Extracts; Silver; Water Pollutants, Chemical

In the present work, a noncovalent and eco-friendly approach was proposed to prepare a carbon-black/β-cyclodextrin (CB/β-CD) nanocomposite. CB/β-CD-nanocomposite-modified screen-printed carbon electrodes were applied for the simultaneous determination of the anticancer drug flutamide (Flut) and the environmental pollutant 4-nitrophenol (4-NP). The electrochemical performance of the proposed sensor relied on the conductivity of CB, the different binding strengths of the guests (Flut and 4-NP) to the host (β-CD), and the different reduction potentials of the nitroaromatic compounds. Fascinatingly, the proposed sensor exhibited an excellent electrochemical performance with high sensitivity, selectivity, and reproducibility. The obtained wide linear ranges were 0.05-158.3 and 0.125-225.8 μM for Flut and 4-NP. The low detection limits of 0.016 and 0.040 μM with the higher sensitivities of 5.476 and 9.168 μA μM

Topics: Antineoplastic Agents, Hormonal; beta-Cyclodextrins; Carbon; Drinking Water; Environmental Pollutants; Flutamide; Humans; Nanocomposites; Nitrophenols

Novel mesoporous ZnCo

Topics: Biosensing Techniques; Catalysis; Cobalt; Graphite; Limit of Detection; Nanostructures; Nitrophenols; Oxides; Zinc Compounds

The present study investigated the synthesis of gold nanoparticles (AuNPs) using mangrove plant extract from

Topics: Aminophenols; Avicennia; Biodegradation, Environmental; Gold; Green Chemistry Technology; Metal Nanoparticles; Nanocomposites; Nitrophenols; Oxidation-Reduction; Particle Size; Plant Extracts; Spectrophotometry, Ultraviolet

Adaptation of the colorimetric method for the determination of β-d-galactosidase, β-d-glucuronidase and α-l-fucosidase activities in serums from hemolyzed blood, the material currently being discarded.. The materials included serums from hemolyzed and non-hemolyzed blood, obtained from 26 healthy volunteers. The adaptation of the method involved precipitation of the proteins with trichloroacetic acid after incubating serums with substrates, but before determining the products of enzymatic reactions.. In serums from hemolyzed and non-hemolyzed blood of the same persons, we found high correlations among the results obtained using hemolyzed blood (with adapted) and non-hemolyzed blood (with non-adapted) methods.. We are able to determine the β-d-galactosidase, β-d-glucuronidase and α-l-fucosidase activities in serums from hemolyzed blood (with adapted) and non-hemolyzed blood (with non-adapted) methods, with the same accuracy and precision.

Topics: Adult; alpha-L-Fucosidase; beta-Galactosidase; Female; Glucuronidase; Hemoglobins; Hemolysis; Humans; Hydrogen-Ion Concentration; Kinetics; Male; Middle Aged; Nitrophenols; Young Adult

We report the design and realization of yolk-shell structured nanospheres with periodic mesoporous organosilica (PMO) nanospheres or noble metal nanoparticles encapsulated in mesoporous silica shells via a selective etching method. These architectures have well controlled structure, size and morphology. The yolk-shell structured PMO@SiO2 nanoparticles can be precisely functionalized with different catalytic functionalities, even incompatible acidic and basic groups: the PMO core with amino (-NH2) groups and the mesoporous silica shell with sulfonic acid (-SO3H) groups. As a nanoreactor, the as-synthesized Au@SiO2 nanospheres show faster reduction of 4-nitrophenol than that of nitrobenzene. Furthermore, the prepared PMO-NH2@SiO2-SO3H nanoparticles can be used as bifunctional catalysts with highly efficient catalytic performance for catalyzing the deacetalization-Henry cascade reaction.

Topics: Catalysis; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nanospheres; Nitrobenzenes; Nitrophenols; Organogold Compounds; Particle Size; Porosity; Silicon Dioxide; Sulfonic Acids; Water

In this study, selective green synthesis of gold nanoparticles (nAu) with the use of Tarragon extract (Artemisia dracunculus) was investigated. Characterization of the synthetized nAu was carried out using several techniques including: UV-Vis, SEM, zeta potential analysis, DLS, and ATR-FTIR. Based on measurements of Tarragon extract by HPLC-MS, significant chemical substances participating as reducing and stabilizing agents were identified. FTIR confirmed typical functional groups that could be found in these acids on the nAu surface, such as O-H, C=O and C-O. The effects of various parameters (concentration of Tarragon extract, Au precursor, and initial pH of the synthesis) on the shape and size of the nanoparticles have been investigated. UV-Vis and SEM confirmed the formation of nAu at various concentrations of the extract and Au precursor and showed correlation between the added extract concentration and shift in maximal absorbance towards higher frequencies, indicating the formation of smaller nanoplates. Zeta potential determined at various pH levels revealed that its value decreased with pH, but for all experiments in the pH range of 2.8 to 5.0, the value is below - 30 mV, an absolute value high enough for long-term nAu stability. In order to evaluate nAu catalytic activity, the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride was used as a model system. The reaction takes place 1.5 times faster on Au-triangles than on Au-spherical NPs.

Topics: Aminophenols; Artemisia; Borohydrides; Catalysis; Chromatography, High Pressure Liquid; Gold; Green Chemistry Technology; Hydrogen-Ion Concentration; Metal Nanoparticles; Microscopy, Electron, Scanning; Nitrophenols; Particle Size; Plant Extracts; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tandem Mass Spectrometry

To realize surfactant-free synthesis of biomass-derived hollow mesoporous carbon spheres and their derivatives, choice of synthetic methodology and carbon precursor is crucial. Herein, a brand-new hollow mesoporous carbon sphere (HMCS) is first synthesized from 8-quinolinol modified chitosan via an in situ stöber templating approach without surfactant followed by pyrolysis and alkali washing. The resultant HMCS is uniform, and shows a cavity size of 417 nm, a shell thickness of 5 nm, and a narrow mesopore size distribution centered at 3.9 nm. The HMCS is then upgraded by encapsulation of a single Au nanocrystal (NC) into the void of HMCS to form a yolk-shell architecture, YS-Au@HMCS. Its cavity size and shell thickness are decreased to 187 and 3 nm, while the mesopore size is increased to 4.3 nm, the surface area (215 m

Topics: Carbon; Chitosan; Gold; Methylene Blue; Nanoparticles; Nitrophenols; Oxidation-Reduction; Oxyquinoline; Photolysis; Porosity

Silver nanoparticles (AgNPs) have several technological applications and may be synthetized by chemical, physical and biological methods. Biosynthesis using fungi has a wide enzymatic range and it is easy to handle. However, there are few reports of yeasts with biosynthetic ability to produce stable AgNPs. The purpose of this study was to isolate and identify soil yeasts (Rhodotorula glutinis and Rhodotorula mucilaginosa). After this step, the yeasts were used to obtain AgNPs with catalytic and antifungal activity evaluation. Silver Nanoparticles were characterized by UV-Vis, DLS, FTIR, XRD, EDX, SEM, TEM and AFM. The AgNPs produced by R. glutinis and R. mucilaginosa have 15.45 ± 7.94 nm and 13.70 ± 8.21 nm (average ± SD), respectively, when analyzed by TEM. AgNPs showed high catalytic capacity in the degradation of 4-nitrophenol and methylene blue. In addition, AgNPs showed high antifungal activity against Candida parapsilosis and increase the activity of fluconazole (42.2% for R. glutinis and 29.7% for R. mucilaginosa), while the cytotoxicity of AgNPs was only observed at high concentrations. Finally, two yeasts with the ability to produce AgNPs were described and these particles showed multifunctionality and can represent a technological alternative in many different areas with potential applications.

Topics: Anti-Bacterial Agents; Antifungal Agents; Brazil; Candida parapsilosis; Catalysis; Cell Line; Cell Survival; Drug Combinations; Drug Synergism; Fluconazole; Humans; Metal Nanoparticles; Methylene Blue; Microbial Sensitivity Tests; Nitrophenols; Particle Size; Phylogeny; Rhodotorula; Silver; Soil Microbiology; Wastewater; Water Purification

Topics: Bacteria; Biodegradation, Environmental; Cold Temperature; Groundwater; Nitrophenols; Soil; Wastewater; Water Pollutants, Chemical

Pseudomonas putida DLL-E4 can efficiently degrade para-nitrophenol and its intermediate metabolite hydroquinone at 37 °C and 30 °C. However, mutant strain Pseudomonas putida MT54, obtained by transposon mutagenesis from P. putida DLL-E4, could not degrade para-nitrophenol at 37 °C. The mutant genes including DW66_0143, DW66_0153 and pnpB were discovered in strain MT54 by whole genome resequencing. Gene knockout and complementation confirmed the necessity of PnpB in PNP degradation by temperature-sensitive strain MT54. PnpA catalyzes the first step in complete degradation of PNP, and we found its activity was significantly enhanced by PnpB. The measurement of bacterial two-hybrid system indicated that the effect was not mediated by the direct interaction between PnpA and PnpB, but caused by the elimination of product inhibition of PnpA. Furthermore, PnpA was characterized as a psychrophilic enzyme with optimum temperature of 20 °C. We concluded that the lowered activity of PnpA resulted from inactivation of PnpB at the restrictive temperature induced the temperature-sensitive characteristic of P. putida MT54.

Topics: Nitrophenols; Oxygenases; Pseudomonas putida; Temperature

An excellent catalyst (GNiO

Topics: 4-Aminobenzoic Acid; Borohydrides; Catalysis; Galactans; Mannans; Nanoparticles; Nickel; Nitrophenols; Oxidation-Reduction; Phenylenediamines; Plant Gums

p-Nitrophenol 4-monooxygenase PnpA, the key enzyme in the hydroquinone pathway of p-nitrophenol (PNP) degradation, catalyzes the monooxygenase reaction of PNP to p-benzoquinone in the presence of FAD and NADH. Here, we determined the first crystal structure of PnpA from Pseudomonas putida DLL-E4 in its apo and FAD-complex forms to a resolution of 2.04 Å and 2.48 Å, respectively. The PnpA structure shares a common fold with hydroxybenzoate hydroxylases, despite a low amino sequence identity of 14-18%, confirming it to be a member of the Class A flavoprotein monooxygenases. However, substrate docking studies of PnpA indicated that the residues stabilizing the substrate in an orientation suitable for catalysis are not observed in other homologous hydroxybenzoate hydroxylases, suggesting PnpA employs a unique catalytic mechanism. This work expands our understanding on the reaction mode for this enzyme class.

Topics: Bacterial Proteins; Benzoquinones; Binding Sites; Biocatalysis; Crystallography, X-Ray; Flavin-Adenine Dinucleotide; Models, Molecular; Molecular Structure; Nitrophenols; Oxygenases; Protein Binding; Protein Conformation; Pseudomonas putida; Substrate Specificity

In the present study, silver and gold nanoparticles (AgNPs and AuNPs) were green synthesised using the aqueous plant extract of Stemona tuberosa Lour. When plant extract was mixed with AgNO

Topics: Catalysis; Color; Gold; Green Chemistry Technology; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Plant Extracts; Silver; Spectrometry, X-Ray Emission; Stemonaceae

Silver nanoparticles with average diameter of 10±3nm were synthesized within the sieves of poly(N-isopropylacrylamide-2-hydroxyethylmethacrylate-acrylic acid) (p(NIPAAm-HEMA-AAc)) polymer microgels. Free radial emulsion polymerization was employed for synthesis of p(NIPAAm-HEMA-AAc) polymer microgels. Silver nanoparticles were introduced within the microgels sphere by in situ reduction method. Microgels and hybrid microgels were characterized by Fourier transform infrared spectroscopy, ultra violet-visible spectroscopy, transmission electron microscopy and dynamic light scattering measurements. Catalytic activity of Ag-p(NIPAAm-HEMA-AAc) hybrid microgels was studied using catalytic reduction of 4-nitrophenol (4-NP) as a model reaction in aqueous media. The influence of sodium borohydride (NaBH

Topics: Metal Nanoparticles; Models, Chemical; Nitrophenols; Silver

Topics: Asteraceae; Green Chemistry Technology; Metal Nanoparticles; Nanocomposites; Nitrophenols; Oxidation-Reduction; Pistacia; Plant Extracts; Plant Leaves; Seeds; Silver

Catalytic Reduction of p-nitrophenol and Methylene blue by Microbiologically Synthesized Silver Nanoparticles was studied in the present investigation. Catalytic reduction of 4-Nitophenol/p-nitrophenol (PNP) and methylene blue (MB) was assessed using both intra and extracellular silver nanoparticles (AgNP) with and without immobilization. Both intracellular and extracellular AgNP were synthesized from actinomycetes. Antimicrobial activity of AgNP was also assessed and it was found that, intracellular AgNP have significant antibacterial activity against E. coli, S. typhi and B. subtilis. Synthesized biogenic silver nanoparticles were characterized by UV-visible spectrophotometry, FTIR, XRD, and TEM-EDS. It was found that, extracellular AgNP are efficient as compared to intracellular AgNP in terms of PNP reduction.

Topics: Actinobacteria; Metal Nanoparticles; Methylene Blue; Nitrophenols; Oxidation-Reduction; Silver

This study presents an efficient and facile method for biosynthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using aqueous extract of burdock root (BR), A. lappa, and their applications. The nanoparticles were characterized by ultraviolet-visible spectrophotometry, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, thermogravimetry, and differential thermal analysis. AgNPs capped the BR extract (BR-AgNPs) possessed roughly spherical geometry with an average diameter of 21.3 nm while uneven geometry of AuNPs capped the BR extract (BR-AuNPs) showed multi shapes in average size of 24.7 nm. The BR-AgNPs strongly inhibited five tested microorganism strains. In particular, the nanoparticles showed excellent catalytic activity for the conversion of pollutants within wastewater. Pseudo-first-order rate constants for the degradation of 4-nitrophenol, methyl orange, and rhodamine B were respectively found 6.77 × 10

Topics: Anti-Infective Agents; Arctium; Azo Compounds; Catalysis; Gold; Metal Nanoparticles; Microbial Sensitivity Tests; Microscopy, Electron, Transmission; Nitrophenols; Plant Extracts; Rhodamines; Silver; Spectrophotometry, Ultraviolet; Thermogravimetry; Water Pollutants, Chemical; X-Ray Diffraction

As an emerging two-dimensional material, MXenes have attracted much attention due to their unique physicochemical properties, but their application in biosensing has been lagging far behind because of their poor salt tolerance. Herein, a titanium carbide MXene quantum dot (Ti

Topics: Alkaline Phosphatase; Fluorescent Dyes; Human Embryonic Stem Cells; Humans; Limit of Detection; Nitrophenols; Organophosphorus Compounds; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Substrate Specificity; Titanium

Crumpled graphene oxide nanosheets have drawn large attentions due to its compressibility and self-avoiding stacking as flat graphene sheets trend to aggregate and restack. Up to now, most of the synthesis approaches were relied on external substrates, such as elastic substrates or ultrasonic atomizer, and the crumpled structures were obtained in a solid state directly. Here we report a facile method to produce crumpled dispersive nanosheets in solution through general base-washing treatment by taking advantage of the amphipathy of GO nanosheets. With the dissociation of oxygen-functional groups on nanosheets in alkaline environment, highly water-soluble oxidative debris (OD) would fall off from the nanosheets due to the increase of electrostatic repulsions, and resulted in the crumple of the flat sheets, while the covalent oxygen-functional groups on the nanosheets were reserved. As a result, the nanosheets remained dispersible in solution, and could be used directly for surface modifications. Pt nanoparticles could be directly deposited onto both sides of the sheets through common nucleation and growth from precursor ions process. Compared with flat graphene-based hybrid, the catalytic performance of crumpled-graphene-Pt (CG-Pt) is more excellent and attractive, and corresponding apparent kinetic rate constant (k

Topics: Catalysis; Graphite; Nanoparticles; Nanostructures; Nitrophenols; Oxidation-Reduction; Oxides; Platinum

We report a facile and sensitive method for the detection of alkaline phosphatase (ALP) activity in serum and live cells using molybdenum disulfide quantum dots (MoS

Topics: Alkaline Phosphatase; Disulfides; Fluorescent Dyes; Humans; Limit of Detection; MCF-7 Cells; Microscopy, Confocal; Molybdenum; Nitrophenols; Quantum Dots; Spectrometry, Fluorescence

Concentrating cells from aqueous samples is a common requirement for the enumeration of biomass, investigations of microbial diversity and detection of relatively rare organisms in the environment. Accurately representing the initial sampled environments in the concentrated cells is of particular importance when the subsequent analyses have tangible environmental, economic and societal consequences, as is the case with environmental exposure and risk assessment of chemicals. This study investigated the potential use of four different cell concentration methods: centrifugation, membrane filtration, tangential flow filtration and column colonisation. These methods were assessed against a series of scientific and practical criteria, including: similarity of concentrated community to initial environmental sample; cell concentration achieved; biodegradation test outcome; sample throughput; and capital and maintenance costs. All methods increased cell concentration by as little as 10-fold to as much as 1000-fold. DGGE and 454 pyrosequencing analysis showed concentrated communities to have >60% similarity to each other, and the initial sample. There was a general trend for a more reliable assessment of 4-nitrophenol biodegradation in 96-well plate biodegradation assays, with increasing cell concentration. Based on the selection criteria, it is recommended that there is not one concentration method fit for all purposes, rather, the appropriate method should be selected on a case-by-case basis. Membrane filtration would be the most suitable method for low sample volumes; the increased throughput capacity of tangential flow filtration renders it most suitable for large volumes; and centrifugation is most suitable for samples with high initial biomass concentrations. The poor similarity in microbial community composition of the column colonised samples compared to the initial samples, suggested a concentration basis; this combined with its low sample throughput precluded this approach for future concentration studies of planktonic bacterial samples.

Topics: Bacteria; Biodegradation, Environmental; Biomass; Ecology; Environmental Monitoring; Environmental Pollutants; Filtration; Nitrophenols; Plankton; Risk Assessment

A new isolate of genus Scytonema distinct from its closest relative cyanobacterium, Scytonema hofmanni was found efficient in the removal and degradation of organophosphorus (OP) pesticide, methyl parathion (MP). The cyanobacterial isolate was also capable of utilizing the phosphorus present in the MP following its degradation, which was evident from the increase in growth (chlorophyll content), biomass, protein content, and total phosphorus in comparison to cyanobacterium grown in phosphate-deficient cultures. The rapid removal of MP by the cyanobacterium during initial 6 hours of incubation was defined by the pseudo-second-order biosorption kinetics model, which indicated the involvement of chemosorption in initial removal of pesticide. Further, degradation of MP was also confirmed by the appearance of p-nitrophenol in the medium after 24 hours of incubation. Thus, the cyanobacterial isolate of Scytonema sp. BHUS-5 seems to be a potential bioremediation agent for the removal of OP pesticide, MP from the habitat.

Topics: Biodegradation, Environmental; Cyanobacteria; Methyl Parathion; Nitrophenols; Phosphates

A sensitive and selective fluorescent method for detection of cholesterol based on β-cyclodextrin functionalized carbon quantum dots (β-CD-CQD) nanoprobe through competitive host-guest recognition has been developed. The bright fluorescence of β-CD-CQD nanoprobe can be effectively quenched by the introduction of a very small amount of p-nitrophenol, and strong quenching ability of p-nitrophenol to the probe was identified. This efficient fluorescence quenching as a static quenching is due to the formation of nonfluorescent complex between β-CD-CQD and p-nitrophenol induced by host-guest interaction between them. Cholesterol, as a more suited guest molecule of β-cyclodextrin, can form an inclusion complex with β-cyclodextrin with a much greater binding constant than p-nitrophenol. As a result, the presence of cholesterol causes a replacement of guest molecule of β-CD moiety in the probe through a competitive way, and the inclusion of cholesterol in the probe as the removal of p-nitropheonl induces significant fluorescence enhancement. The fluorescence recovery can be achieved by continuous addition of cholesterol. In terms of this relationship between enhanced fluorescence and concentration of cholesterol, a quantitative measurement for cholesterol based on β-CD-CQD nanoprobe has been established. Under the optimized detection conditions, this method shows good analytical performance in detection of cholesterol with lowest detection limit of 0.7±0.1µM and a relatively wide linear scope of 110µM. Specificity test and complex matrix test show that this method possesses excellent selectivity to cholesterol, and complex matrix such as serum does not exert apparent influence on the analytical performance, which enables its use in practical serum samples.

Topics: Animals; beta-Cyclodextrins; Biosensing Techniques; Carbon; Cattle; Cholesterol; Fluorescence; Fluorometry; Limit of Detection; Nitrophenols; Quantum Dots

We developed a sensitive and selective method for detection of 4-Nitrophenol (PNP) using Ag nanoclusters (NCs) as fluorescence probe. Bovine serum albumin (BSA) was used as the template for preparing Ag NCs via wet chemistry. The fluorescence of as-prepared Ag NCs was significantly quenched in the presence of PNP, showing excellent linear relationships between the quenching degree of the fluorescence intensity and the concentrations of PNP in the range of 0.5 μM to 60 μM. The fluorescence quenching mechanism was also investigated. Furthermore, this method was applied for the recognition of PNP in environmental samples.

Topics: Animals; Cattle; Fluorescence; Fluorescent Dyes; Metal Nanoparticles; Nitrophenols; Serum Albumin, Bovine; Silver; Spectrometry, Fluorescence

Topics: Acinetobacter baumannii; Anti-Bacterial Agents; Borohydrides; Chitosan; Drug Resistance, Multiple, Bacterial; Escherichia coli; Glucose; Metal Nanoparticles; Microbial Sensitivity Tests; Nitrophenols; Oxidation-Reduction; Pseudomonas aeruginosa; Silver; Sodium Hydroxide; Staphylococcus aureus; Static Electricity

A simple, green method is described for the synthesis of Gold (Au) nanoparticles (NPs) using Cotoneaster horizontalis extract as a phyto-reducer and capping agent with superior photo inhibition activity against Pseudomonas aeruginosa. Different from the other methods used elevated temperatures for nanoparticles synthesis, the novelty of our method lies in its energy saving process and fast synthesis rates (~5min for AuNPs), and its potential to tune the nanoparticles size and afterward their catalytic activity. The starch, fatty acid and reducing sugars present in the extract are mostly responsible for repaid reduction rate Au

Topics: Anti-Bacterial Agents; Borohydrides; Catalysis; Gold; Green Chemistry Technology; Light; Metal Nanoparticles; Microbial Sensitivity Tests; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Plant Extracts; Plant Leaves; Pseudomonas aeruginosa; Rosaceae; Spectrometry, X-Ray Emission; Surface Plasmon Resonance

Herein we report a rapid low cost one step green synthetic method using Actinidia deliciosa fruit extract for preparation of stable and multifunctional silver and gold nanoparticles. The synthesized nanoparticles were successfully used as green catalysts for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB). The enhanced biological activity of the prepared nanoparticles was investigated based on its highly stable antioxidant, anticancer and bactericidal effects. TEM micrographs showed that the silver nanoparticles (AgNPs) formed were predominantly spherical in shape having diameters ranging from 25 to 40nm, while gold nanoparticles (AuNPs) shown particle size ranges from 7 to 20nm. EDAX (energy-dispersive X-ray spectroscopy) and XPS (X-ray photoelectron spectroscopy) results confirmed the presence of elemental silver and gold. X-ray diffraction (XRD) pattern revealed the formation of face-centered cubic structure for AgNPs and AuNPs. The Fourier-transform infrared (FTIR) spectrum indicated the presence of possible functional groups in the biomolecule responsible for capping the nanoparticles. The AgNPs treated HCT116 cells showed 78% viability at highest concentration (350μg/mL), while AuNPs showed 71% viability at highest concentration (350μg/mL) using MTT assay, which provides promising approach for alternative nano-drug development. The antimicrobial activity of the nanoparticles was investigated using Pseudomonas aeruginosa (P.aeruginosa) in which damaging the cell membrane was observed by TEM images. Our results revealed that the green synthesis method is easy, rapid, inexpensive, eco-friendly and efficient in developing multifunctional nanoparticles in near future in the field of biomedicine, water treatment and nanobiotechnology.

Topics: Actinidia; Anti-Bacterial Agents; Antineoplastic Agents; Antioxidants; Catalysis; Cell Survival; Fruit; Gold; Green Chemistry Technology; HCT116 Cells; Humans; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Transmission; Nitrophenols; Particle Size; Photoelectron Spectroscopy; Plant Extracts; Pseudomonas aeruginosa; Silver; Spectrometry, X-Ray Emission; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction

4-Nitrophenol (PNP), a well-established human carcinogen, has been proven to have detrimental effects on reproductive system of male rats in previous studies. The molecular mechanisms involved PNP-induced damage remain to be established. Autophagy can exert protective effects on various cytotoxic factors that induce injury. In the present study, we aim to investigate whether autophagy is induced by PNP and the function of autophagy in PNP-induced injury in NHPrE1, a normal human prostate epithelial progenitor cell line. Our results indicate that PNP induced oxidative stress as evidenced by increased MDA levels and decreased activity of SOD and GSH-Px. PNP also increased apoptosis of NHPrE1 cells as evidenced by western blot and Hoechst 33258 staining and activated autophagy in NHPrE1 cells detected by RT-PCR and western blot. Inhibition of autophagy by 3-MA further increased PNP-induced oxidative stress and apoptosis of NHPrE1 cells. We also found that PNP-induced apoptosis was suppressed by N-acetylcysteine, suggesting oxidative stress may play an important role in PNP cytotoxicity. Furthermore, phosphorylation of mTOR protein was inhibited by PNP, indicating that PNP might induce autophagy in NHPrE1 cells via inhibiting mTOR pathway. In conclusion, these results suggest that activation of autophagy should play a protective role in PNP-induced oxidative stress and apoptosis of NHPrE1 cells, which might be mediated through mTOR pathway.

Topics: Animals; Apoptosis; Autophagy; Humans; Male; Nitrophenols; Oxidative Stress; Prostate; Rats; Stem Cells

An improved method based on the p-nitrophenyl long chain esters method is proposed for measuring lipase hydrolytic activity in aqueous media. Using ethylene glycol as co-solvent for hydrophobic p-nitrophenyl substrates in aqueous buffer, lipase activity is measured by following the release of p-nitrophenol. This fast and easy to handle method improves the solubility of both substrate and product, and also the stability of the substrate. It avoids the use of solvents such as ethanol or propanol, permits the comparison of all the p-nitrophenol acyl ester substrates and allows the influence of ions like Ca

Topics: Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Kinetics; Lipase; Mucor; Nitrophenols; Solubility; Solvents; Water

Biochars derived from three microalgal strains (namely, Chlorella sp. Cha-01, Chlamydomonas sp. Tai-03 and Coelastrum sp. Pte-15) were evaluated for their capacity to adsorb p-nitrophenols (PNP) using raw microalgal biomass and powdered activated carbon (PAC) as the control. The results show that BC-Cha-01 (biochar from Chlorella sp. Cha-01) exhibited a high PNP adsorption capacity of 204.8mgg

Topics: Adsorption; Charcoal; Chlorella; Microalgae; Nitrophenols

Iron oxide/Pd hybrid nanostructures with controllable Pd loading from 0.05 to 1.0 (calculated as Pd/Fe molar ratio) have been synthesized by chemical reduction of Pd

Topics: Ferric Compounds; Lead; Nanostructures; Nitrophenols; Peroxidase; Peroxidases

Celecoxib is known to alter the preferred position of SULT2A1-catalyzed sulfonation of 17β-estradiol (17β-E2) and other estrogens from the 3- to the 17-position. Understanding the effects of celecoxib on estrogen sulfonation is of interest in the context of the investigational use of celecoxib to treat breast cancer. This study examined the effects on celecoxib on cytosolic sulfotransferases in human and rat liver and on SULT enzymes known to be expressed in liver. Celecoxib's effects on the sulfonation of several steroids catalyzed by human liver cytosol were similar but not identical to those observed previously for SULT2A1. Celecoxib was shown to inhibit recombinant SULT1A1-catalyzed sulfonation of 10nM estrone and 4μM p-nitrophenol with IC

Topics: Adult; Animals; Arylsulfotransferase; Celecoxib; Estradiol; Estrone; Female; Gene Expression; Hepatocytes; Humans; Isoenzymes; Liver; Male; Models, Molecular; Molecular Docking Simulation; Nitrophenols; Primary Cell Culture; Quercetin; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Species Specificity; Structural Homology, Protein; Sulfates; Sulfotransferases; Triclosan

4-nitrophenol (PNP), isolated from diesel exhaust particles, has estrogenic and anti-androgenic activities, and affects the hypothalamus-pituitary-gonad axis in male rats. However, the effect of PNP on the reproduction of the female rats is still unknown. The aim of the study was to investigate the effect of neonatal PNP exposure on the ovarian function of female rats. The neonatal female rats were exposed to PNP (10 mg/kg, subcutaneously injection), the ovary and serum samples were collected at postnatal day (PND) 7, 14 and 21. The results showed that the ratio of primordial and primary follicles increased whereas the ratio of antral follicles decreased in the PNP treated ovaries at PND21. Even though no abnormality was observed in cyclicity, there was a significantly delayed timing of vaginal opening in PNP treated rats. The ovarian expression of steroidogenic enzymes including StAR, P450scc, P450c17 and P450arom increased at PND14 in the PNP treated rats compared with the control rats. In consistent with the gene expression, the concentration of estradiol-17β showed the similar pattern. However, PNP exposure failed to cause any significant change in the expression of steroidogenic enzymes in cultured neonatal ovaries. Furthermore, PNP suppressed the expression of estrogen receptor β (ERβ), but not estrogen receptor α (ERα), in cultured ovaries or developmental ovaries. These results suggested that PNP might directly affect the expression of ERβ in the rat ovaries, resulting in the disrupted steroidogenesis during ovarian development and the delayed puberty.

Topics: Androgen Antagonists; Animals; Aromatase; Estradiol; Estrogen Receptor alpha; Estrogen Receptor beta; Female; Hazardous Substances; Nitrophenols; Ovarian Follicle; Ovary; Rats; Reproduction; Steroid 17-alpha-Hydroxylase; Toxicity Tests

To explore high-performance noble metal nanomaterials for the reduction of the biotoxin 4-nitrophenol (4-NP) in medicine, we developed a green synthesis strategy of bovine serum albumin-stabilized Au nanoparticles (Au@BSA NPs). The as-synthesized Au@BSA NPs were characterized by ultraviolet-visible absorption spectrum, fourier transformed infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The functional bio-nanocomposites showed Au-protein core-shell structure and uniform distribution, and their sizes were dependent on the additive amount of HAuCl

Topics: Aminophenols; Gold; Metal Nanoparticles; Nitrophenols

Platinum based drugs are considered as effective agents against various types of carcinoma; however, the severe toxicity associated with the chemically prepared platinum complexes limit their practical applications. Similarly, water pollution caused by various organic moieties is another serious health problem worldwide. Hence, an intense need exists to develop new, effective and biocompatible materials with catalytic and biomedical applications. In the present contribution, we prepared platinum nanoparticles (PtNPs) by a green route using phytochemicals as a source of reducing and stabilizing agents. Well dispersed and crystalline PtNPs of spherical shapes were prepared and characterized. The bio-fabricated PtNPs were used as catalyst and anticancer agents. Catalytic performance of the PtNPs showed that 84% of the methylene blue can be reduced in 32min under visible light irradiation (K=0.078min

Topics: Antineoplastic Agents; Biological Transport; Catalysis; Cell Line, Tumor; Drug Stability; Humans; Lung Neoplasms; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Platinum

Chars and other black carbons are reactive toward certain compounds. Such reactivity has been attributed to reduction of O

Topics: Cellulose; Hydrogen Peroxide; Lignin; Nitrophenols

Through the use of an enrichment technique, we isolated from the agricultural soils of Morelos in central México a strain of Burkholderia zhejiangensis identified as CEIB S4-3, it's could use the pesticide methyl parathion (MP) as the only source of carbon and degrade completely p-nitrophenol (PNP). For more efficient MP and PNP degradation by the CEIB S4-3 strain, the absence of an extra carbon source, a large inoculum and an MP concentration up to 50 mg/l are required. Sequence and annotation analysis of the draft genome, showed presence of mpd functional gene, which was expressed and its activity on the MP was confirmed. Additionally, the genes coding for enzymes in the benzoquinone pathway (conducted by Gram-negative bacteria) and the benzenotriol pathway (conducted by Gram-positive bacteria) were found, which was corroborated by identification of intermediary metabolites by HPLC. Thus, we propose that B. zhejiangensis CEIB S4-3 uses both degradation pathways.

Topics: Agriculture; Biodegradation, Environmental; Burkholderia; Chromatography, High Pressure Liquid; Methyl Parathion; Nitrophenols; Pesticides; Soil; Soil Microbiology

In this work, gold nanoparticles protected by the macrocycle cucurbit[7]uril were used as a catalyst in the reduction of the hazardous antimicrobial nitrofurantoin. 4-Nitrophenol was also employed as the substrate of the reduction for comparative purposes. The kinetic data were modeled to the Langmuir-Hinshelwood equation to know the affinities of the reactants for the surface and the real kinetic constants, a comparison at the molecular level that is made for the first time. From the results, it was observed that the adsorption of nitrofurantoin was stronger than that of 4-nitrophenol whilst the kinetic constant on the surface was higher for 4-nitrophenol than for nitrofurantoin. Additionally, shifts in the nanoparticle surface plasmon band permitted insights to be obtained into the adsorption rate and strength. The reaction induction times were also investigated and were highly dependent on the borohydride concentration and, due to the higher surface affinity of nitrofurantoin compared with 4-nitrophenol, an increase in nitrofurantoin concentration increased the induction time, while a lag phase was not observed for 4-nitrophenol.

Topics: Adsorption; Anti-Infective Agents; Bridged-Ring Compounds; Catalysis; Gold; Imidazoles; Kinetics; Magnetic Resonance Spectroscopy; Metal Nanoparticles; Nitrofurantoin; Nitrophenols; Oxidation-Reduction; Surface Plasmon Resonance

Zebrafish are an attractive model organism for toxicology; however, an important consideration in translating between species is xenobiotic metabolism/bioactivation. CYP2E1 metabolizes small hydrophobic molecules, e.g. ethanol, cigarette smoke, and diesel exhaust components. CYP2E1 is thought to only be conserved in mammals, but recent reports identified homologous zebrafish cytochrome P450s. Herein, ex vivo biochemical measurements show that unlike mammals, zebrafish possess a low-affinity 4-nitrophenol hydroxylase (K

Topics: Animals; Brain; Cytochrome P-450 CYP2E1; Enzyme Induction; Ethanol; Liver; Male; Microsomes, Liver; Mitochondria; Mixed Function Oxygenases; Myocardium; Nitrophenols; Rats; Zebrafish; Zebrafish Proteins

para-Nitrophenol (PNP), 3-methyl-4-nitrophenol (3M4NP), and 2-chloro-4-nitrophenol (2C4NP) are highly toxic compounds that have caused serious environmental issues. We inoculated an artificially contaminated soil with Burkholderia sp. strain SJ98, which has the ability to degrade PNP, 3M4NP, and 2C4NP, and quantified bioremediation. There was accelerated degradation of all nitrophenols in inoculated treatments compared to the un-inoculated treatments. The indigenous bacteria were able to degrade PNP, but not 3M4NP or 2C4NP. Real-time PCR targeting the catabolic gene pnpA showed that levels of strain SJ98 remained stable over the incubation period. High-throughput sequencing revealed that both contamination and bioaugmentation influenced the bacterial community structure. Bioaugmentation seemed to protect Kineosporia, Nitrososphaera, and Schlesneria from nitrophenol inhibition, as well as led to a sharp increase in the abundance of Nonomuraea, Kribbella, and Saccharopolyspora. There was a significant increase in the relative abundances of Thermasporomyces, Actinomadura, and Streptomyces in both contaminated and bioaugmented treatments; this indicated that these bacteria are likely directly related to nitrophenol degradation. To our knowledge, this is the first report of the simultaneous removal of PNP, 3M4NP, and 2C4NP using bioaugmentation. This study provides valuable insights into the bioremediation of soils contaminated with nitrophenols.

Topics: Biodegradation, Environmental; Biodiversity; Burkholderia; Cresols; Nitrites; Nitrophenols; Phylogeny; RNA, Ribosomal, 16S; Soil; Soil Microbiology; Soil Pollutants

The chemical process scale-up, from lab studies to industrial production, is challenging and requires deep knowledge of the kinetic model and the reactions that take place in the system. This knowledge is also useful in order to be employed for the reactor design and the determination of the optimal operational conditions. In this study, a model substituted phenol such as p-nitrophenol was degraded by electro-Fenton process and the reaction products yielded along the treatment were recorded. The kinetic model was developed using Matlab software and was based on main reactions that occurred until total mineralization which allowed predicting the degradation pathway under this advanced oxidation process. The predicted concentration profiles of p-nitrophenol, their intermediates and by-products in electro-Fenton process were validated with experimental assays and the results were consistent. Finally, based on the developed kinetic model the degradation process was optimized using central composite design taking as key parameters the ferrous ion concentration and current density.

Topics: Hydrogen Peroxide; Iron; Kinetics; Models, Chemical; Nitrophenols; Oxidation-Reduction; Phenol; Water Pollutants, Chemical

Multicomponent porous colloidal spheres are of interest because they not only show a combination of the properties associated with all different components, but also usually present synergy effects. However, a combination of different components in a single porous sphere is still greatly challenged due to the different precipitation behaviors of each component. In this work, we have developed a general synthetic route to prepare several categories of porous monodisperse rare-earth (RE)-based colloidal spheres with customizable elemental compositions and a uniform element distribution. The two-step synthetic strategy is based on the integration of coordination chemistry precipitation of RE ions and a subsequent ion-exchange process, which steers clear of obstacles, such as differences in solubility product constant, that are to be found in traditional co-precipitation methods. Our approach provides a new mixing mechanism to realize homogeneous distribution of each element within the porous spheres. An array of binary, ternary, and even senary RE colloidal porous spheres with diameters of 500 nm to 700 nm has been successfully synthesized. Taking advantage of their good dispersibility, porosity, and customizable components, these porous RE oxide spheres show excellent catalytic activity for the reduction of 4-nitrophenol, and promising application in single-phase multifunctional bioprobes.

Topics: Catalysis; Colloids; Ion Exchange; Magnetic Resonance Imaging; Metals, Rare Earth; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Particle Size; Porosity; Spectrophotometry; X-Ray Diffraction

Topics: Anthemis; Catalysis; Congo Red; Copper; Flowers; Green Chemistry Technology; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Plant Extracts; Silicates; Spectrometry, X-Ray Emission; Thermogravimetry; Zeolites

Food processing alters the physicochemical state of soy which can enhance chemical and enzymatic conversion of isoflavones to their aglycone forms. This study investigated the role of β-glycosidase from processed soy-ingredient mixture (SIM) or almonds, and examined the impact of isoflavone composition in mediating conversion to aglycones. β-Glycosidase activity was quantified using p-nitrophenol-β-d-glucopyranoside and SIM isoflavone extracts. Almond β-glycosidase activity was significantly (p<0.001) reduced after roasting (99% reduction) or steaming (97% reduction) compared to raw almonds. SIM β-glycosidase activity, however, increased, with steaming by 66% (p<0.001) and with roasting by 52% (p=0.022), compared to raw SIM. After incubation with β-glycosidase, percentage of aglycone (total aglycone/total isoflavones) in SIM isoflavone extracts increased significantly in raw (35%), fermented (48%), roasted (88%) and steamed (91%) SIM, compared to their initial (∼5%) compositions. Manipulation of β-glycosidase activity and isoflavone composition can be used to modulate aglycone content in soy food products.

Topics: Glycoside Hydrolases; Glycosides; Isoflavones; Nitrophenols; Prunus dulcis

This work describes cell associated and extracellular synthesis of nanoparticles by the yeast, Williopsis saturnus. The yeast was able to grow in the absence and presence of sodium chloride (NaCl) and form nanoparticles in a cell associated manner. The content of melanin, a stress-associated pigment was found to be progressively greater in the presence of increasing concentrations of NaCl. With higher quantities of melanin (extracted from yeast cells grown in the presence of 4% of NaCl), smaller sized nanoparticles were obtained. This is the first report on understanding the relationship between halotolerance, production of a stress-related pigment (melanin) and synthesis of nanoparticles with antioxidant properties by using W. saturnus as a model system. The cell free extracts derived from cultures grown in the absence of NaCl were able to mediate extracellular synthesis of gold and silver nanoparticles and the biomolecule mediating nanoparticle synthesis was identified to be a glycolipid. Extracellularly synthesized gold nanoparticles displayed good catalytic activity and rapidly mediated the reduction of 4-nitrophenol to 4-aminophenol.

Topics: Aminophenols; Antioxidants; Glycolipids; Melanins; Metal Nanoparticles; Nitrophenols; Salt Tolerance; Sodium Chloride; Williopsis

The bacterium KS-1, capable of degrading fluoroglycofen, was isolated from sludge collected at a herbicide factory. The isolate was identified as Lysinibacillus sp. according to its phenotypic features and 16S rDNA phylogeny. KS-1 degraded 85.25% of the fluoroglycofen (50 mg L-1) within 3 days of incubation. The optimum temperature and pH for fluoroglycofen degradation were 30°C and 7.0, respectively. Furthermore, Zn2+ and Cu2+ could significantly decrease the degradation rate. Three degradation products, which appeared during KS-1-mediated fluoroglycofen metabolism, were identified as deethyl-fluoroglycofen, acifluorfen and decarboxylate-acifluorfen. The fluE gene, which encodes a novel esterase that catalyzes the cleavage of carboxyl ester bonds of fluoroglycofen, was cloned from the KS-1 strain. Sequence alignment reveals that FluE shares 30%-40% amino acid sequence identity with members of the hormone sensitive lipase family. FluE was expressed in Escherichia coli BL21 and purified by Ni-NTA affinity chromatography. Purified FluE could efficiently hydrolyze fluoroglycofen and short-chain p-nitrophenol esters. However, no lipolytic activity was observed with esters containing acyl chains longer than 10 carbon atoms, thereby indicating that this enzyme is an esterase.

Topics: Bacillaceae; Biodegradation, Environmental; Cloning, Molecular; DNA, Ribosomal; Esterases; Genomic Library; Herbicides; Hydrocarbons, Halogenated; Hydrogen-Ion Concentration; Nitrobenzoates; Nitrophenols; Phylogeny; Sewage; Temperature

Topics: Bacillus; Biodegradable Plastics; Biodegradation, Environmental; Butyrates; Carboxylic Ester Hydrolases; Enzyme Stability; Nitrophenols; Polyesters; Substrate Specificity; Temperature

Nanoparticles were synthesized on the surface of green nanocomposite based on carbon black dispersed in chitosan (CB-CS) fibres. The nanoparticles were monometallic Co, Ag and Cu and bimetallic Co + Cu and Co + Ag. The CB-CS fibres were prepared and introduced into separate metal salt solutions containing Co

Topics: Anti-Bacterial Agents; Catalysis; Chitosan; Coloring Agents; Environmental Restoration and Remediation; Green Chemistry Technology; Metal Nanoparticles; Nanocomposites; Nitrophenols; Soot

The tumor-specific sensitive fluorescence sensing of cellular alkaline phosphatase (ALP) activity on the basis of host-guest specific and pH sensitivity was conducted on coated surfaces and aqueous states. Cross-linked fluorescent nanoparticles (C-FNP) consisting of β-cyclodextrin (β-CD)/boronic acid (BA) and fluorescent hyaluronic acid [FNP(HA)] were conjugated to fluorescent polydopamine [FNP(pDA)]. To determine the quenching effect of this system, hydrolysis of 4-nitrophenyl phosphate (NPP) to 4-nitrophenol (NP) was performed in the cavity of β-CD in the presence of ALP activated photoinduced electron transfer (PET) between NP and C-FNP. At an ALP level of 30-1000 U/L, NP caused off-emission of C-FNP because of their specific host-guest recognition. Fluorescence can be recovered under pH shock due to cleavage of the diol bond between β-CD and BA, resulting in release of NP from the fluorescent system. Sensitivity of the assays was assessed by confocal imaging not only in aqueous states, but also for the first time on coated surfaces in MDAMB-231 and MDCK cells. This novel system demonstrated high sensitivity to ALP through generation of good electron donor/acceptor pair during the PET process. Therefore, this fluorescence sensor system can be used to enhance ALP monitoring and cancer diagnosis on both coated surfaces and in aqueous states in clinical settings.

Topics: Alkaline Phosphatase; Animals; beta-Cyclodextrins; Carbon; Cell Line, Tumor; Cross-Linking Reagents; Dogs; Fluorescence; Fluorescent Dyes; Humans; Hydrogen-Ion Concentration; Indoles; Madin Darby Canine Kidney Cells; Nanoparticles; Nitrophenols; Organophosphorus Compounds; Particle Size; Polymers; Solutions; Surface Properties; Water

In this research work, copper (Cu), palladium (Pd) and their bimetallic palladium@ copper (Pd@Cu) nanoparticles were synthesized using trisodium citrate as a stabilizing agent using the known chemical reduction method. The synthesized Cu, Pd and Pd@Cu nanoparticles were characterized by the ultraviolet-visible spectroscopy, scanning electron microscopy and X-ray diffraction spectroscopy, respectively. The different volumes of trisodium citrate were used for the stability of synthesized monometallic Cu, Pd and bimetallic Pd@Cu nanoparticles. The synthesized Cu, Pd and their bimetallic Pd@Cu nanoparticles were used as catalysts for the reduction of 4-nitrophenol in the presence of NaBH

Topics: Anti-Infective Agents; Catalysis; Citrates; Copper; Gram-Negative Bacteria; Gram-Positive Bacteria; Metal Nanoparticles; Microscopy, Electron, Scanning; Nitrophenols; Palladium; X-Ray Diffraction

4-Nitrophenol (PNP) is well known as an environmental endocrine disruptor. The aim of this study was to clarify the mechanism of PNP-induced liver damage and determine the regulatory involvement of the aryl hydrocarbon receptor (AhR) signaling pathway and associated gene expression. Immature male Wistar-Imamichi rats (28 days old) were randomly divided into control and PNP groups, which consisted of 1- and 3-day exposure (1 DE and 3 DE, respectively) and 3-day exposure followed by 3-day recovery (3 DE + 3 DR), groups. Each group was administered the vehicle or PNP (200 mg kg

Topics: Animals; Body Weight; Cytochrome P-450 CYP1A1; Endocrine Disruptors; Gene Expression Regulation; Glutathione Transferase; Liver; Male; Nitrophenols; Organ Size; Rats, Wistar; Receptors, Aryl Hydrocarbon; Signal Transduction

Morphological and functional changes have been investigated in the rat model of Crohn's disease. The inflammatory bowel disease was induced by indomethacin (1 × 10 mg/kg s.c. for 3 days). Morphological alterations were evaluated by macroscopic scoring system and on the base of histological changes in the small intestine. Functional activities were studied by determination of the intestinal and hepatic elimination of p-Nitrophenol (PNP) and its metabolites (PNP-glucuronide: PNP-G and PNP-sulfate: PNP-S) during the luminal perfusion of PNP. It was found that the indomethacin induced severe macroscopic changes (hyperaemia, petechia, bleeding, erosions, ulcerations) and significant histological alterations in the small intestine of rats which were definitely inhibited by mesalazine (1000 mg/kg by gastric tube for 3 days). Disappearance of PNP from the luminal perfusion solution was diminished by indomethacin which was corrected by administration of mesalazine. Significant depression was found in the luminal appearance of PNP metabolites by giving of indomethacin and these alterations could not be compensated by mesalazine.Hepatic elimination of PNP (biliary excretion of PNP and its metabolites) was decreased definitely by indomethacin which was - at least partly - compensated by mesalazine.The findings of the present study suggest that the indomethacin-induced inflammation in the small intestine represents a useful rat model of Crohn's disease. Morphological and functional alterations caused by indomethacin can be compensated by mesalazine.

Topics: Animals; Crohn Disease; Disease Models, Animal; Glucuronates; Indomethacin; Inflammation; Inflammatory Bowel Diseases; Intestine, Small; Liver; Male; Mesalamine; Nitrobenzenes; Nitrophenols; Rats; Rats, Wistar

The previously developed Sphingomonas sp. based optical microplate biosensor for methyl parathion (MP) was good as it detected multiple samples but had poor stability and low sensitivity. The present study aims to overcome these limitations. Silica nanoparticles (Si NP) were thus functionalized with polyethyleneimine (PEI) and the functionalized silica nanoparticles (

Topics: Biosensing Techniques; Cells, Immobilized; Food Analysis; Fruit; Limit of Detection; Methyl Parathion; Nanoparticles; Nitrophenols; Pesticides; Polyethyleneimine; Silicon Dioxide; Sphingomonas; Vitis; Water Pollutants, Chemical

A facile one-pot eco-friendly process for synthesis of gold nanoparticles (AuNPs) with high catalytic activity was achieved using cell-free extracts of Aspergillus sp. WL-Au as reducing, capping and stabilizing agents. The surface plasmon resonance band of UV-vis spectrum at 532nm confirmed the presence of AuNPs. Transmission electron microscopy images showed that quite uniform spherical AuNPs were synthesized and the average size of nanoparticles increased from 4nm to 29nm with reaction time. X-ray diffraction analysis verified the formation of nano-crystalline gold particles. Fourier transform infrared spectra showed the presence of functional groups on the surface of biosynthesized AuNPs, such as OH, NH, CO, CH, COH and COC groups, which increased the stability of AuNPs. The biogenic AuNPs could serve as a highly efficient catalyst for 4-nitrophenol reduction. The reaction rate constant was linearly correlated with the concentration of AuNPs, which increased from 0.59min

Topics: Aspergillus; Catalysis; Gold; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Surface Properties

The present study was conducted to synthesize palladium nanoparticles (Pd NPs) through a facile and green route using non-toxic and renewable natural black tea leaves (Camellia sinensis) extract, as the reducing and stabilizing agent. The as-prepared Pd@B.tea NPs catalyst was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The Pd@B.tea NPs catalyst could be used as an efficient and heterogeneous catalyst for Suzuki coupling reactions between phenylboronic acid and a range of aryl halides (X=I, Br, Cl) and also the reduction of 4-nitrophenol (4-NP) using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled 7 times without any significant loss of its catalytic activity.

Topics: Borohydrides; Boronic Acids; Camellia sinensis; Catalysis; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Plant Extracts; Plant Leaves

The application of metal nanoparticles (NPs) in catalysis has drawn significant research interest, including in their applications to the wastewater treatment. Nanocellulose can be a versatile support/carrier in stabilizing metal NPs catalysts, due to its unique properties. In this paper, hexadecyl-trimethylammonium bromide (CTAB) surfactant-adsorbed cellulose nanocrystals (CNC) was employed as a support for silver nanoparticles (Ag NPs). The obtained CNC/CTAB/Ag nanohybrid composite was characterized by ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results of the catalytic reaction experiments showed that Ag NPs immobilized on CTAB-adsorbed CNC displayed higher catalytic efficiency towards the reduction of 4-nitrophenol to 4-aminophenol, compared to the control Ag NPs and CNC/Ag samples. The enhanced catalytic performance of Ag NPs was attributed to the improved dispersity and narrow distribution of silver nanoparticles in the catalytic system. This work provides a novel catalyst based on CNC-CTAB stabilized Ag NPs which would have promising applications towards catalytic treatment of wastewater.

Topics: Catalysis; Cellulose; Cetrimonium; Cetrimonium Compounds; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Silver

Topics: Borohydrides; Catalysis; Metal Nanoparticles; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanocomposites; Nanotubes, Carbon; Nitrophenols; Photoelectron Spectroscopy; Shewanella; Silver; X-Ray Diffraction

The ortho-nitrophenol (ONP)-utilizing Alcaligenes sp. strain NyZ215, meta-nitrophenol (MNP)-utilizing Cupriavidus necator JMP134 and para-nitrophenol (PNP)-utilizing Pseudomonas sp. strain WBC-3 were assembled as a consortium to degrade three nitrophenol isomers in sequential batch reactors. Pilot test was conducted in flasks to demonstrate that a mixture of three mononitrophenols at 0·5 mol l. Nitroaromatic compounds are readily spread in the environment and pose great potential toxicity concerns. Here, we report the simultaneous degradation of three isomers of mononitrophenol in a single system by employing a consortium of three bacteria, both in flasks and lab-scale sequential batch reactors. The results demonstrate that simultaneous biodegradation of three mononitrophenol isomers can be achieved by a tailor-made microbial consortium immobilized in sequential batch reactors, providing a pilot study for a novel approach for the bioremediation of mixed pollutants, especially isomers present in wastewater.

Topics: Bacteria; Biodegradation, Environmental; Bioreactors; Isomerism; Microbial Consortia; Nitrophenols; Pilot Projects; Real-Time Polymerase Chain Reaction; Wastewater; Water Pollutants, Chemical

Topics: Azo Compounds; Catalysis; Coloring Agents; Congo Red; Green Chemistry Technology; Metal Nanoparticles; Methylene Blue; Nanotechnology; Nitrophenols; Oxidation-Reduction; Palladium; Plant Extracts; Prunus armeniaca; Rhodamines; Salvia

Paraoxonase-1 (PON-1) is a high-density lipoprotein-associated (HDL) enzyme, which has been shown to reduce susceptibility to low-density lipoprotein (LDL) peroxidation. Epicardial adipose tissue (EAT) is a marker of atherosclerosis. The aim of this study was to determine the relationship between PON-1 activity and EAT in hemodialysis (HD) patients.. This is a cross-sectional study conducted on 72 (43 males) HD patients with end-stage renal disease. Serum levels for lipid profiles, C-reactive protein, calcium, phosphate, and parathyroid hormone were measured. PON-1 activity was also measured and compared to the rate of enzymatic hydrolysis of paraoxon to p-nitrophenol. Echocardiography was used to measure EAT thickness (EATT). The correlation between PON-1 and EATT was assessed, while independent predictors of EATT in HD patients were similarly assessed using multivariate regression analysis.. There was a significant low mean value of PON-1 activity in HD patients compared with the control group (82.1 ± 31.6 vs. 164.3 ± 61.5 U/l, p = 0.0001) and significant high mean value of EATT in HD patients, compared with controls (6.2 ± 1.7 vs. 3.9 ± 1.1 mm, p = 0.0001). In addition, there was a significant negative correlation between PON-1 activity and EATT (r = -0.484, p = 0.0001) and a significant positive correlation between PON-1 activity and HDL-C (r = 0.417, p = 0.0003). PON-1, total cholesterol, triglycerides, LDL, HDL, age, and body mass index were found to be independent predictors of EATT.. Our study demonstrated that PON-1 activity was significantly lower in HD patients compared with healthy controls and that PON-1 activity was inversely correlated with EATT in this population.

Topics: Adipose Tissue; Adult; Aryldialkylphosphatase; Biomarkers; Body Mass Index; Cross-Sectional Studies; Echocardiography; Egypt; Female; Humans; Kidney Failure, Chronic; Lipoproteins, LDL; Male; Middle Aged; Nitrophenols; Pericardium; Renal Dialysis; Statistics as Topic

In this work, our goal was to study the capability of a single metallic oxide to neutralize a chemical agent and to exhibit an antibacterial effect. We tested two types of magnesium oxides, MgO. The first MgO sample tested, which commercial data size characteristic was -325 mesh (MgO-1) destroyed in 3 h, 89.7% of paraoxon and 93.2% of 4-nitrophenol, the first degradation product. The second MgO sample, which commercial data size was <50 nm (MgO-2) neutralized in the same time, 19.5% of paraoxon and 10.9% of 4-nitrophenol. For MgO-1 no degradation products could be detected by GC-MS. MgO-1 had a bactericidal activity on Escherichia coli (6 log in 1 h), and showed a decrease of almost 3 log on a Staphylococcus aureus population in 3 h. MgO-2 caused a decrease of 2 log of a E.coli culture but had no activity against S. aureus. Neither of these two products had an activity on Bacillus subtilis spores. Analytical investigations showed that the real sizes of MgO nanoparticles were 11 nm for MgO-1 and 25 nm for MgO-2. Moreover, their crystalline structures were different. These results highlighted the importance of the size of the nanoparticles and their microscopic arrangements to detoxify chemical products and to inhibit or kill microbial strains.

Topics: Bacillus subtilis; Escherichia coli; Gas Chromatography-Mass Spectrometry; Magnesium Oxide; Metal Nanoparticles; Nitrophenols; Organothiophosphorus Compounds; Paraoxon; Particle Size; Spores, Bacterial; Staphylococcus aureus

Metallogel of iron-carboxylates was obtained from trans-1,2-cyclohexanedicarboxylic acid in dimethylformamide (DMF) at basic condition. Spectroscopic and SEM morphology study of the iron-metallogel revealed that the iron complex with dicarboxylic acid was linked together via carboxylates and led to a supramolecular helical like architecture. The synthesized metallogel served as an excellent template for in-situ reduction of silver ion to silver particles micro to nano scale range. Variation of AgNO

Topics: Aminophenols; Catalysis; Cyclohexanecarboxylic Acids; Dicarboxylic Acids; Gels; Iron Compounds; Metal Nanoparticles; Models, Molecular; Nitrophenols; Oxidation-Reduction; Silver

Topics: Catalysis; Equisetum; Juglans; Methylene Blue; Nanocomposites; Nitrophenols; Palladium; Plant Extracts; Plant Leaves

In this work, a novel approach for simple and sensitive determination of alkaline phosphatase (ALP) is developed on the basis of an inner filter effect of p-nitrophenylphosphate (PNPP) on the fluorescence of gold nanoclusters (AuNCs). AuNCs with a high quantum yield of 12% were synthesized by one-pot strategy and were directly applied as fluorescent substance. When AuNCs were mixed with PNPP, the fluorescence of the AuNCs was remarkably quenched or was decreased via the inner filter effect since the absorption spectrum of PNPP overlaps well with the excitation spectrum of the AuNCs. While in the presence of ALP, PNPP was catalytically hydrolyzed into p-nitrophenol, which has different absorption characteristics from those of PNPP, resulting in the recovery of the AuNCs fluorescence. Thus, a novel "turn-on" fluorescent sensor for detecting ALP was established with a detection limit as low as 0.002 U/L (signal-to-noise ratio of 3). The turn-on fluorescent sensor exhibits many merits such as high sensitivity, excellent selectivity, and high signal output because of the low background signals. In addition, the developed sensing method was successfully applied to investigate ALP inhibitors and ALP determination in serum samples. A good linear relationship was obtained in the range from 0.02 to 50 U/L, and satisfactory recoveries at four spiking levels of ALP ranged from 95% to 106% with precision below 5%. The very simple sensing approach proposed here should promote the development of fluorescence turn-on chemosensors for chemo/biodetection.

Topics: Alkaline Phosphatase; Gold; Metal Nanoparticles; Nitrophenols; Signal-To-Noise Ratio

This work describes the development of a novel fluorescent biosensor based on the inhibition of alkaline phosphatase (ALP). The biosensor is composed of the enzyme ALP and the conjugated cationic polyfluorene HTMA-PFP. The working principle of the biosensor is based on the fluorescence quenching of this polyelectrolyte by p-nitrophenol (PNP), a product of the hydrolysis reaction of p-nitrophenyl phosphate (PNPP) catalyzed by ALP. Because HTMA-PFP forms unstable aggregates in buffer, with low fluorescence efficiency, previous stabilization of the polyelectrolyte was required before the development of the biosensor. HTMA-PFP was stabilized through its interaction with lipid vesicles to obtain stable blue-emitting nanoparticles (NPs). Fluorescent NPs were characterized, and the ability to be quenched by PNP was evaluated. These nanoparticles were coupled to ALP and entrapped in a sol-gel matrix to produce a biosensor that can serve as a screening platform to identify ALP inhibitors. The components of the biosensor were examined before and after sol-gel entrapment, and the biosensor was optimized to allow the determination of phosphate ion in aqueous medium.

Topics: Alkaline Phosphatase; Biosensing Techniques; Fluorenes; Liposomes; Nanoparticles; Nitrophenols; Phosphates

Bimetallic nanoparticles are generally believed to have improved catalytic activity and stability due to geometric and electronic changes. In this work, biogenic-Pd (bio-Pd), biogenic-Pt (bio-Pt), and biogenic-PdPt (bio-PdPt) nanoparticles were synthesized by Shewanella oneidensis MR-1 in the absence or presence of quinone. Compared with direct microbial reduction process, the addition of anthraquinone-2,6-disulfonate (AQDS) could promote the reduction efficiency of Pd(II) or/and Pt(IV) and result in decrease of particles size. All kinds of nanoparticles could catalyze 4-nitrophenol reduction by NaBH

Topics: Anthraquinones; Biodegradation, Environmental; Catalysis; Nanoparticles; Nitrophenols; Palladium; Particle Size; Shewanella; Triazines

A facile method was reported to achieve hollow-tubular-oriented polydopamine (HTO-PDA) layer using natural kapok fiber (KF) as the bio-template without any pretreatments by altering hydrophobic fiber into hydrophilic one. Subsequently, the HTO-PDA can be utilized for direct in-situ deposition of Ag nanoparticles (NPs). The structures of pristine fiber and HTO-PDA, as well as the resulting Ag NPs attached HTO-PDA (Ag@HTO-PDA) were well characterized by means of scanning electron microscopy (SEM) coupled energy dispersion spectrum (EDS), x-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. Due to the presence of relatively uniform Ag NPs attached onto PDA layer, Ag@KF-HTO-PDA shows stable catalytic ability towards the reduction of 4-nitrophenol into its amino derivative. Further, this method was used for facile fabrication of Calotropis gigantea fiber derived, surface-functionalized material. The experimental data demonstrated also its excellent catalytic efficiency towards 4-nitrophenol reduction.

Topics: Cellulose; Indoles; Metal Nanoparticles; Nitrophenols; Polymers; Silver

A polymeric membrane-supported catalyst with immobilized gold nanoparticles (AuNPs) was prepared through the extraction and in situ reduction of Au

Topics: Aminophenols; Catalysis; Gold; Green Chemistry Technology; Membranes, Artificial; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Polymers; Water

Zero-valent iron (ZVI) is a valuable material for environmental remediation, because of its safeness, large availability, and inexpensiveness. Moreover, its reactivity can be improved by addition of (nano-) particles of other elements such as noble metals. However, common preparation methods for this kind of iron-based composites involve wet precipitation of noble metal salt precursors, so they are often expensive and not green. Mechanochemical procedures can provide a solvent-free alternative, even at a large scale. The present study demonstrates that it is possible to tailor functional properties of ZVI-based materials, utilizing high-energy ball milling. All main preparation parameters are investigated and discussed. Specifically, a copper-carbon-iron ternary composite was prepared for fast degradation of 4-nitrophenol (utilized as model pollutant) to 4-aminophenol and other phenolic compounds. Copper and carbon are purposely chosen to insert specific properties to the composite: Copper acts as efficient nano-cathode that enhances electron transfer from iron to 4-nitrophenol, while carbon protects the iron surface from fast oxidation in open air. In this way, the reactive material can rapidly reduce high concentration of nitrophenols in water, it does not require acid washing to be activated, and can be stored in open air for one week without any significant activity loss.

Topics: Carbon; Copper; Iron; Iron Compounds; Nitrophenols; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical

Topics: Electrolysis; Hydrogen Peroxide; Nitrophenols; Ozone; Pilot Projects; Ultraviolet Rays; Waste Disposal, Fluid; Water Pollutants, Chemical

Topics: Antioxidants; Biopolymers; Ethanol; Hydrolysis; Lignin; Magnetic Resonance Spectroscopy; Molecular Weight; Nitrophenols; Oxidation-Reduction; Palm Oil; Plant Oils; Solubility; Solvents; Spectroscopy, Fourier Transform Infrared; Water

The synthesis of glycosidic structures by catalysis via glycosynthases has gained much interest due to the potential high product yields and specificity of the enzymes. Nevertheless, the characterisation and implementation of new glycosynthases is greatly hampered by the lack of high-throughput methods for reaction analysis and screening of potential glycosynthase variants. Fluoride detection, via silyl ether chemosensors, has recently shown high potential for the identification of glycosynthase mutants in a high-throughput manner, though limited by the low maximal detection concentration. In the present paper, we describe a new version of a glycosynthase activity assay using a silyl ether of p-nitrophenol, allowing fast reliable detection of fluoride even at concentrations of 4mM and higher. This improvement of detection allows not only screening and identification but also kinetic characterisation of glycosynthases and synthetic reactions in a fast microtiter plate format. The applicability of the assay was successfully demonstrated by the biochemical characterisation of the mesophilic β-glucosynthase of Abg-E358S (Rhizobium radiobacter) and psychrotolerant β-glucosynthase BglU-E377A (Micrococcus antarcticus). The limitation of hyperthermophilic glycosidases as potential glycosynthases, when using glycosyl fluoride donors, was also illustrated by the example of the putative β-galactosidase GalPf from Pyrococcus furiosus.

Topics: Biosensing Techniques; Catalysis; Colorimetry; Enzyme Assays; Escherichia coli; Escherichia coli Proteins; Fluorides; Genetic Vectors; Glycoside Hydrolases; Glycosides; Kinetics; Nitrophenols; Point Mutation; Pyrococcus furiosus; Substrate Specificity

The crystal structure of hydroquinone 1,2-dioxygenase, a Fe(II) ring cleaving dioxygenase from Sphingomonas sp. strain TTNP3, which oxidizes a wide range of hydroquinones to the corresponding 4-hydroxymuconic semialdehydes, has been solved by Molecular Replacement, using the coordinates of PnpCD from Pseudomonas sp. strain WBC-3. The enzyme is a heterotetramer, constituted of two subunits α and two β of 19 and 38kDa, respectively. Both the two subunits fold as a cupin, but that of the small α subunit lacks a competent metal binding pocket. Two tetramers are present in the asymmetric unit. Each of the four β subunits in the asymmetric unit binds one Fe(II) ion. The iron ion in each β subunit is coordinated to three protein residues, His258, Glu264, and His305 and a water molecule. The crystal structures of the complexes with the substrate methylhydroquinone, obtained under anaerobic conditions, and with the inhibitors 4-hydroxybenzoate and 4-nitrophenol were also solved. The structures of the native enzyme and of the complexes present significant differences in the active site region compared to PnpCD, the other hydroquinone 1,2-dioxygenase of known structure, and in particular they show a different coordination at the metal center.

Topics: Amino Acid Sequence; Binding Sites; Catalytic Domain; Crystallography, X-Ray; Dioxygenases; Hydroquinones; Iron; Nitrophenols; Parabens; Protein Conformation; Sequence Homology, Amino Acid; Sphingomonas

This is the first in vitro study to investigate gender-related differences in the regulation of human cytochrome P450 by the flavonoids. Activities of CYP2E1 and CYP3A were measured in the presence of quercetin, myricetin, or isorhamnetin in hepatic microsomal pools from male and female donors. Hydroxylation of p-nitrophenol (PNPH) was measured to determine CYP2E1 activity, and O-dealkylation of 7-benzyloxy-4-trifluoromethylcoumarin (BFC) was measured to determine CYP3A activity. Quercetin, but not myricetin or isorhamnetin, competitively inhibited PNPH activity in human recombinant cDNA-expressed CYP2E1 with the Ki=52.1±6.31μM. In the human microsomes, slight inhibition of PNPH activity by quercetin was not considered as physiologically relevant. Quercetin inhibited BFC activity in human recombinant cDNA-expressed CYP3A4 competitively with the Ki=15.4±1.52μM, and myricetin - noncompetitively with the Ki=74.6±7.99μM. The degree of inhibition by quercetin was similar between genders. Myricetin showed somewhat stronger inhibition in female pools, but the Ki values were higher than physiologically relevant concentrations. Isorhamnetin did not affect either PNPH or BFC activity. We concluded that observed inhibition of CYP2E1 and CYP3A by some flavonols were not gender-dependent.

Topics: Coumarins; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Cytochrome P-450 CYP3A; Enzyme Inhibitors; Female; Flavonoids; Humans; Hydroxylation; Male; Microsomes, Liver; Nitrophenols; Quercetin; Sex Factors

A single liter of water contains hundreds, if not thousands, of bacterial and archaeal species, each of which typically makes up a very small fraction of the total microbial community (<0.1%), the so-called "rare biosphere." How often, and via what mechanisms, e.g., clonal amplification versus horizontal gene transfer, the rare taxa and genes contribute to microbial community response to environmental perturbations represent important unanswered questions toward better understanding the value and modeling of microbial diversity. We tested whether rare species frequently responded to changing environmental conditions by establishing 20-liter planktonic mesocosms with water from Lake Lanier (Georgia, USA) and perturbing them with organic compounds that are rarely detected in the lake, including 2,4-dichlorophenoxyacetic acid (2,4-D), 4-nitrophenol (4-NP), and caffeine. The populations of the degraders of these compounds were initially below the detection limit of quantitative PCR (qPCR) or metagenomic sequencing methods, but they increased substantially in abundance after perturbation. Sequencing of several degraders (isolates) and time-series metagenomic data sets revealed distinct cooccurring alleles of degradation genes, frequently carried on transmissible plasmids, especially for the 2,4-D mesocosms, and distinct species dominating the post-enrichment microbial communities from each replicated mesocosm. This diversity of species and genes also underlies distinct degradation profiles among replicated mesocosms. Collectively, these results supported the hypothesis that the rare biosphere can serve as a genetic reservoir, which can be frequently missed by metagenomics but enables community response to changing environmental conditions caused by organic pollutants, and they provided insights into the size of the pool of rare genes and species.

Topics: 2,4-Dichlorophenoxyacetic Acid; Archaea; Bacteria; Biodegradation, Environmental; Biodiversity; Caffeine; Ecosystem; Fresh Water; Georgia; Lakes; Metagenomics; Microbial Consortia; Nitrophenols; Phylogeny; Real-Time Polymerase Chain Reaction; RNA, Ribosomal, 16S; Water Pollutants, Chemical

A green approach was envisaged for the rapid synthesis of stable silver nanoparticles in an aqueous medium using phenolic rich ethanolic bark extract from D. indica with marked free radical scavenging and reducing ability. Biosynthesis of silver nanoparticles (AgNPs) was confirmed and characterized by using UV-visible spectroscopy, particle size analyzer, X-ray diffractometry (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FT-IR). Bio-reduction of Ag+ was confirmed with the appearance of golden yellow coloration within 5-10min at 45°C with maximum absorbance at 421nm. XRD analysis of AgNPs indicated the crystalline nature of metallic Ag. As analyzed by TEM, AgNPs were found to be spherical in shape, well dispersed and size varied from 15 to 35nm and dynamic light scattering (DLS) studies showed the average particle size of 29nm with polydispersity index (PDI) of 0.280. Synthesized AgNPs were showing surface functionalization as revealed through FTIR studies. These AgNPs were observed to be highly stable at room temperature (28±2°C) for more than 3months, thereby indicating the ethanolic extract of D. indica was a reducing as well as a capping agent for stabilization of AgNPs. Moreover, these green synthesized AgNPs showed enhanced free radical scavenging and excellent catalytic activities when used in the reduction of 4-nitrophenol and methylene blue dye, at room temperature.

Topics: Catalysis; Dilleniaceae; Free Radical Scavengers; Green Chemistry Technology; Metal Nanoparticles; Methylene Blue; Nitrophenols; Oxidation-Reduction; Particle Size; Phenols; Plant Bark; Plant Extracts; Silver

In current research, Ag/RGO/Fe

Topics: Catalysis; Coloring Agents; Ferrosoferric Oxide; Graphite; Lotus; Nitrophenols; Oxidation-Reduction; Plant Extracts; Silver

To predict the mechanism of liver injury induced by Genkwa Flos, we investigated the effect of chloroform extract on UGTs and UGT1A1 activities of the liver microsomes in rat and human. In the present study, 4-nitrophenol(4-NP) and β-estradiol were elected as substrates to determine activities of UGTs and UGT1A1 by UV and HPLC. The results showed that there were 1.00% of apigenin, 6.40% of hydroxygenkwanin and 18.38% of genkwanin in chloroform extract; and total diterpene mass fraction was 31.40%. Compared with the control group, chloroform extract could significantly inhibit the activity of UGTs in rat liver microsomes(RLM) system, while the inhibitory effect was not obvious in human liver microsomes(HLM) system. UGT1A1 activity was inhibited by chloroform extract in rat liver microsomes and human liver microsomes (based on genkwanin, IC₅₀=8.76, 10.36 μmol•L⁻¹). The inhibition types were non-competitive inhibition(RLM) and uncompetitive inhibition(HLM). In conclusion, the results indicated that chloroform extract showed different inhibitory effects on UGTs and UGT1A1 activity, which may be one of the mechanisms of liver injury induced by Genkwa Flos.

Topics: Animals; Apigenin; Chromatography, High Pressure Liquid; Daphne; Drugs, Chinese Herbal; Estradiol; Flavones; Flavonoids; Glucuronosyltransferase; Humans; Microsomes, Liver; Nitrophenols; Plant Extracts; Rats

In the present study, the removal of

Topics: Adsorption; Fractals; Hydrogen-Ion Concentration; Industrial Waste; Kinetics; Nitrophenols; Temperature; Thermodynamics; Water; Water Pollutants, Chemical

Fabrication of Au nanostars (AuNSs) can expand the application range of Au nanoparticles because of their high electron density and localized surface plasmon resonance (LSPR) on branches. Exploiting this potential requires further refinement of length of the branches and radius of their tips. To this end, we successfully synthesized AuNSs with uniform and sharply-pointed branches by combining benzyldimethylammonium chloride (BDAC) and cetyltrimethylammonium bromide (CTAB) at low BDAC/CTAB ratios. Once mixed with CTAB, BDAC lowers the critical micelle concentration (CMC) for quick formation of the micelles, which provides favorable growth templates for AuNSs formation. Besides, BDAC increases the concentration of Cl(-), which favors Ag(+) in adsorbing on Au facets. This feature is crucial for the yield boosting and synergic shape control of AuNSs regardless of types of Au seeds used. Use of less amounts of seeds as the center of nucleation benefited sharper and longer growth of the branches. AuNSs exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) intensities as the result of high electron density localized at the tips; however, the enhancement degree varied in accordance with the size of branches. In addition, AuNSs showed high catalytic performance toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Efficient catalysis over AuNSs originates from their corners, stepped surfaces and high electron density at the tips.

Topics: Aminophenols; Benzylammonium Compounds; Catalysis; Cetrimonium; Cetrimonium Compounds; Gold; Metal Nanoparticles; Micelles; Nitrophenols; Particle Size; Spectrum Analysis, Raman; Surface Properties

Here we report the use of β-cyclodextrin polyurethane nanosponges cross-linked with 1,6-hexamethylene diisocyanate as a template for the preparation of Aun quantum clusters, by the core-etching of glutathione-capped Au nanoparticles. The study of temporal evolution of the core-etching process using different Au concentrations indicated that formation of Aun clusters embedded in the nanosponge is favored by the use of lower Au concentrations, since it began at shorter times and lead to higher cluster loading. An estimation of the number of Au atoms based on the maximum photoluminescence wavelength suggested that, depending on the Au concentration and the core etching time, clusters with 11-15 atoms were formed. After excluding the possibility of an inclusion complex formation, evaluation of the catalytic activity of nanosponge-loaded Aun clusters toward the reduction of 4-nitrophenol has shown that the reaction is catalyzed by the Aun clusters with no induction time, following the Langmuir-Hinshelwood kinetic model.

Topics: beta-Cyclodextrins; Catalysis; Glutathione; Gold; Isocyanates; Models, Molecular; Molecular Conformation; Nitrophenols; Oxidation-Reduction; Polyurethanes; Quantum Dots

We present wastewater-mediated activation of catalytic micromotors for the degradation of nitroaromatic pollutants in water. These next-generation hybrid micromotors are fabricated by growing catalytically active Pd particles over thin-metal films (Ti/Fe/Cr), which are then rolled-up into self-propelled tubular microjets. Coupling of catalytically active Pd particles inside the micromotor surface in the presence of a 4-nitrophenol pollutant (with NaBH4 as reductant) results in autonomous motion via the bubble-recoil propulsion mechanism such that the target pollutant mixture (wastewater) is consumed as a fuel, thereby generating nontoxic byproducts. This study also offers several distinct advantages over its predecessors including no pH/temperature manipulation, limited stringent process control and complete destruction of the target pollutant mixture. The improved intermixing ability of the micromotors caused faster degradation ca. 10 times higher as compared to its nonmotile counterpart. The high catalytic efficiency obtained via a wet-lab approach has promising potential in creating hybrid micromotors comprising of multicatalytic systems assembled into one entity for sustainable environmental remediation and theranostics.

Topics: Catalysis; Environmental Restoration and Remediation; Microspheres; Nitrophenols; Titanium; Wastewater; Water Pollutants, Chemical; Water Purification

A reduced graphene oxide (RGO)/Fe3O4 based nanocomposite with palladium nanoparticles (Pd NPs) has been synthesized via a green route by Withania coagulans leaf extract as a reducing and stabilizing agent and its catalytic activity has been tested for the reduction of 4-nitrophenol (4-NP) in water at room temperature. The hydroxyl groups of phenolics in W. coagulans leaf extract is directly responsible for the reduction of Pd(2+), Fe(3+) ions and GO. The nanocomposite was characterized by X-ray diffraction (XRD), fourier transformed infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), Vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). Furthermore, due to the magnetic separability and high stability of the composite the catalyst can be recovered and recycled several times without marked loss of activity.

Topics: Catalysis; Ferric Compounds; Graphite; Green Chemistry Technology; Nanocomposites; Nitrophenols; Oxidation-Reduction; Palladium; Plant Extracts; Plant Leaves; Withania

Generation of environmentally persistent free radicals (EPFRs) on solid particles has recently attracted increasing research interest. EPFRs potentially have high reactivity and toxicity. However, the impact of EPFRs on organic contaminant behavior is unclear. We hypothesized that EPFRs in biochars can degrade organic contaminants and play an important role in organic contaminant behavior. We observed obvious degradation of p-nitrophenol (PNP) in the presence of biochars, through the detection of NO3(-) as well as organic byproducts. The extent of PNP degradation was correlated to the intensity of EPR signals of biochar particles. tert-Butanol (a •OH scavenger) did not completely inhibit PNP degradation, indicating that •OH could not fully explain PNP degradation. The decreased PNP degradation after tert-butanol addition was better correlated with reduced PNP sorption on biochars. PNP degradation through the direct contact with EPFRs in biochar particles could be an important contribution to the PNP concentration reduction in the aqueous phase. The coating of natural organic matter analogue (tannic acid) on biochars did not considerably inhibit PNP degradation, suggesting the ability of biochars to degrade PNP in soil and natural water. Similar EPFR-promoted degradation was observed for five different types of biochars and one activated carbon, as well as one additional chemical (p-aminophenol). Therefore, organic chemical degradation by EPFRs in biochars can be a common process in the environment and should be incorporated in organic chemical fate and risk studies.

Topics: Charcoal; Free Radicals; Nitrophenols; Soil Pollutants; Water Pollutants, Chemical

A new high-performance liquid chromatography method using fused-core column for fast separation of resveratrol and polydatin has been developed and used for quality control of nutraceuticals with resveratrol and polydatin content. Retention characteristics (log k) were studied under different conditions on C-18, RP-Amide C-18, Phenyl-hexyl, Pentafluorophenyl (F5) and Cyano stationary phases for both compounds. The effect of the volume fraction of acetonitrile on a retention factors log k of resveratrol and polydatin were evaluated. The optimal separation conditions for resveratrol, polydatin and internal standard p-nitrophenol were found on the fused-core column Ascentis Express ES-Cyano (100×3.0mm), particle size 2.7μm, with mobile phase acetonitrile/water solution with 0.5% acetic acid pH 3 (20:80, v/v) at a flow rate of 1.0mL/min and at 60°C. The detection wavelength was set at 305nm. Under the optimal chromatographic conditions, good linearity with regression coefficients in the range (r=0.9992-0.9998; n=10) for both compounds was achieved. Commercial samples of nutraceuticals were extracted with methanol using ultrasound bath for 15min. A 5μL sample volume of the filtered solution was directly injected into the HPLC system. Accuracy of the method defined as a mean recovery was in the range 83.2-107.3% for both nutraceuticals. The intraday method precision was found satisfactory and relative standard deviations of sample analysis were in the range 0.8-4.7%. The developed method has shown high sample throughput during sample preparation process, modern separation approach, and short time (3min) of analysis. The results of study showed that the declared content of resveratrol and polydatin varied widely in different nutraceuticals according the producers (71.50-115.00% of declared content).

Topics: Acetonitriles; Chromatography, High Pressure Liquid; Dietary Supplements; Glucosides; Indicators and Reagents; Nitrophenols; Quality Control; Resveratrol; Solutions; Stilbenes

Recovery of gold from aqueous solution using simple and economical methodologies is highly desirable. In this work, recovery of gold as gold nanoparticles (AuNPs) by Shewanella haliotis with sodium lactate as electron donor was explored. The results showed that the process was affected by the concentration of biomass, sodium lactate, and initial gold ions as well as pH value. Specifically, the presence of sodium lactate determines the formation of nanoparticles, biomass, and AuCl4 (-) concentration mainly affected the size and dispersity of the products, reaction pH greatly affected the recovery efficiency, and morphology of the products in the recovery process. Under appropriate conditions (5.25 g/L biomass, 40 mM sodium lactate, 0.5 mM AuCl4 (-), and pH of 5), the recovery efficiency was almost 99 %, and the recovered AuNPs were mainly spherical with size range of 10-30 nm (~85 %). Meanwhile, Fourier transforms infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that carboxyl and amine groups might play an important role in the process. In addition, the catalytic activity of the AuNPs recovered under various conditions was testified by analyzing the reduction rate of p-nitrophenol by borohydride. The biorecovered AuNPs exhibited interesting size and shape-dependent catalytic activity, of which the spherical particle with smaller size showed the highest catalytic reduction activity with rate constant of 0.665 min(-1).

Topics: Borohydrides; Catalysis; Gold; Metal Nanoparticles; Nitrophenols

We investigated the effect of phytosterol (PS) in regard to liver damage induced by 4-nitrophenol (PNP). Twenty rats were randomly divided into four groups (Control, PS, PNP, and PNP+PS). The PS and PNP+PS groups were pretreated with PS for one week. The PNP and PNP+PS groups were injected subcutaneously with PNP for 28 days. The control group received a basal diet and was injected with vehicle alone. Treatment with PS prevented the elevation of the total bilirubin levels, as well as an increase in serum alkaline transaminase and aspartate transaminase, which are typically caused by PNP-induced liver damage. Histopathologically showed that liver damage was significantly mitigated by PS treatment. However, there was no significant change in antioxidant enzyme activities, and the Nrf2-antioxidant system was not activated after treatment with PS. These results suggest that PS could mitigate liver damage induced by PNP, but does not enhance antioxidant capacity.

Topics: Animals; Bilirubin; Chemical and Drug Induced Liver Injury; Gene Expression Regulation, Enzymologic; Injections, Subcutaneous; Male; NF-E2-Related Factor 2; Nitrophenols; Phytosterols; Rats; Rats, Sprague-Dawley; Transaminases

Although in vitro chromosomal aberration tests and micronucleus tests have been widely used for genotoxicity evaluation, false-positive results have been reported under strong cytotoxic conditions. To reduce false-positive results, the new Organization for Economic Co-operation and Development (OECD) test guideline (TG) recommends the use of a new cytotoxicity index, relative increase in cell count or relative population doubling (RICC/RPD), instead of the traditionally used index, relative cell count (RCC). Although the use of the RICC/RPD may result in different outcomes and require re-evaluation of tested substances, it is impractical to re-evaluate all existing data. Therefore, we established a method to estimate test results from existing RCC data. First, we developed formulae to estimate RICC/RPD from RCC without cell counts by considering cell doubling time and experiment time. Next, the accuracy of the cytotoxicity index transformation formulae was verified by comparing estimated RICC/RPD and measured RICC/RPD for 3 major chemicals associated with false-positive genotoxicity test results: ethyl acrylate, eugenol and p-nitrophenol. Moreover, 25 compounds with false-positive in vitro chromosomal aberration (CA) test results were re-evaluated to establish a retrospective evaluation method based on derived estimated RICC/RPD values. The estimated RICC/RPD values were in good agreement with the measured RICC/RPD values for every concentration and chemical, and the estimated RICC suggested the possibility that 12 chemicals (48%) with previously judged false-positive results in fact had negative results. Our method enables transformation of RCC data into RICC/RPD values with a high degree of accuracy and will facilitate comprehensive retrospective evaluation of test results.

Topics: Acrylates; Animals; Cell Count; Cell Survival; Cells, Cultured; Chromosome Aberrations; DNA Damage; Eugenol; Guidelines as Topic; Humans; Mammals; Micronucleus Tests; Mutagenicity Tests; Nitrophenols; Retrospective Studies

The compound p-nitrophenol, which shows the anti-androgenic activity, can easily become anthropogenic pollutants and pose a threat to the environment and human health. Previous work indicates that the anti-androgenic mechanism of p-nitrophenol is complex and may involve several components in the AR signaling pathway, but the molecular details of how p-nitrophenol inhibits AR signaling are still not quite clear. Here, we characterized p-nitrophenol binds to the FK1 domain of an AR positive regulator FKBP51 with micromolar affinity and structural analysis of FK1 domain in complex with p-nitrophenol revealed that p-nitrophenol occupies a hydrophobic FK1 pocket that is vital for AR activity enhancement. Molecular dynamics simulation indicated that p-nitrophenol is stably bound to the FK1 pocket and the hotspot residues that involved p-nitrophenol binding are mainly hydrophobic and overlap with the AR interaction site. Furthermore, we showed that p-nitrophenol inhibits the androgen-dependent growth of human prostate cancer cells, possibly through down-regulating the expression levels of AR activated downstream genes. Taken together, our data suggests that p-nitrophenol suppresses the AR signaling pathway at least in part by blocking the interaction between AR and its positive regulator FKBP51. We believe that our findings could provide new guidelines for assessing the potential health effects of p-nitrophenol.

Topics: Androgen Receptor Antagonists; Cell Line, Tumor; Cell Survival; Endocrine Disruptors; Humans; Molecular Dynamics Simulation; Nitrophenols; Protein Structure, Tertiary; Receptors, Androgen; Signal Transduction; Tacrolimus Binding Proteins

The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m(2)/g), high pore volume (1.23 cm(3)/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution.

Topics: Adsorption; Carbon; Charcoal; Coal; Dinitrobenzenes; Models, Chemical; Nitrophenols; Porosity; Sulfamethoxazole; Sulfonamides; Water Purification

A simple and sensitive fluorescent assay for detecting alkaline phosphatase (ALP) based on the inner filter effect (IFE) has been proven, which is conceptually different from the previously reported ALP fluorescent assays. In this sensing platform, N-doped carbon dots (CDs) with a high quantum yield of 49% were prepared by one-pot synthesis and were directly used as a fluorophore in IFE. p-Nitrophenylphosphate (PNPP) was employed to act as an ALP substrate, and its enzyme catalytic product (p-nitrophenol (PNP)) was capable of functioning as a powerful absorber in IFE to influence the excitation of fluorophore (CDs). When in the presence of ALP, PNPP was transformed into PNP and induced the absorption band transition from 310 to 405 nm, which resulted in the complementary overlap between the absorption of PNP and the excitation of CDs. Because of the competitive absorption, the excitation of CDs was significantly weakened, resulting in the quenching of CDs. The present IFE-based sensing strategy showed a good linear relationship from 0.01 to 25 U/L (R(2) = 0.996) and provided an exciting detection limit of 0.001 U/L (signal-to-noise ratio of 3). The proposed sensing approach was successfully applied to ALP sensing in serum samples, ALP inhibitor investigation and phosphatase cell imaging. The presented IFE-based CDs fluorescence sensing strategy gives new insight on the development of the facile and sensitive optical probe for enzyme activity assay because the surface modification or the linking between the receptor and the fluorophore is no longer required.

Topics: Alkaline Phosphatase; Animals; Biosensing Techniques; Carbon; Cell Line; Enzyme Assays; Fluorescence; Light; Mice; Nitrophenols; Organophosphorus Compounds; Quantum Dots

Our quest for a green, non-toxic and environmentally benign synthetic design for the fabrication of metal nanoparticles has led to the use of essential oil present in plant parts as the bioreductant. In this report, silver particles at nanoscale have been synthesized using essential oil present in the leaves of Coleus aromaticus at physiological pH and at 373 K. UV-vis spectra of the colloid display strong plasmon bands centred around 396-411 nm, characteristic of silver nanoparticles. Comparative studies of the FTIR spectra of essential oil and silver nanoparticles reveal the involvement of terpenes and their phenolic derivatives in reduction and subsequent stabilization. TEM micrographs and XRD pattern show the formation of 26 and 28 nm sized face centred cubic structured crystalline nanospheroids with intermittent formation of nanorods. The phytosynthesized silver nanoparticles are found to be effective in degrading hazardous organic pollutants including methyl orange, methylene blue, eosin yellowish and para nitro phenol within a span of a few minutes. Dose dependant antibacterial activity of the biogenic nanosilver against pathogenic Gramme-negative Escherichia coli (ATCC 25922) and Gramme-positive Staphylococcus aureus (ATCC 25923) has been portrayed through agar-well dispersion method. The antioxidant activity including antiradical activity and reducing power have been depicted through superoxide radical scavenging activity, hydroxyl radical scavenging activity, hydrogen peroxide scavenging activity, nitric oxide scavenging activity, DPPH assay and reducing power activity involving the reduction of ferric ion.

Topics: Anti-Bacterial Agents; Antioxidants; Azo Compounds; Catalysis; Coleus; Eosine Yellowish-(YS); Escherichia coli; Green Chemistry Technology; Metal Nanoparticles; Methylene Blue; Microbial Sensitivity Tests; Nitrophenols; Oils, Volatile; Plant Leaves; Silver; Spectroscopy, Fourier Transform Infrared; Staphylococcus aureus; Superoxides; Water Pollutants, Chemical

Flower-like ruthenium-copper (RuCu) nanodendrites were readily synthesized by RuCl3·xH2O and CuCl with oleylamine as the reducing agent, stabilizer and solvent. The nanodendrites contained various small particles and demonstrated efficient catalytic ability in the hydrogenation of p-nitrophenol as a model reaction. Notably, by adding β-cyclodextrin, the reaction rate can be greatly enhanced.

Topics: beta-Cyclodextrins; Catalysis; Copper; Hydrogenation; Nanostructures; Nitrophenols; Ruthenium; Spectrophotometry, Ultraviolet

The emphasis of science and technology shifts toward environmentally friendly and sustainable resources and processes. Herein, we report a facile, one-pot and green synthesis of biomaterial-supported gold nanoparticles (AuNPs) with superior catalytic activity. Cellulose nanocrystal (CNC)-supported AuNPs were prepared by heating the aqueous mixture of HAuCl4, CNCs and polyethylene glycol, avoiding toxic chemicals, extreme condition and complicated procedure. The resultant CNC-supported AuNPs exhibited catalytic activities for the reduction of 4-nitrophenol by sodium borohydride. The maximum apparent rate constant reached 1.47×10(-2)s(-1), and the turnover frequency reached 641h(-1). The superior catalytic performance can be ascribed to the large amount of highly dispersed AuNPs with few nanometers in size which are loaded on CNCs. About 90% of the AuNPs are smaller than 10nm, and nearly 60% of the AuNPs are smaller than 5nm. The synthesis is eco-friendly, facile and low-cost, thus has great potential for industrial and medical applications.

Topics: Catalysis; Cellulose; Chemistry Techniques, Synthetic; Gold; Green Chemistry Technology; Hot Temperature; Metal Nanoparticles; Models, Molecular; Molecular Conformation; Nanotechnology; Nitrophenols; Oxidation-Reduction; Polyethylene Glycols

The present paper deals with a complete batch adsorption study of 4-nitrophenol (4NP) from aqueous solution onto activated carbon prepared from Acacia glauca sawdust (AGAC). The surface area of the adsorbent determined by methylene blue method is found to be 311.20 m(2)/g. The optimum dose of adsorbent was found to be 2 g/l with 4NP uptake of 25.93 mg/g. The equilibrium time was found to be 30 minutes with the percentage removal of 96.40 at the initial concentration of 50 ppm. The maximum removal of 98.94% was found to be at pH of 6. The equilibrium and kinetic study revealed that the Radke-Prausnitz isotherm and pseudo second order kinetics model fitted the respective data well. In the thermodynamic study, the negative value of Gibbs free energy change (-26.38 kJ/mol at 30°C) and enthalpy change (-6.12 kJ/mol) showed the spontaneous and exothermic nature of the adsorption process.

Topics: Acacia; Adsorption; Charcoal; Environmental Restoration and Remediation; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Waste Products; Water Pollutants, Chemical; Wood

Inspired by the composition of adhesive and reductive proteins secreted by marine mussels, polydopamine (PDA) was used to coat cotton microfiber (CMF), and then acted as reducing agent for the growth of Pd nanoparticles on PDA coated CMF (PDA@CMF) composites. The resultant CMF@PDA/Pd composites were then packed in a column for the further use in fixed-bed system. For the catalysis of the reduction of 4-nitrophenol, the flow rate of the 4-aminophenol solution (0.5 mM) was as high as 60 mL/min. The obtained fixed-bed system even exhibited superior performance to conventional batch reaction process because it greatly facilitated the efficiency of the catalytic fibers. Consequently, its turnover frequency (TOF) was up to 1.587 min(-1), while the TOF in the conventional batch reaction was 0.643 min(-1). The catalytic fibers also showed good recyclability, which can be recycled for nine successive cycles without a loss of activity. Furthermore, the catalytic system based on CMF@PDA/Pd can also be applied for Suzuki coupling reaction with the iodobenzene conversion up to 96.7%. The strategy to prepare CMF@PDA/Pd catalytic fixed bed was simple, economical and scalable, which can also be applied for coating different microfibers and loading other noble metal nanoparticles, was amenable for automated industrial processes.

Topics: Adhesives; Animals; Biomimetic Materials; Bivalvia; Catalysis; Cotton Fiber; Equipment Reuse; Indoles; Iodobenzenes; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Polymers

Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed.

Topics: Catalysis; Cold Temperature; Membranes, Artificial; Nitrophenols; Palladium; Polymers; Sulfones

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively.

Topics: Chlorophenols; Chromatography, High Pressure Liquid; Dimethylpolysiloxanes; Hydrogen-Ion Concentration; Limit of Detection; Nitrophenols; Osmolar Concentration; Phenols; Reproducibility of Results; Rivers; Spectrophotometry, Ultraviolet; Triazines; Water Pollutants, Chemical

We report the application of exfoliated graphite (EG) as an electrode material in the electrochemical degradation of p-nitrophenol in water. Bulk electrolysis (degradation) of p-nitrophenol was carried out at a potential of 2.0 V (vs. Ag/AgCl) in the presence of 0.1 M Na2SO4 supporting electrolyte, while UV-Vis spectrophotometry was used to monitor the degradation efficiency. An initial p-nitrophenol load concentration of 0.2 mM for 3 h electrolysis time was studied under the optimized conditions of pH 7, and 10 mAcm(-2) current density. The electro-degradation reaction displayed a pseudo-first-order kinetic behavior with a rate constant (k(r)) of 11×10(-3) min(-1). The removal efficiency was found to be 91.5%. Chromatography coupled with time of flight mass spectrometry revealed p-benzoquinone as a major intermediate product. These results demonstrate the potential and viability of electrochemical technology as an alternative approach to water treatment using a low cost graphite electrode.

Topics: Electrodes; Electrolysis; Graphite; Humans; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical; Water Purification

The potential of 4-nitrophenol (PNP) to affect testicular function of rats was assessed by intratesticular injection (IT). The protective effects of phytosterin (PS) on PNP-induced injury were assessed. Rats were sacrificed on days 1, 3, and 7 after IT of PNP (0.1 M, 50 μl). PNP induced hemorrhage in intertubular areas and denudation of germinal epithelium. The expression of caspase-3 and sperm abnormalities were significantly increased (P < 0.05). The concentrations of testosterone in serum were significantly increased (P < 0.05) on the 1st and 3rd day. PNP induced oxidative stress in testes, which manifested increased SOD, CAT, GSH-Px activities, and increases in MDA, GSH, H2O2 concentrations (P < 0.05). The Nrf2 antioxidant pathway was activated as indicated by increased expression of Nrf2, HO-1, and GCLC mRNA (P < 0.05). Moreover, supplementation with PS resulted in an amelioration of PNP-induced oxidative damage. These results suggest that PNP induced activation of Nrf2 antioxidant pathway and apoptosis of the germ cells.

Topics: Animals; Antioxidants; Apoptosis; Male; NF-E2-Related Factor 2; Nitrophenols; Rats; Signal Transduction; Spermatozoa; Testis

Pulsed discharge plasma (PDP) combined with charcoal (PDP-charcoal) was employed to treat dye wastewater, with methyl orange (MO) as the model pollutant. The charcoal was prepared using spent tea leaves and was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and Boehm titration to investigate the adsorption and catalytic characteristics before and after adsorption and PDP treatment. The prepared charcoal exhibited a high MO adsorption capacity, and the adsorption process followed the pseudo-second-order kinetic model and the Freundlich model. The MO decoloration efficiency reached 69.8 % within 7.5 min of treatment in the PDP-charcoal system, whereas values of 29.2 and 25.9 % were achieved in individual PDP and charcoal systems, respectively. The addition of n-butanol and H2PO4 (-) presented inhibitive effects on MO decoloration in the PDP system. However, these effects were much weaker in the PDP-charcoal system. In addition, the effects of charcoal on O3 and H2O2 formation were evaluated, and the results showed that both the O3 and H2O2 concentrations decreased in the presence of charcoal. The MO decomposition intermediates were analyzed using UV-Vis spectrometry and GC-MS. 1,4-Benzoquinone, 4-nitrophenol, 4-hydroxyaniline, and N,N'-dimethylaniline were detected. A possible pathway for MO decomposition in this system was proposed.

Topics: Adsorption; Aminophenols; Azo Compounds; Benzoquinones; Camellia sinensis; Charcoal; Color; Coloring Agents; Hydrogen Peroxide; Kinetics; Microscopy, Electron, Scanning; Nitrophenols; Ozone; Plant Leaves; Spectroscopy, Fourier Transform Infrared; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical

The self-assembly of an amphiphilic peptide molecule to form nanofibers facilitated by Ag(+) ions was investigated. Ultrafine AgNPs (NPs=nanoparticles) with an average size of 1.67 nm were synthesized in situ along the fibers due to the weak reducibility of the -SH group on the peptide molecule. By adding NaBH4 to the peptide solution, ultrafine AgNPs and AuNPs were synthesized with an average size of 1.35 and 1.18 nm, respectively. The AuNPs, AgNPs, and AgNPs/nanofibers all exhibited excellent catalytic activity toward the reduction of 4-nitrophenol, with turnover frequency (TOF) values of 720, 188, and 96 h(-1) , respectively. Three dyes were selected for catalytic degradation by the prepared nanoparticles and the nanoparticles showed selective catalysis activity toward the different dyes. It was a surprising discovery that the ultrafine AuNPs in this work had an extremely high catalytic activity toward methylene blue, with a reaction rate constant of 0.21 s(-1) and a TOF value of 1899 h(-1) .

Topics: Catalysis; Circular Dichroism; Coloring Agents; Gold; Metal Nanoparticles; Methylene Blue; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Nanofibers; Nitrophenols; Oxidation-Reduction; Particle Size; Peptides; Silver; Spectrophotometry, Ultraviolet

To promote the in situ generation of hydrogen peroxide (H2O2) in electro-Fenton system, a new air diffusion electrode (ADE) was put forward in the present work using N-doped multi-walled carbon nanotubes (NCNT) as the catalyst layer, multi-walled carbon nanotubes (CNT) as the diffusion layer, and nickel foam (NF) as the supporting material, respectively. The catalyst layer in ADE was characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. Then the performances of H2O2 accumulation and p-nitrophenol (p-NP) degradation with the electrode (NCNT/NF/CNT ADE) were investigated. The experimental results showed that H2O2 accumulation on the NCNT/NF/CNT ADE was greatly improved by the presence of N doping, and H2O2 accumulation concentration could reach 307 mg L(-1) after 120 min at the current intensity of 100 mA. Moreover, the NCNT/NF/CNT ADE presented more effective performance on p-NP degradation than the CNT/NF/CNT ADE or the NF ADE. p-NP of initial 50 mg L(-1) could be almost completely removed after 30 min, and the total organic carbon removal efficiency reached 62.61% after 120 min when 0.4 mM Fe(2+) was added into the system. The repeatability test suggested that the stability of the NCNT/NF/CNT ADE was very good.

Topics: Catalysis; Electrochemical Techniques; Electrodes; Hydrogen Peroxide; Nanotubes, Carbon; Nickel; Nitrophenols; Photoelectron Spectroscopy; Water Pollutants, Chemical; Water Purification

Metal-support interfaces play a prominent role in heterogeneous catalysis. However, tailoring the metal-support interfaces to realize full utilization remains a major challenge. In this work, we propose a graceful strategy to maximize the metal-oxide interfaces by coating confined nanoparticles with an ultrathin oxide layer. This is achieved by sequential deposition of ultrathin Al2 O3 coats, Pt, and a thick Al2 O3 layer on carbon nanocoils templates by atomic layer deposition (ALD), followed by removal of the templates. Compared with the Pt catalysts confined in Al2 O3 nanotubes without the ultrathin coats, the ultrathin coated samples have larger Pt-Al2 O3 interfaces. The maximized interfaces significantly improve the activity and the protecting Al2 O3 nanotubes retain the stability for hydrogenation reactions of 4-nitrophenol. We believe that applying ALD ultrathin coats on confined catalysts is a promising way to achieve enhanced performance for other catalysts.

Topics: Aluminum Oxide; Catalysis; Hydrogenation; Metal Nanoparticles; Nanotubes; Nitrophenols; Platinum; Spectrophotometry, Ultraviolet; Temperature

UDP-glucuronosyltransferase (UGT) is an enzyme that catalyses a major phase II reaction in drug metabolism. Glucuronidation occurs mainly in the liver, but UGTs are also expressed in extrahepatic tissues, where they play an important role in local metabolism. UGT1A isoforms catalyse the glucuronidation of several drugs, neurotransmitters and neurosteroids that exert pharmacological and physiological effects on the brain. The aim of the current study was to determine UGT1A mRNA expression levels and glucuronidation activities in different regions of the rat brain (namely the cerebellum, frontal cortex, parietal cortex, piriform cortex, hippocampus, medulla oblongata, olfactory bulb, striatum and thalamus). It was found that all UGT1A isoforms were expressed in all the nine regions, but their expression levels differed between the regions. The difference between the regions of the brain where the mRNA levels were highest and those where they were lowest ranged between 2.1- to 7.8-fold. Glucuronidation activities were measured using the UGT substrates such as mycophenolic acid, p-nitrophenol and umbelliferone. Glucuronidation activity was detected in all nine regions of the brain. Activity levels differed between the regions, and were highest in the cerebellum, medulla oblongata and olfactory bulb. Differences in glucuronidation activity between regions with the highest rates and those with the lowest rates ranged from 5.3- to 10.1-fold. These results will contribute to our current understanding of the physiological and pharmacokinetic roles of drug-metabolizing enzymes in the brain. Copyright © 2016 John Wiley & Sons, Ltd.

Topics: Animals; Brain; Glucuronides; Glucuronosyltransferase; Male; Microsomes, Liver; Mycophenolic Acid; Nitrophenols; Rats, Sprague-Dawley; RNA, Messenger; Umbelliferones

The marine hemoglobin dehaloperoxidase (DHP) from Amphitrite ornata was found to catalyze the H2O2-dependent oxidation of nitrophenols, an unprecedented nonmicrobial degradation pathway for nitrophenols by a hemoglobin. Using 4-nitrophenol (4-NP) as a representative substrate, the major monooxygenated product was 4-nitrocatechol (4-NC). Isotope labeling studies confirmed that the O atom incorporated was derived exclusively from H2O2, indicative of a peroxygenase mechanism for 4-NP oxidation. Accordingly, X-ray crystal structures of 4-NP (1.87 Å) and 4-NC (1.98 Å) bound to DHP revealed a binding site in close proximity to the heme cofactor. Peroxygenase activity could be initiated from either the ferric or oxyferrous states with equivalent substrate conversion and product distribution. The 4-NC product was itself a peroxidase substrate for DHP, leading to the secondary products 5-nitrobenzene-triol and hydroxy-5-nitro-1,2-benzoquinone. DHP was able to react with 2,4-dinitrophenol (2,4-DNP) but was unreactive against 2,4,6-trinitrophenol (2,4,6-TNP). pH dependence studies demonstrated increased reactivity at lower pH for both 4-NP and 2,4-DNP, suggestive of a pH effect that precludes the reaction with 2,4,6-TNP at or near physiological conditions. Stopped-flow UV-visible spectroscopic studies strongly implicate a role for Compound I in the mechanism of 4-NP oxidation. The results demonstrate that there may be a much larger number of nonmicrobial enzymes that are underrepresented when it comes to understanding the degradation of persistent organic pollutants such as nitrophenols in the environment.

Topics: Animals; Catalysis; Hemoglobins; Hydrogen Peroxide; Mixed Function Oxygenases; Nitrophenols; Oxidation-Reduction; Oxygen; Peroxidases; Polychaeta

The extraction of p-nitrophenol (PNP) from aqueous solutions through a pseudo-emulsion hollow fiber strip dispersion (PEHFSD) system was conducted in a microporous hydrophobic polypropylene hollow fiber membrane contactor. For the optimization of the process variables, face-centered central composite design (FCCD) has been used. It was observed that initial feed concentration, carrier composition and stripping phase concentration were the three FCCD factors, which influenced the nitrophenol extraction. Using the optimized process conditions for the separation of PNP, experiments were also performed for the separation of other nitrophenols through PEHFSD system. By the FCCD design and analysis, almost 99% extraction of all three nitrophenols was achieved at optimum conditions. A mass transfer model was also developed and aqueous and membrane resistances were evaluated as 196.46 s cm(-1) and 50.14 s cm(-1), respectively.

Topics: Emulsions; Membranes, Artificial; Models, Theoretical; Nitrophenols; Polypropylenes; Solutions; Water Pollutants, Chemical

A convenient, reliable and highly sensitive assay for alkaline phosphatase (ALP) activity in the real-time manner is developed based on β-cyclodextrin-modified carbon quantum dots (β-CD-CQDs) nanoprobe through specific host-guest recognition. Carbon quantum dots were first functionalized with 3-aminophenyl boronic acid to produce boronic acid-functionalized CQDs, and then further modified with hydropropyl β-cyclodextrins (β-CD) through B-O bonds to form β-CD-CQDs nanoprobe. p-Nitrophenol phosphate disodium salt is used as the substrate of ALP, and can hydrolyze to p-nitrophenol under the catalysis of ALP. The resulting p-nitrophenol can enter the cavity of β-CD moiety in the nanoprobe due to their specific host-guest recognition, where photoinduced electron transfer process between p-nitrophenol and CQDs takes place to efficiently quench the fluorescence of the probe. The correlation between quenched fluorescence and ALP level can be used to establish quantitative evaluation of ALP activity in a broad range from 3.4 to 100.0U/L with the detection limit of 0.9U/L. This assay shows a high sensitivity to ALP even in the presence of a very high concentration of glucose. This study demonstrates a good electron donor/acceptor pair, which can be used to design general detection strategy through PET process, and also broadens the application of host-guest recognition for enzymes detection in clinical practice.

Topics: Alkaline Phosphatase; Animals; beta-Cyclodextrins; Biosensing Techniques; Carbon; Cattle; Enzyme Assays; Fluorometry; Limit of Detection; Nitrophenols; Organophosphorus Compounds; Quantum Dots

In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min(-1) (R(2) = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn't show much decrease of the catalytic capability.

Topics: Aminophenols; Catalysis; Equipment Reuse; Ferrosoferric Oxide; Gold; Indoles; Kinetics; Magnetite Nanoparticles; Microscopy, Electron, Scanning; Nanocomposites; Nitrophenols; Oxidation-Reduction; Polyethyleneimine; Polymers; Silicon Dioxide; Silver; Static Electricity

To investigate green synthesis of gold nanoparticles (AuNPs) by Trichosporon montevideense, and to study their reduction of nitroaromatics.. AuNPs had a characteristic absorption maximum at 535 nm. Scanning electron microscopy images revealed that the biosynthesized nanoparticles were attached on the cell surface. X-ray diffraction analysis indicated that the particles formed as face-centered cubic (111)-oriented crystals. The average size of AuNPs decreased from 53 to 12 nm with increasing biomass concentration. The catalytic reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitrophenylamine and m-nitrophenylamine (0.1 mM) by NaBH4 had reaction rate constants of 0.32, 0.44, 0.09, 0.24 and 0.39 min(-1) with addition of 1.45 × 10(-2) mM AuNPs.. An eco-friendly approach for synthesis of AuNPs by T. montevideense is reported for the first time. The biogenic AuNPs could serve as efficient catalysts for hydrogenation of various nitroaromatics.

Topics: Catalysis; Gold; Green Chemistry Technology; Hydrogenation; Metal Nanoparticles; Nitrophenols; Trichosporon

In this work, open-tubular capillary column coated with zeolite imidazolate framework-8 (ZIF-8) nanocrystals was prepared by a layer-by-layer method. The coating was formed by growing ZIF-8 nanocrystals on either bare fused silica capillary wall or the capillary column premodified with amino groups. The shape and the thickness of the coating formed by using these two methods were almost the same. However, the coverage of the ZIF-8 crystals on the bare fused silica capillary wall was higher than that on the capillary column premodified with amino groups. The ZIF-8 coated capillary column was evaluated for open-tubular capillary electrochromatography. The effect of pH value, buffer concentration, and applied voltage on the separation of phenols was investigated. Good separation of nine phenolic isomers was achieved because of the strong interaction between unsaturated Zn sites and phenols. The column performance for o-nitrophenol was as high as 208 860 plates m(-1) . The run-to-run, day-to-day, and column-to-column reproducibility of retention time and resolution for p-nitrophenol and o-nitrophenol were very good with RSDs of less than 6.5%.

Topics: Capillary Electrochromatography; Imidazoles; Nanoparticles; Nitrophenols; Zeolites

The performance and mechanisms of 4-nitrophenol (4-NP) degradation by the Fe(0)/bisulfite system were systematically investigated for the first time. The evidences presented in this study verified that O2 was a crucial factor that affected the mechanism of Fe(0)/bisulfite-driven 4-NP degradation. In the Fe(0)/bisulfite/O2 system, Fe(0) acted as a supplier of Fe(2+) to catalyze bisulfite oxidation that induced a chain reaction to produce reactive radicals for 4-NP degradation. While under N2 purging condition, bisulfite worked as a specified reductant that facilitated the transformation of Fe(3+) to nascent Fe(2+) ions, which principally accounted for the reductive removal of 4-NP. The application of a weak magnetic field (WMF) efficiently improved the removal rate of 4-NP and did not alter the mechanisms in both Fe(0)/bisulfite/O2 and Fe(0)/bisulfite/N2 processes. The secondary radicals, HO(·), SO4 (·-), and SO5 (·-), were considered as the most possible active oxidants contributing to the oxidative removal of 4-NP and even partial mineralization under an oxic condition. Compared with anoxic conditions, the performance removal of 4-NP by the WMF-Fe(0)/bisulfite/O2 system showed less pHini dependence. To facilitate the application of WMF-Fe(0)/bisulfite/O2 technology in real practice, premagnetization of Fe(0) was employed to combine with bisulfite/O2 and proved to be an effective and applicable method for 4-NP removal.

Topics: Environmental Pollutants; Iron; Magnetic Fields; Models, Chemical; Nitrophenols; Oxidation-Reduction; Oxygen; Sulfites

4-nitrophenol (PNP) is generally regarded as a diesel exhaust particle (DEP). Arginine plays an important role as a new feed additive, possessing highly efficient antioxidant activities. Here we investigated the effects of dietary supplementation with arginine against ovarian damage induced by PNP in rats. A total of thirty-two female rats postnatal day 28 (PND 28) were randomly divided into four groups. Two groups were fed with basal diet or 13 g/kg arginine in diet for 4 weeks, respectively; the other two groups were given PNP (100 mg/kg b.w.) daily by subcutaneous injection for 2 weeks following pretreatment with either basal diet or arginine diet for 2 weeks. The values of body weight gain (BWG), average daily gain (ADG) and percentage weight gain (PWG) upon PNP treatment were significantly reduced than those in other groups. The relative liver weight in the PNP group was significantly decreased compared with the control group. Treatment with PNP significant reduced the number of corpora lutea, although serum 17β-estradiol (E2) and progesterone (P4) concentrations were unchanged. The morphology of the ovaries in PNP-treated rats displayed necrosis, follicular deformation and granulosa cells irregular arrangement. Moreover, exposure to PNP enhanced production of malondialdehyde (MDA) and hydrogen peroxide (H2O2), and decreased the activities of total superoxide dismutase (T-SOD) and catalase (CAT), and the co-administration of arginine can attenuate the oxidative stress caused by PNP. These results suggest that arginine may have a protective effect against ovarian damage induced by PNP owing to its antioxidant capacity effect.

Topics: Animals; Antioxidants; Arginine; Biomarkers; Catalase; Cytoprotection; Estradiol; Female; Hydrogen Peroxide; Malondialdehyde; Necrosis; Nitrophenols; Ovarian Follicle; Ovary; Oxidative Stress; Progesterone; Rats, Sprague-Dawley; Superoxide Dismutase

Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 10³ for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to -NO₂ group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

Topics: Catalysis; Gold; Nanoparticles; Nitrophenols; Porosity; Silicon Dioxide; Surface Properties

4-Nitrophenol (PNP) is a persistent organic pollutant that was proven to be an environmental endocrine disruptor. The aim of this study was to evaluate the role of the estrogen receptor-α (ER-α) and aryl hydrocarbon receptor (AhR) signaling pathway in regulating the damage response to PNP in the small intestine of rats. Wistar-Imamichi male rats (21 d) were randomly divided into two groups: the control group and PNP group. Each group had three processes that were gavaged with PNP or vehicle daily: single dose (1 d), repeated dose (3 consecutive days) (3 d), and repeated dose with recovery (3 consecutive days and 3 recovery days) (6 d). The weight of the body, the related viscera, and small intestine were examined. Histological parameters of the small intestine and the quantity of mucus proteins secreted by small goblet cells were determined using HE staining and PAS staining. The mRNA expression of AhR, ER-α, CYP1A1, and GST was measured by real-time qPCR. In addition, we also analyzed the AhR, ER-α, and CYP1A1 expression in the small intestine by immunohistochemical staining. The small intestines histologically changed in the PNP-treated rat and the expression of AhR, CYP1A1, and GST was increased. While ER-α was significantly decreased in the small intestine, simultaneously, when rats were exposed to a longer PNP treatment, the damages disappeared. Our results demonstrate that PNP has an effect on the expression of AhR signaling pathway genes, AhR, CYP1A1, and GST, and ER-α in the rat small intestine.

Topics: Animals; Cytochrome P-450 CYP1A1; Endocrine Disruptors; Estrogen Receptor alpha; Gene Expression Regulation; Glutathione Transferase; Intestine, Small; Male; Nitrophenols; Rats, Wistar; Receptors, Aryl Hydrocarbon; Signal Transduction

Routine high-dose Fe supplementation in non-anaemic pregnant women may induce oxidative stress and eventually affect birth outcomes. The aim of the present study was to measure oxidative stress markers in pregnant women with low/normal and high Hb values in trimester 1 (Hb1) and to relate these to birth weight.. A cross-sectional study where selected oxidative stress markers were analysed in both maternal (trimester 1; T1) and cord blood samples and correlated with birth weight.. A tertiary hospital in urban South India.. One hundred women were chosen based on their Hb1 values (forty women with low/normal Hb1 (<110 g/l) and sixty women with high Hb1 (≥120 g/l)).. In T1, women with high Hb1 values were found to have lower paraoxonase-1 (PON-1) activity (424·7 (sd 163·7) v. 532·9 (sd 144·7) pmol p-nitrophenol formed/min per ml plasma, P=0·002) and higher lipid peroxides compared with women with low/normal Hb1. Routine supplementation of Fe to these women resulted in persistent lower PON-1 activity in cord blood (P=0·02) and directionally lower (P=0·142) birth weights. Furthermore, women with high Hb1 who delivered low-birth-weight babies were observed to have lowest PON-1 activity in T1. No changes were observed in other markers (myeloperoxidase activity and total antioxidant levels).. Routine Fe supplementation in pregnant women with high Hb1 associated with increased oxidative stress, as reflected by low PON-1 activity in T1, could potentially lead to deleterious effects on birth weight.

Topics: Adult; Antioxidants; Aryldialkylphosphatase; Birth Weight; Cross-Sectional Studies; Female; Fetal Blood; Hemoglobins; Humans; India; Lipid Peroxides; Nitrophenols; Oxidative Stress; Peroxidase; Pregnancy; Young Adult

In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H2O2) has been designed using 3,3',5,5'-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H2O2 in wide linear range of 5 μM-500 μM and 500 μM-4 mM with low detection limit of 1.6 μM (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas.

Topics: Biomimetic Materials; Carbon; Catalysis; Gold; Metal Nanoparticles; Models, Molecular; Molecular Conformation; Nanotechnology; Nitrophenols; Oxidation-Reduction; Palladium; Peroxidase; Quantum Dots; Reducing Agents

The present study deals about the vicinity of phytochemicals present in the Phyllanthus emblica (P. emblica) seed extract. The bio-active compounds present in the methanolic seed extract have been identified using Gas Chromatography Mass Spectroscopy (GC-MS)·The antioxidant activity of P. emblica seed extract was evaluated using assistance of DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay. The determination of total phenol and flavonoid substance were contemplated. Further blood clot lysis activity was also done to check the percentage of clot lysis in methanolic seed extract. The result proved that seed extract has potential application. The GCMS results of P. emblica suggest that Octyl-β-d-Glucopyranoside is present in major quantity. The work has been designed towards the degradation of 2-nitrophenol and 4-nitrophenol using P. emblica methanolic seed extract. The progress of nitrophenol degradation has been observed in UV-visible spectroscopy. At 5min duration, the 4-nitrophenol has been degraded up to 82.42%. This may be due to the presence of secondary metabolites such as alkaloids, carbohydrate and phenols in the P. emblica seed extract. The seed extract showed good scavenging activity which resulted in IC50 value of 85.92μg/mL. The total phenol and flavonoid content present in the extract were 48.242 and 12.72mg/mL. Also the seed extract showed good lysis when compared to the standard streptokinase.

Topics: Catalysis; Free Radical Scavengers; Gas Chromatography-Mass Spectrometry; Glucosides; Light; Nitrophenols; Photolysis; Phyllanthus emblica; Plant Extracts; Seeds; Spectrophotometry, Ultraviolet

P-nitrophenol is one of the most common contaminants in chemical industrial wastewater, and in situ real-time monitoring of PNP cannot be achieved by conventional analytical techniques. Here, a two-chamber microbial fuel cell with an aerobic anode chamber was tested as a biosensor for in situ real-time monitoring of PNP. Pseudomonas monteilii LZU-3, which was used as the biological recognition element, can form a biofilm on the anode electrode using PNP as a sole substrate. The optimal operation parameters of the biosensor were as follows: external resistance 1000Ω, pH 7.8, temperature 30°C, and maximum PNP concentration 50mgL(-1). Under these conditions, the maximum voltages showed a linear relationship with PNP concentrations ranging from 15±5 to 44±4.5mgL(-1). Furthermore, we developed a novel portable device for in situ real-time monitoring of PNP. When the device was applied to measure PNP in wastewater containing various additional aromatic compounds and metal ions, the performance of the biosensor was not affected and the correlation between the maximum voltages and the PNP concentrations ranging from 9±4mgL(-1) to 36 ± 5mgL(-1) was conserved. The results demonstrated that the MFC biosensor provides a rapid and cost-efficient analytical method for real-time monitoring of toxic and recalcitrant pollutants in environmental samples.

Topics: Bioelectric Energy Sources; Biofilms; Biosensing Techniques; Electrodes; Equipment Design; Limit of Detection; Nitrophenols; Pseudomonas; Wastewater; Water Pollutants, Chemical

With thousands of organic chemicals released every day into our environment, Europe and other continents are confronted with increased risk of health and environmental problems. Even if a strict regulation such as REgistration, Authorization and restriction of CHemicals (REACH) is imposed and followed by industry to ensure that they prove the harmlessness of their substances, not all testing procedures are designed to cope with the complexity of the environment. This is especially true for the evaluation of persistence through biodegradability assessment guidelines. Our new approach has been to adapt "in the lab" biodegradability assessment to the environmental conditions and model the probability for a biodegradation test to be positive in the form of a logistic function of both the temperature and the viable cell density. Here, a proof of this new concept is proposed with the establishment of tri-dimensional biodegradability profiles of six chemicals (sodium benzoate, 4-nitrophenol, diethylene glycol, 2,4,5-trichlorophenol, atrazine, and glyphosate) between 4 to 30 °C and 10(4) to 10(8) cells ml(-1) as can be found in environmental compartments in time and space. The results show a significant increase of the predictive power of existing screening lab-scale tests designed for soluble substances. This strategy can be complementary to those current testing strategies with the creation of new indicators to quantify environmental persistence using lab-scale tests.

Topics: Atrazine; Bacteria; Biodegradation, Environmental; Chlorophenols; Ethylene Glycols; Glycine; Glyphosate; Laboratories; Models, Theoretical; Nitrophenols; Sodium Benzoate

The study employs draft genome sequence data to explore p-nitrophenol (PNP) degradation activity of Pseudomonas putida strain SF-1 at a genomic scale. Annotation analysis proposes that the strain SF1 not only possesses the gene cluster for PNP utilization but also for the utilization of benzoate, catechol, hydroxybenzoate, protocatechuate, and homogentisate. Further, the analysis was carried out to understand more details of PNP 4-monooxygenase and its regulator. A comparative analysis of PNP 4-monooxygenase from SF1 was carried out for prediction of its tertiary structure; and also its binding affinity with PNP, FAD, NADH and NADPH using FlexX docking. The tertiary structure of regulator was also predicted along with its conserved DNA binding residues. Regulator binding site (RBS) and promoter region were mapped for the PNP degradation gene cluster. Based on genome sequence analysis, the study unveiled the genomic attributes for a versatile catabolic potential of Pseudomonas putida strain SF-1 for different aromatic compounds.

Topics: Biodegradation, Environmental; Computer Simulation; Consensus Sequence; Genome, Bacterial; Multigene Family; Nitrophenols; Promoter Regions, Genetic; Protein Structure, Tertiary; Pseudomonas putida

In this study, Broccoli green extract was reported as a green and environmental friendly precursor for the one-pot biosynthesis of copper nanoparticles. The synthesized nanoparticles were characterized by UV-vis, FTIR, TEM, DLS, XRD and cyclic voltammetry. The TEM and DLS results showed that the NPs are in spherical and monodispersed with an average particle size of ~4.8nm. The FTIR results confirmed the occurrence of bioactive functional groups that are responsible for reducing cupric sulphate to copper ions. The UV-vis spectrophotometry was used for catalytic reduction of 4-nitrophenol and its dynamic reaction in Britton-Robinson buffer solution. This catalytic activity was further supported with methylene blue and methyl red dyes degradation. The nanocatalyst can be recovered from the reaction mixture and reused many times with none vital loss of catalytic activity. The Broccoli green extract modified copper nanoparticles coated on screen printing electrode laid a new sensing platform and has an excellent electrocatalytic activity. Furthermore, surface modified CuNPs with Broccoli green extract exhibited no cytotoxicity at the concentration ranging from 0.5 to 1.5μM on the prostate cancer (PC-3) cell lines. The maximum scavenging % of Broccoli green extract modified CuNPs was found to be >70.50% at the concentration of 0.25mM against 1,1-diphenyl-2-picrylhydrazyl.

Topics: Antioxidants; Brassica; Catalysis; Cell Line, Tumor; Cell Survival; Copper; Dynamic Light Scattering; Electrochemical Techniques; Green Chemistry Technology; Humans; Male; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Transmission; Nitrophenols; Plant Extracts; Prostatic Neoplasms; Spectroscopy, Fourier Transform Infrared

It is useful for whole-cell biosensors to be based on colorimetric detection because the output signal can be easily visualized. However, colorimetric-based whole-cell biosensors suffer higher detection limits as compared to bioluminescence- or fluorescence-based biosensors. In this work, we attempt to reduce the detection limit for a colorimetric-based whole-cell biosensor by applying directed evolution techniques on a transcription regulator, DmpR, to alter the expression level of its cognate promoter, which was fused to mRFP1 to output red coloration in the presence of organophosphate pesticides containing a phenolic group. We selected the two best-performing mutants, DM01 and DM12, which were able to develop red coloration in the presence of parathion as low as 10 μM after just 6 h of induction at 30 °C. This suggests that engineering of the transcription regulator in the sensing domain is useful for improving various properties of whole-cell biosensors, such as reducing the detection limit for simple colorimetric detection of organophosphate pesticides.

Topics: Bacterial Proteins; Biosensing Techniques; Carbohydrate Epimerases; Colorimetry; Escherichia coli; Fenitrothion; Gene Deletion; Genes, Reporter; Luminescent Proteins; Mutation; Nitrophenols; Organophosphorus Compounds; Plasmids; Promoter Regions, Genetic; Protein Engineering; Red Fluorescent Protein; Trans-Activators

Bioelectrochemical denitrification system (BEDS) is a promising technology for nitrate removal from wastewaters. The hazards and effects concerning p-nitrophenol (PNP) towards BEDS lack enough investigations and possess great research prospects. This study investigated how PNP affected the nitrate removal efficiency, microbial communities, functional denitrifying genes abundances, nitrate and nitrite reductase activities, diffusible signal factors (DSF) release, and extracellular polymeric substances (EPS) production in the BEDS. Results indicated that nitrate removal efficiency decreased with initial PNP concentration increased from 0 to 100mg/L. Phylum Firmicutes and class Clostridia were the main contributors for denitrification process in this BEDS. The abundances of the denitrifying genes nirS, nirK, napA, and narG all presented decreased trends with increasing PNP. In addition, the concentrations of nitrate reductase (NR), nitrite reductase (NIR), and EPS obviously decreased, while the concentration of DSF increased with increasing PNP, which demonstrated that higher PNP would inhibit the biofilm formation.

Topics: Biofilms; Biotechnology; Clostridium; Denitrification; Electrochemistry; Firmicutes; Nitrate Reductase; Nitrates; Nitrite Reductases; Nitrophenols; Polymers; Real-Time Polymerase Chain Reaction; Sequence Analysis, DNA; Spectrophotometry; Wastewater

We report a facile and efficient approach for synthesis of well-dispersed and stable silver nanoparticles (Ag NPs) using water-soluble cellulose acetate (CA) as both reductant and stabilizer. Partially substituted CA with highly active hydroxyl groups and excellent water-solubility is able to reduce silver ions in homogeneous aqueous medium effectively. The synthesized Ag NPs were characterized by UV-vis spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscope analysis. The as-prepared Ag NPs were well-dispersed, showing a surface plasmon resonance peak at 426nm. The resulted Ag NPs@CA nanohybrids exhibit high catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH

Topics: Anti-Bacterial Agents; Catalysis; Cellulose; Escherichia coli; Metal Nanoparticles; Microbial Sensitivity Tests; Nitrophenols; Silver; Solubility; Spectrometry, X-Ray Emission; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Staphylococcus aureus; X-Ray Diffraction

The synthesis of Au@AgAu yolk-shell cuboctahedra nanoparticles formed by galvanic replacement in a seed-mediated method is described. Initially, single-crystal Au seeds are used for the formation of Au@Ag core-shell nanocubes, which serve as the template material for the deposition of an external Au layer. The well-controlled synthesis yields the formation of cuboctahedra nanoparticles with smooth inner and outer Au/Ag surfaces. The deposition/oxidation process is described to understand the formation of cuboctahedra and octahedra nanoparticles. The Au core maintains the initial morphology of the seed and remains static at the center of the yolk-shell because of residual Ag. Structural analysis of the shell indicates intrinsic stacking faults (SFs) near the surface. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) compositional analysis show an Au-Ag nonordered alloy forming the shell. The three-dimensional structure of the nanoparticles presented open facets on the [111] as observed by electron tomography SIRT reconstruction over a stack of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The geometrical model was validated by analyzing the direction of streaks in coherent nanobeam diffraction (NBD). The catalytic activity was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NTP) by NaBH4 in the presence of Au@AgAu yolk-shell nanoparticles.

Topics: Borohydrides; Catalysis; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Particle Size; Silver

A waste-treats-waste approach has been used for the removal of two common pollutants, namely p-nitrophenol and/or Fe(III) from aqueous solution. Polyethyleneterephthalate (PET) from bottle waste has been used as the precursor for the preparation of activated carbons (ACs) by physical activation with steam and chemical activation with potassium hydroxide under controlled heating conditions and atmospheres. The resulting ACs were characterized in terms of chemical composition, porous texture and surface chemistry, and morphology. Selected ACs were tested as adsorbents for the removal of the aforementioned pollutants in aqueous solution. For comparison purposes, a commercial AC was also used. In general, the yield of the process of preparation of ACs is lower than 10% with steam and between 24.62 and 32.07% with potassium hydroxide. ACs possess a very high carbon content and a very low ash content. The BET surface areas reach 1235 m(2) g(-1) with steam and 1002 m(2) g(-1) with potassium hydroxide at most. Also, the degrees of development of micro- and mesoporosity are markedly larger with steam. Conversely, the development of macroporosity is much larger with potassium hydroxide. The PET-derived ACs exhibit a better adsorption behavior towards p-nitrophenol than the commercial AC, both in terms of adsorption rate and adsorption capacity. On the contrary, the commercial AC acts as a better adsorbent of Fe(III) ions. As compared to separately, the simultaneous presence of both solutes in the adsorptive solution scarcely affects the adsorption process except for equilibrium for Fe(III).

Topics: Adsorption; Carbon; Charcoal; Hydroxides; Kinetics; Nitrophenols; Polyethylene Terephthalates; Porosity; Potassium Compounds; Steam; Surface Properties; Waste Products; Water Pollutants, Chemical

A novel catalyst for the reduction of 4-nitrophenol (4-NP) was prepared using carboxyl group-functionalized multiwalled carbon nanotubes (MWCNTs), polymer matrix, and silver nanoparticles (AgNPs). The AgNPs were prepared by the reduction of silver nitrate by trisodium citrate in the MWCNTs-polymer nanocomposite; the size of the synthesized AgNPs was found to be 3nm (average diameter). The synthesized nanocomposites were characterized using several analytical techniques. Ag@MWCNTs-polymer composite in the presence of sodium borohydride (NaBH4) in aqueous solution is an effective catalyst for the reduction of 4-NP. The apparent kinetics of reduction has a pseudo-first-order kinetics, and the rate constant and catalytic activity parameter were found to be respectively 7.88×10(-3)s(-1)and 11.64s(-1)g(-1). The MWCNTs-polymer nanocomposite renders stability to AgNPs against the environment and the reaction medium, which means that the Ag@MWCNTs-polymer composite can be re-used for many catalytic cycles.

Topics: Catalysis; Chitosan; Cross-Linking Reagents; Glutaral; Metal Nanoparticles; Nanotubes, Carbon; Nitrophenols; Oxidation-Reduction; Silver

A facilely prepared ratiometric fluorescent molecularly imprinted sensor has been constructed for highly sensitive and selective detection of 4-nitrophenol (4-NP) using carbon dots (CDs) as the target sensitive fluorophore and YVO4: Eu(3+) nanoparticles (NPs) as the reference fluorophore. Through the hydrolysis and condensation reactions of the silica precursor, CDs and YVO4 Eu(3+) NPs can be incorporated into silica networks through silylation reaction by one pot synthesis procedure. The as-prepared fluorescent molecularly imprinted sensor shows characteristic fluorescence emissions of CDs (blue) and YVO4:Eu(3+) (red) under a single excitation wavelength. With the addition of 4-NP, the fluorescence of CDs is selectively quenched, resulting in the ratiometric fluorescence response. Under optimum conditions, the proposed sensor exhibits a high sensitivity with a linear range from 0 to 12.0μM and shows the limit of detection as low as 0.15μM in the determination of 4-NP, which is probably benefits from the tailor-made imprinted cavities for binding 4-NP. Furthermore, the proposed method was successfully applied for the determination of 4-NP in real water samples and human urine samples with great potentials for monitoring of 4-NP in environmental application.

Topics: Carbon; Europium; Metal Nanoparticles; Molecular Imprinting; Nitrophenols; Reproducibility of Results; Sensitivity and Specificity; Spectrometry, Fluorescence; Vanadium Compounds

Topics: Adsorption; Aminophenols; Azo Compounds; Catalysis; Cellulose; Chitosan; Coloring Agents; Metal Nanoparticles; Nanocomposites; Nickel; Nitrophenols; Paper

Nowadays cost reduction is a very important issue in wastewater treatment plants. One way, is to minimize the sludge production. Microorganisms break down the organic matter into inorganic compounds through catabolism. Uncoupling metabolism is a method which promote catabolism reactions instead of anabolism ones, where adenosine triphosphate synthesis is inhibited. In this work, the influence of the addition of para-nitrophenol and a commercial reagent to a sequencing batch reactor (SBR) on sludge production and process performance has been analyzed. Three laboratory SBRs were operated in parallel to compare the effect of the addition of both reagents with a control reactor. SBRs were fed with synthetic wastewater and were operated with the same conditions. Results showed that sludge production was slightly reduced for the tested para-nitrophenol concentrations (20 and 25 mg/L) and for a LODOred dose of 1 mL/day. Biological process performance was not influenced and high COD removals were achieved.

Topics: Bioreactors; Nitrophenols; Sewage; Waste Disposal, Fluid

A whole-cell biosensor utilizing a transcription factor (TF) is an effective tool for sensitive and selective detection of specialty chemicals or anthropogenic molecules, but requires access to an expanded repertoire of TFs. Using homology modeling and ligand docking for binding pocket identification, assisted by conservative mutations in the pocket, we engineered a novel specificity in an Acinetobacter TF, PobR, to 'sense' a chemical p-nitrophenol (pNP) and measured the response via a fluorescent protein reporter expressed from a PobR promoter. Out of 10(7) variants of PobR, four were active when dosed with pNP, with two mutants showing a specificity switch from the native effector 4-hydroxybenzoate (4HB). One of the mutants, pNPmut1 was then used to create a smart microbial cell responding to pNP production from hydrolysis of an insecticide, paraoxon, in a coupled assay involving phosphotriesterase (PTE) enzyme expressed from a separate promoter. We show the fluorescence of the cells correlated with the catalytic efficiency of the PTE variant expressed in each cell. High selectivity between similar molecules (4HB versus pNP), high sensitivity for pNP detection (∼2 μM) and agreement of apo- and holo-structures of PobR scaffold with predetermined computational models are other significant results presented in this work.

Topics: Bacterial Proteins; Biosensing Techniques; Crystallography, X-Ray; Flow Cytometry; Hydrolysis; Ligands; Molecular Docking Simulation; Nitrophenols; Organophosphates; Paraoxon; Plasmids; Protein Engineering; Structural Homology, Protein; Transcription Factors

We describe herein a unique approach to synthesize zinc oxide-silica-silver (ZnO-SiO2-Ag) nanocomposite, in a simple, one-pot process. The typical process for ZnO synthesis by alkaline precipitation of zinc salts has been tweaked to replace alkali by alkaline sodium silicate. The free acid from zinc salts helps in the synthesis of silica nanoparticles, whereas the alkalinity of sodium silicate precipitates the zinc salts. Addition of silver ions into the reaction pot prior to addition of sodium silicate, and subsequent reduction by borohydride, gives additional functionality of metallic centres for catalytic applications. The synthesis strategy is based on our recent work typically involving acid-base type of cross-reactions and demonstrates a novel strategy to synthesize nanocomposites in a one-pot approach. Each component in the composite offers a unique feature. ZnO besides displaying mild catalytic and anti-bacterial behaviour is an excellent and a cheap 3-D support for heterogeneous catalysis. Silver nanoparticles enhance the catalytic & anti-bacterial properties of ZnO. Silica is an important part of the composite; which not only "glues" the two nanoparticles thereby stabilizing the nanocomposite, but also significantly enhances the surface area of the composite; which is an attractive feature of any catalyst composite. The nanocomposite is found to show excellent catalytic performance with very high turnover frequencies (TOFs) when studied for catalytic reduction of Rhodamine B (RhB) and 4-Nitrophenol (4-NP). Additionally, the composite has been tested for its anti-bacterial properties on three different bacterial strains i.e. E. coli, B. Cereus and Bacillus firmus. The mechanism for enhancement of catalytic performance has been probed by understanding the role of silica in offering accessibility to the catalyst via its porous high surface area network. The nanocomposite has been characterized by a host of different analytical techniques. The uniqueness of our product and process stems from the novel synthesis strategy, the choice and combination of the three moieties, increased surface area offered by silica, and cost effectiveness, thereby making our product and process commercially viable and sustainable for industrial applications.

Topics: Alkalies; Anti-Bacterial Agents; Bacillus cereus; Bacillus firmus; Borohydrides; Catalysis; Chemical Precipitation; Escherichia coli; Hydrogen-Ion Concentration; Metal Nanoparticles; Microbial Sensitivity Tests; Nanocomposites; Nitrophenols; Oxidation-Reduction; Rhodamines; Silicates; Silicon Dioxide; Silver; Surface Properties; Zinc Oxide

Highly Sensitive and ultra-small Rhenium (Re) metal nanoparticles (NPs) were successfully stabilized in water by the staging and fencing action of the versatile biomolecule DNA that resulted in two distinct aggregated chain-like morphologies with average grain sizes of 1.1±0.1nm and 0.7±0.1nm for the very first time within a minute of reaction time. Re NPs are formed by the borohydride reduction of ammonium perrhenate (NH4ReO4) in the presence of DNA at room temperature (RT) under stirring. The morphologies were controlled by carefully monitoring the molar ratio of NH4ReO4 and DNA. The synthesized material was employed in two potential applications: as a substrate for surface enhanced Raman scattering (SERS) studies and as a catalyst for the reduction of aromatic nitro compounds. SERS study was carried out by taking methylene blue (MB) as the probe and the highest SERS enhancement factor (EF) of 2.07×10(7) was found for the aggregated chain-like having average grain size of 0.7±0.1nm. Catalytic reduction of 4-nitro phenol (4-NP), 2-nitro phenol (2-NP) and 4-nitroaniline (4-NA) with a rate constant value of 6×10(-2)min(-1), 33.83×10(-2)min(-1) and 37.4×10(-2)min(-1) have testified the excellent catalytic performance of our Re NPs immobilized on DNA. The overall study have revealed the capability of DNA in stabilizing the highly reactive Re metal at nanoscale and made them applicable in practice. The present route can also be extended to prepare one dimensional (1-D), self-assembled NPs of other reactive metals, mixed metals or even metal oxides for specific applications in water based solutions.

Topics: Adsorption; Aniline Compounds; Borohydrides; Catalysis; DNA; Humans; Kinetics; Metal Nanoparticles; Methylene Blue; Nitrophenols; Oxidation-Reduction; Particle Size; Rhenium; Spectrum Analysis, Raman; Surface Properties; Temperature; Thermodynamics

In order to predict the fate of chemicals in the environment, a range of regulatory tests are performed with microbial inocula collected from environmental compartments to investigate the potential for biodegradation. The abundance and distribution of microbes in the environment is affected by a range of variables, hence diversity and biomass of inocula used in biodegradation tests can be highly variable in space and time. The use of artificial or natural biofilms in regulatory tests could enable more consistent microbial communities be used as inocula, in order to increase test consistency. We investigated spatial and temporal variation in composition, biomass and chemical biodegradation potential of bacterial biofilms formed in river water. Sampling time and sampling location impacted the capacity of biofilms to degrade p-nitrophenol (PNP). Biofilm bacterial community structure varied across sampling times, but was not affected by sampling location. Degradation of PNP was associated with increased relative abundance of Pseudomonas syringae. Partitioning of the bacterial metacommunity into core and satellite taxa revealed that the P. syringae could be either a satellite or core member of the community across sampling times, but this had no impact on PNP degradation. Quantitative PCR analysis of the pnpA gene showed that it was present in all samples irrespective of their ability to degrade PNP. River biofilms showed seasonal variation in biomass, microbial community composition and PNP biodegradation potential, which resulted in inconsistent biodegradation test results. We discuss the results in the context of the mechanisms underlying variation in regulatory chemical degradation tests.

Topics: Biodegradation, Environmental; Biofilms; Biomass; Fresh Water; Nitrophenols; Pseudomonas syringae; Rivers; Seasons; Water Pollutants, Chemical

Promiscuous enzymes are generally considered to be starting points in the evolution of offspring enzymes with more specific or even novel catalytic activities, which is the molecular basis of producing new biological functions. Mhg, a typical α/β fold hydrolase, was previously reported to have both γ-lactamase and perhydrolase activities. However, despite having high structural similarity to and sharing an identical catalytic triad with an extensively studied esterase from Pseudomonas fluorescens, this enzyme did not show any esterase activity. Molecular docking and sequence analysis suggested a possible role for the entry of the binding pocket in blocking the entrance tunnel, preventing the ester compounds from entering into the pocket. By engineering the entrance tunnel with only one or two amino acid substitutions, we successfully obtained five esterase variants of Mhg. The variants exhibited a very broad substrate acceptance, hydrolyzing not only the classical p-nitrophenol esters but also various types of chiral esters, which are widely used as drug intermediates. Site 233 at the entrance tunnel of Mhg was found to play a pivotal role in modulating the three catalytic activities by adjusting the size and shape of the tunnel, with different amino acid substitutions at this site facilitating different activities. Remarkably, the variant with the L233G mutation was a very specific esterase without any γ-lactamase and perhydrolase activities. Considering the amino acid conservation and differentiation, this site could be a key target for future protein engineering. In addition, we demonstrate that engineering the entrance tunnel is an efficient strategy to regulate enzyme catalytic capabilities.. Promiscuous enzymes can act as starting points in the evolution of novel catalytic activities, thus providing a molecular basis for the production of new biological functions. In this study, we identified a critical amino acid residue (Leu233) at the entry of the substrate tunnel of a promiscuous enzyme, Mhg. We found that substitution of this residue with smaller amino acids such as Gly, Ala, Ser, or Pro endowed the enzyme with novel esterase activity. Different amino acids at this site can facilitate different catalytic activities. These findings exhibited universal significance in this subset of α/β fold hydrolases, including Mhg. Furthermore, we demonstrate that engineering the entrance tunnel is an efficient strategy to evolve new enzyme catalytic capabilities. Our study has important implications for the regulation of enzyme catalytic promiscuity and development of protein engineering methodologies.

Topics: Amides; Amino Acid Substitution; Binding Sites; Biocatalysis; Carboxylic Acids; Carboxylic Ester Hydrolases; Catalytic Domain; Escherichia coli; Esterases; Hydrolysis; Kinetics; Models, Molecular; Molecular Docking Simulation; Mutagenesis, Site-Directed; Nitrophenols; Protein Engineering; Pseudomonas fluorescens

A catalytic membrane reactor, which contains a membrane matrix and a catalytic film of alloy nanoparticle-loaded β-lactoglobulin fibrils (NPs@β-LGF), was developed for the continuous-flow reduction of 4-nitrophenol (4-NP). The Cu-Ag and Cu-Ag-Au alloy NPs were synthesized using β-LGF as a scaffold and stabilizing agent. In this process, the Cu nanoclusters were formed in the initial stage and were able to promote the synthesis of Ag

Topics: Alloys; Bioreactors; Catalysis; Nanoparticles; Nitrophenols; Proteins

A reversible luminescence nanoswitch through competitive hydrophobic interaction among copper nanoclusters, p-nitrophenol and α-cyclodextrin is established, and a reliable real-time luminescent assay for acid phosphatase (ACP) activity is developed on the basis of this luminescence nanoswitch. Stable and intensely luminescent copper nanoclusters (CuNCs) were synthesized via a green one-pot approach. The hydrophobic nature of CuNCs aggregate surface is identified, and further used to drive the adsorption of p-nitrophenol on the surface of CuNCs aggregate due to their hydrophobic interaction. This close contact switches off the luminescence of CuNCs aggregate through static quenching mechanism. However, the introduction of α-cyclodextrin switches on the luminescence since stronger host-guest interaction between α-cyclodextrin and p-nitrophenol causes the removal of p-nitrophenol from the surface of CuNCs. This nanoswitch in response to external stimulus p-nitrophenol or α-cyclodextrin can be run in a reversible way. Luminescence quenching by p-nitrophenol is further utilized to develop ACP assay using p-nitrophenyl phosphate ester as the substrate. Quantitative measurement of ACP level with a low detection limit of 1.3 U/L was achieved based on this specific detection strategy. This work reports a luminescence nanoswitch mediated by hydrophobic interaction, and provides a sensitive detection method for ACP level which is capable for practical detection in human serum and seminal plasma.

Topics: Acid Phosphatase; Copper; Fluorescent Dyes; Humans; Hydrophobic and Hydrophilic Interactions; Luminescence; Metal Nanoparticles; Nitrophenols; Solanum tuberosum; Spectrometry, Fluorescence; Time Factors

The general toxic and hepatocarcinogenic effects of diethylnitrosamine after stimulation of its metabolism with 1,4-bis[2-(3,5-dichloropyridyloxy)]-benzene (TCPOBOP) were studied. The hydroxylating activity of liver microsomes of C57Bl/6Mv mice towards p-nitrophenol increased more than 4-fold 3 days after injection of TCPOBOP. Injection of diethylnitrosamine 3 days after TCPOBOP caused a lesser body weight loss and decrease of food consumption in C57Bl/6Mv mice than in response to diethylnitrosamine without preinduction. Injection of diethylnitrosamine to suckling ICR mice after TCPOBOP induction of cytochrome P450 2e1 activity led to development of 2-fold lesser number of tumors and pretumorous nodes in the liver in comparison with animals injected with diethylnitrosamine without induction. These data indicated that metabolism stimulation reduced the general toxic and hepatocarcinogenic effects of diethylnitrosamine.

Topics: Animals; Animals, Suckling; Body Weight; Carcinogenesis; Cytochrome P-450 CYP2E1; Cytochrome P-450 Enzyme Inducers; Diethylnitrosamine; Inactivation, Metabolic; Liver; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred C57BL; Mice, Inbred ICR; Microsomes, Liver; Nitrophenols; Pyridines; Tumor Burden

para-Nitrophenol (pNP)-tagged α2-8-linked sialosides containing different sialic acid forms were chemoenzymatically synthesized using an efficient one-pot three-enzyme α2-8-sialylation system. The resulting compounds allowed high-throughput substrate specificity studies of the α2-8-sialidase activity of a recombinant human cytosolic sialidase hNEU2 and various bacterial sialidases. The sialoside substrate profiles obtained can be used to guide the selection of suitable sialidases for sialylglycan analysis and for cell and tissue surface glycan modification. They can also be used to guide sialidase inhibitor design.

Topics: Bacteria; High-Throughput Screening Assays; Humans; Neuraminidase; Nitrophenols; Recombinant Proteins; Sialic Acids; Substrate Specificity

The novel nonlinear optical single crystal of L-Tryptophan p-nitrophenol (LTPN) has been successfully synthesized by taking the appropriate amount of L-Tryptophan and p-nitrophenol. The single crystals have been grown by slow evaporation solution growth technique. The single crystal XRD studies confirmed that the grown crystal belongs to the monoclinic system. The various functional groups presented in the crystal were confirmed by FT-IR and (1)H NMR spectroscopic studies. The absorptions of the grown crystals were analyzed using UV-Vis-NIR spectral studies. The thermal analysis was performed to study the thermal stability of the grown crystals. The second harmonic generation behavior of L-Tryptophan p-nitrophenol crystal was tested by Kurtz-Perry powder technique.

Topics: Crystallization; Differential Thermal Analysis; Nitrophenols; Nonlinear Dynamics; Optical Phenomena; Proton Magnetic Resonance Spectroscopy; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Temperature; Thermogravimetry; Tryptophan; X-Ray Diffraction

Catalytic activity of Zr and Ag co-doped TiO2 nanoparticles on the reduction of 4-nitrophenol, degradation of methylene blue and methyl orange was studied using sodium borohydride as reducing agent. The nanoparticles were characterized using X-ray diffraction, energy dispersive X-ray, high resolution transmission electron microscopy, selected area electron diffraction and UV-Vis spectroscopy. The rate of the reduction/degradation was found to increase with increasing amount of the photocatalyst which could be attributed to higher dispersity and small size of the nanoparticles. The catalytic activity of Zr and Ag co-doped TiO2 nanoparticles showed no significant difference even after recycling the catalyst four times indicating a promising potential for industrial application of the prepared photocatalyst.

Topics: Azo Compounds; Catalysis; Environmental Pollutants; Light; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Silver; Spectrometry, X-Ray Emission; Spectrophotometry, Ultraviolet; Titanium; X-Ray Diffraction; Zirconium

Handling of two nitro-aromatic compounds, 4-nitroaniline (4NA) and 4-nitrophenol (4NP), simultaneously by Chlorella pyrenoidosa was investigated. Algae would secrete or degrade nitro-aromatic compounds depending on different environmental conditions, in which the mode of handling was determined by the relative formation and degradation rate of the compound. Repeated intermittent trigger with externally added 4NA would induce the continuous secretion of 4NA by algae. Simultaneous exposure of both 4NA and 4NP to algae at normal condition would induce the algae to secrete both compounds. An increase in 4NA exposure concentration would elevate both 4NA and 4NP secretion, and that would be inhibited by the stress conditions of starving or lack of oxygen. Increased 4NA degradation per production rate induced by starving or lack of oxygen might explain the subsequent decrease in 4NA secretion in the presence of 4NP in algae. For 4NP in the presence of 4NA, secretion at normal condition was completely stopped and turned to degradation mode in stress conditions. The decreased formation and increased degradation of 4NP during starving for replenishing energy would explain the net degradation of 4NP in starving condition. The condition of lack of oxygen would inhibit the 4NP formation from 4NA via oxidative deamination, while the degradation of 4NP might not be significantly affected because alternative pathway of degradation via nitro-reduction was available. It may lead to the degradation rate exceeding the formation and explain the net degradation of 4NP in the condition of lack of oxygen.

Topics: Aniline Compounds; Chlorella; Chromatography, High Pressure Liquid; Environmental Exposure; Nitrophenols; Oxidation-Reduction; Oxygen; Stress, Physiological

A sensitive fluorescence probing strategy for parathion-methyl (PM) detection was developed based on electron transfer (ET) between p-nitrophenol (the hydrolysate of PM) and CdTe quantum dots (QDs) in cetyltrimethylammonium bromide (CTAB). PM was hydrolyzed by organophosphorus hydrolase (OPH) to form p-nitrophenol. P-nitrophenol is a typically electron-deficient compound due to the strong electron-withdrawing effect of the nitro groups. The positive charge of CTAB which make it assemble with electronegative mercaptopropionic acid-capped QDs, could be used as an absorbent for p-nitrophenol due to the strong hydrophobic interaction between the long alkyl chain of CTAB and aromatic ring of p-nitrophenol. Thus, the fluorescence intensity of CdTe QDs/CTAB probe could be quenched by p-nitrophenol due to the ET mechanism. The fluorescence intensity of the QD/CTAB system was proportional to PM concentration in the range of 25-3000 ng mL(-1), with a detection limit of 18 ng mL(-1). Furthermore, the proposed method was simple in design and fast in operation, and has been successfully used for PM detection in environmental and agricultural samples with satisfactory recovery.

Topics: Cadmium Compounds; Cetrimonium; Cetrimonium Compounds; Fluorescent Dyes; Limit of Detection; Methyl Parathion; Nitrophenols; Oryza; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

This work demonstrates the synthesis and characterization of porous ZnO-SnO2 nanosheets prepared by the simple and facile hydrothermal method at low-temperature. The prepared nanosheets were characterized by several techniques which revealed the well-crystallinity, porous and well-defined nanosheet morphology for the prepared material. The synthesized porous ZnO-SnO2 nanosheets were used as an efficient photocatalyst for the photocatalytic degradation of highly hazardous dye, i.e., direct blue 15 (DB 15), under visible-light irradiation. The excellent photocatalytic degradation of prepared material towards DB 15 dye could be ascribed to the formation of ZnO-SnO2 heterojunction which effectively separates the photogenerated electron-hole pairs and possess high surface area. Further, the prepared porous ZnO-SnO2 nanosheets were utilized to fabricate a robust chemical sensor to detect 4-nitrophenol in aqueous medium. The fabricated sensor exhibited extremely high sensitivity of ~ 1285.76 µA/mmol L(-1)cm(-2) and an experimental detection limit of 0.078 mmol L(-1) with a linear dynamic range of 0.078-1.25 mmol L(-1). The obtained results confirmed that the prepared porous ZnO-SnO2 nanosheets are potential material for the removal of organic pollutants under visible light irradiation and efficient chemical sensing applications.

Topics: Azo Compounds; Biosensing Techniques; Catalysis; Light; Limit of Detection; Microscopy, Electron, Transmission; Nanostructures; Nitrophenols; Photolysis; Porosity; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tin Compounds; Zinc Oxide

Paraoxonase 1 (PON1) is a calcium-dependent hydrolase associated with serum high-density lipoprotein particles. PON1 hydrolyzes some organophosphates (OPs), including some nerve agents, through nucleophilic attack of hydroxide ion (from water) in the active site. Most OPs are hydrolyzed inefficiently. This project seeks to identify nucleophiles that can enhance PON1-mediated OP degradation. A series of novel nucleophiles, substituted phenoxyalkyl pyridinium oximes, has been synthesized which enhance the degradation of surrogates of sarin (nitrophenyl isopropyl methylphosphonate; NIMP) and VX (nitrophenyl ethyl methylphosphonate; NEMP). Two types of in vitro assays have been conducted, a direct assay using millimolar concentrations of substrate with direct spectrophotometric quantitation of a hydrolysis product (4-nitrophenol) and an indirect assay using submicromolar concentrations of substrate with quantitation by the level of inhibition of an exogenous source of acetylcholinesterase from non-hydrolyzed substrate. Neither NIMP nor NEMP is hydrolyzed effectively by PON1 if one of these novel oximes is absent. However, in the presence of eight novel oximes, PON1-mediated degradation of both surrogates occurs. Computational modeling has created a model of PON1 embedded in phospholipid and has indicated general agreement of the binding enthalpies with the relative efficacy as PON1 enhancers. PON1 enhancement of degradation of OPs could be a unique and unprecedented mechanism of antidotal action.

Topics: Antidotes; Aryldialkylphosphatase; Catalytic Domain; Enzyme Activation; Enzyme Activators; Humans; Hydrolysis; Hydroxides; Inactivation, Metabolic; Molecular Dynamics Simulation; Nitrophenols; Organothiophosphorus Compounds; Oximes; Pyridinium Compounds; Sarin; Spectrophotometry; Water

In this work, a new hybrid nanocatalyst, namely titanium dioxide (TiO2) composite nanowires, encapsulated with graphene (G) and palladium nanoparticles (Pd NPs) (designated as G-Pd@TiO2-CNWs), was prepared. In preparing the nanowires, a combination of electrospinning and hydrothermal approaches was employed. The visible-light-driven photocatalytic performance of G-Pd@TiO2-CNWs was investigated using the reduction of 4-nitrophenol (4-NP) as a model reaction. The results showed that G-Pd@TiO2-CNWs converted nearly 100% of 4-NP under visible light irradiation. The reaction kinetics of the photocatalytic reduction of 4-NP was studied by UV-vis spectrophotometry and the apparent rate constant was determined and compared with those for other supported TiO2 catalysts. Furthermore, the spent G-Pd@TiO2-CNWs could be recovered by simple centrifugation and reused. The work is expected to shed new light on the development of G-incorporated hybrid nanostructures for harvesting light energy and on the development of new photocatalysts for the removal of environmental pollutants.

Topics: Graphite; Nanowires; Nitrophenols; Photolysis; Titanium; Water Pollutants, Chemical

Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole carbon and energy source. The genes involved in PNP degradation are organized in the following three operons: pnpA, pnpB, and pnpCDEFG. How the expression of the genes is regulated is unknown. In this study, an LysR-type transcriptional regulator (LTTR) is identified to activate the expression of the genes in response to the specific inducer PNP. While the LTTR coding gene pnpR was found to be not physically linked to any of the three catabolic operons, it was shown to be essential for the growth of strain WBC-3 on PNP. Furthermore, PnpR positively regulated its own expression, which is different from the function of classical LTTRs. A regulatory binding site (RBS) with a 17-bp imperfect palindromic sequence (GTT-N11-AAC) was identified in all pnpA, pnpB, pnpC, and pnpR promoters. Through electrophoretic mobility shift assays and mutagenic analyses, this motif was proven to be necessary for PnpR binding. This consensus motif is centered at positions approximately -55 bp relative to the four transcriptional start sites (TSSs). RBS integrity was required for both high-affinity PnpR binding and transcriptional activation of pnpA, pnpB, and pnpR. However, this integrity was essential only for high-affinity PnpR binding to the promoter of pnpCDEFG and not for its activation. Intriguingly, unlike other LTTRs studied, no changes in lengths of the PnpR binding regions of the pnpA and pnpB promoters were observed after the addition of the inducer PNP in DNase I footprinting.

Topics: Binding Sites; Biotransformation; Carbon; Consensus Sequence; DNA, Bacterial; Energy Metabolism; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Nitrophenols; Operon; Promoter Regions, Genetic; Pseudomonas; Sequence Analysis, DNA; Transcriptional Activation

A microtiter plate-based assay was developed to evaluate the ability of lipases to perform transesterifications when employed in different organic solvents. A 4-nitrophenol assay was carried out employing seven different lipase formulations and two fatty acid methyl esters with different chain lengths in a total of six organic solvents with logP values approximately between 1 and -1. This assay delivered results within comparatively short times measured by a color reaction and thus facilitates the choice of an enzyme-solvent combination for the synthesis of glycolipids. To validate the findings, glycolipid syntheses were performed using the same lipase formulation in the same solvents. When comparing the results obtained using the microtiter plate-based assay to the results of the glycolipid syntheses using the same lipases and solvents, matching results were obtained.

Topics: Colorimetry; Enzyme Inhibitors; Esterification; Lipase; Nitrophenols; Solvents

Monodisperse silver nanocages (AgNCs) with specific interiors were successfully synthesized by an azeotropic distillation (AD) assisted method and exhibited excellent catalytic activities for reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) due to the unique hollow morphology and small thickness of the silver shell.

Topics: Aminophenols; Catalysis; Distillation; Nanostructures; Nitrophenols; Oxidation-Reduction; Silver

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2.

Topics: Catalysis; Chlorophenols; Kinetics; Manganese Compounds; Nitrophenols; Organic Chemicals; Oxidants; Oxidation-Reduction; Oxides; Phenols; Potassium Permanganate; Triclosan; Water; Water Pollutants, Chemical

Obtaining accurate power characteristics of ultrasonic treatment systems is an important step towards their industrial scalability. Calorimetric measurements are most commonly used for quantifying the dissipated ultrasonic power. However, accuracy of these measurements is affected by various heat losses, especially when working at high power densities. In this work, electrical power measurements were conducted at all locations in the piezoelectric ultrasonic system equipped with ½″ and ¾″ probes. A set of heat transfer calculations were developed to estimate the convection heat losses from the reaction solution. Chemical dosimeters represented by the oxidation of potassium iodide, Fricke solution and 4-nitrophenol were used to chemically correlate the effect of various electrical amplitudes and treatment regimes. This allowed estimation of sonochemical-efficiency (SE) and energy conversion (XUS) of the ultrasonic system. Results of this study showed overall conversion efficiencies of 60-70%. This correlated well with the chemical dosimeter yield curves of both organic and inorganic aqueous solutions. All dosimeters showed bubble shielding and coalescence effects at higher ultrasonic power levels, less pronounced for the ½″ probe case. SE and XUS values in the range of 10(-10) mol/J and 10(-3) J/J respectively confirmed that conversion of ultrasonic power to chemical yield declined with amplitude.

Topics: Calibration; Calorimetry; Convection; Electric Power Supplies; Iodine; Iron; Nitrophenols; Oxidation-Reduction; Thermal Conductivity; Ultrasonography

Herein, we are reporting for the first time one step biogenic synthesis of silver nanoparticles (AgNPs) at room temperature by using Ziziphus Jujuba leaf extract as a reducing and stabilizing agent. The process of nanoparticles preparation is green, rapid, environmentally benign and cost effective. The synthesized AgNPs were characterized by means of UV-Vis., XRD, FT-IR, TEM, DLS and Zeta potential. The absorption band centered at λmax 434 nm in UV-Vis. reflects surface plasmon resonance (SPR) of AgNPs. XRD analysis revealed, that biosynthesized AgNPs are crystalline in nature with the face centered cubic structure. FT-IR analysis indicates that nanoparticles were capped with the leaf extract. TEM images shows the synthesized nanoparticles are having different shapes with 20-30 nm size. The data obtained from DLS that support the hydrodynamic size of 28 nm. Zeta potential of -26.4 mV indicates that the nanoparticles were highly stable in colloidal state. The effect of pH, quantity of leaf extract and concentrations of AgNO3 were also studied to attend control over the particle size and stability. The synthesized AgNPs shows highly efficient catalytic activity towards the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) and Methylene Blue (MB) for environmental protection. Synthesized AgNPs also exhibited good antimicrobial activity against Escherichia coli.

Topics: Anti-Bacterial Agents; Catalysis; Escherichia coli; Green Chemistry Technology; Hydrogen-Ion Concentration; Light; Metal Nanoparticles; Microbial Sensitivity Tests; Nitrophenols; Particle Size; Plant Extracts; Plant Leaves; Scattering, Radiation; Silver; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Static Electricity; Time Factors; X-Ray Diffraction; Ziziphus

One-pot green approach to the synthesis of Prussian blue nanocubes/reduced graphene oxide (PBNCs/RGO) nanocomposite had been attempted. It was based on the extract of mushroom with K3[Fe(CN)6] and graphene oxide (GO) as precursors, where the reduction of GO and the deposition of PBNCs occurred simultaneously. The obtained nanocomposite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and electrochemical techniques. With the introduction of β-cyclodextrin (β-CD), the β-CD/PBNCs/RGO system showed linear behavior in the range from 0.01 to 700 μM for 4-nitrophenol with a low detection limit of 2.34 nM (S/N=3).

Topics: Agaricales; beta-Cyclodextrins; Electrochemical Techniques; Ferrocyanides; Graphite; Microscopy, Electron, Transmission; Nanocomposites; Nanotubes; Nitrophenols; Oxidation-Reduction; Oxides; Spectrum Analysis, Raman; Water

Several epidemiological studies have shown that tea consumption is associated with higher bone mineral density in women. Flavonoids in tea are recognized as potential estrogen mimics and may positively influence bone metabolism in estrogen-deficient women. Luteolin and orientin, flavonoids from rooibos tea, are of particular interest as rooibos tea contains no caffeine that can be detrimental to bone health. This study analyzed changes in mineral content when luteolin or orientin was added to a human osteoblast cell line and the potential mechanisms involved. Measurements included alkaline phosphatase (ALP) activity, cell mitochondrial activity, toxicity, and changes in regulatory proteins involved in osteoblast metabolism.. Mineral was significantly elevated in Saos2 cells treated with orientin (0.1-1.0 μM, 15-100 μM) or luteolin (5.0 μM) and was associated with increased ALP and mitochondrial activity, as determined by the production of p-nitrophenol and the reduction of 2-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, respectively. Greater mineral content was also associated with lower toxicity as determined by lactate dehydrogenase activity and lower expression of TNF-α, IL-6, sclerostin, osteopontin, and osteoprotegerin.. Orientin and luteolin, flavonoids in rooibos tea, enhance mineral content in Saos2 cells. These findings provide guidance for doses to be studied in well-established animal models.

Topics: Adaptor Proteins, Signal Transducing; Alkaline Phosphatase; Aspalathus; Bone Morphogenetic Proteins; Calcification, Physiologic; Cell Line; Flavonoids; Genetic Markers; Glucosides; Humans; Luteolin; Mitochondria; Nitrophenols; Osteoblasts; Osteopontin; Osteoprotegerin; Tumor Necrosis Factor-alpha; Wnt Signaling Pathway

Ordered porous zeolite/chitosan (Zel/Chi) monoliths were prepared by a unidirectional freeze-drying method, and their properties and structures were characterized by various instrumental methods. The metal ion adsorption and the drug release performance of the porous Zel/Chi monoliths were also studied. The release rate of cefalexin from drug-loaded Zel/Chi monoliths depended on the composition and porous structure of the monoliths. The metal ion adsorption capacity of the Zel/Chi monoliths was related to the concentration of the metal ions, the adsorption time and the Zel/Chi ratio. An experimentally maximum adsorption of 89 mg/g was achieved for Cu(2+) ions. The Zel/Chi monoliths with adsorbed Cu(2+) ions effectively catalyzed the reduction of 4-nitrophenol to 4-aminophenol and had good recyclability. They were easily recovered by simply removing them from the reaction system and rinsing them with water.

Topics: Adsorption; Aminophenols; Catalysis; Cellulose; Chitosan; Drug Carriers; Drug Liberation; Ionic Liquids; Metals, Heavy; Nitrophenols; Oxidation-Reduction; Porosity; Wastewater; Water Pollutants, Chemical; Zeolites

A unique Ag-bridged Ag2O nanowire network/TiO2 nanotube array p-n heterojunction (Ag-Ag2O/TiO2 NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO2 NT and then were partly oxidized to Ag2O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag2O nanowire network. The Ag-Ag2O/TiO2 NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag-Ag2O self-stability structure and p-n heterojunction permitted high and stable photocatalytic activity of Ag-Ag2O/TiO2 NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag-Ag2O/TiO2 NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO2 NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag-Ag2O/TiO2 NT remained highly stable photocatalytic activity.

Topics: Azo Compounds; Benzenesulfonates; Catalysis; Coloring Agents; Light; Nanotubes; Nanowires; Nitrophenols; Oxides; Silver; Silver Compounds; Titanium; Water Pollutants, Chemical

1. Cattle are an important component of the human food chain. Drugs used either legally or illegally in cattle may therefore enter the food chain and it is thus important to understand pathways of drug metabolism in this species, including sulfation catalyzed by the sulfotransferases (SULTs). 2. In this study, we have analyzed the sulfation of 4-nitrophenol and other compounds in male and female bovine liver and characterized recombinant bovine SULT isoforms 1A1 and 1B1 expressed in Escherichia coli. 3. We found that, in contrast to most other mammalian species, the major phenol sulfotransferase SULT1A1 is not expressed in bovine liver. Rather SULT1B1 seems to be a major form in both male and female bovine liver. 4. We also identified kinetic differences between bovine and human SULT1A1 and, using the human SULT1A1 crystal structure, identified two amino acid positions in the active site of bovine SULT1A1 (Ile89Val and Phe247Val) that may be responsible for these differences.

Topics: Animals; Arylsulfotransferase; Cattle; Crystallography, X-Ray; Female; Humans; Isoenzymes; Liver; Male; Nitrophenols; Sulfotransferases

l-tryptophan p-nitrophenol trisolvate (LTPN), an organic nonlinear optical material was synthesized using ethanol-water mixed solvent and the crystals were grown by a slow solvent evaporation method. The crystal structure and morphology were studied by single crystal X-ray diffraction analysis. The crystalline perfection of the LTPN crystal was analyzed by high-resolution X-ray diffraction study. The molecular structure of the crystal was confirmed by observing the various characteristic functional groups of the material using vibrational spectroscopy. The cut-off wavelength, optical transmission, refractive index and band gap energy were determined using UV-visible data. The variation of refractive index with wavelength shows the normal behavior. The second harmonic generation of the crystal was confirmed and the efficiency was measured using Kurtz Perry powder method. Single and multiple shot methods were employed to measure surface laser damage of the crystal. The photoluminescence spectral study revealed that the emission may be associated with the radiative recombination of trapped electrons and holes. Microhardness measurements revealed that LTPN belongs to a soft material category.

Topics: Crystallization; Differential Thermal Analysis; Hardness; Lasers; Luminescence; Molecular Conformation; Nitrophenols; Optical Phenomena; Refractometry; Solubility; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Thermogravimetry; Tryptophan; Vibration; X-Ray Diffraction

Modern technology demands ever smaller and more efficient nanoparticles, wires and networks. The natural tendency for amyloid proteins to form fibrillar structures is leveraged in creating high aspect ratio, nano-sized protein fibers as scaffolds for metallized nanowires. The morphology of fibrils is influenced by induced strain during denaturing and early aggregation and subsequent fibril deposition with platinum leads to controlled catalyst surfaces based on the initial protein precipitate. Here we have created insulin fibrils with varying morphologies produced in the presence of heat and strain and investigated their metallization with platinum by TEM. The catalytic activity of the metal-coated protein fibrils was resolved by tracking the reaction kinetics of the conversion of 4-nitrophenol to 4-aminophenol in the presence of the produced nanowires using UV-Vis spectroscopy. The effects of fibril morphology and temperature on the pseudo-first-order kinetics of conversion are investigated. Conversion to 4-aminophenol occurs on the order of minutes and is independent of temperature in the range tested (7 to 20°C). Two regimes of conversion are identified, an early higher rate, followed by a slower later rate.

Topics: Aminophenols; Catalysis; Insulin; Kinetics; Microscopy, Electron, Transmission; Nanowires; Nitrophenols; Platinum; Spectrophotometry, Ultraviolet; Temperature

Heat shock protein 70 (Hsp70) is one of the most widely used biomarker for monitoring environment perturbations in biological systems. To facilitate the analysis of hsp70 expression as a biomarker, we generated a Tg(hsp70:gfp) transgenic medaka line in which green fluorescence protein (GFP) reporter gene was driven by the medaka hsp70 promoter. Here, we characterized Tg(hsp70:gfp) medaka for inducible GFP expression by seven environment-relevant heavy metals, including mercury, arsenic, lead, cadmium, copper, chromium, and zinc. We found that four of them (mercury, arsenic, lead, and cadmium) induced GFP expression in multiple and different organs. In general, the liver, kidney, gut, and skin are among the most frequent organs to show induced GFP expression. In contrast, no detectable GFP induction was observed to copper, chromium, or zinc, indicating that the transgenic line was not responsive to all heavy metals. RT-qPCR determination of hsp70 mRNA showed similar induction and non-induction by these metals, which also correlated with the levels of metal uptake in medaka exposed to these metals. Our observations suggested that these heavy metals have different mechanisms of toxicity and/or differential bioaccumulation in various organs; different patterns of GFP expression induced by different metals may be used to determine or exclude metals in water samples tested. Furthermore, we also tested several non-metal toxicants such as bisphenol A, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 4-introphenol, and lindane; none of them induced significant GFP expression in Tg(hsp70:gfp) medaka, further suggesting that the inducibility of Tg(hsp70:gfp) for GFP expression is specific to a subset of heavy metals.

Topics: Animals; Animals, Genetically Modified; Benzhydryl Compounds; Female; Fish Proteins; Gene Expression Regulation; Genes, Reporter; Green Fluorescent Proteins; Hexachlorocyclohexane; HSP70 Heat-Shock Proteins; Intestinal Mucosa; Intestines; Kidney; Liver; Male; Metals, Heavy; Nitrophenols; Oryzias; Phenols; Polychlorinated Dibenzodioxins; Promoter Regions, Genetic; Recombinant Fusion Proteins; RNA, Messenger; Skin; Water Pollutants, Chemical

A rapid and sensitive electrochemical sensor based on disulfides bridged β-cyclodextrin dimer-functionalized multi-walled carbon nanotube (DBβ-CD-MWCNT) nanohybrids with higher supramolecular recognition capability was successfully constructed for the first time. Simultaneous trace analysis of three phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP) in tap-water and wastewater samples was performed based on the constructed sensor. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy were utilized to characterize the properties of the modified electrode. The proposed DBβ-CD-MWCNT-modified electrode displayed electrochemical signal superior to those of β-CD-MWCNT and MWCNT towards 4-AP, 4-CP, and 4-NP. Under optimal conditions, differential pulse voltammetry was used to simultaneously quantify 4-AP, 4-CP, and 4-NP within the concentration range of 0.01-20, 0.1-200, and 0.1-200 µM, respectively. The detection limits (S/N=3) of the DBβ-CD-MWCNT nanohybrid electrode for 4-AP, 4-CP, and 4-NP were 0.0042, 0.028, and 0.048 µM, respectively. Satisfactory results revealed that this proposed electrochemical sensor can provide a promising candidate for the simultaneous trace analysis of 4-AP, 4-CP, and 4-NP in environmental monitoring of water and wastewater samples. The present work might broaden the channel toward the application of bridged CD in the electrochemical sensing or biosensing.

Topics: Aminophenols; beta-Cyclodextrins; Biosensing Techniques; Chlorophenols; Dielectric Spectroscopy; Environmental Monitoring; Limit of Detection; Nanotubes, Carbon; Nitrophenols

Batch experiments were conducted to examine mechanisms for removal of p-nitrophenol (PNP) from aqueous solution using zero-valent iron (ZVI). Removal of PNP using ZVI was mainly attributed to three mechanisms: degradation, precipitation and adsorption. A complete removal of 30 mg L(-1) PNP with ZVI dosage of 1000 mg L(-1) achieved within 30 min at pH 3. The PNP removal rate in the acidic solutions was significantly suppressed at higher pH. The modified Langmuir-Hinshelwood kinetic model could successfully describe the PNP removal process using ZVI at different pH conditions. Total organic carbon (TOC) removal efficiencies were found to be almost independent of pH. While the TOC removal at lower pH was profoundly affected by the reductive and/or oxidative degradation, the adsorption was favorable at higher pH. The effect of dissolved oxygen on PNP removal was investigated at pH 3 where a maximum contribution of oxidative degradation could be expected. The PNP removal in the anoxic system purged with nitrogen gas was quick as well as that in the system being open to the air. However, the TOC removal under the anoxic condition was negligible as compared with that in the oxic system. The profiles of the intermediates formed during the PNP degradation indicated that the reductive degradation was predominant in the initial phase of the removal and subsequently the oxidative degradation occurred.

Topics: Adsorption; Hydrogen-Ion Concentration; Iron; Kinetics; Nitrophenols; Oxidation-Reduction; Oxygen; Waste Disposal, Fluid; Water Pollutants, Chemical

A polymeric potassium complex of p-nitrophenol was synthesized and characterized by analytical and spectroscopic techniques. Molecular structure of the complex was determined by single crystal X-ray diffraction study. X-ray structural data show that crystals contain polymeric K(+) complex of p-nitrophenol. Asymmetric unit consists of one p-nitrophenolate, one K(+) ion and one water molecule. All bond lengths and angles in the phenyl rings have normal Csp2-Csp2 values and are in the expected ranges. The p-nitrophenolate is close to planar with small distortions by some atoms. Each potassium ion in the polymeric structure is identical and eight-coordinate, bonded to four nitro, two phenolate oxygen atoms from five p-nitrophenolate ligands and two oxygen atoms from two water molecules. Electronic, electrochemical, photoluminescence and thermal properties of the complex were also investigated.

Topics: Coordination Complexes; Crystallography, X-Ray; Electrochemical Techniques; Luminescence; Models, Molecular; Nitrophenols; Polymers; Potassium

The aim of this study was to evaluate the crosslinking abilities of divinyl sulfone (DVS) for the preparation of novel water-insoluble cyclodextrin-based polymers (CDPs) capable of forming inclusion complexes with different guest molecules. Reaction of DVS with native α-cyclodextrin (α-CD), β-cyclodextrin (β-CD) and/or starch generates a variety of homo- and hetero-CDPs with different degrees of crosslinking as a function of the reactants' stoichiometric ratio. The novel materials were characterized by powder X-ray diffraction, electron microscopy and for their sorption of phenol and 4-nitrophenol. They were further evaluated as sorbents with phenolic pollutants (bisphenol A and β-naphthol) and bioactive compounds (the hormone progesterone and curcumin). Data obtained from the inclusion experiments show that the degree of cross-linking has a minor influence on the yield of inclusion complex formation and highlight the important role of the CDs, supporting a sorption process based on the formation of inclusion complexes. In general, the inclusion processes are better described by a Freundlich isotherm although an important number of them can also be fitted to the Langmuir isotherm with R2 ≥ 0.9, suggesting a sorption onto a monolayer of homogeneous sites.

Topics: Adsorption; Benzhydryl Compounds; Cross-Linking Reagents; Curcumin; Cyclodextrins; Hydrogen-Ion Concentration; Naphthols; Nitrophenols; Phenols; Polymers; Progesterone; Starch; Sulfones; X-Ray Diffraction

We report the green synthesis of palladium/CuO nanoparticles (Pd/CuO NPs) using Theobroma cacao L. seeds extract and their catalytic activity for the reduction of 4-nitrophenol and Heck coupling reaction under aerobic conditions. The catalyst was characterized using the powder XRD, TEM, EDS, UV-vis and FT-IR. This method has the advantages of high yields, elimination of surfactant, ligand and homogeneous catalysts, simple methodology and easy work up. The catalyst can be recovered from the reaction mixture and reused several times without any significant loss of catalytic activity.

Topics: Cacao; Catalysis; Copper; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Plant Extracts; Seeds

Pseudomonas sp. strain WBC-3 mineralizes the priority pollutant para-nitrophenol (PNP) and releases nitrite (NO2 (-)), which is probably involved in the nitrification. In this study, the rate of PNP removal in soil bioaugmented with strain WBC-3 was more accelerated with more NO2 (-) accumulation than in uninoculated soils. Strain WBC-3 survived well and remained stable throughout the entire period. Real-time polymerase chain reaction (real-time PCR) indicated a higher abundance of ammonia-oxidizing bacteria (AOB) than ammonia-oxidizing archaea (AOA), suggesting that AOB played a greater role in nitrification in the original sampled soil. Real-time PCR and multivariate analysis based on the denaturing gradient gel electrophoresis showed that PNP contamination did not significantly alter the abundance and community structure of ammonia oxidizers except for inhibiting the AOB abundance. Bioaugmentation of PNP-contaminated soil showed a significant effect on AOB populations and community structure as well as AOA populations. In addition, ammonium (NH4 (+)) variation was found to be the primary factor affecting the AOB community structure, as determined by the correlation between the community structures of ammonia oxidizers and environmental factors. It is here proposed that the balance between archaeal and bacterial ammonia oxidation could be influenced significantly by the variation in NH4 (+) levels as caused by bioaugmentation of contaminated soil by a pollutant containing nitrogen.

Topics: Ammonia; Archaea; Bacteria; Biota; Denaturing Gradient Gel Electrophoresis; Nitrophenols; Oxidation-Reduction; Real-Time Polymerase Chain Reaction; Soil Microbiology; Soil Pollutants

In this work, a novel and convenient strategy was developed to prepare molecularly imprinted polymers (MIPs) on the surface of graphene sheet. In this route, vinyl group functionalized graphene (GR/NVC) was first prepared by immobilizing 4-vinylcarbazole onto the surface of graphene via π-π interaction. The subsequent grafting copolymerization of methacrylic acid and ethylene glycol dimethacrylate in the presence of 4-nitrophenol (4-NP, template molecule) was carried out at GR/NVC surface, leading to the formation of GR/MIPs composite. The GR/MIPs composite was characterized by FTIR, fluorescence, TGA, SEM and AFM, and was used to fabricate electrochemical sensor for the detection of 4-NP. The electrochemical behavior of GR/MIPs sensor for 4-NP was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The effects of the preparation conditions, such as concentration of the NVC and template, the solution pH, and incubation time, were also optimized. Under optimized conditions, the DPV current response of GR/MIPs sensor was nearly 12 times than that of the GR/NIPs sensor. It also should be noted that as compared to traditional MIP, shorter response time and much higher current response were demonstrated. In addition, the GR/MIPs sensor could recognize 4-NP from its structural analogs, indicating the excellent selectivity of the GR/MIPs sensor. The peak current is linearly proportional to the concentration of 4-NP ranging from 0.01 μM to 100 μM and 200 μM to 1000 μM with a significantly low detection limit of 5 nM, a wider response range and lower detection limits as compared to most of the previously reported electrochemical sensors for 4-NP. Furthermore, the GR/MIPs sensor exhibits good stability with adequate reproducibility and has been successfully used to determine 4-NP in water samples.

Topics: Electrochemical Techniques; Graphite; Molecular Imprinting; Molecular Structure; Nitrophenols; Polymers

Self-assembly of the naturally occurring sweetening agent, glycyrrhizic acid (GA) in water is studied by small-angle X-ray scattering and microscopic techniques. Statistical analysis on atomic force microscopy images reveals the formation of ultralong GA fibrils with uniform thickness of 2.5 nm and right-handed twist with a pitch of 9 nm, independently of GA concentration. Transparent nematic GA hydrogels are exploited to create functional hybrid materials. Two-fold and three-fold hybrids are developed by introducing graphene oxide (GO) and in situ-synthesized gold nanoparticles (Au NPs) in the hydrogel matrix for catalysis applications. In the presence of GO, the catalytic efficiency of Au NPs in the reduction of p-nitrophenol to p-aminophenol is enhanced by 2.5 times. Gold microplate single crystals are further synthesized in the GA hydrogel, expanding the scope of these hybrids and demonstrating their versatility in materials design.

Topics: Aminophenols; Catalysis; Glycyrrhizic Acid; Gold; Graphite; Hydrogels; Metal Nanoparticles; Microscopy, Atomic Force; Nanostructures; Nitrophenols; Oxidation-Reduction; Scattering, Small Angle; Surface Properties; X-Ray Diffraction

Investigation illustrates that the bromate-4-nitrophenol reaction in a stirred batch reactor undergoes spontaneous oscillations under very broad initial reactant concentrations. The addition of ferroin has subtle influences on the nonlinear behavior, in which the frequency and total number of oscillations were greatly reduced at a low or high ferroin concentration, as opposed to the significant increase at a moderate ferroin concentration. Temporal oscillations with a modulating frequency were also observed in the ferroin-bromate-4-nitrophenol system. In a capillary tube the ferroin-bromate-4-nitrophenol reaction generated propagating wave trains with various complex behaviors such as period-doubled intermittent propagation failure. Illumination was found to have a profound effect on the temporal oscillations in the bromate-4-nitrophenol reaction and on those long lasting wave activities. Spectroscopic studies were able to identify 1,4-benzoquinone, 2-bromo-1,4-benzoquinone, and 2-bromo-4-nitrophenol as major components during the reaction.

Topics: Bromates; Kinetics; Nitrophenols; Phenanthrolines; Photochemical Processes

P-Nitrophenol (PNP) is considered to be one of nitrophenol derivatives of diesel exhaust particles. PNP is a major metabolite of some organophosphorus compounds. PNP is a persistent organic pollutant as well as one of endocrine-disrupting compounds. Consequently, bioaccumulation of PNP potentiates toxicity. The objectives of the current study were to assess in vivo adverse effects of long-term low doses of PNP exposure on reproductive system during development stage. Twenty-eight-day-old male Japanese quails were orally administered different doses of PNP (0, 0.01, 0.1, 1 mg/kg body weight) daily for 2.5 months. Testicular histopathology, hormones, caspase-3 (CASP3), and claudin-1 (CLDN1) tight junction protein, as well as plasma hormones were analyzed. The results revealed that long-term PNP exposure caused testicular histopathological changes such as vacuolation of spermatogenic cell and spermatocyte with significant testicular and cloacal gland atrophy. PNP activated CASP3 enzyme that is an apoptosis-related cysteine peptidase. Besides, it disrupted the expression of CLDN1. Furthermore, a substantial decrease in plasma concentrations of luteinizing hormone (LH) and testosterone was observed after 2 and 2.5 months in the PNP-treated groups. Meanwhile, the pituitary LH did not significantly change. Site of action of PNP may be peripheral on testicular development and/or centrally on the hypothalamic-pituitary-gonadal axis through reduction of pulsatile secretion of gonadotrophin-releasing hormone. Consequently, it may reduce the sensitivity of the anterior pituitary gland to secrete LH. In conclusion, PNP induced profound endocrine disruption in the form of hormonal imbalance, induction of CASP3, and disruption of CLDN1 expression in the testis. Hence, it may hinder the reproductive processes.

Topics: Animals; Caspase 3; Claudin-1; Coturnix; Endocrine Disruptors; Environmental Pollutants; Luteinizing Hormone; Male; Nitrophenols; Pituitary Gland; Testis; Testosterone; Vehicle Emissions

Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1,064 nm.

Topics: Calorimetry, Differential Scanning; Crystallization; Hydrogen Bonding; Luminescence; Molecular Conformation; Nitrophenols; Optical Phenomena; Proline; Proton Magnetic Resonance Spectroscopy; Solubility; Solvents; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Temperature; Thermogravimetry; Water; X-Ray Diffraction

The use of peptides as capping ligands for materials synthesis has been widely explored. The ambient conditions of bio-inspired syntheses using molecules such as peptides represent an attractive route for controlling the morphology and activity of nanomaterials. Although various reductants can be used in such syntheses, no comprehensive comparison of the same bio-based ligand with different reductants has been reported. In this contribution, peptides AuBP1, AuBP2, and Pd4 are used in the synthesis of Au nanoparticles. The reductant strength is varied by using three different reducing agents: NaBH4, hydrazine, and ascorbic acid. These changes in reductant produce significant morphological differences in the final particles. The weakest reductant, ascorbic acid, yields large, globular nanoparticles with rough surfaces, whereas the strongest reductant, NaBH4, yields small, spherical, smooth nanomaterials. Studies of 4-nitrophenol reduction using the Au nanoparticles as catalysts reveal a decrease in activation energy for the large, globular, rough materials relative to the small, spherical, smooth materials. These studies demonstrate that modifying the reductant is a simple way to control the activity of peptide-capped nanoparticles.

Topics: Amino Acid Sequence; Catalysis; Gold; Kinetics; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Peptides; Reducing Agents; Spectrophotometry, Ultraviolet; Thermodynamics

The primary focus of the present work is the study of the effects that two ligands and the crystallization pH have on the crystalline forms of human insulin. For this purpose, human insulin (HI) was co-crystallized with two distinct phenolic derivatives: the organic ligands meta-cresol (m-cresol) and 4-nitrophenol. The formation of polycrystalline precipitates was then followed by means of structural characterization of the individual specimens in terms of unit-cell symmetry and parameters. In both cases, two different polymorphs were identified via X-ray powder diffraction measurements, the first of hexagonal symmetry (R3 space group) at higher pH values and the second of monoclinic symmetry (space group P21) with unit-cell parameters a = 87.4282 (5), b = 70.5020 (3), c = 48.3180 (4) Å, β = 106.8958 (4)°, the latter of which to our knowledge has never been observed before.

Topics: Cresols; Crystallization; Crystallography, X-Ray; Humans; Insulins; Models, Molecular; Nitrophenols; Phase Transition; Powder Diffraction; X-Ray Diffraction

We demonstrate the fabrication of yolk-shell catalysts consisting of a single M (M = Ag, Au) nanoparticle encapsulated within a hollow mesoporous organosilica shell via an organosilane-assisted strategy. The advantages of our method lie in its good controllability of the void space as well as the thickness of the mesoporous shell. The M@CTAB/SiO2 synthesized through a modified Stöber method can transform to yolk-shell structures after adding (3-aminopropyl)trimethoxysilane (APTMS)/TEOS or (3-aminopropyl)triethoxysilane (APTES)/TEOS into the synthetic medium. We give unambiguous evidence that the middle CTAB/SiO2 layer transforms into a less dense APTMS-rich organic-inorganic layer which was selectively removed in alkaline aqueous solution, while the amino-functionalized hybrid shells remain intact. Moreover, we discuss the role of alkylamino groups in the shell in the transformation from Ag@SiO2 nanorattles to hollow structures when impregnating the as-synthesized Ag@SiO2 nanorattles in HAuCl4 aqueous solution. The nanorattles also exhibit high catalytic activity for the catalytic reduction of p-nitrophenol.

Topics: Aminophenols; Catalysis; Gold; Molecular Structure; Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Porosity; Silanes; Silicon Dioxide; Silver; Surface Properties

Graphdiyne (GDY), a novel kind of two-dimensional carbon allotrope consisting of sp- and sp(2)-hybridized carbon atoms, is found to be able to serve as the reducing agent and stabilizer for electroless deposition of highly dispersed Pd nanoparticles owing to its low reduction potential and highly conjugated electronic structure. Furthermore, we observe that graphdiyne oxide (GDYO), the oxidation form of GDY, can be used as an even excellent substrate for electroless deposition of ultrafine Pd clusters to form Pd/GDYO nanocomposite that exhibits a high catalytic performance toward the reduction of 4-nitrophenol. The high catalytic performance is considered to benefit from the rational design and electroless deposition of active metal catalysts with GDYO as the support.

Topics: Carbon; Catalysis; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Oxides; Palladium; Particle Size; Reducing Agents

In recent years, removal of pollutants from wastewater by electrochemical oxidation has become an attractive method. The present investigation deals with the degradation of 4-para-nitrophenol (4-PNP) by electrochemical oxidation using three different anodes, namely TiO2-RuO2-IrO2/Ti (titanium substrate insoluble anode - TSIA)), IrO2-PbO2/Ti and graphite. Electrochemical oxidation of 4-PNP was carried out employing sodium chloride as the supporting electrolyte, at pH 7 with a current density of 15 mA/cm(2). The degradation of 4-PNP by electro-oxidation was characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy and high-performance liquid chromatography. The performance efficiency and current efficiency of the three anodic materials in this study were evaluated by chemical oxygen demand (COD). Comparisons of energy consumption for the three anodes employed were also calculated. Among electrodes investigated, the IrO2-PbO2/Ti electrode resulted in 98% of COD removal in 30 min comparatively at a less energy consumption of 1 × 10(-2) kWh m(-3), depicting its higher performance efficiency in 4-PNP degradation.

Topics: Electrochemical Techniques; Electrodes; Graphite; Nitrophenols; Oxidation-Reduction; Oxides; Water Pollutants, Chemical

This work reported on the synthesis of a series of nitrogen doped Ca2Nb2O7 with tunable nitrogen content that were found to be efficient and green noble-metal-free catalysts toward catalytic reduction of p-nitrophenol. XPS and ESR results indicated that the introduction of nitrogen in Ca2Nb2O7 gave rise to a large number of defective nitrogen and oxygen species. Defective nitrogen and oxygen species were found to play synergetic roles in the reduction of p-nitrophenol. The underlying mechanism is completely different from those reported for metallic nanoparticles. Moreover, the more negative conduction band edge potential enabled nitrogen doped Ca2Nb2O7 to show photo-synergistic effects that could accelerate the reduction rate toward p-nitrophenol under UV light irradiation. This work may provide a strategy for tuning the catalytic performance by modulating the chemical composition, electronic structure as well as surface defect chemistry.

Topics: Calcium Compounds; Catalysis; Niobium; Nitrogen; Nitrophenols

Luminal appearance of 4-nitrophenol (PNP) metabolites (4-nitrophenol-β-glucuronide (PNP-G) and 4-nitrophenol-sulfate (PNP-S)) and activity of the related metabolic enzymes have been investigated in control and experimental diabetic rats. Experimental diabetes was induced by administration of streptozotocin (65 mg/kg i.v.). PNP (500 μmol/L) was luminally perfused in the small intestine and the metabolites were determined in the perfusion solution. Effect of insulin replacement was also investigated in the diabetic rats. It was found that experimental diabetes increased the luminal appearance of PNP-G, which could be completely compensated by rapid-acting insulin administration (1 U/kg i.v.). Activities of the enzymes involved in PNP-G production (UDP-glucuronyltransferase and β-glucuronidase) were also elevated; however, these changes were only partially compensated by insulin. Luminal appearance of PNP-S was not significantly changed by administration of streptozotocin and insulin. Activities of the enzymes of PNP-S production (sulfotransferases and arylsulfatases) did not change in the diabetic rats. The results indicate that experimental diabetes can provoke changes in intestinal drug metabolism. It increased intestinal glucuronidation of PNP but did not influence sulfate conjugation. No direct correlation was found between the changes of metabolic enzyme activities and the luminal appearance of the metabolites.

Topics: Animals; Diabetes Mellitus, Experimental; Glucuronates; Glucuronosyltransferase; Insulin; Intestine, Small; Liver; Male; Nitrophenols; Rats; Rats, Wistar; Streptozocin

Spectrophotometric-dual-enzyme-simultaneous-assay (SDESA) for enzyme-linked-immunosorbent-assay (ELISA) of two components in one well is a patented platform when a special pair of labels is accessible. With microplate readers, alkaline phosphatase on 4-nitro-1-naphthylphosphate (4NNPP) served as label A; Pseudomonas aeruginosa arylsulfatase (PAAS) and acetylcholinesterase (AChE) on their substrates derived from 4-nitrophenol/analogue served as candidate label B, and were compared for SDESA with an engineered alkaline phosphatase of Eschrichia coli (ECAP). For SDESA, the interference from overlapped absorbance was corrected based on linear additivity of absorbance to derive initial rates reflected by absorbance change at 450 nm for ECAP and at 405 nm for PAAS or AChE, after the correction of spontaneous hydrolysis. For SDESA with ECAP, AChE already had sufficient activity in an optimized buffer; PAAS was more favorable for substrate stability and product absorbance except for lower activity. Therefore, PAAS engineered for sufficient activity plus alkaline phosphatase is absorbing for ELISA via SDESA.

Topics: Acetylcholinesterase; Alkaline Phosphatase; Arylsulfatases; Enzyme-Linked Immunosorbent Assay; Hydrolysis; Naphthalenes; Nitro Compounds; Nitrophenols; Pseudomonas aeruginosa; Spectrophotometry

The paper at hand deals with the influence of the pH-value on the conformation and activity of the lipase B from Candida antarctica (CalB) which is incorporated in a bicontinuous microemulsion. The microemulsion used for this purpose consists of water/NaCl, n-octane, and the non-ionic surfactant penthaethylene glycol monodecylether (C10E5). The conformational study clearly shows (1) that CalB molecules are partitioned between the interfacial monolayer and the water domains and (2) that the pH-value of the microemulsion's water domains strongly influences the conformation of CalB at the interfacial monolayer. From these observations we conclude that there is a continuous exchange between the CalB molecules, which are located at the interfacial monolayer and those which are located in the water domains of the microemulsion. This exchange strongly influences the CalB conformation in both regions. In addition to the conformation, we also studied the catalytic activity of CalB. The catalytic measurements revealed a bell-shaped dependence between the CalB activity and the pH-value. The maximum catalytic activity of CalB in bicontinuous microemulsions was observed at pH=5.5. At this pH we observed the highest amount of α-helix conformation of the CalB molecules that are located at the interfacial monolayer, which, in turn, allows connecting the activity with the conformation.

Topics: Biocatalysis; Candida; Circular Dichroism; Emulsions; Fungal Proteins; Hydrogen-Ion Concentration; Kinetics; Lipase; Models, Chemical; Molecular Structure; Nitrophenols; Octanes; Palmitates; Palmitic Acid; Protein Conformation; Sodium Chloride; Surface Properties; Surface-Active Agents; Water

We report here a visible light driven selective nitro-reduction and oxidation of saturated sp(3) C-H bonds using ultrathin (0.8 nm) sheet mediated uniform CdS flowers as catalyst under a household 40 W CFL lamp and molecular oxygen as oxidant. The CdS flowers were synthesized using a simple surfactant assisted hydrothermal method.

Topics: Cadmium Compounds; Carbon; Catalysis; Coordination Complexes; Hydrazines; Hydrogen; Nanoparticles; Nitrophenols; Oxidation-Reduction; Oxygen; Photochemical Processes; Sulfides

A facile, efficient and environmentally-friendly protocol has been developed for the green synthesis of CuO nanoparticles (NPs) by aqueous extract of Gundelia tournefortii as a mild, renewable and non-toxic reducing agent. CuO NPs were characterized by SEM, TEM, XRD, EDS, FT-IR and UV-vis spectroscopy. More importantly, the green synthesized CuO NPs presented excellent catalytic activity for reduction of 4-nitrophenol and synthesis of N-monosubstituted ureas via hydration of cyanamides with the aid of acetaldoxime as an effective water surrogate in ethanol as a green solvent. The catalyst was easily separated and the recovered catalyst was reused many times without any significant loss of the catalytic activity.

Topics: Asteraceae; Catalysis; Copper; Cyanamide; Equipment Reuse; Green Chemistry Technology; Nanoparticles; Nitrophenols; Oxidation-Reduction; Oximes; Plant Extracts; Urea

Black carbons (BCs) may sequester non-ionic organic compounds by adsorption and/or partition to varying extents. Up to now, no experimental method has been developed to accurately resolve the combined adsorption and partition capacity of a compound on a BC. In this study, a unique "adsorptive displacement method" is introduced to reliably resolve the adsorption and partition components for a solute-BC system. It estimates the solute adsorption on a BC by the use of an adsorptive displacer to displace the adsorbed target solute into the solution phase. The method is validated by tests with uses of activated carbon as the model carbonaceous adsorbent, soil organic matter as the model carbonaceous partition phase, o-xylene and 1,2,3-trichlorobenzene as the reference solutes, and p-nitrophenol as the adsorptive displacer. Thereafter, the adsorption-partition resolution was completed for the two solutes on selected model BCs: four biochars and two National Institute of Standards and Technology (NIST) standard soots (SRM-2975 and SRM-1650b). The adsorption and partition components resolved for selected solutes with given BCs and their dependences upon solute properties enable one to cross-check the sorption data of other solutes on the same BCs. The resolved components also provide a theoretical basis for exploring the potential modes and extents of different solute uptakes by given BCs in natural systems.

Topics: Adsorption; Charcoal; Chlorobenzenes; Nitrophenols; Organic Chemicals; Soot; Xylenes

Alloy nanoparticles are important in many fields, including catalysis, plasmonics, and electronics, due to the chemical and physical properties that arise from the interactions between their components. Typically, alloy nanoparticles are made by solution-based synthesis; however, scanning-probe-based methods offer the ability to make and position such structures on surfaces with nanometer-scale resolution. In particular, scanning probe block copolymer lithography (SPBCL), which combines elements of block copolymer lithography with scanning probe techniques, allows one to synthesize nanoparticles with control over particle diameter in the 2-50 nm range. Thus far, single-element structures have been studied in detail, but, in principle, one could make a wide variety of multicomponent systems by controlling the composition of the polymer ink, polymer feature size, and metal precursor concentrations. Indeed, it is possible to use this approach to synthesize alloy nanoparticles comprised of combinations of Au, Ag, Pd, Ni, Co, and Pt. Here, such structures have been made with diameters deliberately tailored in the 10-20 nm range and characterized by STEM and EDS for structural and elemental composition. The catalytic activity of one class of AuPd alloy nanoparticles made via this method was evaluated with respect to the reduction of 4-nitrophenol with NaBH4. In addition to being the first catalytic studies of particles made by SPBCL, these proof-of-concept experiments demonstrate the potential for SPBCL as a new method for studying the fundamental science and potential applications of alloy nanoparticles in areas such as heterogeneous catalysis.

Topics: Alloys; Catalysis; Cobalt; Gold; Metal Nanoparticles; Metals; Nanotechnology; Nickel; Nitrophenols; Oxidation-Reduction; Palladium; Platinum; Polymers; Silver

A novel photoelectrochemical strategy for the sensitive determination of p-nitrophenol (PNP) was developed using a glassy carbon electrode (GCE) modified with CdSe quantum dots (QDs) and DNA composite film (CdSe-DNA/GCE). Various surface analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), were employed to characterize the synthesized CdSe QDs and CdSe-DNA modified electrode. The interfacial behaviors of the modified electrodes were analyzed by electrochemical impedance spectroscopy (EIS), and the interaction between PNP and DNA was studied by UV-visible spectrometry. Due to the PNP-DNA interaction, CdSe-DNA/GCE exhibited a sensitive photocurrent response toward PNP under visible-light irradiation. The influencing factors, such as the concentration of DNA used for fabricating CdSe-DNA/GCE and the bias potential applied in the photoelectrochemical measurement, were investigated. Under the optimized conditions, the photocurrent on CdSe-DNA/GCE was linearly increased with the PNP concentration from 0.7 to 50 μmol L(-1), with a detection limit (3 S/N) of 0.27 μmol L(-1). The proposed photoelectrochemical strategy was successfully applied to monitoring the degradation of PNP.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Carbon; DNA; Electrochemistry; Electrodes; Hydrogen Peroxide; Light; Limit of Detection; Nitrophenols; Photochemical Processes; Quantum Dots; Selenium Compounds

Hazardous pollutants in dredged sediment pose great threats to ecological environment and human health. A novel approach, named pulsed discharge plasma (PDP), was employed for the degradation of p-nitrophenol (PNP) in dredged sediment. Experimental results showed that 92.9% of PNP in sediment was smoothly removed in 60 min, and the degradation process fitted the first-order kinetic model. Roles of some active species in PNP degradation in sediment were studied by various gas plasmas, OH radical scavenger, hydrated electron scavenger and O2(·-) scavenger; and the results presented that O3, OH radical, eaq(-) and O2(·-) all played significant roles in PNP removal, and eaq(-) and O2(·-) mainly participated in other oxidising active species formation. FTIR analysis showed that PNP molecular structure was destroyed after PDP treatment. The main degradation intermediates were identified as hydroquinone, benzoquinone, phenol, acetic acid, NO2(-) and NO3(-). PNP degradation pathway in dredged sediment was proposed. It is expected to contribute to an alternative for sediment remediation by pulse discharge plasma.

Topics: Geologic Sediments; Nitrophenols; Soil Pollutants

Sustainable and greener synthesis of intracellular gold nanoparticles using mushroom Flammulina velutipes is reported. Incubation of a mushroom in chloroaurate solution resulted in the synthesis and immobilization of stable gold nanoparticles inside the mushroom mycelia. Transmission electron microscopic (TEM) analysis revealed the presence of gold nanoparticles (⩽20nm) inside the mycelia, primarily on the inner surface of the cell membrane. Inductively coupled plasma-optical emission spectrometry (ICP-OES) revealed that the accumulated gold concentration ranged from 64.4 to 330.5mgkg(-1) dry weight (DW) in the mushroom mycelia. The reduction of Au(3+) ions to Au(0) and stabilization of gold nanoparticles occurred within 1h, and the formation of fcc crystalline gold nanoparticles was confirmed by X-ray diffraction (XRD) analysis. This facile intracellular synthesis of gold nanoparticles by a mushroom without using any toxic chemicals or technologically expensive processes is used as a heterogeneous catalyst in the reduction of organic pollutants methylene blue (MB) and 4-nitrophenol (4NP). The reduction reaction follows pseudo-first order kinetics with a reaction rate constant of 0.0529min(-1) and 0.1236min(-1) for MB and 4NP, respectively. This biological process of biomatrixing of metal nanoparticles for heterogeneous catalytic reactions is simple, nontoxic, environmentally benign, and economically viable compared to the chemical synthetic routes.

Topics: Catalysis; Environmental Pollutants; Flammulina; Gold; Kinetics; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Scanning; Microscopy, Fluorescence; Mycelium; Nitrophenols; Surface Properties; X-Ray Diffraction

Microbial degradation is a major determinant of the fate of pollutants in the environment. para-Nitrophenol (PNP) is an EPA-listed priority pollutant with a wide environmental distribution, but little is known about the microorganisms that degrade it in the environment. We studied the diversity of active PNP-degrading bacterial populations in river water using a novel functional marker approach coupled with [(13)C6]PNP stable isotope probing (SIP). Culturing together with culture-independent terminal restriction fragment length polymorphism analysis of 16S rRNA gene amplicons identified Pseudomonas syringae to be the major driver of PNP degradation in river water microcosms. This was confirmed by SIP-pyrosequencing of amplified 16S rRNA. Similarly, functional gene analysis showed that degradation followed the Gram-negative bacterial pathway and involved pnpA from Pseudomonas spp. However, analysis of maleylacetate reductase (encoded by mar), an enzyme common to late stages of both Gram-negative and Gram-positive bacterial PNP degradation pathways, identified a diverse assemblage of bacteria associated with PNP degradation, suggesting that mar has limited use as a specific marker of PNP biodegradation. Both the pnpA and mar genes were detected in a PNP-degrading isolate, P. syringae AKHD2, which was isolated from river water. Our results suggest that PNP-degrading cultures of Pseudomonas spp. are representative of environmental PNP-degrading populations.

Topics: Bacterial Proteins; Biodegradation, Environmental; Carbon Isotopes; Molecular Sequence Data; Nitrophenols; Phylogeny; Pseudomonas; Rivers; RNA, Ribosomal, 16S

While most published studies used buffers to maintain the pH, there is limited knowledge regarding the reactivity of nanoscale zerovalent iron (NZVI) in poorly buffered pH systems to date. In this work, the effect of pH and Fe(II) dissolution on the reactivity of NZVI was investigated during the reduction of 4-nitrophenol (4-NP) in unbuffered pH systems. The reduction rate increased exponentially with respect to the NZVI concentration, and the ratio of dissolved Fe(II)/initial NZVI was related proportionally to the initial pH values, suggesting that lower pH (6-7) with low NZVI loading may slow the 4-NP reduction through acceleration of the dissolution of NZVI particles. Additional experiments using buffered pH systems confirmed that high pH values (8-9) can preserve the NZVI particles against dissolution, thereby enhancing the reduction kinetics of 4-NP. Furthermore, reduction tests using ferrous ion in suspensions of magnetite and maghemite showed that surface-bound Fe(II) on oxide coatings can play an important role in enhancing 4-NP reduction by NZVI at pH 8. These unexpected results highlight the importance of pH and Fe(II) dissolution when NZVI technology is applied to poorly buffered systems, particularly at a low amount of NZVI (i.e., <0.075 g/L).

Topics: Buffers; Decontamination; Environment; Ferric Compounds; Ferrosoferric Oxide; Hydrogen-Ion Concentration; Iron; Kinetics; Nanoparticles; Nitrophenols; Oxidation-Reduction; Solubility

The synthesis and characterization of a novel biodegradable graft copolymer based on partially hydrolyzed polymethylacrylate (PMA) grafted amylopectin (AP) was reported which was developed for the synthesis of silver nanoparticles from silver nitrate solution by facile green technique. The prepared graft copolymer was biodegradable which was shown by fungal growth. Characterization of silver nanoparticles was carried out by UV-VIS spectroscopy (417nm), HR-TEM, SAED and FESEM analysis. The TEM findings revealed that the silver nanoparticles are crystalline and globular shaped with average particle size ranging from 11 to 15nm. The synthesized silver nanoparticles exhibit excellent antibacterial sensitivity towards both Gram negative and Gram positive bacteria namely Vibrio parahaemolyticus (ATCC-17802) and Bacillus cereus (ATCC-14579) respectively and were also shown a good catalytic activity towards 4-nitrophenol reduction.

Topics: Anti-Bacterial Agents; Biocompatible Materials; Biopolymers; Disk Diffusion Antimicrobial Tests; Hydrogen-Ion Concentration; Metal Nanoparticles; Nitrophenols; Proton Magnetic Resonance Spectroscopy; Silver; Spectroscopy, Fourier Transform Infrared; Starch; Temperature; Tissue Engineering; Tissue Scaffolds

Accumulated evidence has shown that in vitro mammalian cell genotoxicity assays produce high frequencies of "misleading" positive results, i.e. predicted hazard is not confirmed in in vivo and/or carcinogenicity studies [1], raising the question of relevance to human risk assessment. A recent study of micronucleus (MN) induction [2] showed that commonly used p53-deficient rodent cell lines (CHL, CHO and V79) gave a higher frequency of "misleading" positive results with 9 non-DNA reactive, Ames-negative and in vivo negative chemicals [3] than human p53-competent cells (blood lymphocytes, TK6 and HepG2 cell lines). This raised the question of whether these differences were due to p53 status or species origin. This present study compared human versus mouse and p53-competent versus p53-mutated function. The same 9 chemicals were tested for induction of MN in mouse lymphoma L5178Y (mutated p53), human TK6 (functional p53) and WIL2-NS (TK6 related, with mutated p53) cells. Six chemicals provided clear positive increases in MN frequency in at least one cell type. L5178Y cells yielded clear positive responses with more chemicals than either TK6 or WIL2-NS, indicating origin rather than p53 functionality was most relevant. Apoptosis induction (measured via caspase-3/7) was also investigated with clear differences in the timing and extent of apoptosis induction between mouse and human cells noted. With curcumin in TK6 cells, induction of caspase-3/7 activity coincided with MN induction, whereas for L5178Y cells, MN induction occurred in the absence of increased caspase activity. By contrast, with MMS in TK6 cells, MN induction preceded increased caspase-3/7 activity. These data suggest that MN induction by "misleading positive" genotoxins in p53-competent human cell lines may result from apoptosis, whereas in p53-defective rodent cells such as L5178Y, MN induction may be independent of apoptosis.

Topics: Acrylates; Animals; Apoptosis; Cell Line; Cell Line, Tumor; Cell Survival; Chlorophenols; Curcumin; Cytochalasin B; DNA Damage; Dose-Response Relationship, Drug; Eugenol; Lymphocytes; Mice; Micronucleus Tests; Mutation; Nitrophenols; Organic Chemicals; ortho-Aminobenzoates; Phthalic Anhydrides; Propyl Gallate; Reproducibility of Results; Resorcinols; Tumor Suppressor Protein p53

Nanoscale assemblies composed of different types of nanoparticles (NPs) can reveal interesting aspects about material properties beyond the functions of individual constituent NPs. This research direction may also represent current challenges in nanoscience toward practical applications. With respect to the assembling method, synthetic or biological nanostructures can be utilized to organize heterogeneous NPs in specific sites via chemical or physical interactions. However, those assembling methods often encounter uncontrollable particle aggregation or phase separation. In this study, we anticipated that the self-segregating properties of block copolymer micelles could be particularly useful for organizing heterogeneous NPs, because the presence of chemically distinct domains such as the core and the corona can facilitate the selective placement of constituent NPs in separate domains. Here, we simultaneously functionalized the core and the corona of micelles by Au NPs and Ag NPs, which exhibited plasmonic and catalytic functions, respectively. Our primary question is whether these plasmonic and catalytic functions can be combined in the assembled structures to engineer the kinetics of a model chemical reaction. To test this hypothesis, the catalytic reduction of 4-nitrophenol was selected to evaluate the collective properties of the micellar assemblies in a chemical reaction.

Topics: Acrylates; Catalysis; Gold; Metal Nanoparticles; Micelles; Nitrophenols; Polymers; Polystyrenes; Silver; Spectrophotometry, Ultraviolet; Ultraviolet Rays

p-Nitrophenol (PNP), used primarily for manufacturing pesticides and dyes, has been recognized as a priority environmental pollutant. It is therefore important to reduce the input of this toxicant into the environment and to establish approaches for its removal from the contaminated sites. PNP monooxygenase, a novel enzyme from Gram-positive bacteria like Arthrobacter sp. and Bacillus sp., that comprises two components, a flavoprotein reductase and an oxygenase, catalyzes the initial two sequential monooxygenations to convert PNP to trihydroxybenzene. Accurate and reliable prediction of this enzyme-substrate interactions and binding affinity are of vital importance in understanding these catalytic mechanisms of the two sequential reactions. As crystal structure of the enzyme has not yet been published, we built a homology model for PNP monooxygenase using crystallized chlorophenol 4-monooxygenase from Burkholderia cepacia AC1100 (3HWC) as the template. The model was assessed for its reliability using PROCHECK, ERRAT and ProSA. Molecular docking of the physiological substrates, PNP and 4-nitrocatechol (4-NC), was carried out using Glide v5.7 implemented in Maestro v9.2, and the binding energies were calculated to substantiate the prediction. Docking complexes formed by molecular level interactions of PNP monooxygenase-PNP/4-NC without or with the cofactors, FAD and NADH, showed good correlation with the established experimental evidence that the two-component PNP monooxygenase catalyzes both the hydroxylation of PNP and the oxidative release of nitrite from 4-NC in B. sphaericus JS905. Furthermore, molecular dynamics simulations performed for docking complexes using Desmond v3.0 showed stable nature of the interactions as well.

Topics: Arthrobacter; Bacterial Proteins; Binding Sites; Biodegradation, Environmental; Catalysis; Catalytic Domain; Catechols; Environmental Pollutants; Molecular Docking Simulation; Molecular Dynamics Simulation; Nitrophenols; Oxygenases; Protein Binding; Protein Conformation; Substrate Specificity

The simultaneous extraction of acidic, basic and amphiprotic pollutants from various samples is a considerable and disputable concept in sample preparation strategies. In this study, for the first time, coextraction of acidic, basic and amphiprotic pollutants (polar and apolar) with multiwalled carbon nanotubes/Fe3O4@polypyrrole (MWCNTs/Fe3O4@PPy) composite based dispersive micro-solid phase extraction followed by high performance liquid chromatography-photo diode array detection was introduced. Firstly, the extraction efficiency of various magnetic nanosorbents including Fe3O4, MWCNTs/Fe3O4, graphene oxide/Fe3O4 (GO/Fe3O4), Fe3O4@PPy, MWCNTs/Fe3O4@PPy and GO/Fe3O4@PPy were compared. The results revealed that MWCNTs/Fe3O4@PPy nanocomposite has higher extraction efficiency for five selected model analytes (4-nitrophenol, 3-nitroaniline, 2,4-dichloroaniline, 3,4-dichloroaniline and 1-amino-2-naphthol). Box-Behnken design methodology combined with desirability function approach was applied to find out the optimal experimental conditions. The opted conditions were: pH of the sample, 8.2; sorbent amount, 12 mg; sorption time, 5.5 min; salt concentration, 14% w/w; type and volume of the eluent, 120 μL acetonitrile; elution time; 2 min. Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 0.1-0.25 μg L(-1) and 0.5-600 μg L(-1), respectively. The percent of extraction recovery and relative standard deviations (n=5) were in the range of 45.6-82.2 and 4.0-8.5, respectively. Ultimately, the applicability of this method was successfully confirmed by analyzing rain, snow and river water samples and satisfactory results were obtained.

Topics: Aniline Compounds; Chromatography, High Pressure Liquid; Environmental Pollutants; Limit of Detection; Magnetite Nanoparticles; Nanotubes, Carbon; Naphthols; Nitrophenols; Polymers; Pyrroles; Solid Phase Extraction

Aerobic microorganisms have evolved a variety of pathways to degrade aromatic and heterocyclic compounds. However, only several classes of oxygenolytic fission reaction have been identified for the critical ring cleavage dioxygenases. Among them, the most well studied dioxygenases proceed via catecholic intermediates, followed by noncatecholic hydroxy-substituted aromatic carboxylic acids. Therefore, the recently reported hydroquinone 1,2-dioxygenases add to the diversity of ring cleavage reactions. Two-subunit hydroquinone 1,2-dioxygenase PnpCD, the key enzyme in the hydroquinone pathway of para-nitrophenol degradation, catalyzes the ring cleavage of hydroquinone to γ-hydroxymuconic semialdehyde. Here, we report three PnpCD structures, named apo-PnpCD, PnpCD-Fe(3+), and PnpCD-Cd(2+)-HBN (substrate analog hydroxyenzonitrile), respectively. Structural analysis showed that both the PnpC and the C-terminal domains of PnpD comprise a conserved cupin fold, whereas PnpC cannot form a competent metal binding pocket as can PnpD cupin. Four residues of PnpD (His-256, Asn-258, Glu-262, and His-303) were observed to coordinate the iron ion. The Asn-258 coordination is particularly interesting because this coordinating residue has never been observed in the homologous cupin structures of PnpCD. Asn-258 is proposed to play a pivotal role in binding the iron prior to the enzymatic reaction, but it might lose coordination to the iron when the reaction begins. PnpD also consists of an intriguing N-terminal domain that might have functions other than nucleic acid binding in its structural homologs. In summary, PnpCD has no apparent evolutionary relationship with other iron-dependent dioxygenases and therefore defines a new structural class. The study of PnpCD might add to the understanding of the ring cleavage of dioxygenases.

Topics: Amino Acid Sequence; Bacterial Proteins; Catalysis; Catalytic Domain; Circular Dichroism; Crystallography, X-Ray; Dioxygenases; Hydroquinones; Ions; Iron; Metabolism; Metals; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Nitriles; Nitrophenols; Oxygen; Protein Binding; Protein Folding; Protein Structure, Secondary; Pseudomonas aeruginosa; Sequence Homology, Amino Acid

Magnetically recoverable noble metal nanoparticles are promising catalysts for chemical reactions. However, the chemical synthesis of these nanocatalysts generally causes environmental concern due to usage of toxic chemicals under extreme conditions. Here, Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites are biosynthesized under ambient and physiological conditions by Shewanella oneidensis MR-1. Microbial cells firstly transform akaganeite into magnetite, which then serves as support for the further synthesis of Pd, Au and PdAu nanoparticles from respective precursor salts. Surface-bound cellular components and exopolysaccharides not only function as shape-directing agent to convert some Fe3O4 nanoparticles to nanorods, but also participate in the formation of PdAu alloy nanoparticles on magnetite. All these three kinds of magnetic nanocomposites can catalyze the reduction of 4-nitrophenol and some other nitroaromatic compounds by NaBH4. PdAu/Fe3O4 demonstrates higher catalytic activity than Pd/Fe3O4 and Au/Fe3O4. Moreover, the magnetic nanocomposites can be easily recovered through magnetic decantation after catalysis reaction. PdAu/Fe3O4 can be reused in at least eight successive cycles of 4-nitrophenol reduction. The biosynthesis approach presented here does not require harmful agents or rigorous conditions and thus provides facile and environmentally benign choice for the preparation of magnetic noble metal nanocatalysts.

Topics: Alloys; Catalysis; Crystallography, X-Ray; Ferric Compounds; Gold; Hydrocarbons, Aromatic; Kinetics; Magnetic Phenomena; Nanocomposites; Nitrogen Compounds; Nitrophenols; Oxidation-Reduction; Palladium; Photoelectron Spectroscopy; Shewanella

To investigate the application potential of the p-nitrophenol-degrading bacterium Arthrobacter sp. CN2 in practice, the effects of pH, salinity and additional carbon source were determined, and the degradation kinetics of p-nitrophenol was analyzed. Strain CN2 could degrade p-nitrophenol efficiently in a wide range of pH (7.0-8.0) and elevated salinity (0-60 g · L(-1)). Investigation of additional glucose found that 0.5% of glucose could significantly increase the degrading speed and the time to reach 90% of degradation rate was shortened by 16 hours. These results indicated that strain CN2 could degrade p-nitrophenol efficiently under different conditions and had a great potential for application in practice.

Topics: Arthrobacter; Biodegradation, Environmental; Kinetics; Nitrophenols; Salinity

In this work, a self-reporting hydrogel for the rapid in situ detection of bacterial enzymes is reported. To implement the reporting function for the bacterium Escherichia coli into a film-based sensing format, chitosan hydrogel films on solid backing supports were equipped with a reporting function for the enzyme β-glucuronidase (β-GUS), which is secreted by >98% of all known E. coli strains. Covalent coupling of the fluorogenic substrate 4-methylumbelliferyl-β-D-glucuronide or the complementary chromogenic substrate 4-nitrophenyl-β-D-glucuronide via amide bond formation afforded an attachment that is stable for >24 h under physiological conditions. By contrast, in the presence of β-GUS, the reporter dyes were very rapidly cleaved and produced a signal for the presence of the enzyme, which was detectable by bare eye under appropriate illumination. Detailed investigations of the enzymatic reaction for both types of substrates in neat enzyme solution as well as in bacterial supernatant revealed the apparent reaction kinetics and allowed us to determine the concentration of β-GUS in the supernatant. Under optimized conditions, the 4-methylumbelliferyl-β-D-glucuronide-functionalized hydrogel reported the presence of β-GUS within 15 min with a limit of detection of <1 nM. Finally, the function of the generally applicable hydrogel-film-based sensing approach, which is compatible with polymer-film-based applications, including wound dressings and packaging materials, and is also amenable to address noncultivatable pathogenic bacteria by using appropriate fluorogenic or chromogenic substrates, was demonstrated by direct application with bacterial medium.

Topics: Chitosan; Escherichia coli; Glucuronidase; Glucuronides; Hydrogels; Nitrophenols; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Substrate Specificity

A low-temperature-active alkaline esterase, Est12, from a marine sediment metagenomic fosmid library was identified. Est12 prefers short- and middle-chain p-nitrophenol esters as substrate with optimum temperature and pH value of 50 °C and 9.0, respectively, and nearly 50 % of maximum activity retained at 5 °C. The hydrolysis activity of Est12 was stable at 40 °C. Ca(2+) especially activated the activity of Est12 to about 151 % of the control. DEPC and PMSF inhibited the activity of Est12 to 34 and 25 %, respectively. In addition, Est12 was more tolerable to methanol compared to other organic solvents tested. The crystal structure of Est12 at 1.39 Å resolution showed that the cap domain which is composed of an α-helix and a flexible region resulted in a relatively wide spectrum of substrate, with p-nitrophenol caproate as the preferred one. Furthermore, the flexible cap domain and the high percentage of Gly, Ser, and Met may play important roles in the adaptation of Est12 to low temperature.

Topics: Amino Acid Sequence; Calcium; China; Crystallography, X-Ray; Esterases; Gene Library; Geologic Sediments; Hydrogen-Ion Concentration; Metagenomics; Methanol; Models, Molecular; Nitrophenols; Oceans and Seas; Protein Structure, Tertiary; Substrate Specificity; Temperature

In previous studies of the organophosphate degradation gene cluster, we showed that expression of an open reading frame (orf306) present within the cluster in Escherichia coli allowed growth on p-nitrophenol (PNP) as sole carbon source. We have now shown that expression of orf306 in E. coli causes a dramatic up-regulation in genes coding for alternative carbon catabolism. The propionate, glyoxylate, and methylcitrate cycle pathway-specific enzymes are up-regulated along with hca (phenylpropionate) and mhp (hydroxyphenylpropionate) degradation operons. These hca and mhp operons play a key role in degradation of PNP, enabling E. coli to grow using it as sole carbon source. Supporting growth experiments, PNP degradation products entered central metabolic pathways and were incorporated into the carbon backbone. The protein and RNA samples isolated from E. coli (pSDP10) cells grown in (14)C-labeled PNP indicated incorporation of (14)C carbon, suggesting Orf306-dependent assimilation of PNP in E. coli cells.

Topics: Carbon; Escherichia coli; Esterases; Genes, Bacterial; Nitrophenols; Organophosphates; Phenylpropionates; Up-Regulation

The photocatalytic degradation of p-nitrophenol using a titanium dioxide suspension was studied in an annular column photoreactor operating in batch recycle mode with an aerated reservoir tank. The dependency of the process efficiency on the initial PNP concentration was quantitatively defined using an exponential function. The degradation rate was highest at pH 7-7.2. The appearance of p-benzoquinone, p-hydroquinone, and phenol during the degradation process was confirmed by high-performance liquid chromatography analysis. The formation of similar intermediates during the microbial degradation of PNP has been reported previously. The formation of hydroxyl. radicals is predominant in the PNP photodegradation route, and fluctuations of the chemical oxygen demand may be indicative of the appearance of unidentified and probably nonbiodegradable intermediates formed during photocatalysis. These compounds likely contribute to the COD variations. Herein, the results of PNP removal via photocatalytic degradative reactions are discussed, and the intermediates are compared to those observed in enzymatic reactions.

Topics: Hydrogen-Ion Concentration; Kinetics; Molecular Structure; Nitrophenols; Photolysis; Waste Disposal, Fluid; Water Pollutants, Chemical

Cytochrome P450 2E1 (CYP2E1) detoxifies or bioactivates many low molecular-weight compounds. Most knowledge about CYP2E1 activity relies on studies of the enzyme localized to endoplasmic reticulum (erCYP2E1); however, CYP2E1 undergoes transport to mitochondria (mtCYP2E1) and becomes metabolically active. We report the first comparison of in vitro steady-state kinetic profiles for erCYP2E1 and mtCYP2E1 oxidation of probe substrate 4-nitrophenol and pollutants styrene and aniline using subcellular fractions from rat liver. For all substrates, metabolic efficiency changed with substrate concentration for erCYP2E1 reflected in non-hyperbolic kinetic profiles but not for mtCYP2E1. Hyperbolic kinetic profiles for the mitochondrial enzyme were consistent with Michaelis-Menten mechanism in which metabolic efficiency was constant. By contrast, erCYP2E1 metabolism of 4-nitrophenol led to a loss of enzyme efficiency at high substrate concentrations when substrate inhibited the reaction. Similarly, aniline metabolism by erCYP2E1 demonstrated negative cooperativity as metabolic efficiency decreased with increasing substrate concentration. The opposite was observed for erCYP2E1 oxidation of styrene; the sigmoidal kinetic profile indicated increased efficiency at higher substrate concentrations. These mechanisms and CYP2E1 levels in mitochondria and endoplasmic reticulum were used to estimate the impact of CYP2E1 subcellular localization on metabolic flux of pollutants. Those models showed that erCYP2E1 mainly carries out aniline metabolism at all aniline concentrations. Conversely, mtCYP2E1 dominates styrene oxidation at low styrene concentrations and erCYP2E1 at higher concentrations. Taken together, subcellular localization of CYP2E1 results in distinctly different enzyme activities that could impact overall metabolic clearance and/or activation of substrates and thus impact the interpretation and prediction of toxicological outcomes.

Topics: Aniline Compounds; Animals; Biotransformation; Catalytic Domain; Cytochrome P-450 CYP2E1; Endoplasmic Reticulum; Female; Kinetics; Liver; Mitochondria, Liver; Models, Biological; Nitrophenols; Oxidation-Reduction; Protein Binding; Protein Transport; Rats, Sprague-Dawley; Styrene; Substrate Specificity

Catalytic nanofibers are prepared by the immobilization of Au nanoparticles (AuNPs) onto the surface of cross-linked electrospun poly(4-vinylpyridine) (P4VP) nanofibers. The crosslinking of the P4VP nanofibers by 1,4-diiodobutane via quaternization reaction greatly enhances the stability of the nanofibers against the solvent dissolution, which can then be used as promising platform for the immobilization of catalytic metal nanoparticles. The AuNPs immobilized cross-linked P4VP nanofibers have shown a good catalytic activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP).

Topics: Cross-Linking Reagents; Electrochemical Techniques; Gold; Metal Nanoparticles; Nanofibers; Nanotechnology; Nitrophenols; Oxidation-Reduction; Polyvinyls

An ultrasensitive and highly selective electrochemical sensor for the determination of p-nitrophenol (p-NP) was developed based on electrochemically treated nano polypyrrole/sodium dodecyl sulphate film (ENPPy/SDS film) modified glassy carbon electrode. The nano polypyrrole/sodium dodecyl sulphate film (NPPy/SDS film) was prepared and treated electrochemically in phosphate buffer solution. The surface morphology and elemental analysis of treated and untreated NPPy/SDS film were characterized by FESEM and EDX analysis, respectively. Wettability of polymer films were analysed by contact angle test. The hydrophilic nature of the polymer film decreased after electrochemical treatment. Effect of the pH of electrolyte and thickness of the ENPPy/SDS film on determination of p-NP was optimised by cyclic voltammetry. Under the optimised conditions, the p-NP was determined from the oxidation peak of p-hydroxyaminophenol which was formed from the reduction of p-NP in the reduction segment of cyclic voltammetry. A very good linear detection range (from 0.1 nM to 100 μM) and the best LOD (0.1 nM) were obtained for p-NP with very good selectivity. This detection limit is below to the allowed limit in drinking water, 0.43 μM, proposed by the U.S. Environmental Protection Agency (EPA) and earlier reports. Moreover, ENPPy/SDS film based sensor exhibits high sensitivity (4.4546 μA μM(-1)) to p-NP. Experimental results show that it is a fast and simple sensor for p-NP.

Topics: Electrochemical Techniques; Limit of Detection; Microscopy, Electron, Scanning; Nitrophenols; Polymers; Pyrroles; Sodium Dodecyl Sulfate; Wettability

P-Nitrophenol is a major metabolite of some organophosphorus compounds. It is considered to be one of nitrophenol derivatives of diesel exhaust particles that induce substantial hazards impacts on human and animal health. P-Nitrophenol (PNP) is a persistent organic pollutant. Consequently, bioaccumulation of PNP potentiates toxicity. The objectives of the current study were to assess the potential hepatic toxicity and pathway associated with long-term exposure to PNP. Japanese quails were orally administered different doses of PNP for 75 days. Liver and plasma samples were collected at days 45 (45D), days 60 (60D) and days 75 (75D). Liver histological changes and plasma corticosterone levels were assessed. Basal mRNA level of cytochromes P450 (CYP 450) (CYP1A4, 1A5, 1B1), heme oxygenase (HO-1), and aryl hydrocarbon receptor 1 (AhR1), from the liver of exposed birds and primary hepatocytes cultured for 24 hr with PNP, were analyzed using quantitative real-time PCR. The results revealed various histopathological changes in the liver, such as lymphocytes aggregation and hepatocytes degeneration. Significant increases in corticosterone levels were reported. After 60-days of in vivo exposure, the birds exhibited an overexpression in the liver CYP1A4, 1B1, AhR1, and HO-1. Furthermore, with continuous PNP administration, an overall downregulation of the tested genes was observed. In vitro, although a significant overexpression of CYP1A4, 1B1, and HO-1 was observed, CYP1A5 was downregulated. In conclusion, PNP can interfere with the liver CYP 450 enzymes and modulate HO-1 expression in the in vitro and in vivo experiments. Hence, it could have serious deleterious effects on humans, livestock, and wild animals.

Topics: Animals; Avian Proteins; Coturnix; Cytochrome P-450 Enzyme System; Endocrine Disruptors; Environmental Pollutants; Gene Expression Regulation; Heme Oxygenase-1; Hepatocytes; Liver; Male; Nitrophenols; Receptors, Aryl Hydrocarbon

Cost-efficient nanoparticle carbocatalysts composed of fluorescent carbon dots (CDs) embedded in carbon matrix were synthesized via one-step acid-assisted hydrothermal treatment (200 °C) of glucose. These as-synthesized CD-based carbocatalysts have excellent photoluminescence (PL) properties over a broad range of wavelengths and the external visible or NIR irradiation on the carbocatalysts could produce electrons to form electron-hole (e(-)-h(+)) pairs on the surface of carbocatalysts. These restant electron-hole pairs will react with the adsorbed oxidants/reducers on the surface of the CD-based carbocatalysts to produce active radicals for reduction of 4-nitrophenol and degradation of dye molecules. Moreover, the local temperature increase over CD-based carbocatalyst under NIR irradiation can enhance the electron transfer rate between the organic molecules and CD-based carbocatalysts, thus obviously increase the catalytic activity of the CD-based carbocatalyst for the reduction of 4-nitrophenol and the degradation of dye molecules. Such a type of CD-based carbocatalysts with excellent properties and highly efficient metal-free photocatalytic activities is an ideal candidate as photocatalysts for the reduction of organic pollutants under visible light and NIR radiation.

Topics: Biomass; Carbon; Catalysis; Coloring Agents; Environmental Pollutants; Light; Nanoparticles; Nitrophenols; Photochemical Processes; Titanium

Palladium nanoparticles (Pd NPs) were synthesised by using gum kondagogu (GK), a non-toxic ecofriendly biopolymer. GK acted as both reducing and stabilising agent for the synthesis of Pd NPs. Various reaction parameters, such as concentration of gum, Pd chloride and reaction pH were standardised for the stable synthesis of GK reduced stabilised Pd NPs (GK-Pd NPs). The nanoparticles have been characterised using ultraviolet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. Physical characterisation revealed that the gum synthesised Pd NPs were in the size range of 6.5 ± 2.3 nm and crystallised in face centred cubic (FCC) symmetry. Fourier transform infrared spectroscopy implicated the role of carboxyl, amine and hydroxyl groups in the synthesis. The synthesised Pd NPs were found to be highly stable in nature. The synthesised nanoparticles were found to function as an effective green catalyst (k = 0.182 min⁻¹) in the reduction of 4-nitrophenol by sodium borohydride, which was evident from the colour change of bright yellow (nitrophenolate; λ(max) - 400 nm) to colourless (4-AP; λ(max) - 294 nm) solution. The overall objectives of the current communication were: (i) to synthesize the Pd NPs using a green reducing/capping agent; GK and (ii) to determine the catalytic performance of the synthesised Pd NPs.

Topics: Biological Products; Biopolymers; Bixaceae; Catalysis; Green Chemistry Technology; Materials Testing; Metal Nanoparticles; Nitrophenols; Palladium; Particle Size; Plant Bark; Plant Extracts; Water Pollutants, Chemical

An original activated carbon prepared from walnut peel, which was activated by zinc chloride, was modified with ammonium hydroxide or sodium hydroxide in order to contrast the adsorption property of the three different activated carbons. The experiment used a static adsorption test for p-nitrophenol. The effects of parameters such as initial concentration, contact time and pH value on amount adsorbed and removal are discussed in depth. The thermodynamic data of adsorption were analyzed by Freundlich and Langmuir models. The kinetic data of adsorption were measured by the pseudo-first-order kinetics and the pseudo-second-order kinetics models. The results indicated that the alkalized carbon samples derived from walnut peel had a better performance than the original activated carbon treated with zinc chloride. It was found that adsorption equilibrium time was 6 h. The maximum removal rate of activated carbon treated with zinc chloride for p-nitrophenol was 87.3% at pH 3,whereas the maximum removal rate of the two modified activated carbon materials was found to be 90.8% (alkalized with ammonium hydroxide) and 92.0% (alkalized with sodium hydroxide) at the same pH. The adsorption data of the zinc chloride activated carbon were fitted to the Langmuir isotherm model. The two alkalized activated carbon samples were fitted well to the Freundlich model. The pseudo-second-order dynamics equation provided better explanation of the adsorption dynamics data of the three activated carbons than the pseudo-first-order dynamics equation.

Topics: Adsorption; Ammonium Hydroxide; Carbon; Chlorides; Hydrogen-Ion Concentration; Juglans; Kinetics; Models, Chemical; Nitrophenols; Sodium Hydroxide; Thermodynamics; Time Factors; Zinc Compounds

This study was aimed at estimation of the diuretic and saluretic activity of 4-nitrophenyl-O-β-D-glucopyranoside and its aglicon 4-nitrophenol in rats. Test animals daily received 4-nitrophenyl-O-β-D-glucopyranoside (group 1) and 4-nitrophenol (group 2) intragastrically in 2 mL of distilled water in a dose of 18 µmol/kg from 1st to 7th day and 54 µmol/kg from 8th to 14th days. During the experiment, the most pronounced diuretic activity was observed for 4-nitrophenyl-O-β-D-glucopyranoside in a dose of 54 µmol/kg, which increased the diuresis in rats 2.5 times as compared to the control value.

Topics: Animals; Cations, Monovalent; Diuresis; Diuretics; Drug Administration Schedule; Female; Gastric Absorption; Glucosides; Nitrophenols; Potassium; Rats; Rats, Wistar; Sodium; Water

Organoclays are effective sorbents for removal of organic contaminants from water, but their regeneration capacity limits their practical use as a biotechnological process for bioremediation. Here, the sorption of p-nitrophenol (PNP) to crystal violet (CV)-modified montmorillonite and its biodegradation by the bacterium Arthrobacter sp. 4Hβ were studied in a batch aqueous system. The degree of PNP sorption was dependent on the degree of CV modification (loaded at 80 % or 100 % of the clay's cation-exchange capacity-CVM80 and CVM100, respectively). CV sorption to the clay reduced its toxicity to bacteria. PNP at an initial concentration of 0.72 mM was degraded at rates of 65 % and 42 % in CVM80 and CVM100 suspensions, respectively. Both free and CV-clay-adsorbed PNP concentrations were reduced by the bacteria at rates proportional to the degree of CV modification. Three successive cycles of PNP reloading-degradation in the organoclay suspension demonstrated the potential of this matrix's regeneration and reuse toward maximal removal efficiency of organic pollutants.

Topics: Adsorption; Aluminum Silicates; Arthrobacter; Clay; Gentian Violet; Nitrophenols; Water Purification

A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO3 using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH4. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated.

Topics: Alginates; Aminophenols; Anti-Infective Agents; Bacteria; Catalysis; Fungi; Glucuronic Acid; Green Chemistry Technology; Hexuronic Acids; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Silver; X-Ray Diffraction

Nanoparticle-catalyzed reductive bleaching reactions of colored substrates are emerging as a class of novel indicator reactions for fabricating enzyme-free amplified colorimetric biosensing (turn-off mode), which are exactly opposite to the commonly used oxidative coloring processes of colorless substrates in traditional enzyme-catalyzed amplified colorimetric bioassays (turn-on mode). In this work, a simple theoretical analysis shows that the sensitivity of this colorimetric bioassay can be improved by increasing the amplification factor (kcatΔt), or enhancing the binding affinity between analyte and receptor (Kd), or selecting the colored substrates with high extinction coefficients (ε). Based on this novel strategy, we have developed a turn-off and cost-effective amplified colorimetric thrombin aptasensor. This aptasensor made full use of sandwich binding of two affinity aptamers for increased specificity, magnetic particles for easy separation and enrichment, and gold nanoparticle (AuNP)-catalyzed reductive bleaching reaction to generate the amplified colorimetric signal. With 4-nitrophenol (4-NP) as the non-dye colored substrate, colorimetric bioassay of thrombin was achieved by the endpoint method with a detection limit of 91pM. In particular, when using methylene blue (MB) as the substrate, for the first time, a more convenient and efficient kinetic-based colorimetric thrombin bioassay was achieved without the steps of acidification termination and magnetic removal of particles, with a low detection limit of 10pM, which was superior to the majority of the existing colorimetric thrombin aptasensors. The proposed colorimetric protocol is expected to hold great promise in field analysis and point-of-care applications.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Catalysis; Colorimetry; Gold; Humans; Limit of Detection; Nanoparticles; Nitrophenols; Oxidation-Reduction; Thrombin

OECD ready biodegradability tests have been central to understanding the biodegradation of chemicals from a regulatory perspective for many decades. They are not fit for contemporary prioritisation of chemicals based on persistence, however, due to the low concentration of inocula used, short duration and high variability between tests. Two OECD standard inoculum pretreatment methods (settlement and filtration) were investigated to observe their effect on the probability of biodegradation and associated changes in bacterial community structure and diversity of inocula sourced from the activated sludge process of wastewater treatment plants. Both settlement and filtration were shown to dramatically and significantly reduce the probability and increase the variability of biodegradation of 4-nitrophenol compared to the use of unprocessed inocula. These differences were associated with a significant hundred-fold reduction in cell numbers and solids content and a significant shift in bacterial community structure that was sometimes accompanied by significant reductions in detectable operational taxonomic unit richness and evenness. The natural variation (between different environments) and variation due to differential selection of bacterial communities (by different pretreatment methods) is offered as an explanation for the historical high variability in standard OECD ready biodegradability tests.

Topics: Bacteria; Biodegradation, Environmental; Environmental Monitoring; Nitrophenols; Reproducibility of Results; Sewage

We report an aqueous-phase synthetic route to copper nanoparticles (CuNPs) using a copper-surfactant complex and tests of their catalytic efficiency for a simple nitrophenol reduction reaction under atmospheric conditions. Highly stable, water-dispersed CuNPs were obtained with the aid of polyacrylic acid (PAA), but not with other dispersants like surfactants or polymethacrylic acid (PMAA). The diameter of the CuNPs could be controlled in the range of approximately 30-85 nm by modifying the ratio of the metal precursor to PAA. The catalytic reduction of p-nitrophenol to p-aminophenol takes place at the surface of CuNPs at room temperature and was accurately monitored by UV/Vis spectroscopy. The catalytic efficiency was found to be remarkably high for these PAA-capped CuNPs, given the fact that at the same time PAA is efficiently preventing their oxidation as well. The activity was found to increase as the size of the CuNPs decreased. It can therefore be concluded that the synthesized CuNPs are catalytically highly efficient in spite of the presence of a protective PAA coating, which provides them with a long shelf life and thereby enhances the application potential of these CuNPs.

Topics: Acrylic Resins; Aminophenols; Catalysis; Copper; Metal Nanoparticles; Molecular Structure; Nitrophenols; Oxidation-Reduction; Particle Size; Surface Properties; Water

A simple spectrophotometric microplate assay that allows quantification of the interaction between phospholipids and metal ions or other small cationic compounds has been developed. The assay is based on the competition of the phospholipids for the Fe(3+) ion in the purple-colored Fe(III)-γ-resorcylate complex and for other cations. To compare the binding affinities of several cation-phospholipid interactions, K0.5 values were derived from binding curves constructed by determination of the absorbance of the Fe(III)-γ-resorcylate at 490 nm as a function of the cation concentration. The assay was used to analyze the binding of lanthanide ions, calcium ions, and amines (hydrochlorides of ethanolamine, spermidine, and hexyltrimethylammonium chloride) to small unilamellar vesicles (SUVs) and mixed micelles containing anionic lipids such as phosphatidic acid and phosphatidyl-p-nitrophenol. The method was evaluated by fluorescence measurements with Eu(3+) ions as tracer. Lanthanide ions such as La(3+) and Ce(3+) ions showed K0.5 values smaller by one to two orders of magnitude compared with Ca(2+) ions. In the presence of increasing amounts of detergents such as Triton X-100, the method also reflected transitions from SUVs to micelles. The binding capacity for metal ions was higher for phospholipid-containing micelles than for the corresponding SUVs.

Topics: Amines; Anions; Calcium; Cations; Coordination Complexes; Europium; Ferric Compounds; Kinetics; Micelles; Nitrophenols; Octoxynol; Phospholipids; Spectrophotometry; Unilamellar Liposomes

The use of environmentally benign procedures is highly desirable for the synthesis of nanoparticles. Here we report a simple, versatile, economic, ecofriendly and reproducible green method for the size-tunable synthesis of stable and crystalline gold nanoparticles of varied shape using aqueous extract of Garcinia Combogia fruit. The predominant anisotropic nature in the morphology of synthesized particles at lower quantities of extract gradually shifted to spherical particles with larger quantity of extract and increase of temperature. The onset of reduction, the time-evolution of the Surface Plasmon Resonance (SPR) and the catalytic activity are studied using UV-Visible spectroscopy. The Selected Area Diffraction (SAED) pattern, the lattice fringes in the High Resolution Transmission Electron Microscopic (HRTEM) image and the X-ray Diffraction (XRD) pattern clearly show the pure crystalline nature of the synthesized gold nanoparticles. The role of carboxyl group present in Garcinia Combogia fruit extract in the reduction of chloroaurate ions is established using Fourier Transform Infrared (FTIR) spectra. The size dependent catalytic activity of the green synthesized gold nanoparticles on the reduction of 4-Nitrophenol to 4-Aminophenol using sodium borohydride is studied and reported for the first time. The first order kinetics is fitted and rate constants are calculated. Catalytically active green synthesized gold nanoparticles with controllable size and shape presents an advanced step in future biomedical and chemical applications.

Topics: Aminophenols; Catalysis; Garcinia; Gold; Green Chemistry Technology; Nanoparticles; Nanotechnology; Nitrophenols; Oxidation-Reduction; Surface Plasmon Resonance; X-Ray Diffraction

A greener method based on cloud point extraction was developed for removing phenol species including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 4-nitrophenol (4-NP) in water samples by using the UV-Vis spectrophotometric method. The non-ionic surfactant DC193C was chosen as an extraction solvent due to its low water content in a surfactant rich phase and it is well-known as an environmentally-friendly solvent. The parameters affecting the extraction efficiency such as pH, temperature and incubation time, concentration of surfactant and salt, amount of surfactant and water content were evaluated and optimized. The proposed method was successfully applied for removing phenol species in real water samples.

Topics: Chlorophenols; Green Chemistry Technology; Nitrophenols; Spectrophotometry; Surface-Active Agents; Water; Water Pollutants, Chemical; Water Purification

A biosensor based on AuNP modified GC electrodes has been developed for direct detection of methyl parathion. AuNP can be introduced to mixed monolayers of aryldiazonium salt modified GC electrodes by Au-C bonding through aryldiazonium salt chemistry, which provides a stable interface showing efficient electron transfer between biomolecules and electrodes. PEG molecules were introduced to the interface to resist non-specific protein adsorption. AuNP surfaces were further modified with 4-carboxyphenyl followed by covalent immobilization of methyl parathion hydrolase (MPH), a specific biocatalytic enzyme to methyl parathion. Exposure of this interface to methyl parathion resulted in a change in amperometric signal due to the MPH catalytic hydrolysis of methyl parathion producing electroactive compound 4-nitrophenol. This biosensor shows high selectivity, specificity, reproducibility and stability, and is functional for the detection of methyl parathion in real samples. The linear range for detection of methyl parathion is 0.2-100 ppb with a detection limit of 0.07 ppb in 0.1M phosphate buffer at pH 7.0.

Topics: Biosensing Techniques; Carbon; Gold; Hydrolases; Insecticides; Limit of Detection; Metal Nanoparticles; Methyl Parathion; Nitrophenols

To enhance the catalytic activity of gold nanoparticles (AuNPs) for the hydrogenation of nitro-aromatic chemicals, Pt was introduced into AuNPs to form "bare" PtAu alloy NPs using a physical approach, pulsed laser ablation in liquid (PLAL), on single metal-mixture targets. These PLAL-NPs are deemed to favor catalysis due to the absence of any surfactant molecules on their unique "bare and clean" surface. The PLAL-NPs were facilely assembled onto CeO2 nanotubes (NTs) by simply mixing them without conducting any surface functionalization, representing another advantage of these NPs. Their catalytic activity was assessed in 4-nitrophenol (4-NP) hydrogenation. The reaction catalyzed by alloy-NP/CeO2-NT catalysts demonstrates a remarkably higher reaction rate in comparison with that catalyzed by pure Au and Pt NPs, and other similar Au and Pt containing catalysts reported recently. A "volcano-like" catalytic activity dependence of the alloy NPs on their chemical composition suggests a strong synergistic effect between Au and Pt in the 4-NP reduction, far beyond the simple sum of their individual contributions. It leads to the significantly enhanced catalytic activity of Pt30Au70 and Pt50Au50 alloy NPs, outperforming not only each single constituent, but also their physical mixtures and most recently reported AuNP based nanocatalysts. The favorable d-band center shift of Pt after alloying, and co-operative actions between Pt clusters and nearby Au (or mixed PtAu) sites were proposed as possible mechanisms to explain such a strong synergistic effect on catalysis.

Topics: Alloys; Catalysis; Cerium; Gold; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Platinum

A green synthesis route was reported to explore the reducing and capping potential of Phoenix dactylifera extract for the synthesis of gold nanoparticles. The processes of nucleation and growth of gold nanoparticles were followed by monitoring the absorption spectra during the reaction. The size and morphology of these nanoparticles was typically imaged using transmission electron microscopy (TEM). The particle size ranged between 32 and 45 nm and are spherical in shape. Fourier transform infrared (FTIR) analysis suggests that the synthesized gold nanoparticles might be stabilized through the interactions of hydroxyl and carbonyl groups in the carbohydrates, flavonoids, tannins and phenolic acids present in P. dactylifera. The as-synthesized Au colloids exhibited good catalytic activity for the degradation of 4-nitrophenol.

Topics: Aminophenols; Arecaceae; Catalysis; Gold; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Photosynthesis; Plant Extracts; Plant Leaves; Solutions; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared

A novel approach, named multi-channel pulsed corona discharge in soil, was developed for remediating organic pollutants contaminated soil, with p-nitrophenol (PNP) as the model pollutant. The feasibility of PNP degradation in soil was explored by evaluating effects of pulse discharge voltage, air flow rate and soil moisture on PNP degradation. Based on roles of chemically active species and evolution of degradation intermediates, PNP degradation processes were discussed. Experimental results showed that about 89.4% of PNP was smoothly degraded within 60min of discharge treatment at pulse discharge voltage 27kV, soil moisture 5% and air flow rate 0.8Lmin(-1), and the degradation process fitted the first-order kinetic model. Increasing pulse discharge voltage was found to be favorable for PNP degradation, but not for energy yield. There existed appropriate air flow rate and soil moisture for obtaining gratifying PNP degradation efficacy. Roles of radical scavenger and measurement of active species suggested that ozone, H2O2, and OH radicals played very important roles in PNP degradation. CN bond in PNP molecule was cleaved, and the main intermediate products such as hydroquinone, benzoquinone, catechol, phenol, acetic acid, formic acid, oxalic acid, NO2(-) and NO3(-) were identified. Possible pathway of PNP degradation in soil in such a system was proposed.

Topics: Environmental Restoration and Remediation; Feasibility Studies; Nitrophenols; Plasma Gases; Soil Pollutants

Orderly porous graphene oxide/carboxymethyl cellulose (GO/CMC) monoliths were prepared by a unidirectional freeze-drying method. The porous monoliths were characterized by Fourier transform infrared spectra, X-ray diffraction and scanning electron microscopy. Their properties including compressive strength and moisture adsorption were measured. The incorporation of GO changed the porous structure of the GO/CMC monoliths and significantly increased their compressive strength. The porous GO/CMC monoliths exhibited a strong ability to adsorb metal ions, and the Ni(2+) ions adsorbed on GO/CMC monolith were reduced by NaBH4 to obtain Ni GO/CMC monolith which could be used as catalyst in the reduction of 4-nitrophenol to 4-aminophenol. Since CMC is biodegradable and non-toxic, the porous GO/CMC monoliths are potential environmental adsorbents.

Topics: Adsorption; Aminophenols; Carboxymethylcellulose Sodium; Catalysis; Compressive Strength; Graphite; Metals, Heavy; Nitrophenols; Oxidation-Reduction; Oxides; Porosity; Water Pollutants, Chemical

The objective of this study was to develop chromatographic methods for the determination of the modification degree and the characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers (PEG-PAMAMs). The PEG-PAMAMs were prepared by reacting PAMAM generation 4 with monomethoxy PEG-nitrophenyl carbonate (mPEG-NPC). The modification degrees of PEG-PAMAMs were determined by quantifying 4-nitrophenol released from mPEG-NPC after PEGylation reaction using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The PEG-PAMAMs, which have poor UV absorbances, were characterized by HPLC with charged aerosol detection. This study demonstrates that the combination of these two detectors is a powerful tool for the preparation and characterization of PEG-PAMAMs.

Topics: Chromatography, High Pressure Liquid; Dendrimers; Nitrophenols; Polyamines; Polyethylene Glycols

A stability indicating gradient reverse phase UPLC-MS/MS method was developed and validated for the simultaneous determination of three phenol impurities in ritonavir drug substance. The chromatographic separation was performed on Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm) using gradient elution of 0.05% ammonia in methanol and 5.0 mM ammonium acetate buffer (30:70, v/v) at a flow rate of 0.2 mL/min. Both negative and positive electrospray ionization (ESI) modes were operated simultaneously for the quantification of three phenol impurities. The total run time was 11 min, within which ritonavir and its three impurities were well separated. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. The calibration curves showed a good linearity over the concentration range of 0.3-1.5 ppm for phenol and 0.1-1.5 ppm for both 4-nitrophenol and N-phenoxycarbonyl-L-valine (NPV). The determination coefficient obtained was >0.9998 in each case. The method had very low limit of detection (LOD) and limit of quantification (LOQ) and the accuracy lies between 97.8% and 103.2% for all the three phenol impurities. The developed method was successfully applied for five formulation batches of ritonavir to determine its phenol impurities.

Topics: Chromatography, High Pressure Liquid; Drug Contamination; Drug Stability; Limit of Detection; Nitrophenols; Phenols; Reproducibility of Results; Ritonavir; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Valine

A novel method for fabricating hypercrosslinked magnetic polymer beads with improved acid resistance was developed. Magnetite nanoparticles were covered with tetraethoxysilane and vinyltriethoxysilane, followed by co-polymerization and post-crosslinking. The resulting M150 beads were highly stable at pH ≥ 2 and were superparamagnetic, with a saturation magnetization of 3.1 emu/g. M150 exhibited a specific surface area of 1022.4m(2)/g and an average pore width of 2.6 nm. The adsorption of p-nitrophenol and chlorotetracycline (CTC) onto M150 and the commercial non-magnetic resins NDA 150 and XAD-4 followed both pseudo-first-order and pseudo-second-order equations. M150 displayed much faster kinetics than the other resins because of its small particle size and abundant macropores. The adsorption isotherm of p-nitrophenol onto the three resins fitted the Freundlich equation (R(2)>0.98), whereas CTC adsorption was better described by the Langmuir isotherm. p-Nitrophenol adsorption was optimal at pH ≤ 4, whereas CTC adsorption was optimal at pH 5-6. All three sorbents showed high reusability for p-nitrophenol adsorption. XAD-4 demonstrated the highest reusability for CTC. The CTC adsorption capacities of M150 and NDA150 decreased by 12.42% and 20% after 10 adsorption-desorption cycles, respectively.

Topics: Adsorption; Chlortetracycline; Magnetic Phenomena; Magnetite Nanoparticles; Nitrophenols; Porosity; Silanes

As hybrid nanostructures have become more important in many fields of chemistry, Ag nanoparticles (NPs) are being increasingly immobilized onto Fe3O4 microspheres in situ. Structural characterization reveals that the Ag NPs are uniformly immobilized in the Fe3O4 microsphere-based supports. Moreover, Ag NPs are more stable in the hybrid structure than in the naked state and show high catalytic activity for the reduction of nitro compounds and hydration of nitriles to amides in water. The Fe3O4 microspheres were recycled several times using an external magnet.

Topics: Amides; Catalysis; Citrates; Ferric Compounds; Magnetic Phenomena; Metal Nanoparticles; Microspheres; Nitriles; Nitrophenols; Oxidation-Reduction; Recycling; Silver; Sodium Citrate; Solvents; Water

Gold-magnetite heterostructures are novel nanomaterials which can rapidly catalyze the reduction reaction of nitroaromatics. In this study, the interfacially structural and electronic properties of various morphologies of Au-Fe3O4 heterostructures were systematically investigated using X-ray absorbance spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). The effect of change in electronic structure and charge transfer on electrochemically catalytic activity of Au-Fe3O4 heterostructures was further evaluated by oxygen reduction reaction (ORR). The shifts in binding energy of Au4f and Fe2p peaks in XPS spectra indicate the charge transfer between the Au and Fe3O4 nanoparticles. The increase in d-hole population of Au seeds after the conjugation with iron oxides follows the order flower-like Au-Fe3O4 (FLNPs)>dumbbell-like Au-Fe3O4 (DBNPs)>Au seeds. In addition, the Fe(2+) valence state increases in Au-Fe3O4 heterostructures, which provides evidence to support the hypothesis of charge transfer between Au and Fe3O4 nanoparticles. The theoretical simulation of Au L3-edge XAS further confirms the production of Au-Fe and Au-O bonds at the interface of Au/Fe3O4 and the epitaxial linkage relationship between Au and Fe3O4 nanoparticles. In addition, the electron deficient of Au seeds increases upon increasing Fe3O4 nanoparticles on a single Au seed, and subsequently decreases the catalytic activity of Au in the Au-Fe3O4 heterostructures. The catalytic activity of Au-Fe3O4 toward ORR follows the order Au seeds>Au-Fe3O4 DBNPs>Au-Fe3O4 FLNPs, which is positively correlated to the extent of electronic deficiency of Au in Au-Fe3O4 heterostructures.

Topics: Catalysis; Electrons; Environmental Pollutants; Ferrosoferric Oxide; Gold; Magnetite Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Oxygen; Photoelectron Spectroscopy; Silver; Static Electricity; Thermodynamics; X-Ray Absorption Spectroscopy

Organophosphates (OPs) widely exist in ecosystem as toxic substances, for which sensitive and rapid analytical methods are highly requested. In the present work, by using N-terminal of ice nucleation protein (INP) as anchoring motif, a genetically engineered Escherichia coli (E. coli) strain surface displayed mutant organophosphorus hydrolase (OPH) (S5) with improved enzyme activity was successfully constructed. The surface location of INP-OPH fusion was confirmed by SDS-PAGE analysis and enzyme activity assays. The OPH-displayed bacteria facilitate the hydrolysis of p-nitrophenol (PNP) substituted organophosphates to generate PNP, which can be detected spectrometrically at 410 nm. Over 90% of the recombinant protein present on the surface of microbes demonstrated enhanced enzyme activity and long-term stability. The OPH activity of whole cells was 2.16 U/OD₆₀₀ using paraoxon as its substrate, which is the highest value reported so far. The optimal temperature for OPH activity was around 55 °C, and suspended cultures retained almost 100% of its activity over a period of one month at room temperature, exhibiting the better stability than free OPH. The recombinant E. coli strain could be employed as a whole-cell biocatalyst for detecting PNP substituted OPs at wider ranges and lower detection limits. Specifically, the linear ranges of the calibration curves were 0.5-150 μM paraoxon, 1-200 μM parathion and 2.5-200 μM methyl parathion, and limits of detection were 0.2 μM, 0.4 μM and 1 μM for paraoxon, parathion and methyl parathion, respectively (S/N=3). These results indicate that the engineered OPH strain is a promising multifunctional bacterium that could be used for further large-scale industrial and environmental applications.

Topics: Aryldialkylphosphatase; Bacterial Outer Membrane Proteins; Biocatalysis; Calibration; Carrier Proteins; Cell Membrane; Environmental Pollutants; Escherichia coli Proteins; Fenitrothion; Genes, Synthetic; Glycosylphosphatidylinositols; Hydrogen-Ion Concentration; Methyl Parathion; Molecular Structure; Nitrophenols; Organophosphates; Paraoxon; Parathion; Pesticide Residues; Recombinant Fusion Proteins; Spectrophotometry; Temperature

The production and performance of activated carbon prepared from date pits was investigated. Date pits are an abundant local waste product in many countries; converting them to a commercial product would increase the sustainability of this fruit crop. The date pit activated carbon was shown to have similar characteristics of pore size and surface functional groups as other commercial carbons. Batch experiments were conducted with o- and p-nitrophenol to evaluate the performance of this carbon. Results were analyzed according to Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms. The adsorption capacity of o-nitrophenol was 142.9 mg/g while that of p-nitrophenol was 108.7 mg/g. The adsorption process was physical in nature. The position of the -NO(2) group in the benzene ring has a considerable effect on the adsorption capacity and rate of uptake. The kinetic results showed that a pseudo second-order model appropriately describes the experimental data. The analysis of kinetic data revealed that the mechanism of adsorption is complex with both liquid film diffusion and intraparticle diffusion contributing to adsorption of both adsorbates.

Topics: Adsorption; Carbon; Charcoal; Nitrophenols

Molecularly imprinted Fe(3)O(4)/SiO(2) core-shell magnetic composites (Fe(3)O(4)/SiO(2)-MIP) were successfully prepared via anchoring p-nitrophenol (p-NP) imprinted functional polymers on the surface of amino-modified Fe(3)O(4)/SiO(2) core-shell particles. Synthesized magnetic Fe(3)O(4)/SiO(2)-MIP composites were characterized by X-ray diffraction, scanning electronic microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and magnetic property measurement. The preferential catalytic ozonation of p-nitrophenol was evaluated in comparison with the competitive reaction in the presence of coexistent phenol. The results showed that the prepared Fe(3)O(4)/SiO(2)-MIP composites exhibit strong adsorption ability due to the strong bonding between p-NP and the molecularly imprinted layer. The Fe(3)O(4)/SiO(2)-MIP demonstrated a preferential catalytic ozonation of p-NP by the recognition ability of the molecularly imprinted layer to the target p-NP. The enhanced catalytic activity using Fe(3)O(4)/SiO(2)-MIP composites could be attributed to the excellent recognition absorption of the MIP layer on the surface of Fe(3)O(4)/SiO(2)-MIP to p-NP.

Topics: Catalysis; Ferrosoferric Oxide; Magnetite Nanoparticles; Microscopy, Atomic Force; Nitrophenols; Silicon Dioxide

The photocatalytic properties of functionalized TiO2 with silver nanoparticles (AgNPs) for the conversion of 4-nitrophenol to 4-aminophenol in the presence of hydrazine were investigated. The TiO2 semiconductor synthesized by the sol-gel method was functionalized with AgNPs at different loadings, and their structural and optical properties were characterized by several techniques. The functionalized TiO2 with 1.5wt% AgNPs presented the highest photocatalytic activity for the conversion of 4-nitrophenol with appropriate hydrazine concentrations (0.5M). The photoefficiency enhancement under UV light irradiation was attributed to the electron transfer from the TiO2 semiconductor surface to the adsorbed acceptor reactant (4-nitrophenol) through the deposited AgNPs.

Topics: Catalysis; Hydrazines; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Phase Transition; Photochemical Processes; Semiconductors; Silver; Surface Properties; Titanium

Biomimetic nanotechnologies that use peptides to guide the growth and assembly of nanostructures offer new avenues for the creation of functional nanomaterials and manipulation of their physicochemical properties. However, the impacts of peptide sequence and binding motif upon the surface characteristics and physicochemical properties of nanoparticles remain poorly understood. The configurations of the biomolecules are expected to be extremely important for directing the synthesis and achieving desired material functionality, and these binding motifs will vary with the peptide sequence. Here, we have prepared a series of Au nanoparticles capped with a variety of materials-directing peptides with known affinity for metal surfaces. These nanomaterials were characterized by UV-vis and circular dichroism spectroscopies, transmission electron microscopy, and ζ-potential measurement. Then their catalytic activity for 4-nitrophenol reduction was analyzed. The results indicate that substantially different Au-peptide interfaces are generated using different peptide sequences, even when these sequences have similar binding affinity. This is consistent with recent work showing that Au-peptide binding affinity can have varying entropic and enthalpic contributions, with enthalpically- and entropically-driven binders exhibiting quite different ensembles of configurations on the Au surface. The catalytic activity, as reflected by the measured activation energy, did not correlate with the particle size or with the binding affinity of the peptides, suggesting that the reactivity of these materials is governed by the more subtle details of the conformation of the bound peptide and on the nanoparticle surface reconstruction as dictated by the peptide structure. Such variations in both nanoparticle surface reconstruction and peptide configuration could potentially be used to program specific functionality into the peptide-capped nanomaterials.

Topics: Amino Acid Sequence; Catalysis; Gold; Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Peptides; Surface Properties; Thermodynamics

New catalyst, prepared through Au nanoparticles anchored on the Ionic Liquid of 3,4,9,10-perylene tetracarboxylic acid-noncovalent functionalized graphene (Au/PDIL-GS), was fabricated using a facile and environment-friendly approach. The information of the morphologies, sizes, dispersion of Au nanoparticles (NPs) and chemical composition for the as-prepared catalysts was verified by systematic characterizations, including transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra, X-ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS). As a new catalyst, the resulting Au/PDIL-GS exhibited excellent catalytic activity in the reduction of 4-nitrophenol because of the synergistic effect between the PDIL-GS and Au NPs. The facile and environment-friendly approach provides a green way to effectively synthesize low cost Au-based catalysts for 4-NP reduction and is promising for the development of other useful materials.

Topics: Catalysis; Gold; Graphite; Green Chemistry Technology; Ionic Liquids; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Perylene; Waste Disposal, Fluid; Water Pollutants, Chemical

Facile, efficient, and robust immobilization of metal nanostructures on porous bioscaffolds is an interesting topic in materials chemistry and heterogeneous catalysis. This study reports a facile in situ method for the synthesis and immobilization of small silver nanoparticles (AgNPs) at room temperature on natural eggshell membrane (ESM), which presents interwoven fibrous structure and can be used as a unique protein-based biotemplate. Procyanidin (Pro), a typical plant polyphenol extracted from grape seeds and skins, was first grafted onto ESM fibers to serve as both reductant and stabilizer during the synthesis process. As a result, the AgNPs were facilely synthesized and robustly immobilized on the ESM fibers without additional chemical reductant or physical treatments. The morphology and microstructure of the as-prepared AgNPs@Pro-ESM composites were characterized by combined microscopy and spectroscopy technologies. The results indicate that small AgNPs with mean diameter of 2.46 nm were successfully prepared on the Pro-ESM biotemplate. The composites exhibited good catalytic activity toward the reduction of 4-nitrophenol (4-NP). More importantly, these composite catalysts can be easily recovered and reused for more than eight cycles because of their high stability.

Topics: Animals; Biflavonoids; Catalysis; Catechin; Cell Membrane; Chickens; Metal Nanoparticles; Nitrophenols; Ovum; Oxidation-Reduction; Particle Size; Polymers; Proanthocyanidins; Silver

In Traditional Chinese Medicine, liver targeting is usually achieved by coadministration with Vinegar-baked Radix Bupleuri (VBRB), but the mechanism is unclear. In this paper, the influence of VBRB on the activity of β-glucuronidase was investigated and compared with that of saikosaponins. The activity of β-glucuronidase was measured by microplate reader using a 4-nitrophenyl-β-d-glucuronide substrate. The change of 4-nitrophenol content was used to characterize the activity of β-glucuronidase. Bupleurum chinenes were found to be the inhibitor of β-glucuronidase. The inhibition rate of Bupleurum chinenes extracts BC1 (high molecular weight polysaccharides), BC2 (ethanol soluble/water insoluble component), BC3 (extracted by n-butanol, soluble in water), and BC4 (low molecular weight water soluble parts) on the activity of β-glucuronidase was found to be 45.15%, 33.94%, 24.94%, and 34.54%, respectively, after 1 h incubation, with BC1 showing the highest inhibition rate. In contrast, the saikosaponins were demonstrated to be the promoter of β-glucuronidase, with promotion rates of 333.56%, 217.04%, 247.87%, 149.75%, and 92.50% for saikosaponin standard samples A, B, B2, C, and D, respectively, (p<0.05). In conclusion, inhibiting the activity of β-glucuronidase might be one of the reasons why VBRB could influence drug distribution upon its coadministration with other drugs. Since saikosaponins and VBRB extracts have opposite effect, more attention should be paid to the content of saikosaponins in the extracts upon its application.

Topics: 1-Butanol; Acetic Acid; Bupleurum; Drugs, Chinese Herbal; Glucuronates; Glucuronidase; Liver; Nitrophenols; Oleanolic Acid; Saponins

Two novel macrocyclic 6-methyluracilic amphiphiles (uracilophanes) with four (UP1) and two (UP2) uracil moieties and ammonium groups have been synthesized. Tetracationic multi-uracilophane is composed of two macrocyclic units bridged each other with an external methylene spacer, while in the cryptand-like dicationic uracilophane pyrimidinic moieties are connected with an internal methylene spacer. This internal spacer provided a conformational rigidity to the macrocycle. The self-assembly of the uracilophanes is studied and compared with a reference dicationic uracilophane (UP3) with no spacer fragment. Compounds UP1 and UP3 are capable of aggregating, which is characterized by the analogous critical micelle concentration of 1mM, although the former has four decyl tails versus two decyl tails in UP3 molecule. NMR self-diffusion, fluorimetry and DLS techniques revealed that bimodal size distribution occurs in the UP1 solution, with small (≤2nm) and large (ca. 30-50 nm) aggregates contributed. Unexpectedly, the cryptand-like uracilophane UP2 with the same hydrophobicity as UP3 does not form aggregates. The balance of the geometry and energetic factors was analyzed and compared with those contributing to the aggregation of the reference compound UP3. It was established that it is the geometry that controls the packing of the cryptand-like uracilophanes upon aggregation, while hydrophobic effect plays a minor role. In contrast, both factors control the aggregation of oligomeric macrocycle, with energetic factor prevailing. These findings are of importance for (i) the understanding the diverse structural behavior of bioamphiphiles that have very similar chemical structure, but different conformations; and (ii) the design of amphiphiles with controlled model of self-assembly. Supramolecular systems studied can be recommended for biotechnological applications.

Topics: Conductometry; Diffusion; Electric Conductivity; Hydrolysis; Light; Macrocyclic Compounds; Magnetic Resonance Spectroscopy; Nitrophenols; Particle Size; Scattering, Radiation; Solutions; Spectrometry, Fluorescence; Surface Tension; Surface-Active Agents; Temperature; Uracil

A series of lead dioxide electrodes developed on titania nanotube arrays with different matrix were fabricated by electrodeposition. Before the deposition of PbO₂, the matrix of this anode was electrochemically reduced in (NH₄)₂SO₄ solution and/or pre-deposited with certain amounts of copper. To gain insight into these pretreatments, the PbO₂ electrodes were characterized by SEM, LSV, and XRD, and their electrocatalytic activities for pollutant degradation were compared using p-nitrophenol (p-NP) as a model. It was confirmed that the electrochemical reduction with (NH4)₂SO₄ resulted in the partial conversion of TiO₂ into Ti₄O₇ and Ti₅O₉, which increased the conductivity of PbO₂ anode, but decreased its electrochemical activity, while the Ti/TNTs*-Cu/PbO₂ electrode with both pretreatments possessed the highest oxygen evolution overpotential of 2.5 V (vs. SCE) and low substrate resistance. After a 180-min treatment on this electrode, the removal efficiency of p-NP reached 82.5% and the COD removal achieved 42.5% with the energy consumption of 9.45 kWh m(-3), demonstrating the best performance among these electrodes with different matrices. Therefore, this titania nanotube array-based PbO₂ electrode has a promising application in the industrial wastewater treatment.

Topics: Biological Oxygen Demand Analysis; Copper; Electrochemistry; Electrodes; Electroplating; Lead; Nanotubes; Nitrophenols; Oxidation-Reduction; Oxides; Titanium; Waste Disposal, Fluid; Water Pollutants, Chemical

In this paper, a facile in situ method is reported for the preparation of catalytic silver nanoparticles (AgNPs) using N-acyl tyramine (NATA) with variable hydrophobic acyl length. Scanning electron microscopic analysis shows that NATA exists initially as larger aggregates in alkaline aqueous solution. The addition of AgNO3 dissociates these larger aggregate and subsequently promotes the formation of self-assembled NATA and AgNPs. Characterization of AgNPs using UV-vis spectroscopy, scanning electron microscope and transmission electron microscope revealed that the hydrophobic acyl chain length of NATA does not influence the particle size, shape and morphology. All NATA-AgNPs yielded relatively identical values in full width at half-maximum (FWHM) analysis, indicating that the AgNPs prepared with NATA are relatively polydispersed at all tested acyl chain lengths. These nanoparticles are able to efficiently catalyze the reduction of 4-nitro phenol to 4-amino phenol, 2-nitro aniline to 1,2-diamino benzene, 2,4,6-trinitro phenol to 2,4,6-triamino phenol by NaBH4 in an aqueous environment. The reduction reaction rate is determined to be pseudo-first order and the apparent rate constant is linearly dependent on the hydrophobic acyl chain length of the NATA. All reaction kinetics presented an induction period, which is dependent on the N-acyl chain length, indicating that the hydrophobic effects play a critical role in bringing the substrate to the metal nanoparticle surface to induce the catalytic reaction. In this study, however, the five catalytic systems have similar size and polydispersity, differing only in terms of capping agent hydrophobicity, and shows different catalytic activity with respect to the alkyl chain length of the capping agent. As discussed, the ability to modulate the metal nanoparticles catalytic property, by modifying the capping agent hydrophobicity represents a promising future for developing an efficient nanocatalyst without altering the size, shape and morphology of the nanoparticles.

Topics: Catalysis; Hydrophobic and Hydrophilic Interactions; Metal Nanoparticles; Nitrophenols; Silver; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tyramine

Magnetic FeNi@Ni nanocables were prepared as a superior recyclable catalyst towards the hydrogenation reduction of p-nitrophenol to p-aminophenol through a two-step tunable assembly process in a solvothermal system. The proposed fabrication mechanism was verified through characterization by SEM, TEM, XRD, XPS, and UV-Vis. The as-prepared FeNi@Ni nanocomposites are core-shell-structured nanocables with Ni nanoparticles (NPs) attached on FeNi nanorods (NRs) surface loosely. The catalytic reactivity monitored by means of a UV-vis dynamic process shows FeNi@Ni nanocables can catalyse the transformation of p-nitrophenol to p-aminophenol completely under an ambient atmosphere at room temperature, and enable the catalysis to be more efficient than its counterparts FeNi NRs and Ni NPs due to the interfacial synergistic effect. Additionally, the resultant hierarchical metal-alloy nanocomposites possess ferromagnetic behaviour, and can be easily separated and recycled by an external magnet field for application.

Topics: Aminophenols; Catalysis; Hydrogenation; Iron; Magnets; Nanostructures; Nanotechnology; Nickel; Nitrophenols; Oxidation-Reduction

The water-soluble 3-n-propyl-4-picolinium silsesquioxane chloride (Si4Pic(+)Cl(-)) polymer was prepared, characterized and used as a stabilizing agent for the synthesis of gold nanoparticles (nAu). The ability of Si4Pic(+)Cl(-) to adsorb anionic metal complexes such as AuCl4(-) ions allowed well-dispersed nAu to be obtained with an average particle size of 4.5nm. The liquid suspension of nAu-Si4Pic(+)Cl(-) was deposited by the drop coating method onto a glassy carbon electrode (GCE) surface to build a sensor (nAu-Si4Pic(+)Cl(-)/GCE) which was used for the detection of o-nitrophenol (o-NP) and p-nitrophenol (p-NP). Under optimized experimental conditions the reduction peak current increased with increasing concentrations of both nitrophenol isomers in the range of 0.1-1.5μmolL(-1). The detection limits were 46nmolL(-1) and 55nmolL(-1) for o-NP and p-NP, respectively. These findings indicate that the nAu-Si4Pic(+)Cl(-) material is a very promising candidate to assemble electrochemical sensors for practical applications in the field of analytical chemistry.

Topics: Catalysis; Electrochemical Techniques; Gold; Metal Nanoparticles; Nitrophenols; Organosilicon Compounds; Polymers; Solubility; Water; Water Pollutants, Chemical

An efficient method to degrade 4-nitrophenol (4-NP) using cadmium sulphide nanoparticles (CdS NPs) prepared by a novel method as a photocatalyst in the presence of H2O2 as a free radical generator was developed. To investigate the degradation mechanism, the interaction between the substrate (4-NP) and the catalyst (CdS NPs) was studied using UV-visible absorption and emission spectral techniques. Investigation on the effect of pH of the medium on the degradability of 4-NP revealed that neither the acidic (pH 4) nor alkaline (pH 9) is as suitable as pH 6 due to the desorption of 4-NP from the catalyst surface at the former condition and the existence of 4-NP in its most stable quinonoid form at the latter pH. Similarly, the effect of ratio between the photocatalyst (CdS NPs) and the substrate (4-NP) was also investigated to achieve higher efficiency in the photocatalytic reaction.

Topics: Absorption; Animals; Cadmium Compounds; Catalysis; Egg Shell; Free Radicals; Hydrogen Peroxide; Hydrogen-Ion Concentration; Nanoparticles; Nitrophenols; Organic Chemicals; Photochemistry; Photolysis; Spectrophotometry, Ultraviolet; Sulfides; Time Factors; Water Pollutants, Chemical

The current study deals with the synthesis of gold nanoparticles (AuNPs) using Salicornia brachiata (Sb) and evaluation of their antibacterial and catalytic activity. The SbAuNPs showed purple color with a characteristic surface plasmon resonance peak at 532 nm. Scanning electron microscopy and transmission electron microscopy revealed polydispersed AuNPs with the size range from 22 to 35 nm. Energy dispersive X-ray and thin layer X-ray diffraction analysis clearly shows that SbAuNPs was pure and crystalline in nature. As prepared gold nanoparticles was used as a catalyst for the sodium borohydride reduction of 4-nitro phenol to 4-amino phenol and methylene blue to leucomethylene blue. The green synthesized nanoparticles exhibited potent antibacterial activity against the pathogenic bacteria, as evidenced by their zone of inhibition. In addition, we showed that the SbAuNPs in combination with the regular antibiotic, ofloxacin, exhibit superior antibacterial activity than the individual.

Topics: Aminophenols; Anti-Bacterial Agents; Borohydrides; Catalysis; Chenopodiaceae; Fourier Analysis; Gold; Green Chemistry Technology; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nitrophenols; Ofloxacin; Plant Extracts; Spectrophotometry, Ultraviolet; Surface Plasmon Resonance; X-Ray Diffraction

This research investigated the removal mechanisms of p-nitrophenol, p-methoxyphenol, and p-benzoquinone at a porous Ti4O7 reactive electrochemical membrane (REM) under anodic polarization. Cross-flow filtration experiments and density functional theory (DFT) calculations indicated that p-benzoquinone removal was primarily due to reaction with electrochemically formed OH(•), while the dominant removal mechanism of p-nitrophenol and p-methoxyphenol was a function of the anodic potential. At low anodic potentials (1.7-1.8 V/SHE), p-nitrophenol and p-methoxyphenol were removed primarily by an electrochemical adsorption/polymerization mechanism on the REM. Increasing anodic potentials (1.9-3.2 V/SHE) resulted in the electroassisted adsorption mechanism contributing far less to p-methoxyphenol removal compared to p-nitrophenol. DFT calculations indicated that an increase in anodic potential resulted in a shift in p-methoxyphenol removal from a 1e(-) direct electron transfer (DET) reaction that resulted in radical formation and significant adsorption/polymerization, to a 2e(-) DET reaction that formed nonadsorbing products (i.e., p-benzoquinone). However, the anodic potentials were too low for the 2e(-) DET reaction to be thermodynamically favorable for p-nitrophenol. The decreased COD adsorption for p-nitrophenol at higher anodic potentials was attributed to reaction of soluble/adsorbed organics with OH(•). These results provide the first mechanistic explanation for p-substituted phenolic compound removal during advanced electrochemical oxidation processes.

Topics: Adsorption; Anisoles; Benzoquinones; Biological Oxygen Demand Analysis; Electrochemistry; Membranes, Artificial; Models, Chemical; Molecular Conformation; Nitrophenols; Oxidation-Reduction; Phenols; Porosity; Quantum Theory; Thermodynamics; Time Factors; Titanium

Carbon nanotubes (CNTs) are promising nanomaterials that have the potential to revolutionize water treatment practices in the future. The direct use of unbounded CNTs, however, poses health risks to humans and ecosystems because they are difficult to separate from treated water. Here, we report the design and synthesis of carbon nanotube ponytails (CNPs) by integrating CNTs into micrometer-sized colloidal particles, which greatly improves the effectiveness of post-treatment separation using gravitational sedimentation, magnetic attraction, and membrane filtration. We further demonstrate that CNPs can effectively perform major treatment tasks including adsorption, disinfection, and catalysis. Using model pollutants such as methylene blue, Escherichia coli, and p-nitrophenol, we show that all the surfaces of individual CNTs in CNPs are accessible during water treatment. Our results suggest that the rational design of hierarchical structures represents a feasible approach to develop nanomaterials for engineering applications such as water and wastewater treatment.

Topics: Adsorption; Filtration; Humans; Nanotubes, Carbon; Nitrophenols; Water; Water Pollutants, Chemical; Water Purification

L-lysine 4-nitrophenolate monohydrate (LLPNP) has been synthesized and grown by solution growth method at room temperature using deionised water as a solvent. The crystal structure of the materials was solved by single crystal X-ray diffraction analysis and it was found that the material has orthorhombic system. The crystallinity of the grown crystals was studied by the powder X-ray diffraction analysis. Molecular structure of the grown crystal was investigated by 1H NMR spectroscopy. The various functional groups of the sample were identified by Fourier transform infrared and Fourier transform-Raman spectroscopic analyses. Thermal stability of the grown crystal has been studied by Thermogravimetric and Differential thermal (TG&DTA) analysis. The optical absorption of the grown crystals has been ascertained by UV-Vis-NIR absorption studies. Second harmonic generation (SHG) efficiency of the material has been determined by Kurtz and Perry technique and the efficiency was found to be 4.45 and 1.4 times greater than that of standard KDP and urea samples, respectively.

Topics: Crystallization; Crystallography, X-Ray; Fourier Analysis; Lysine; Magnetic Resonance Spectroscopy; Materials Testing; Molecular Conformation; Nitrophenols; Optics and Photonics; Organic Chemicals; Powders; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Thermogravimetry; Urea; X-Ray Diffraction

A new mode of ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) is developed. In this work, [C6MIm][PF6] was chosen as the extraction solvent, and two kinds of hydrophilic ionic liquids, [EMIm][BF4] and [BSO3HMIm][OTf], functioned as the dispersive solvent. So in the whole extraction procedure, no organic solvent was used. With the aid of SO3H group, the acidic compound was extracted from the sample solution without pH adjustment. Two phenolic compounds, namely, 2-naphthol and 4-nitrophenol were chosen as the target analytes. Important parameters affecting the extraction efficiency, such as the type of hydrophilic ionic liquids, the volume ratio of [EMIm][BF4] to [BSO3HMIm][OTf], type and volume of extraction solvent, pH value of sample solution, sonication time, extraction time and centrifugation time were investigated and optimized. Under the optimized extraction conditions, the method exhibited good sensitivity with the limits of detection (LODs) at 5.5 μg L(-1)and 10.0 μg L(-1) for 4-nitrophenol and 2-naphthol, respectively. Good linearity over the concentration ranges of 24-384 μg L(-1) for 4-nitrophenol and 28-336 μg L(-1) for 2-naphthol was obtained with correlation coefficients of 0.9998 and 0.9961, respectively. The proposed method can directly extract acidic compound from environmental sample or even more complex sample matrix without any pH adjustment procedure.

Topics: Chromatography, High Pressure Liquid; Environmental Monitoring; Hydrogen-Ion Concentration; Industrial Waste; Ions; Limit of Detection; Liquid Phase Microextraction; Naphthols; Nitrophenols; Phenol; Reproducibility of Results; Solvents; Ultrasonics; Water; Water Pollutants, Chemical

Oligosaccharide-based amphiphiles were readily prepared by click chemistry from ω-azido-hexanoic or dodecanoic acids with propargyl-functionalized maltoheptaose or xyloglucanoligosaccharides. These amphiphilic compounds were used as capping/stabilizer agents in order to obtain highly stable catalytic silver glyconanoparticles (Ag-GNPs) through the in situ reduction of silver nitrate with NaBH4. With a view to long-term storage, the stabilization was optimized using a multivariate approach, and the nanoparticles were characterized by UV-vis, TEM, SAXS, and DLS. In order to explore the functionality of the Ag-GNPs in catalysis, a full kinetic analysis of the reduction of p-nitrophenol by NaBH4 in water and in water/ethanol mixtures was performed under semi-heterogeneous and quasi-homogeneous conditions. A pseudomonomolecular surface reaction was performed, and the kinetic data obtained were treated according to the Langmuir model. The Ag-GNPs were very active, and both substrates adsorbed onto the surface of the nanoparticles. For comparison purposes, the reaction was also performed in the presence of silver-sodium dodecanoate nanoparticles, which showed catalytic activity similar to that of the glyconanoparticles, supporting the choice of the carboxyl group as the stabilizing agent, although it provided much lower temporal stability. Finally, by combining kinetic and water/ethanol surface tension data it was possible to observe the effect of the addition of the less polar solvent (ethanol) to the reaction medium.

Topics: Adsorption; Carbohydrates; Catalysis; Chromatography, Thin Layer; Ethanol; Microscopy, Electron, Transmission; Nanoparticles; Nanotechnology; Nitrophenols; Oligosaccharides; Scattering, Radiation; Silver; Silver Compounds; Sodium; Surface Properties; Water

A new competitive-type immunosensing system based on gold nanoparticles toward catalytic reduction of 4-nitrophenol (4-NP) was developed for sensitive monitoring of antibiotic residue (chloramphenicol, CAP, used in this case) by using ultraviolet-visible (UV-vis) spectrometry. Gold nanoparticle (AuNP) with 16 nm in diameter was initially synthesized and functionalized with CAP-bovine serum albumin (CAP-BSA) conjugate, which were used as the competitor on monoclonal anti-CAP antibody-coated polystyrene microtiter plate (MTP). In the presence of target CAP, the labeled CAP-BSA on the AuNP competed with target CAP for the immobilized antibody on the MTP. The conjugated amount of CAP-BSA-AuNP on the MTP decreased with the increase of target CAP in the sample. Upon addition of 4-NP and NaBH4 into the MTP, the carried AuNP could catalytically reduce 4-NP to 4-aminophenol (4-AP), and the as-produced 4-AP could be monitored by using UV-vis absorption spectroscopy. Experimental results indicated that the absorbance at 403 nm increased with the increment of target CAP concentration in the sample, and exhibited a dynamic range from 0.1 to 100 ng mL(-1) with a detection limit (LOD) of 0.03 ng mL(-1) at the 3s(blank) level. Intra- and inter-assay coefficients of variation were lower than 5.5% and 8.0%, respectively. In addition, the methodology was evaluated for CAP spiked honey and milk samples, respectively. The recovery was 92-112%.

Topics: Animals; Catalysis; Chloramphenicol; Gold; Honey; Immunoassay; Metal Nanoparticles; Milk; Nitrophenols; Oxidation-Reduction

A large family of bifunctional 1,2,3-triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox-robust metal complex, or a β-cyclodextrin unit) has been synthesized by facile "click" chemistry and mildly coordinated to nanogold particles, thus providing stable water-soluble gold nanoparticles (AuNPs) in the size range 3.0-11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence "turn-on" assay, and the catalytic activity of the smallest triazole-AuNPs (core of 3.0 nm) is excellent for the reduction of 4-nitrophenol in water.

Topics: Catalysis; Chemical Warfare Agents; Click Chemistry; Gold; Metal Nanoparticles; Mustard Gas; Nitrophenols; Oxidation-Reduction; Particle Size; Polyethylene Glycols; Spectrometry, Fluorescence; Triazoles

This study deals with the exploration of NixCo₁-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrite nanoparticles as catalysts for reduction of 4-nitrophenol and photo-oxidative degradation of Rhodamine B. The ferrite samples with uniform size distribution were synthesized using the reverse micelle technique. The structural investigation was performed using powder X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray and scanning tunneling microscopy. The spherical particles with ordered cubic spinel structure were found to have the crystallite size of 4-6 nm. Diffused UV-visible reflectance spectroscopy was employed to investigate the optical properties of the synthesized ferrite nanoparticles. The surface area calculated using BET method was found to be highest for Co₀.₄Ni₀.₆Fe₂O₄ (154.02 m(2) g(-1)). Co₀.₄Ni₀.₆Fe₂O₄ showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe₂O₄ was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH₄ on the reaction rates was also scrutinized. The photo-oxidative degradation of Rhodamine B, enhanced oxidation efficacy was observed with the introduction of Ni(2+) in to the cobalt ferrite lattice due to octahedral site preference of Ni(2+). Almost 99% degradation was achieved in 20 min using NiFe₂O₄ nanoparticles as catalyst.

Topics: Catalysis; Cobalt; Coloring Agents; Ferric Compounds; Light; Metal Nanoparticles; Nickel; Nitrophenols; Oxidation-Reduction; Particle Size; Photolysis; Rhodamines; X-Ray Diffraction

The aim of this work was to synthesize gold nanoparticles by Trichoderma viride and Hypocrea lixii. The biosynthesis of the nanoparticles was very rapid and took 10 min at 30 °C when cell-free extract of the T. viride was used, which was similar by H. lixii but at 100 °C. Biomolecules present in cell free extracts of both fungi were capable to synthesize and stabilize the formed particles. Synthesis procedure was very quick and environment friendly which did not require subsequent processing. The biosynthesized nanoparticles served as an efficient biocatalyst which reduced 4-nitrophenol to 4-aminophenol in the presence of NaBH₄ and had antimicrobial activity against pathogenic bacteria. To the best of our knowledge, this is the first report of such rapid biosynthesis of gold nanoparticles within 10 min by Trichoderma having plant growth promoting and plant pathogen control abilities, which served both, as an efficient biocatalyst, and a potent antimicrobial agent.

Topics: Aminophenols; Anti-Infective Agents; Biosynthetic Pathways; Catalysis; Gold; Hypocrea; Kinetics; Metal Nanoparticles; Nitrophenols; Trichoderma

The purpose of this study was to probe active site structure and dynamics of human cytochrome P4502E1 and P4502A6 using a series of related short chain fatty aldehydes. Binding efficiency of the aldehydes was monitored via their ability to inhibit the binding and activation of the probe substrates p-nitrophenol (2E1) and coumarin (2A6). Oxidation of the aldehydes was observed in reactions with individually expressed 2E1, but not 2A6, suggesting alternate binding modes. For saturated aldehydes the optimum chain length for inhibition of 2E1 was 9 carbons (KI=7.8 ± 0.3 μM), whereas for 2A6 heptanal was most potent (KI=15.8 ± 1.1 μM). A double bond in the 2-position of the aldehyde significantly decreased the observed KI relative to the corresponding saturated compound in most cases. A clear difference in the effect of the double bond was observed between the two isoforms. With 2E1, the double bond appeared to remove steric constraints on aldehyde binding with KI values for the 5-12 carbon compounds ranging between 2.6 ± 0.1 μM and 12.8 ± 0.5 μM, whereas steric effects remained the dominant factor in the binding of the unsaturated aldehydes to 2A6 (observed KI values between 7.0 ± 0.5 μM and >1000 μM). The aldehyde function was essential for effective inhibition, as the corresponding carboxylic acids had very little effect on enzyme activity over the same range of concentrations, and branching at the 3-position of the aldehydes increased the corresponding KI value in all cases examined. The results suggest that a conjugated π-system may be a key structural determinant in the binding of these compounds to both enzymes, and may also be an important feature for the expansion of the active site volume in 2E1.

Topics: Aldehydes; Catechols; Cytochrome P-450 CYP2A6; Cytochrome P-450 CYP2E1; Enzyme Inhibitors; Humans; Kinetics; Nitrophenols; Oxidation-Reduction; Structure-Activity Relationship

Weak magnetic field (WMF) and Fe(0) were proposed to activate PS synergistically (WMF-Fe(0)/PS) to degrade dyes and aromatic contaminants. The removal rates of orange G (OG) by WMF-Fe(0)/PS generally decreased with increasing initial pH (3.0-10.0) and increased with increasing Fe(0) (0.5-3.0 mM) or PS dosages (0.5-3.0 mM). Compared to its counterpart without WMF, the WMF-Fe(0)/PS process could induce a 5.4-28.2 fold enhancement in the removal rate of OG under different conditions. Moreover, the application of WMF significantly enhanced the decolorization rate and the mineralization of OG. The degradation rates of caffeine, 4-nitrophenol, benzotriazole and diuron by Fe(0)/PS were improved by 2.1-11.1 fold due to the superimposed WMF. Compared to many other sulfate radical-based advanced oxidation technologies under similar reaction conditions, WMF-Fe(0)/PS technology could degrade selected organic contaminants with much greater rates. Sulfate radical was identified to be the primary radical species responsible for the OG degradation at pH 7.0 in WMF-Fe(0)/PS process. This study unraveled that the presence of WMF accelerated the corrosion rate of Fe(0) and thus promoted the release of Fe(2+), which induced the increased production of sulfate radicals from PS and promoted the degradation of organic contaminants. Employing WMF to enhance oxidation capacity of Fe(0)/PS is a novel, efficient, promising and environmental-friendly method since it does not need extra energy and costly reagents.

Topics: Azo Compounds; Caffeine; Color; Diuron; Hydrogen-Ion Concentration; Iron; Kinetics; Magnetic Fields; Minerals; Nitrophenols; Sulfates; Triazoles; Water Pollutants, Chemical

When used as an N-terminal fusion expression partner, the Escherichia coli stress-responsive protein, CysQ dramatically increased the cytoplasmic solubility of various aggregation-prone heterologous proteins: Pseudomonas putida cutinase (CUT), human granulocyte colony-stimulating factor (hG-CSF), human ferritin light chain (hFTN-L), arginine deiminase (ADI), human interleukin-2 (IL2), human activation induced cytidine deaminase (AID), and deletion mutant of human glutamate decarboxylase (GAD448-585). As compared with well-known fusion tags such as glutathione-S-transferase (GST) and maltose-binding protein (MBP), the performance of CysQ as solubility enhancer was evidently better than GST and was similar to or better than MBP for the seven heterologous proteins above. This is likely due to the intrinsic ability of CysQ to form its native conformation, probably promoting the binding of molecular chaperones during the folding of CysQ-fusion protein. When used as a substrate, p-nitrophenyl butyrate (PNB) was successfully hydrolyzed to p-nitrophenol by CysQ-CUT fusion mutant. Even after CysQ was removed, the solubility of hFTN-L and hG-CSF, the secondary structure of hG-CSF, and self-assembly activity of hFTN-L were successfully maintained. Conclusively, it seems that CysQ is a highly effective solubility enhancer and fusion expression partner for the production of a variety of bio-active recombinant proteins.

Topics: Apoferritins; Butyrates; Carboxylic Ester Hydrolases; Cytoplasm; Escherichia coli; Granulocyte Colony-Stimulating Factor; Humans; Molecular Chaperones; Nitrophenols; Phosphoric Monoester Hydrolases; Protein Aggregates; Protein Folding; Pseudomonas putida; Recombinant Fusion Proteins; Solubility

Inorganic-framework molecularly imprinted TiO2/SiO2 nanocomposite (MIP-TiO2/SiO2) was successfully prepared by sol-hydrothermal method using 4-nitrophenol as template. The morphology, structure, optical property, zeta-potential and photocurrent of MIP-TiO2/SiO2 were characterized. The adsorption performance and photocatalytic selectivity were also studied. MIP-TiO2/SiO2 shows higher adsorption capacity and selectivity than the non-imprinted TiO2/SiO2 (NIP-TiO2/SiO2). Kinetics results show that the adsorption equilibrium of 4-nitrophenol on MIP-TiO2/SiO2 is established within 20 min, and the adsorption process obeys the pseudo-second-order model. Moreover, MIP-TiO2/SiO2 can completely degrade 4-nitrophenol within 30 min, while NIP-TiO2/SiO2 takes 110 min. It was found that the MIP-TiO2/SiO2 photocatalyst shows molecular recognition ability, leading to selective adsorption and molecular recognitive photocatalytic degradation of 4-nitrophenol. Furthermore, because of its inorganic framework, MIP-TiO2/SiO2 shows excellent reusability.

Topics: Adsorption; Catalysis; Electrochemistry; Molecular Imprinting; Nanocomposites; Nitrophenols; Photochemical Processes; Silicon Dioxide; Surface Properties; Titanium; Ultraviolet Rays; Water Pollutants, Chemical

Single crystals of l-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of l-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method.

Topics: Arginine; Crystallization; Crystallography, X-Ray; Differential Thermal Analysis; Hardness; Hydroxybenzoates; Magnetic Resonance Spectroscopy; Models, Molecular; Nitrophenols; Thermogravimetry

In an effort to enhance the photocatalytic activity of ZnO in natural sunlight, V2O5-ZnO nanocomposites were synthesized by co-precipitation technique. The characterization of the synthesized powders by FESEM, XRD and UV-visible diffuse reflectance spectroscopy (DRS) revealed that the both V2O5 and ZnO retain their individual identity in the composites but the increasing concentration of V2O5 affect the particle size of ZnO. As estimated by photoluminescence spectroscopy, in comparison to pure ZnO, the presence of V2O5 significantly suppressed the charge carrier's recombination process. The photocatalytic activity of the synthesized powders was evaluated for the degradation/mineralization of three potential nitrophenol pollutants (2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol). The synthesized composites showed significantly higher activity for both degradation and mineralization of nitrophenols compared to pure ZnO. The progress of the degradation process was evaluated by HPLC while mineralization was monitored by TOC analysis. The degradation/mineralization route was estimated by identifying the intermediates using GC-MS. The correlation of the experimental data revealed that the position of NO2 group in 2- and 4-nitrophenol significantly affect the rate of degradation. The identification of hydroxyl group containing intermediates in the degradation of 4-NP confirmed the formation and vital role of hydroxyl radicals in degradation process. The rapid mineralization of nitrophenol substrates pointed out superoxide anions as major contributors in degradation and mineralization process. The assessment of the release of relevant ions (NO2(-), NO3(-), ONOO(-) and NH4(+)) during the degradation process assisted in identifying the plausible interaction sites.

Topics: 2,4-Dinitrophenol; Chemical Precipitation; Environmental Restoration and Remediation; Nitrophenols; Photolysis; Vanadium Compounds; Water Pollutants, Chemical; Water Pollution, Chemical; Zinc Oxide

Inorganic polyphosphates, linear polymers of orthophosphate, occur naturally throughout biology and have many industrial applications. Their biodegradable nature makes them attractive for a multitude of uses, and it would be important to understand how polyphosphates are turned over enzymatically. Studies of inorganic polyphosphatases are, however, hampered by the lack of high-throughput methods for detecting and quantifying rates of polyphosphate degradation. We now report chromogenic and fluorogenic polyphosphate substrates that permit spectrophotometric monitoring of polyphosphate hydrolysis and allow for high-throughput analyses of both endopolyphosphatase and exopolyphosphatase activities, depending on assay configuration. These substrates contain 4-nitrophenol or 4-methylumbelliferone moieties that are covalently attached to the terminal phosphates of polyphosphate via phosphoester linkages formed during reactions mediated by EDAC (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide). This report identifies Nudt2 as an inorganic polyphosphatase and also adds to the known coupling chemistry for polyphosphates, permitting facile covalent linkage of alcohols with the terminal phosphates of inorganic polyphosphate.

Topics: Acid Anhydride Hydrolases; Alkaline Phosphatase; Digestion; Fluorescent Dyes; Hydrolysis; Nitrophenols; Polyphosphates

Burkholderia sp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) or para-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of the pnp genes in the pnpABA1CDEF cluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activity in vitro in the conversion of 2C4NP to CBQ. Genetic analyses indicated that pnpA plays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels.

Topics: Bacterial Proteins; Benzoquinones; Burkholderia; Mixed Function Oxygenases; Multigene Family; Nitrophenols; Quinone Reductases

Poultry feather is renewable, inexpensive and abundantly available. It holds great business potentials if poultry feather can be converted into valuable functional materials. Herein, we describe a strategy for the catalytic conversion of chicken feather waste to Ni3S2-carbon coaxial nanofibers (Ni3S2@C) which can be further converted to nitrogen doped carbon nanotubes (N-CNTs). Both Ni3S2@C and N-CNTs exhibit high catalytic activity and good reusability in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 with a first-order rate constant (k) of 0.9 × 10(-3) s(-1) and 2.1 × 10(-3) s(-1), respectively. The catalytic activity of N-CNTs is better than that of N-doped graphene and comparable to commonly used noble metal catalysts. The N content in N-CNTs reaches as high as 6.43%, which is responsible for the excellent catalytic performance. This strategy provides an efficient and low-cost method for the comprehensive utilization of chicken feathers. Moreover, this study provides a new direction for the application of N-CNTs.

Topics: Animals; Carbon; Catalysis; Chickens; Feathers; Nanofibers; Nanotubes, Carbon; Nitrogen; Nitrophenols; Oxidation-Reduction; Photoelectron Spectroscopy; Spectrophotometry, Ultraviolet; Spectrum Analysis, Raman; Waste Products; X-Ray Diffraction

The CoMn2O4 hierarchical microspheres assembled by nanosheets through thermal decomposition of the precursor at different temperatures were first used as catalysts in the reduction of p-nitrophenol to p-aminophenol. The sample prepared at 500 °C shows the highest catalytic activity (kapp 14.95 × 10(-3) s(-1)), which is even higher than some results reported for noble metal particles (Au, Ag and Pd). It is suggested that the presence of metal oxide with 'd(7)' (Co element) and 'd(5)' (Mn element) electronic configurations and the special morphology of CoMn2O4 hierarchical microspheres are beneficial to the reduction of p-nitrophenol to p-aminophenol.

Topics: Catalysis; Cobalt; Manganese Compounds; Metals; Microspheres; Nitrophenols; Oxidation-Reduction; Oxides

In this research, folic acid functionalized silver nanoparticles (FA-AgNPs) were selected as a colorimetric and a 'turn on' fluorescent sensor for detecting Hg(2+). After being added into Hg(2+), AgNPs can emit stable fluorescence at 440 nm when the excitation wavelength is selected at 275 nm. The absorbance and fluorescence of the FA-AgNPs could reflect the concentration of the Hg(2+) ions. Thus, we developed a simple, sensitive analytical method to detect Hg(2+) based on the colorimetric and fluorescence enhancement of FA-AgNPs. The sensor exhibits two linear response ranges between absorbance and fluorescence intensity with Hg(2+) concentration, respectively. Meanwhile, a detection limit of 1 nM is estimated based on the linear relationship between responses with a concentration of Hg(2+). The high specificity of Hg(2+) with FA-AgNPs interactions provided the excellent selectivity towards detecting Hg(2+) over other metal ions (Pb(2+), Mg(2+), Zn(2+), Ni(2+), Cu(2+), Co(2+), Ca(2+), Mn(2+), Fe(2+), Cd(2+), Ba(2+), Cr(6+) and Cr(3+)). This will provide a simple, effective and multifunctional colorimetric and fluorescent sensor for on-site and real-time Hg(2+) ion detection. The proposed method can be applied to the analysis of trace Hg(2+) in lake water. Additionally, the FA-AgNPs can be used as efficient catalyst for the reduction of 4-nitrophenol and potassium hexacyanoferrate (III).

Topics: Catalysis; Colorimetry; Coloring Agents; Ferricyanides; Fluorescence; Folic Acid; Gold; Limit of Detection; Mercury; Metal Nanoparticles; Nitrophenols; Sensitivity and Specificity; Silver

With a vision of finding greener materials to synthesize nanoparticles, we report the production and isolation of levan, a polysaccharide with repeating units of fructose, from Acetobacter xylinum NCIM2526. The isolated levan were characterized using potassium ferricyanide reducing power assay, Fourier transform infra-red (FTIR) spectroscopy and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR). To exploit levan in nanotechnology, we present a simple and greener method to synthesize silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using biopolymer, levan as both reducing and stabilizing agents. The morphology and stability of the AgNPs and AuNPs were examined by transmission electron microscopy (TEM) and UV-vis absorption (UV-vis) spectroscopy. The possible capping mechanism of the nanoparticles was postulated using FTIR studies. As synthesized biogenic nanoparticles showed excellent catalytic activity as evidenced from sodium borohydride mediated reduction of 4-nitro phenol and methylene blue.

Topics: Biopolymers; Catalysis; Fructans; Gluconacetobacter xylinus; Gold; Green Chemistry Technology; Metal Nanoparticles; Methylene Blue; Microscopy, Electron, Transmission; Nitrophenols; Reducing Agents; Silver; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared

Enzyme mimetics have recently attracted considerable interest because of their high stability and low cost. We developed a general H2O2-involved fluorescence system using Fe3O4 magnetic microspheres as peroxidase mimetics and benzoic acid (BA) as indicator. Glucose and p-nitrophenol were used as models to determine the characteristics and effectiveness of the system. Glucose oxidase hydrolyzes glucose, in the presence of oxygen, to H2O2 followed by the activation of Fe3O4 MMs, resulting in the catalyzed oxidation of benzoic acid. Glucose can be determined by the quantitative fluorescence production. p-Nitrophenol is determined as model compounds which competes with benzoic acid for H2O2 resulting in the decreased catalytic oxidation of benzoic acid with the Fe3O4 MMs. The detection limit of the Fe3O4/H2O2/BA system is 0.008 μM for H2O2, 0.025 μM for glucose and 0.05 μM for p-nitrophenol. Furthermore, the system had high sensitivity, good selectivity and was capable of sensing glucose in human serum and p-nitrophenol in water samples. The proposed system has great potential in the chemical/biological sensing of a variety of analytes associated with reactions that produce or consume H2O2.

Topics: Biosensing Techniques; Blood Glucose; Colorimetry; Ferric Compounds; Humans; Hydrogen Peroxide; Limit of Detection; Metal Nanoparticles; Molecular Mimicry; Nitrophenols; Peroxidase; Water Pollution, Chemical

In order to resolve the low adsorption capacity of the surface molecularly imprinting methods, an approach was developed for the preparation of magnetic imprinted polymers by pre-grafting the amino functional material, 3-aminopropyltriethoxysilane (APTES), on the surface of the silica coated magnetic substrate. APTES was used for amino functionalization of the silica coated Fe3O4 nanoparticles. Amino groups were used for immobilization of the template molecules on the magnetic surface and additionally to react with the terminal vinyl groups of cross-linker, ethylene glycol dimethacrylate (EGDMA), by the Michael addition reaction. In this way, the imprinting sites of the analytes formed on the substrate were increased. The sorbent was synthesized in the presence of 4-nitrophenol (4-NP) and EGDMA as the template and cross-linker, respectively. Different parameters affecting the adsorption, such as pH, desorption solvent type and adsorption time were evaluated and optimized. The prepared magnetic molecularly imprinted polymer (MMIP) showed high adsorption capacity and proper selectivity for the template molecule. The kinetic adsorption curve indicated that 90 min was sufficient to achieve the adsorption equilibrium for MMIP. The maximum adsorption capacity was 129.1 mg g(-1). The experiments exhibited a linear range of 10-3000 μg L(-1) for 4-NP with the correlation coefficient (R(2)) of 0.997. The results of the real sample analysis confirmed the applicability of the proposed MMIP for quantitative analysis of 4-NP in the aqueous samples.

Topics: Adsorption; Cross-Linking Reagents; Kinetics; Magnetite Nanoparticles; Magnets; Methacrylates; Molecular Imprinting; Nitrophenols; Polymers; Propylamines; Seawater; Silanes; Silicon Dioxide; Water Pollutants, Chemical

Electrolysis and ozonation are two commonly used technologies for treating wastewaters contaminated with nitrophenol pollutants. However, they are often handicapped by their slow kinetics and low yields of total organic carbon (TOC) mineralization. To improve TOC mineralization efficiency, we combined electrolysis using a boron-doped diamond (BDD) anode with ozonation (electrolysis-O3) to treat a p-nitrophenol (PNP) aqueous solution. Up to 91% TOC was removed after 60 min of the electrolysis-O3 process. In comparison, only 20 and 44% TOC was respectively removed by individual electrolysis and ozonation treatment conducted under similar reaction conditions. The result indicates that when electrolysis and ozonation are applied simultaneously, they have a significant synergy for PNP mineralization. This synergy can be mainly attributed to (i) the rapid degradation of PNP to carboxylic acids (e.g., oxalic acid and acetic acid) by O3, which would otherwise take a much longer time by electrolysis alone, and (ii) the effective mineralization of the ozone-refractory carboxylic acids to CO2 by OH generated from multiple sources in the electrolysis-O3 system. The result suggests that combining electrolysis with ozonation can provide a simple and effective way to mutually compensate the limitations of the two processes for degradation of phenolic pollutants.

Topics: Boron; Diamond; Electrodes; Electrolysis; Nitrophenols; Ozone; Water Pollutants, Chemical; Water Purification

Microbial granules cultivated in an aerobic bubble column sequencing batch reactor were used for reduction of Pd(II) and formation of biomass associated Pd(0) nanoparticles (Bio-Pd) for reductive transformation of organic and inorganic contaminants. Addition of Pd(II) to microbial granules incubated under fermentative conditions resulted in rapid formation of Bio-Pd. The reduction of soluble Pd(II) to biomass associated Pd(0) was predominantly mediated by H2 produced through fermentation. X-ray diffraction and scanning electron microscope analysis revealed that the produced Pd nanoparticles were associated with the microbial granules. The catalytic activity of Bio-Pd was determined using p-nitrophenol and Cr(VI) as model compounds. Reductive transformation of p-nitrophenol by Bio-Pd was ∼20 times higher in comparison to microbial granules without Pd. Complete reduction of up to 0.25 mM of Cr(VI) by Bio-Pd was achieved in 24 h. Bio-Pd synthesis using self-immobilized microbial granules is advantageous and obviates the need for nanoparticle encapsulation or use of barrier membranes for retaining Bio-Pd in practical applications. In short, microbial granules offer a dual purpose system for Bio-Pd production and retention, wherein in situ generated H2 serves as electron donor powering biotransformations.

Topics: Biomass; Catalysis; Chromium; Environmental Pollutants; Environmental Restoration and Remediation; Fermentation; Hydrogen; Metal Nanoparticles; Microbial Consortia; Microscopy, Electron, Scanning; Nitrophenols; Palladium; X-Ray Diffraction

Coupling of a bioelectrochemical system (BES) into the upflow anaerobic sludge blanket (UASB) was developed for enhanced p-nitrophenol (PNP) removal in this study. Compared to the control UASB reactor, both PNP removal and the formation of its final reductive product p-aminophenol (PAP) were notably improved in the UASB-BES system. With the increase of current density from 0 to 4.71 A m(-3), the rates of PNP removal and PAP formation increased from 6.16 ± 0.11 and 4.21 ± 0.29 to 6.77 ± 0.00 and 6.11 ± 0.28 mol m(-3) d(-1), respectively. More importantly, the required dosage of organic cosubstrate was significantly reduced in the UASB-BES system than that in the UASB reactor. Organic carbon flux analysis suggested that biogas production from organic cosubstrate was seriously suppressed while direct anaerobic reduction of PNP was not remarkably affected by current input in the UASB-BES system. This study demonstrated that the UASB-BES coupling system had a promising potential for the removal of nitrophenol-containing wastewaters especially without adequate organic cosubstrates inside.

Topics: Anaerobiosis; Bacteria, Anaerobic; Bioelectric Energy Sources; Bioreactors; Methane; Nitrophenols; Sewage; Wastewater; Water Pollutants, Chemical; Water Purification

Long-term stable 3 nm gold nanoparticles are prepared by a simple reaction between HAuCl4 and sodium borohydride in water under ambient conditions which very efficiently catalyze 4-nitrophenol reduction to 4-nitroaniline.

Topics: Aniline Compounds; Borohydrides; Catalysis; Chlorides; Gold; Gold Compounds; Metal Nanoparticles; Molecular Structure; Nitrophenols; Particle Size

In this contribution, we report a new type of Au nanoflower-based nitroaromatic pesticide degradation platform that is fast, efficient, and simple. We found a straightforward, economically viable, and "green" approach for the synthesis and stabilization of relatively monodisperse Au nanoflowers by using nontoxic chemical of hydroxylamine (NH2OH) without stabilizer and the adjustment of the pH environment. This experiment shows that these Au nanoflowers function as effective catalyst for the reduction of pendimethalin in the presence of NaBH4 (otherwise unfeasible if NaBH4 is the only agent employed), which was reflected by the UV/vis spectra of the catalytic reaction kinetics. Importantly, the novel degradation platform could be put in use in two different practical soil samples with satisfactory results under laboratory conditions. To demonstrate the feasibility and universality of our design, two other nitroaromatic pesticides, trifluralin, and p-nitrophenol, were selected and were successfully degraded using this degradation platform.

Topics: Catalysis; Environmental Restoration and Remediation; Gold; Kinetics; Nanostructures; Nitrophenols; Pesticides; Soil Pollutants; Trifluralin

The biodegradation of melamine and p-nitrophenol (PNP) and their impact on wastewater treatment was evaluated after a short-term individual chemical loading in activated sludge treatment systems. Melamine was not degraded and quickly washed out of the system. PNP was degraded, but it led to a prolonged period of nitrification inhibition and deterioration of effluent quality. Both melamine and PNP loadings increased the effluent nitrogen concentrations, with their main contributors being melamine and NH4+, respectively. Nitrosomonas and Nitrospira were dominant in the activated sludge. Melamine did not affect the nitrifying assemblages, whereas PNP led to a reduced Nitrosomonas population size and complete washout of Nitrobacter. The results suggest that melamine is an inert compound if it enters the treatment facility for a short duration. Although the short-term exposure of melamine or PNP decreased effluent water quality,the impact of such aromatic nitrogen compounds on wastewater treatment performance may vary significantly. Water

Topics: Bacteria; Bioreactors; Nitrophenols; Time Factors; Triazines; Wastewater; Water Pollutants, Chemical

Nitrophenols are hazardous and toxic to living organisms. For this study, ferrihydrite was prepared to test its capabilities for p-nitrophenol degradation. A ferrihydrite particle prepared in neutral environmental conditions is sphere-like with a diameter of 2-4 nm and its total surface area is approximately 229 m2 x g(-1). The combination of ferrihydrite and trace H2O2 is effective for the degradation of p-nitrophenol under simulated sunlight irradiation. Hydroquinone, the initial intermediate of p-nitrophenol decomposition, autocatalyses the subsequent degradation of p-nitrophenol because it accelerates the photo-reductive dissolution of ferrihydrite. The effect of key operating parameters such as ferrihydrite dosage, initial solution pH and H2O2 dosage were also studied on the photocatalytic degradation of p-nitrophenol. The results indicate that the combination of 0.2 g x L(-1) ferrihydrite, 0.45 mmol x L(-1) H2O2 is highly efficient for the degradation of p-nitrophenol (0.15 mmol x L(-1)) at pH 2.5-3.0. A ferrihydrite was reused several times, still keeping its original photocatalysis.

Topics: Ferric Compounds; Hydrogen Peroxide; Nitrophenols; Photolysis; Water Pollutants, Chemical

A novel, "wet" and "clean" methodology was developed to prepare Fe(x)Co(100-x) nanoparticles on reduced graphene oxide (RGO) surfaces in an aqueous solution through a coreduction process. Without any surface treatment, Fe(x)Co(100-x) nanoparticles can in situ grow on the RGO sheets. It was found that RGO nanosheets can effectively prevent the aggregation of Fe(x)Co(100-x) nanoparticles. The results reveal that the RGO/Fe(x)Co(100-x) nanocomposites have ferromagnetic characteristics and show composition dependent magnetic properties. The effectiveness of the as-prepared RGO/Fe(x)Co(100-x) nanocomposites as solid phase heterogeneous catalysts have been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess sodium borohydride. The effect of initial 4-NP concentration, and catalyst loading dose were evaluated. The catalyst efficiency was examined on the basis of turnover frequency (TOF) and recyclability. The RGO/Fe25Co75 nanocomposites exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the graphene oxide (GO) supports also enhance the catalytic activity via a synergistic effect. The as-prepared RGO/Fe(x)Co(100-x) nanocomposite catalysts are very efficient, stable, easy to prepare, eco-friendly, cost-effective, and have potential industrial applications.

Topics: Aminophenols; Catalysis; Cobalt; Graphite; Iron; Magnets; Nanocomposites; Nanotechnology; Nitrophenols; Oxidation-Reduction; Oxides

Silver/iron oxide composite nanoparticles have been synthesized successfully via a facile one-pot green route by the use of l-arginine, which created an aqueous solution of about pH 10 and acted as a reducing agent for the successive formation of iron oxide and Ag nanoparticles. The product was characterized to be silver-coated iron oxide and iron oxide hydroxide composite nanoparticles with a mean diameter of about 13.8 ± 3.0 nm and 8.53% of Ag in weight. It exhibited good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride. The reduction reaction followed the pseudo-first-order kinetics. The corresponding rate constants increased with the increases of temperature and catalyst amount but decreased with the increase of initial 4-NP concentration, revealing an activation energy of 28.2 kJ/mol and a diffusion controlled mechanism. In addition, this product had quite good stability. No significant activity loss was observed after reuse for 5 cycles.

Topics: Arginine; Ferric Compounds; Green Chemistry Technology; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Silver; Waste Disposal, Fluid; Water Pollutants, Chemical

FT-IR and FT-Raman spectra of 2-methyl-4-nitrophenol (PNOC) and 3-methyl-4-nitrophenol (PNMC) were recorded and analyzed in the solid phase in the region 4000-400 cm(-1) and 3500-50 cm(-1) respectively. Molecular modeling of the compounds PNOC and PNMC were done by the density functional theoretical (DFT) method using Becke's three parameter exchange functional combined with the Lee-Yang-Parr correlation functional with 6-31G(d) as basis set. Vibrational assignments of the two compounds have been carried out with the help of Normal coordinate analyses (NCA) followed by the Scaled Quantum Mechanical Force Field calculations (SQMFF). Intra-molecular charge transfer and delocalization within the molecule is confirmed with the aid of natural bond orbital analysis (NBO). PNOC and PNMC are similar compounds with same functional groups, only the position of the methyl group is different. The effect of the position change of the methyl group was interpreted with the vibrational spectra.

Topics: Methylation; Models, Molecular; Nitrophenols; Quantum Theory; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman

A novel visible light sensitized photoelectrochemical sensing platform was constructed based on the perylene-3,4,9,10-tetracarboxylic acid/titanium dioxide (PTCA/TiO(2)) heterojunction as the photoelectric beacon. PTCA was synthesized via facile steps of hydrolysis and neutralization reaction, and then the PTCA/TiO(2) heterojunction was easily prepared by coating PTCA on nano-TiO(2) surface. The resulting photoelectric beacon was characterized by transmission electron microscope, scanning electron microscopy, X-ray diffractometry, FTIR spectroscopy, and ultraviolet and visible spectrophotometer. Using parathion-methyl as a model, after a simple hydrolyzation process, p-nitrophenol as the hydrolysate of parathion-methyl could be obtained, the fabricated derivative photoelectrochemical sensor showed good performances with a rapid response, instrument simple and portable, low detection limit (0.08 nmol L(-1)) at a signal-to-noise ratio of 3, and good selectivity against other pesticides and possible interferences. It had been successfully applied to the detection of parathion-methyl in green vegetables and the results agreed well with that by GC-MS. This strategy not only extends the application of PTCA, but also presents a simple, economic and novel methodology for photoelectrochemical sensing.

Topics: Carboxylic Acids; Electrochemical Techniques; Electrodes; Gas Chromatography-Mass Spectrometry; Light; Metal Nanoparticles; Methyl Parathion; Nitrophenols; Perylene; Pesticides; Titanium; Vegetables

The gamma irradiation-induced degradation of sulfamethazine (SMT) in aqueous solution in the presence of hydrogen peroxide (H2O2) was investigated. The initial SMT concentration was 20mg/L and it was irradiated in the presence of extra H2O2 with initial concentration of 0, 10 and 30 mg/L. The results showed that gamma irradiation was effective for removing SMT in aqueous solution and its degradation conformed to the pseudo first-order kinetics under the applied conditions. When initial H2O2 concentration was in the range of 0-30 mg/L, higher concentration of H2O2 was more effective for the decomposition and mineralization of SMT. However, the removal of total organic carbon (TOC) was not as effective as that of SMT. Total nitrogen (TN) was not removed even at absorbed dose of 5 kGy, which was highest dose applied in this study. Major decomposition products of SMT, including degradation intermediates, organic acids and some inorganic ions were detected by high performance liquid chromatography (HPLC) and ion chromatography (IC). Sulfate (SO4(2-)), formic acid (HCOOH), acetic acid (CH3COOH), 4-aminophenol, 4-nitrophenol were identified in the irradiated solutions. Possible pathways for SMT decomposition by gamma irradiation in aqueous solution were proposed.

Topics: Acetic Acid; Aminophenols; Anti-Bacterial Agents; Carbon; Chromatography; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Formates; Gamma Rays; Hydrogen Peroxide; Kinetics; Nitrophenols; Organic Chemicals; Oxygen; Sulfamethazine; Sulfates; Waste Disposal, Fluid; Water Pollutants, Chemical

Four lipases were purified from ID17, a thermophilic bacterium belonging to Geobacillus genus isolated from Deception Island, Antarctica. Lipase activity was detected by opacity test and p-nitrophenyl laurate methods. Lipase production was better in a medium containing tryptone as the carbon and nitrogen source, without non-ionic detergents and pH 7.5. Proteins were ultrafiltered from supernatant and separated using anion exchange and size exclusion chromatography resulting in four distinct fractions with lipase activity (called Lip1-4). Purified lipases showed an optimal pH at 9.0, 9.5, 10.0 and 8.0 and temperature at 65, 70, 75 and 80 °C for Lip1-4, respectively. Lip1 and Lip2 showed higher activity using p-nitrophenol decanoate as substrate, whereas Lip3 and Lip4 prefer p-nitrophenol laurate. Based on their molecular weight Lip1 and Lip2 are trimeric and pentameric proteins, respectively, whereas Lip3 and Lip4 are monomeric proteins. Lip1 was exceptionally thermostable maintaining 70 % of its activity after incubating it at 70 °C for 8 h. Based on their characteristics, the four lipases obtained from ID17 are good candidates to understand the mechanisms of lipase stability and to be used in different types of industrial applications.

Topics: Antarctic Regions; Geobacillus; Hydrogen-Ion Concentration; Laurates; Lipase; Nitrophenols; Protein Multimerization; Substrate Specificity

In this study, the US-ZVI system was used to produce the strong reductants including H and nascent Fe(2+) ions to eliminate the toxicity of the high concentration p-nitrophenol (PNP) wastewater. The effect of the reactor structure, initial pH, ZVI dosage, ultrasonic power and initial PNP concentration on the removal efficiency of PNP from water was investigated intensively. The results show that a higher removal rate can be obtained by using a conical structure reactor, and the lower initial pH can aid the acceleration of PNP removal rate by using US-ZVI system. Furthermore, the removal efficiencies of PNP increased obviously with the increase of initial ZVI concentration from 0 to 15 gL(-1). Also, the treatment capacity of ZVI was enhanced remarkably by the ultrasonic irradiation, and the US-ZVI system can maintain high treatment efficiency for the high concentration PNP wastewater (500-10,000 mgL(-1)). Meanwhile, the high removal efficiency of PNP was mainly resulted from the synergistic reaction of ZVI and US. At last, the main degradation product (i.e., p-aminophenol) was detected by gas chromatography-mass spectrum (GC-MS). Thus, the reaction pathway of PNP in the US-ZVI system is proposed as a reducing process by the H and nascent Fe(2+) ions.

Topics: Gas Chromatography-Mass Spectrometry; Hydrogen-Ion Concentration; Ions; Iron; Kinetics; Models, Chemical; Nitrophenols; Ultrasonics; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical; Water Pollution; Water Purification

We report the facile one-pot single-phase syntheses of silver nanoparticles stabilized by norbornene type cationic polymers. Silver nanoparticles (AgNPs) stabilized by polyguanidino oxanorbornenes (PG) at 5 and 25 kDa and polyamino oxanorbornenes (PA) at 3 and 15 kDa have been synthesized by the reduction of silver ions with NaBH4 in aqueous solutions at ambient temperature. The four different silver nanoparticles have been characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM) for their particle size distributions. Interestingly, PG stabilizes the silver nanoparticles better than PA as evident from our spectroscopic data. Furthermore, the AgNP-PG-5K (5K = 5 kDa) was found to serve as an effective catalyst for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. The reduction has a pseudo-first-order rate constant of 5.50 × 10(-3) s(-1) and an activity parameter of 1375 s(-1) g(-1), which is significantly higher than other systems reported in the literature.

Topics: Catalysis; Cations; Metal Nanoparticles; Molecular Structure; Nitrophenols; Oxidation-Reduction; Particle Size; Plastics; Silver; Surface Properties

In this study, an analytical procedure for the selective extraction and detection of 4-nitrophenol (4-NP) was investigated by using of molecularly imprinted polymer on the surface of magnetic nanoparticles (MNPs). The magnetic nanoparticles were modified by tetraethyl orthosilicate (TEOS) and 3-methacryloxypropyl trimethoxysilane (MPTS) before imprinting. The magnetic molecularly imprinted polymer (MMIP) was polymerized at the surface of modified MNPs by using of methacrylic acid (MAA) as functional monomer, 4-NP as template and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Experimental design by the Taguchi method was used for the optimization of synthesis procedure of imprinted polymer. The resulting MMIP showed high adsorption capacity, proper selectivity and fast kinetic binding for the template molecule. It was characterized by Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. The maximum adsorption capacity of MMIP was obtained as 57.8mgg(-1) and it took about 2h to achieve the equilibrium state. The adsorption curve of MMIP was also fitted with the Freundlich isotherm equation. The assay exhibited a linear range of 25-1000μgL(-1) for 4-NP with the correlation coefficient (R(2)) of 0.995. The method was also examined for the analysis of 4-NPs in seawater. For recovery evaluation, the seawater samples were spiked at two concentration levels of 50 and 100μgL(-1) of 4-NPs and the recovery values were in the range of 79.3-99.8%. The relative standard deviations (RSD) for the recoveries were less than 5.2%.

Topics: Adsorption; Magnetite Nanoparticles; Methacrylates; Molecular Imprinting; Nitrophenols; Reproducibility of Results; Seawater; Silanes; Water Pollutants, Chemical

This paper presents the fabrication of a molecularly imprinting sol-gel hybrid film by the one-step electrodeposition of the constitutional individuals including chitosan (CS), phenyltrimethoxysilane (PTMS), in situ formed gold nanoparticles (AuNPs) and template p-nitrophenol (p-NP). The electrodeposition was triggered by applying an optimal potential at -0.30 V vs. SCE, leading to the formation of the p-NP imprinting CS/PTMS/AuNPs hybrid film on a glassy carbon electrode (GCE) with a roughly architectural and conductive nature, as revealed by scanning electron microscopy and electrochemical impedance analysis. The mechanism of the hybrid film formation was discussed accordingly. Upon complete removal of the template molecules assisted by cyclic voltammetry, the p-NP imprinted film modified electrode exhibited differential pulse voltammetric (DPV) responses to p-NP in a linear range from 3.0 × 10(-8) to 3.5 × 10(-4) M with a detection limit of 5.0 × 10(-9) M. The selectivity and reusability of the sensor was demonstrated by discriminating the p-NP response from its analogues and successive rebinding/debinding cycles, respectively. The methodology is extendable as a simple and general platform for developing hybrid film sensors for the specific determination of various electrochemically active species.

Topics: Chitosan; Electrochemical Techniques; Electroplating; Gold; Limit of Detection; Molecular Imprinting; Nanoparticles; Nitrophenols; Organosilicon Compounds; Reproducibility of Results

Highly ordered noncrystalline boron-doped nickel nanotube arrays are rapidly synthesized within 150 s by template-based electroless deposition. The as-prepared nanotubes have tunable magnetic properties and exhibit super efficient catalytic activity (∼70 s) for the reduction of 4-nitrophenol.

Topics: Borohydrides; Boron; Catalysis; Crystallization; Gases; Magnetics; Nanotubes; Nickel; Nitrophenols; Oxidation-Reduction; Surface Properties; Temperature

Bacteria in raw milk can produce heat-stable lipases, which survive pasteurisation and subsequently reduce the shelf life of dairy products because of their ability to break down the milk fat and increase rancidity. In this study, four bacteria, originating from the surfaces of raw milk transport tankers, and a known lipase-producing bacterium were evaluated for their ability to produce lipolysis in planktonic and biofilm cultures. Lipolysis was determined using two separate assays that measured hydrolysis of the ester p-nitrophenol palmitate (pnpp) and the lipid tributyrin. The hydrolysis of pnpp per CFU within biofilms and planktonic cultures ranged from 0.01 to 8.35 and 0.01 to 0.07 nU/CFU respectively. The amount of butyric acid released from hydrolysis of tributyrin per CFU within biofilms and planktonic cultures ranged from 0.1 to 1110.3 and 0.1 to 0.3 ng/CFU, respectively. The hydrolysis of pnpp and tributyrin per CFU within biofilms was at least 10 times higher compared with the corresponding planktonic cultures. This is the first study to show that lipolysis occurs within biofilms of bacteria that were originally isolated from the surfaces of raw milk tankers. This is relevant to the dairy industry, highlighting the importance of eliminating biofilms on milk tanker surfaces as a source of heat-stable lipases.

Topics: Animals; Bacteria; Biofilms; Coculture Techniques; Food Microbiology; Food-Processing Industry; Lipase; Lipolysis; Milk; Nitrophenols

In this study, we observed that modification of nano-oxides (e.g., nano-SiO2) with cationic surfactants (e.g., cetyl pyridinium chloride, CPC) could be a potential way to make nano-oxides be superior sorbents with a partition mechanism for the sorptive removal of organic contaminants from wastewater where the coated CPC was an effective organic phase for partitioning. The partitioning of nonpolar naphthalene into coated CPC was induced by hydrophobic effect alone and presenting linear isotherms, while that of polar p-nitrophenol was induced by not only the hydrophobic effect but also the hydrogen-bonding interaction and presenting isotherm nonlinearity. The sorption affinity for naphthalene and p-nitrophenol partitioning into the coated CPC and the configuration of coated CPC remained unchanged although the amounts of coated CPC were increased. Linear relationships were established between the coated CPC amounts and the sorption capacities of naphthalene or p-nitrophenol, which could be used to predict the sorption of organic contaminants on surfactant-modified nano-oxides. In addition, these observed results would be also valuable for estimating the environmental behaviors and risks of nano-SiO2 and organic contaminants because nano-SiO2 would be inevitably coated with ubiquitous surfactants in the environment due to the discharging from the wide domestic and industry applications.

Topics: Adsorption; Cations; Cetylpyridinium; Models, Chemical; Nanoparticles; Naphthalenes; Nitrophenols; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Surface-Active Agents; Temperature

Extracellular activation of hydrophilic glucuronide prodrugs by β-glucuronidase (βG) was examined to increase the therapeutic efficacy of bacteria-directed enzyme prodrug therapy (BDEPT). βG was expressed on the surface of Escherichia coli by fusion to either the bacterial autotransporter protein Adhesin (membrane βG (mβG)/AIDA) or the lipoprotein (lpp) outermembrane protein A (mβG/lpp). Both mβG/AIDA and mβG/lpp were expressed on the bacterial surface, but only mβG/AIDA displayed enzymatic activity. The rate of substrate hydrolysis by mβG/AIDA-BL21cells was 2.6-fold greater than by pβG-BL21 cells, which express periplasmic βG. Human colon cancer HCT116 cells that were incubated with mβG/AIDA-BL21 bacteria were sensitive to a glucuronide prodrug (p-hydroxy aniline mustard β-D-glucuronide, HAMG) with an half maximal inhibitory concentration (IC50) value of 226.53±45.4 μM, similar to the IC50 value of the active drug (p-hydroxy aniline mustard, pHAM; 70.6±6.75 μM), indicating that mβG/AIDA on BL21 bacteria could rapidly and efficiently convert HAMG to an active anticancer agent. These results suggest that surface display of functional βG on bacteria can enhance the hydrolysis of glucuronide prodrugs and may increase the effectiveness of BDEPT.

Topics: Carrier Proteins; Escherichia coli; Glucuronates; Glucuronidase; Glucuronides; HCT116 Cells; Humans; Nitrophenols; Prodrugs; Recombinant Proteins; Tumor Cells, Cultured

Phase inversion of polymer casting mixtures filled with hierarchical functional nanostructures is proposed as a synthetic route for the design of multifunctional membranes. The study tested the hypothesis that by regulating the relative content of components representing different levels in the nanofiller hierarchy, the structure and additional functions of such membranes could be controlled separately. Exfoliated graphite nanoplatelets (xGnPs) decorated by Au nanoparticles (Au NPs), used as a model hierarchical nanofiller, were added to the casting mixture of polysulfone, N-Methyl-2-pyrrolidone and polyethylene glycol prior to forming the membrane by phase inversion. The resulting porous asymmetric nanocomposites were shown to be permselective and catalytically active ultrafiltration membranes that were more resistant to compaction, more permeable than xGnP-free membranes and at least as selective. By designing membrane compositions with different relative amounts of Au-decorated xGnPs and Au-free xGnPs, the structure (controlled by the loading of xGnPs) and catalytic activity (controlled by the loading of Au NPs) could be controlled largely independently.

Topics: Dextrans; Environment; Gold; Graphite; Membranes, Artificial; Molecular Weight; Nanocomposites; Nitrophenols; Permeability; Polymers; Sulfones; Tensile Strength; Water Purification

This study confirmed the feasibility of natural limonite working as the iron catalyst for the PNP wastewater treatment in the BES-Fenton system. After the start-up period of the BES-Fenton systems, air and limonite powder were injected into the cathode chamber as the original materials for manufacturing Fenton reagents of H₂O₂ and Fe(II) respectively. The experiment parameters like pH, external resistance, limonite dosage and initial PNP concentration were investigated in this research. The removal efficiency of PNP (0.25 mM) could achieve 96% in 6h under the optimal experimental conditions. A limonite dosage of 112 mg per 50 ml of PNP solution at 0.25 mM concentration each time could sustain 7 cycles of the BES-Fenton system operation with PNP removal efficiency >94%. This study suggests an efficiency and cost-effective approach for the PNP removal by using the natural limonite as the iron catalyst of the BES-Fenton system.

Topics: Ferric Compounds; Hydrogen Peroxide; Hydrogen-Ion Concentration; Nitrophenols; Waste Disposal, Fluid; Water Pollutants, Chemical

We report results of the studies relating to the fabrication and characterization of a conducting polymer based molecularly imprinted para-nitrophenol (PNP) sensor. A water pollutant, para-nitrophenol is electrochemically imprinted with polyvinyl sulphonic acid (PVSA) doped polyaniline onto indium tin oxide (ITO) glass substrate. This PNP imprinted electrode (PNPI-PANI-PVSA/ITO) prepared via chronopotentiometric polymerization and over-oxidation is characterized by Fourier transform infra-red spectroscopy (FT-IR), UV-visible (UV-vis) spectroscopy, contact angle (CA), scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies. The response studies of PNPI-PANI-PVSA/ITO electrode carried out using DPV reveal a lower detection limit of 1×10(-3) mM, improved sensitivity as 1.5×10(-3) A mM(-1) and stability of 45 days. The PNPI-PANI-PVSA/ITO electrode shows good precision with relative standard deviation of 2.1% and good reproducibility with standard deviation of 3.78%.

Topics: Aniline Compounds; Biosensing Techniques; Limit of Detection; Microscopy, Electron, Scanning; Molecular Imprinting; Molecular Structure; Nitrophenols; Polymers; Polyvinyls; Reproducibility of Results; Spectroscopy, Fourier Transform Infrared; Sulfonic Acids

Three porphyrins containing different functional groups (-OH, C-O2C2H5, -COOH), 5-(4-hydroxy) phenyl-10,15,20-triphenyl porphyrin (1a), 5-(4-ethylacetatatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1b), 5-(4-carboxylatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1c), were synthesized and characterized spectroscopically. The CuPp(2a, 2b, 2c)-TiO2 photocatalysts were then prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS), Fourier-transform infrared spectroscopy (FT-IR). The photocatalytic activities of the photocatalysts were investigated by carrying out the photodegradation of 4-nitrophenol in aqueous solution under simulated solar irradiation. It was found that the CuPp(2a, 2b, 2c)-TiO2 enhanced the photocatalytic efficiency of bare TiO2 in photodegrading the 4-NP due to the interaction between CuPp(2a, 2b, 2c) and TiO2, resulted in the enhancement of the photogenerated electron-hole separation. The reasons of this enhanced photocatalytic activity were also discussed. Based on the present study, it could be considered as a promising photocatalyst for the further industrial application.

Topics: Catalysis; Luminescence; Metalloporphyrins; Microscopy, Electron, Transmission; Nitrophenols; Photoelectron Spectroscopy; Photolysis; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Sunlight; Temperature; Titanium; X-Ray Diffraction

In this work, a facile approach was successfully developed for in situ catalyzing Au nanoparticles loaded on Fe3O4@SiO2 magnetic nanospheres via Sn(2+) linkage and reduction. After the Fe3O4@SiO2 MNPs were first prepared via a sol-gel process, only one step was needed to synthesize the Fe3O4@SiO2-Au magnetic nanocomposites (Fe3O4@SiO2-Au MNCs), so that both the synthesis step and the reaction cost were remarkably decreased. Significantly, the as-synthesized Fe3O4@SiO2-Au MNCs showed high performance in the catalytic reduction of 4-nitrophenol to 4-aminophenol and could be reused for several cycles with convenient magnetic separability. This approach provided a useful platform based on Fe3O4@SiO2 MNPs for the fabrication of Au or other noble metal magnetic nanocatalysts, which would be very useful in various catalytic reductions.

Topics: Aminophenols; Catalysis; Ferrosoferric Oxide; Gold; Magnetics; Metal Nanoparticles; Nanocomposites; Nitrophenols; Oxidation-Reduction; Silicon Dioxide

Au nanostructures attract much attention due to their potential applications in many fields. The controlled synthesis is critical to their properties modulation and applications. AgNO3-assisted synthesis is a widely used method for controllably preparing Au nanostructures in aqueous system. Herein, the effect of AgNO3 on the growth of Au nanostructures in polyol is studied. We observe an unusual effect that AgNO3 can induce the formation of pentatwinned Au nanostructures (nanorods and decahedra) and block the growth of Au nanorods. More interestingly, this blocking effect can be tuned through controlling the amount of AgNO3. A moderate amount of AgNO3 facilitates the formation of Au nanorods. A large amount of AgNO3 completely blocks the growth of nanorods and favors the formation of high quality decahedra (decahedra can be considered as nanorods with 0 nm longitudinal length). Besides, this blocking effect also allows preparation of different high-index-faceted Au nanobipyramids. These prepared Au nanostructures further serve as starting templates to fabricate other heterostructured Au/Ag nanomaterials, such as Ag-Au-Ag segmental nanorods, Au@Ag core-shelled nanostructures. The prepared nanostructures exhibit size- and structure-dependent catalytic performance in the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.

Topics: Aminophenols; Borohydrides; Catalysis; Gold; Nanostructures; Nanotubes; Nitrophenols; Oxidation-Reduction; Polymers; Silver Nitrate; Temperature

Stable Pickering emulsions were prepared using only graphene oxide (GO) as a stabilizer, and the effects of the type of oil, the sonication time, the GO concentration, the oil/water ratio, and the pH value on the stability, type, and morphology of these emulsions were investigated. In addition, the effects of salt and the extent of GO reduction on emulsion formation and stability were studied and discussed. The average droplet size decreased with sonication time and with GO concentration, and the emulsions tended to achieve good stability at intermediate oil/water ratios and at low pH values. In all solvents, the emulsions were of the oil-in-water type, but interestingly, some water-in-oil-in-water (w/o/w) multiple emulsion droplets were also observed with low GO concentrations, low pH values, high oil/water ratios, high salt concentrations, or moderately reduced GO in the benzyl chloride-water system. A Pickering emulsion stabilized by Ag/GO was also prepared, and its catalytic performance for the reduction of 4-nitrophenol was investigated. This research paves the way for the fabrication of graphene-based functional materials with novel nanostructures and microstructures.

Topics: Emulsions; Graphite; Hydrogen-Ion Concentration; Nanostructures; Nitrophenols; Oils; Oxides; Salts; Silver; Surface-Active Agents; Water

Bio-nanomaterials fabricated using a bioinspired templating technique represent a novel class of composite materials with diverse applications in biomedical, electronic devices, drug delivery, and catalysis. In this study, Au nanoparticles (NPs) are synthesized within the solvent channels of cross-linked lysozyme crystals (CLLCs) in situ without the introduction of extra chemical reagents or physical treatments. The as-prepared AuNPs-in-protein crystal hybrid materials are characterized by light microscopy, transmission electron microscopy, x-ray diffraction, and Fourier-transform infrared spectroscopy analyses. Small AuNPs with narrow size distribution reveal the restriction effects of the porous structure in the lysozyme crystals. These composite materials are proven to be active heterogeneous catalysts for the reduction of 4-nitrophenol to 4-aminophenol. These catalysts can be easily recovered and reused at least 20 times because of the physical stability and macro-dimension of CLLCs. This work is the first to use CLLCs as a solid biotemplate for the preparation of recyclable high-performance catalysts.

Topics: Aminophenols; Catalysis; Cross-Linking Reagents; Crystallization; Gold; Metal Nanoparticles; Muramidase; Nitrophenols; Recycling; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Time Factors; X-Ray Diffraction

Inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites with molecular recognitive photocatalytic activity were first prepared successfully by a facile one-step sol-gel method using 2-nitrophenol and 4-nitrophenol as template molecules, and tetrabutyl orthotitanate as titanium source as well as the precursor of functional monomer which could complex with template molecules. The template molecules could be completely removed by means of high-temperature calcination, avoiding the traditional extraction procedures that are time- as well as solvent-consuming. Compared to nonimprinted TiO2/WO3, the molecularly imprinted TiO2/WO3 shows a much higher adsorption capacity and selectivity toward the template molecules. The enhancement in terms of adsorption capacity and selectivity can be attributed to the chemical interaction between target molecules and imprinted cavities, as well as size matching between imprinted cavities and target molecules. The photocatalytic activity of molecularly imprinted TiO2/WO3 toward the target molecules is more than two times that of non-imprinted TiO2/WO3, a result of selective adsorption of target molecules on molecularly imprinted TiO2/WO3. The formation pathway of intermediate products in 2-nitrophenol and 4-nitrophenol degradation process was provided. Moreover, molecularly imprinted TiO2/WO3 exhibits high stability. The results indicate that inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites have a promising prospect in the treatment of wastewater for irrigation.

Topics: Catalysis; Light; Molecular Imprinting; Nanocomposites; Nitrophenols; Oxides; Photolysis; Recycling; Titanium; Tungsten; Waste Disposal, Fluid; Water Pollutants, Chemical

Adsorption equilibria and kinetics of p-nitrophenol adsorbed on HJ-01 were investigated in this study. The result indicated that phenoxy groups were uploaded on the skeleton of HJ-01 successfully, the Friedel-Crafts reaction brought on prodigious changes for the Brunauer-Emmett-Teller (BET) specific surface area and pore structure while the nucleophilic substitution reaction had few effects. The adsorption experiments revealed that the acidic solution was suitable for p-nitrophenol adsorption, the adsorption isotherms could be characterized by the Freundlich isotherm equation and the adsorption thermodynamic parameters were all negative, the adsorption kinetic curves obeyed the pseudo-second-order rate equation.

Topics: Adsorption; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Polystyrenes; Thermodynamics

We report a simple biogenic-route to narrow the band gap of TiO2 nanocrystals for visible light application by offering a greener method. When an electrochemically active biofilm (EAB) was challenged with a solution of Degussa-TiO2 using sodium acetate as the electron donor, greyish blue-colored TiO2 nanocrystals were obtained. A band gap study showed that the band gap of the modified TiO2 nanocrystals was significantly reduced (E(g) = 2.85 eV) compared to the unmodified white Degussa TiO2 (E(g) = 3.10 eV).

Topics: Bioelectric Energy Sources; Catalysis; Cerium; Electrochemical Techniques; Light; Methylene Blue; Nanoparticles; Nitrophenols; Titanium

Montmorillonite (MMT) was converted to organoclays by intercalation of cationic surfactants into its interlayer space. Two types of organoclays were prepared from different surfactants (DDTMA and DDDMA) at different surfactant loadings, and the structural changes in the clays investigated using various techniques. The arrangements of surfactant molecules in the interlayer space was visually aided by molecular mechanical calculation (MM calculation), and the adsorption capacities of MMT and the organoclays for the removal of p-chlorophenol (PCP) and p-nitrophenol (PNP) from aqueous solutions were tested under different conditions. Two adsorption isotherm models (Langmuir and Freundlich isotherms) were used to determine the best fit model and the Freundlich isotherm was found to provide better fit for both PCP and PNP. Due to its hydrophobic properties, the adsorption is more favourable for PNP than PCP. Overall, the adsorption capacity of the organoclays was significantly improved by intercalation with large surfactant molecules as well as highly loaded surfactants as the intercalation with large surfactant molecules created the partitioning phase, which strongly attracted large amounts of organic pollutants. Possible mechanisms and the implications of the results for the use of these organoclays as adsorbents for the removal of phenols from the environment are discussed.

Topics: Adsorption; Aluminum Silicates; Bentonite; Chlorophenols; Clay; Nitrophenols; Phenols; Quaternary Ammonium Compounds; Surface-Active Agents; Water Pollutants, Chemical; X-Ray Diffraction

4-Nitrophenol (4-NP) is a prioritized environmental pollutant and its toxicity has been investigated using zebrafish, advocated as an alternative toxicological model. However, molecular information of 4-NP induced hepatotoxicity is still limited. This study aimed to obtain molecular insights into 4-NP-induced hepatotoxicity using zebrafish as a model.. Adult male zebrafish were exposed to 4-NP for 8, 24, 48 and 96h. Livers were sampled for microarray experiment, qRT-PCR and various histological analyses.. Transcriptomic analysis revealed that genes associated with oxidative phosphorylation and electron transport chain were significantly up-regulated throughout early and late stages of 4-NP exposure due to oxidative phosphorylation uncoupling by 4-NP. This in turn induced oxidative stress damage and up-regulated pathways associated with tumor suppressors Rb and p53, cell cycle, DNA damage, proteasome degradation and apoptosis. Pathways associated with cell adhesion and morphology were deregulated. Carbohydrate and lipid metabolisms were down-regulated while methionine and aromatic amino acid metabolisms as well as NFKB pathway associated with chronic liver conditions were up-regulated. Up-regulation of NFKB, NFAT and interleukin pathways suggested hepatitis. Histological analyses with specific staining methods and qRT-PCR analysis of selected genes corroborated with the transcriptomic analysis suggesting 4-NP induced liver injury.. Our findings allowed us to propose a plausible model and provide a broader understanding of the molecular events leading to 4-NP induced acute hepatotoxicity for future studies involving other nitrophenol derivatives.. This is the first transcriptomic report on 4-NP induced hepatotoxicity.

Topics: Animals; Gene Expression Profiling; Liver; Nitrophenols; Oxidative Phosphorylation; Transcriptome; Zebrafish

A sequencing batch reactor (SBR) was inoculated with p-nitrophenol-degrading activated sludge to biodegrade a mixture of monosubstituted phenols: p-nitrophenol (PNP), PNP and o-cresol; and PNP, o-cresol and o-chlorophenol. Settling times were progressively decreased to promote biomass granulation. PNP was completely biodegraded. The PNP and o-cresol mixture was also biodegraded although some transitory accumulation of intermediates occurred (mainly hydroquinone and catechol). o-Chlorophenol was not biodegraded and resulted in inhibition of o-cresol and PNP biodegradation and complete failure of the SBR within a few days. The biomass had very good settling properties when a settling time of 1 min was applied: sludge volume index (SVI₅) below 50 mL g(-1), SVI₅/SVI₃₀ ratio of 1 and average particle size of 200 μm.

Topics: Acinetobacter; Aerobiosis; Arthrobacter; Batch Cell Culture Techniques; Biodegradation, Environmental; Biomass; Bioreactors; Catechols; Chlorophenols; Cresols; Hydroquinones; In Situ Hybridization, Fluorescence; Nitrophenols; Pseudomonas; Sewage; Temperature; Time Factors

Herein, we report the preparation of poly (cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) nanotubes decorated with Ag nanoparticles (NPs). The PZS nanotubes have been synthesized firstly via an in situ template approach, and then Ag nanoparticles were prepared via in situ reduction of AgNO3 with NaBH4 as the reductant, supported on the surface of the PZS nanotubes. The as-obtained PZS nanotubes and PZS@Ag NPs composites were characterized by means of Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), and UV-vis spectroscopy. Characterization results showed that Ag NPs with good dispersibility were well anchored onto the surface of the PZS nanotubes with superior thermal stability. In addition, the catalytic activities and reusability of these composites were investigated by employing the reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) by NaBH4 as a model reaction.

Topics: Aminophenols; Borohydrides; Catalysis; Metal Nanoparticles; Nanotubes; Nitrophenols; Organophosphorus Compounds; Oxidation-Reduction; Polymers; Silver; Silver Nitrate

The effect of nitro-substituent on mononitrophenol (o-nitrophenol (ONP), m-nitrophenol (MNP) and p-nitrophenol (PNP)) reduction in a bioelectrochemical system (BES) was investigated in this study. The results show that the removal of all three nitrophenols was significantly enhanced with more negative cathode potential and shortened hydraulic retention time in the BESs. Moreover, the reduction of the three nitrophenols followed in the order of ONP > MNP > PNP in the BESs. Both quantum chemical calculation using density function theory and cyclic voltammetry analysis confirmed the reductive sequence of the three nitrophenols. In addition, the acute toxicity of nitrophenol effluent significantly decreased while its biodegradability was enhanced after treatment in the BES. Therefore, the BES technology offers bright prospects for efficient treatment of nitrophenol-containing wastewater.

Topics: Biodegradation, Environmental; Electrochemistry; Molecular Structure; Nitrophenols; Waste Disposal, Fluid; Wastewater

We fabricated block copolymer hollow fiber membranes with self-assembled, shell-side, uniform pore structures. The fibers in these membranes combined pores able to respond to pH and acting as chemical gates that opened above pH 4, and catalytic activity, achieved by the incorporation of gold nanoparticles. We used a dry/wet spinning process to produce the asymmetric hollow fibers and determined the conditions under which the hollow fibers were optimized to create the desired pore morphology and the necessary mechanical stability. To induce ordered micelle assembly in the doped solution, we identified an ideal solvent mixture as confirmed by small-angle X-ray scattering. We then reduced p-nitrophenol with a gold-loaded fiber to confirm the catalytic performance of the membranes.

Topics: Aminophenols; Biotechnology; Catalysis; Gold; Hydrogen-Ion Concentration; Materials Testing; Membranes, Artificial; Metal Nanoparticles; Nanotechnology; Nitrophenols; Polymers; Scattering, Radiation; Scattering, Small Angle; Solubility; Solvents; Surface Properties; Temperature; Ultraviolet Rays; Viscosity; X-Rays

A facile strategy has been explored for loading noble metals onto the surface of ferrite nanoparticles with the assistance of phosphine-functionalized linkers. Palladium loading is shown to occur with participation of both the phosphine function and the surface hydroxyl groups. Hybrid nanoparticles containing simultaneously Pd and Au (or Rh) are obtained by successive loading of metals. Similarly, ferrite nanoparticles decorated with Pd, Au, and Rh have also been formed by using the same strategy. The catalytic properties of the new nanoparticles are evidenced in processes such as reduction of 4-nitrophenol or hydrogenation of styrene. Besides, the sequential process involving a cross-coupling reaction followed by reduction of 1-nitrobiphenyl has been successfully achieved by employing Pd/Au decorated nanoferrite particles.

Topics: Catalysis; Ferric Compounds; Hydrogenation; Metal Nanoparticles; Molecular Structure; Nitrophenols; Styrene

A novel magnetic double-shell Fe3O4@TiO2/Au@Pd@TiO2 microsphere composed of a Fe3O4 core and double TiO2 shells with Au and Pd nanoparticles encapsulated is created. The microsphere can be used as a highly efficient reusable catalyst with superior catalytic activity and stability and magnetic separable capability in reduction of 4-nitrophenol.

Topics: Catalysis; Ferrosoferric Oxide; Gold; Lead; Magnetics; Metal Nanoparticles; Microspheres; Nitrophenols; Oxidation-Reduction; Titanium

A poly(methylene blue)-modified glassy carbon electrode (PMB/GCE) was fabricated by electropolymerisation of methylene blue on a GCE and further utilized to investigate the electrochemical determination of 4-nitrophenol (4-NP) by cyclic voltammetry (CV), differential pulse voltammetry and chronocoulometry. The morphology of the PMB on GCE was examined using a scanning electron microscope (SEM). An oxidation peak of 4-NP at the PMB modified electrode was observed at 0.28 V, and in the case of bare GCE, no oxidation peak was observed, which indicates that PMB/GCE exhibits a remarkable effect on the electrochemical determination of 4-NP. Due to this remarkable effect of PMB/GCE, a sensitive and simple electrochemical method was proposed for the determination of 4-NP. The effect of the scan rate and pH was investigated to determine the optimum conditions at which the PMB/GCE exhibits a higher sensitivity with a lower detection limit. Moreover, kinetic parameters such as the electron transfer number, proton transfer number and standard heterogeneous rate constant were calculated. Under optimum conditions, the oxidation current of 4-NP is proportional to its concentration in the range of 15-250 nM with a correlation coefficient of 0.9963. The detection limit was found to be 90 nM (S/N = 3). The proposed method based on PMB/GCE is simple, easy and cost effective. To further confirm its possible application, the proposed method was successfully used for the determination of 4-NP in real water samples with recoveries ranging from 97% to 101.6%. The interference due to sodium, potassium, calcium, magnesium, copper, zinc, iron, sulphate, carbonate, chloride, nitrate and phosphate was found to be almost negligible.

Topics: Carbon; Electrodes; Glass; Methylene Blue; Nanoparticles; Nanotechnology; Nitrophenols

Conductive polypyrrole-polyaniline/TiO2 nanocomposites (PPy-PANI/TiO2) were prepared by in situ oxidative copolymerization of pyrrole and aniline monomers in the presence of TiO2. For comparison studies, polypyrrole/TiO2 (PPy/TiO2) and polyaniline/TiO2 (PANI/TiO2) were also prepared. The samples were characterized by X-ray diffraction, transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, zeta potential analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and photocurrent tests. In contrast to PPy/TiO2 and PANI/TiO2, PPy-PANI/TiO2 exhibits obvious absorption in the visible-light range, and is much superior to PPy/TiO2 and PANI/TiO2 in thermal stability. It is found that PPy-PANI/TiO2 performs well in the visible-light photocatalytic degradation of 4-nitrophenol. The optimized pyrrole : aniline : TiO2 molar ratio for best performance is 0.75 : 0.25 : 100. The efficacy of PPy-PANI/TiO2 is attributed to its conductivity, conjugated structure, as well as to the synergy amidst polypyrrole, polyaniline and TiO2.

Topics: Aniline Compounds; Catalysis; Light; Nitrophenols; Oxidation-Reduction; Photolysis; Polymers; Pyrroles; Temperature; Titanium

Highly active subnano Pd clusters were synthesized using i-motif DNA as the template through characterization via ESI MS, DLS, XPS, UV-vis, and FTIR. It is indicated that Pd1-Pd5 clusters are generated at a [Pd]/[base] ratio of 0.2, Pd8 to Pd9 clusters are generated at a [Pd]/[base] ratio of 0.5, and large nanoparticles with the size about 2.6 nm are formed at a [Pd]/[base] ratio of 2.0. The i-motif-stabilized Pd8-Pd9 clusters show high catalytic activity toward the reduction of 4-nitrophenol with a relative rate constant value of 2034 min(-1) (mM Pd)(-1). DFT calculations disclose that the unique structure of the i-motif with consecutive hemiprotonated CH(+)·C pairs can efficiently ligate Pd ions at the N3 sites of cytosines and that the synthesized Pd clusters consist of metallic Pd atoms as well as positively charged Pd that is ligated by nucleobases, which is capable of facilitating the activation of the nitryl group of 4-nitrophenol. This work suggests a promising pathway to preparing subnano metal catalysts with enhanced catalytic activity using programmable DNA scaffolds.

Topics: Catalysis; DNA; Metal Nanoparticles; Molecular Structure; Nitrophenols; Nucleotide Motifs; Organometallic Compounds; Palladium; Quantum Theory

Green synthesis of extracellular mycogenic silver nanoparticles using the fungus, Cylindrocladium floridanum is reported. The synthesized mycogenic silver nanoparticles were characterized using UV-Vis absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. The nanoparticles exhibit fcc structure with Bragg's reflections of (111), (200), (220) and (311) was evidenced by XRD pattern, high-resolution TEM lattice fringes and circular rings in selected-area electron diffraction (SAED) pattern. The morphology of nanoparticles was roughly spherical in shape with an average size of ca. 25 nm. From FTIR spectrum, it was found that the biomolecules with amide I and II band were involved in the stabilization of nanoparticles. These mycogenic silver nanoparticles exhibited the homogeneous catalytic potential in the reduction of pollutant, 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride, which followed a pseudo-first-order kinetic model. Thus, the synthesis of metal nanoparticles using sustainable microbial approach opens up possibilities in the usage of mycogenic metal nanoparticles as catalysts in various chemical reactions.

Topics: Aminophenols; Ascomycota; Catalysis; Environmental Pollutants; Green Chemistry Technology; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Silver

The beneficial effects of quercetin on reproductive damage elicited by 4-nitrophenol (PNP) were studied in adult male mice. A six-week treatment of weekly intraperitoneal injections of PNP (50 mg/kg) resulted in severe damage to the seminiferous tubules, a remarkable increase in both hydroxyl radical and malondiadehyde production, and notably decreased glutathione peroxidase and superoxide dismutase activities. Moreover, PNP treatment induced germ cell apoptosis, inhibited Bcl-xl expression, and then activated Bax expression and the caspase-3 enzyme. Exposure to PNP also increased XBP-1 and HO-1 mRNAs levels. However, simultaneous supplementation with quercetin (75 mg/kg) attenuated the toxicity induced by PNP through renewal of the antioxidant enzyme's status, alleviating apoptosis by regulating the expressions of Bax and Bcl-xl, XBP-1 and HO-1mRNAs, and the regulation of caspase-3 activity. Taken together, these findings indicated that the antioxidant quercetin displays a potential preventive effect on PNP-induced oxidative damage in mouse testes and may represent an efficient supplement to attenuate reproductive toxicity from environmental toxicants in order to ensure reproductive health and sperm production.

Topics: Animals; Antioxidants; Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; Blotting, Western; Caspases; Cell Proliferation; Dietary Supplements; DNA-Binding Proteins; Immunoenzyme Techniques; Male; Mice; Mice, Inbred ICR; Nitrophenols; Quercetin; Real-Time Polymerase Chain Reaction; Regulatory Factor X Transcription Factors; Reproduction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Testis; Transcription Factors; X-Box Binding Protein 1

A low-cost, innovative and non-invasive colorimetric test, which can be universally used, is proposed to detect pathogenic bacteria via the simple and fast detection of volatile metabolites released by enzymatic hydrolysis. The proof of concept is shown via three sets of experiments studying the release of the p-nitrophenol metabolite in solution in the E. coli cultures containing 4-nitrophenyl-β-d-glucuronide, the trapping efficiency of the gaseous metabolite by various tailored and functionalized xerogels, and the trapping and detection of gaseous p-nitrophenol released by E. coli bacteria.

Topics: Chromatography, Gas; Colorimetry; Escherichia coli; Gas Chromatography-Mass Spectrometry; Gases; Gels; Glucuronates; Glucuronidase; Hydrogen-Ion Concentration; Hydrolysis; Nitrophenols; Porosity; Volatilization

The aim of these experiments was the investigation of the correlation between the metabolic enzyme activities and the intestinal and hepatic excretion of p-nitrophenol (PNP) and its metabolites (PNP-glucuronide: PNP-G and PNP-sulfate: PNP-S) in the same group of rats (n = 10). A jejunal loop was perfused with isotonic medium containing PNP in a concentration of 500 μM. The samples were obtained from the luminal perfusion medium and from the bile. For enzyme assays tissue samples were obtained from the liver and jejunum at the end of experiments. Significant differences were calculated by the Student's t-test. The activity of UDP-glucuronyltransferase and sulfotransferase was about three times higher in the liver than in the small intestine. The activity of the ß-glucuronidase was about six times higher, the activity of the arylsulfatase was approximately seven times greater in the liver than in the jejunum. No significant difference was found between the luminal appearance and the biliary excretion of PNP-G. Contrary to these findings, the biliary excretion of PNP-S was significantly higher than the luminal appearance of PNP-sulfate. It can be concluded that no direct correlation exists between the activity of metabolic enzymes and the excretion rate of PNP-metabolites in the liver and in the jejunal segment of the small intestine.

Topics: Animals; Arylsulfatases; Bile; Biliary Tract; Enzyme Activation; Glucuronates; Glucuronic Acid; Glucuronidase; Glucuronosyltransferase; Inactivation, Metabolic; Jejunum; Liver; Male; Nitrophenols; Rats; Rats, Wistar; Sulfates; Sulfotransferases

CYP2E1 metabolizes 1,3-butadiene (BD) into genotoxic and possibly carcinogenic 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-epoxy-3,4-butanediol (EB-diol). The dose response of DNA and protein adducts derived from BD metabolites increases linearly at low BD exposures and then saturates at higher exposures in rats, but not mice. It was hypothesized that differences in adduct formation between rodents reflect more efficient BD oxidation in mice than rats. Herein, we assessed whether BD-derived metabolites selectively inhibit rat but not mouse CYP2E1 activity using B6C3F1 mouse and Fisher 344 rat liver microsomes. Basal CYP2E1 activities toward 4-nitrophenol were similar between rodents. Through IC50 studies, EB was the strongest inhibitor (IC50 54μM, mouse; 98μM, rat), BD-diol considerably weaker (IC50 1200μM, mouse; 1000μM, rat), and DEB inhibition nonexistent (IC50>25mM). Kinetic studies showed that in both species EB and BD-diol inhibited 4-nitrophenol oxidation through two-site mechanisms in which inhibition constants reflected trends observed in IC50 studies. None of the reactive epoxide metabolites inactivated CYP2E1 irreversibly. Thus, there was no selective inhibition or inactivation of rat CYP2E1 by BD metabolites relative to mouse Cyp2e1, and it can be inferred that CYP2E1 activity toward BD between rodent species would similarly not be impacted by the presence of BD metabolites. Inhibition of CYP2E1 by BD metabolites is then not responsible for the reported species difference in BD metabolism, formation of BD-derived DNA and protein adducts, mutagenicity and tumorigenesis.

Topics: Animals; Butadienes; Carcinogens; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Inhibitory Concentration 50; Liver; Mice; Mice, Inbred Strains; Microsomes, Liver; Nitrophenols; Rats; Rats, Inbred F344; Species Specificity

The aim of this study was to evaluate the effect of hypothermia on the in-vivo pharmacokinetics of 4-nitrophenol (4NP) using rat liver homogenate and rat liver perfusion system.. Rat liver homogenate was incubated with 4NP, which is mainly metabolized by cytochrome P450 2E1, at 37, 34, 32 or 28°C. The Michaelis constant (Km ) and maximum elimination velocity (Vmax ) of 4NP were calculated by a Hanes-Woolf plot. The hepatic extraction ratio (Eh ) of 4NP was evaluated in a rat liver perfusion study at 37, 34, 32 or 28°C. Moreover, the plasma concentration profiles of 4NP after its intravenous (i.v.) administration to rats were analysed by the moment theory and were compared with in-vitro parameters.. While the Km of 4NP was not changed, the Vmax and Eh were reduced at low temperatures. The plasma concentrations of 4NP after its i.v. administration to rats were significantly increased at 28°C.. Changes in the pharmacokinetics of 4NP under hypothermic conditions were caused by alterations in Vmax and Eh . We may be able to predict the disposition of a drug by in-vitro studies.

Topics: Animals; Body Temperature; Cytochrome P-450 CYP2E1; Hypothermia, Induced; In Vitro Techniques; Liver; Male; Nitrophenols; Perfusion; Rats; Rats, Wistar; Tissue Distribution

A multicommutated flow analysis (MCFA) system constructed of microsolenoid valves and pumps offering simultaneous determination of activity of acid phosphatase (ACP) and alkaline phosphatase (ALP) in human serum samples has been developed. The MCFA system is based on optoelectronic flow-through detector made of two light emitting diodes and operating according to paired emitter detector diode (PEDD) principle. This photometric PEDD device has been dedicated for detection of p-nitrophenol (NP) generated in the course of enzymatic hydrolysis of p-nitrophenyl phosphate and optimized for the determination of NP in human serum samples. The developed PEDD-based MCFA system allows independent optimization of conditions for reaction and detection steps of photometric ACP and ALP bioassays. Moreover, it allows elimination of photometric interferences from serum matrix components according to two-points kinetic mode of measurement. The single measurement cycle takes 12 min, consists of four measurements (two for each phosphoesterase) and enables determination of serum ACP and ALP activities at physiological and pathological levels. The real analytical utility of the developed MCFA system has been confirmed by analysis of control sera as well as real human serum samples from healthy persons and oncological patients.

Topics: Acid Phosphatase; Alkaline Phosphatase; Enzyme Assays; Equipment Design; Flow Injection Analysis; Humans; Nitrophenols; Organophosphorus Compounds; Photometry; Reproducibility of Results

4-Nitrophenol (PNP) is generally regarded as an environmental endocrine disruptor capable of estrogenic and anti-androgenic activities. To investigate PNP-induced reproductive effects, immature male rats were injected subcutaneously with PNP (0.1, 1, 10mg/kg body weight or vehicle) daily for 4 weeks. We assessed reproductive tract alterations, sex hormone balance in the serum and estrogen receptor (ER)-α, -β and androgen receptor (AR) expression in testes. Although no significant difference was observed in body weight or testes weights of PNP-treated rats compared with the controls, the serum concentrations of testosterone in the 10mg/kg PNP-treated group were significantly elevated. This effect was accompanied by Leydig cells hyperplasia in the testes. Conversely, there was a significant decrease in estradiol concentration and aromatase expression in the testes of the 10mg/kg PNP-treated group. Furthermore, we observed a significant increase in ERα expression in the testes of the 10mg/kg PNP-treated group compared with the control group. Conversely, ERβ expression displayed a significant reduction. Moreover, AR expression was significantly increased in the 10mg/kg PNP-treated group compared with the control group. The existence of AR, ER-α and -β in the testes suggests that estradiol and testosterone directly affect germ cells and that differential modulation of AR, ER-α and -β in the testis may be involved in the direct effects of PNP or either the indirect effects of PNP-induced disruption of the estradiol-to-testosterone balance or the Leydig cells hyperplasia. Thus, the measurement of many endpoints is necessary for good risk assessment.

Topics: Androgen Antagonists; Animals; Aromatase; Cell Differentiation; Endocrine Disruptors; Estrogen Receptor alpha; Estrogen Receptor beta; Gonadal Steroid Hormones; Hyperplasia; Immunohistochemistry; Leydig Cells; Male; Nitrophenols; Rats; Rats, Sprague-Dawley; Receptors, Androgen; Testis

To investigate the metabolic enzymatic capacity of the colon mucosa to detoxify noxious carcinogenic compounds.. We investigated the activity of 2 conjugating enzymes-the microsomal uridine glucuronosyltransferase (UGT) and the cytosomal glutathione S-transferase (GST) in the uninvolved mucosa of the colon transversum and sigmoideum in patients with adenomatous polyps and colorectal cancer. Biopsies were taken from the mucosa during colonoscopies which were done for clinical (diagnostic) reasons. After storage, the biopsy material was homogenized and after differential centrifugation the enzyme assays were performed with 4-nitrophenol (UGT) and 1-chloro 2,4-dinitrobenzene (GST) as substrates.. About 48 patients were included of which 28 had adenomas and 20 had colorectal carcinomas confirmed by histopathology. Enzyme activities were expressed as nmol/mg per minute protein for the GST and as pmol/mg per minute protein for the UGT. Analysis of variance (F-test) indicated that both enzymes were more widely distributed in adenoma than in cancer patients. The means ± SD were smaller for cancer patients: GST for adenomas 268 ± 152 vs 241 ± 69 for carcinomas and UGT for adenomas 197 ± 200 vs 150 ± 86 for carcinomas.. Compared to patients with adenomatous colon polyps those with colorectal carcinoma exhibited a lower capacity of detoxifying enzyme metabolism and their activities clustered over a smaller range.

Topics: Adenoma; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Biopsy; Carcinoma; Colonic Neoplasms; Dinitrochlorobenzene; Disease Progression; Female; Glucuronosyltransferase; Glutathione Transferase; Humans; Inactivation, Metabolic; Linear Models; Male; Middle Aged; Nitrophenols; Substrate Specificity

Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles.

Topics: Aldehydes; Catalysis; Gold; Ketones; Metal Nanoparticles; Molecular Structure; Nitrophenols; Oxidation-Reduction; Particle Size; Polystyrenes; Quaternary Ammonium Compounds; Surface Properties; Water

Gold nanoparticles (Au NPs) were prepared by reducing HAuCl4 with NaBH4. Their average particle sizes could be tuned in the range of 1.7 and 8.2 nm, by adjusting the amount of NaBH4 used during synthesis. The obtained Au NPs (colloids) were then loaded onto a commercial Al2O3 support to prepare Au/Al2O3 catalysts with tunable Au particle sizes. An optimal pH value (5.9) of the Au colloid solution was found to be essential for loading Au NPs onto Al2O3 while avoiding the growth of Au NPs. Au NPs and Au/Al2O3 catalysts were tested in the reduction of p-nitrophenol with NaBH4. Interestingly, the catalytic activity depended on the size of Au NPs, being the highest when the average size was 3.4 nm. Relevant characterization by UV-Vis, TEM, and XRD was conducted.

Topics: Aluminum Oxide; Borohydrides; Catalysis; Colloids; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Particle Size; Reducing Agents; Spectrophotometry, Ultraviolet; X-Ray Diffraction

Smart systems on the nanometer scale for continuous flow-through reaction present fascinating advantages in heterogeneous catalysis, in which a parallel array of straight nanochannels offers a platform with high surface area for assembling and stabilizing metallic nanoparticles working as catalysts. Herein we demonstrate a method for finely modifying the nanoporous anodic aluminum oxide (AAO), and further integration of nanoreactors. By using atomic transfer radical polymerization (ATRP), polymer brushes were successfully grafted on the inner wall of the nanochannels of the AAO membrane, followed by exchanging counter ions with a precursor for nanoparticles (NPs), and used as the template for deposition of well-defined Au NPs. The membrane was used as a functional nanochannel for novel flow-through catalysis. High catalytic performance and instantaneous separation of products from the reaction system was achieved in reduction of 4-nitrophenol.

Topics: Aluminum Oxide; Catalysis; Gold; Metal Nanoparticles; Nanopores; Nitrophenols; Oxidation-Reduction; Polymers

This work demonstrates the successful synthesis and characterizations of α-Fe2O3 hexagonal nanoparticles and their effective utilization for the degradation of hazardous Rhodamine B (RhB) dye and smart chemical sensor applications. The as-synthesized materials were characterized by various analytical techniques which revealed that the prepared nanoparticles are well-crystalline, possessing hexagonal shape, grown in high-density and well matched with the rhombohedral α-Fe2O3 structures. The as-synthesized α-Fe2O3 nanoparticles were used as efficient photocatalyst for the photocatalytic degradation of RhB-dye under light illumination which showed substantial degradation (~79%) of RhB-dye in 140 min. The considerable photo-degradation of RhB-dye attributed to the unique morphology of the synthesized α-Fe2O3 nanoparticles which might import the effective electron/hole separation and generate the large number of oxy-radicals. Moreover, the synthesized α-Fe2O3 nanoparticles were utilized as efficient electron mediators for the fabrication of 4-nitrophenol chemical sensor in aqueous media. The fabricated chemical sensor exhibited a high-sensitivity of ~367.6 µA (mol L(-1))(-1) cm(-2) and an experimental detection limit of ~1.56×10(-3) mol L(-1) in a short response time of ~10.0 s with linearity in the range of 1.56×10(-3)-12.5×10(-3) mol L(-1) and correlation coefficient (R) of ~0.99963. These investigations demonstrated that the simply synthesized α-Fe2O3 nanoparticles can effectively be used as efficient photocatalyst for the photocatalytic degradation of organic dyes and effective electron mediators for the fabrication of highly sensitive chemical sensors in aqueous medium.

Topics: Biosensing Techniques; Catalysis; Cold Temperature; Crystallization; Ferric Compounds; Fluorescent Dyes; Light; Limit of Detection; Microscopy, Electron, Transmission; Nanoparticles; Nitrophenols; Photolysis; Rhodamines; Solutions; Water

Reconstructed 3D human epidermal skin models are being used increasingly for safety testing of chemicals. Based on EpiDerm™ tissues, an assay was developed in which the tissues were topically exposed to test chemicals for 3h followed by cell isolation and assessment of DNA damage using the comet assay. Inter-laboratory reproducibility of the 3D skin comet assay was initially demonstrated using two model genotoxic carcinogens, methyl methane sulfonate (MMS) and 4-nitroquinoline-n-oxide, and the results showed good concordance among three different laboratories and with in vivo data. In Phase 2 of the project, intra- and inter-laboratory reproducibility was investigated with five coded compounds with different genotoxicity liability tested at three different laboratories. For the genotoxic carcinogens MMS and N-ethyl-N-nitrosourea, all laboratories reported a dose-related and statistically significant increase (P < 0.05) in DNA damage in every experiment. For the genotoxic carcinogen, 2,4-diaminotoluene, the overall result from all laboratories showed a smaller, but significant genotoxic response (P < 0.05). For cyclohexanone (CHN) (non-genotoxic in vitro and in vivo, and non-carcinogenic), an increase compared to the solvent control acetone was observed only in one laboratory. However, the response was not dose related and CHN was judged negative overall, as was p-nitrophenol (p-NP) (genotoxic in vitro but not in vivo and non-carcinogenic), which was the only compound showing clear cytotoxic effects. For p-NP, significant DNA damage generally occurred only at doses that were substantially cytotoxic (>30% cell loss), and the overall response was comparable in all laboratories despite some differences in doses tested. The results of the collaborative study for the coded compounds were generally reproducible among the laboratories involved and intra-laboratory reproducibility was also good. These data indicate that the comet assay in EpiDerm™ skin models is a promising model for the safety assessment of compounds with a dermal route of exposure.

Topics: 4-Nitroquinoline-1-oxide; Comet Assay; Cyclohexanones; DNA Damage; Drug Evaluation, Preclinical; Epidermis; Ethylnitrosourea; Humans; Laboratory Proficiency Testing; Methyl Methanesulfonate; Models, Biological; Mutagens; Nitrophenols; Phenylenediamines; Reproducibility of Results; Tissue Culture Techniques

Highly efficient coremoval of Cu(II) and p-nitrophenol (PNP) was accomplished using a newly synthesized polyamine chelating resin (CEAD) as compared to three other commercial resins. The mutual effects and inner mechanisms of their adsorption onto CEAD were systematically investigated by binary, preloading, thermodynamic, and dynamic adsorption procedures. PNP was adsorbed onto both hydrophobic and hydrophilic sites, while Cu(II) only interacted with hydrophilic amine group sites. In both preloading and binary systems, the adsorption of PNP was inhibited to the same degree by the presence of Cu(II) because of selective recognition and direct competition. On the other hand, the presence of PNP obviously enhanced the adsorption of Cu(II) by more than 7%, which was related to PNP loading on the hydrophobic surface. As proved by structural characterization, hydroxyl groups facing outward create new sites for coordination with Cu(II). Moreover, ionic strength exerted some positive influence on the properties of CEAD. Finally, more than 98% of PNP and 99% of Cu(II) could be sequentially recovered with dilute NaClO3 and HCl. These superior properties demonstrated with CEAD indicate that it could be applied to wastewaters containing both heavy metals and PNP, even for high saline aqueous media.

Topics: Adsorption; Chelating Agents; Copper; Models, Theoretical; Molecular Structure; Nitrophenols; Photoelectron Spectroscopy; Polyamines; Resins, Synthetic; Spectrophotometry, Atomic; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Water Pollutants, Chemical; Water Purification

We recently reported a chemical approach for half-life extension that utilizes sets of releasable linkers to attach drugs to macromolecules via a cleavable carbamate group (Santi et al., Proc. Nat. Acad. Sci. U.S.A. 2012, 109, 6211-6216). The linkers undergo a β-elimination cleavage to release the free, native amine-containing drug. A limitation of the technology is the requirement for an amino group on the drug in order to form the carbamate bond, since most small molecules do not have an amine functional group. Here, we describe an approach to adapt these same β-elimination carbamate linkers so they can be used to connect other acidic heteroatoms, in particular, phenolic hydroxyl groups. The approach utilizes a methylene adaptor to connect the drug to the carbamate nitrogen, and an electron-withdrawing group attached to carbamate nitrogen to stabilize the system against a pH-independent spontaneous cleavage. Carbamate cleavage is driven by β-elimination to give a carboxylated aryl amino Mannich base which rapidly collapses to give the free drug, an aryl amine, and formaldehyde.

Topics: Carbamates; Drug Design; Kinetics; Macromolecular Substances; Nitrophenols; Polyethylene Glycols; Solvents; Structure-Activity Relationship

The chemical and petrochemical industries produce wastewaters containing ammonium and phenolic compounds. Biological treatment of these wastewaters could be problematic due to the possible inhibitory effects exerted by phenolic compounds. The feasibility of performing simultaneous nitritation and p-nitrophenol (PNP) biodegradation using a continuous aerobic granular reactor was evaluated. A nitrifying granular sludge was bioaugmented with a PNP-degrading floccular sludge, while PNP was progressively added to the feed containing a high ammonium concentration. Nitritation was sustained throughout the operational period with ca. 85% of ammonium oxidation and less than 0.3% of nitrate in the effluent. PNP biodegradation was unstable and the oxygen limiting condition was found to be the main explanation for this unsteadiness. An increase in dissolved oxygen concentration from 2.0 to 4.5 mg O2 L(-1) significantly enhanced PNP removal, achieving total elimination. Acinetobacter genus and ammonia-oxidising bacteria were the predominant bacteria species in the granular biomass.

Topics: Aerobiosis; Ammonium Compounds; Bacteria; Biodegradation, Environmental; Biomass; Biopolymers; Bioreactors; Nitrification; Nitrophenols; Oxidation-Reduction; Sewage; Volatilization; Wastewater

Esterases with excellent merits suitable for commercial use in ester production field are still insufficient. The aim of this research is to advance our understanding by seeking for more unusual esterases and revealing their characterizations for ester synthesis.. A novel esterase-encoding gene from Rhizomucor miehei (RmEstA) was cloned and expressed in Escherichia coli. Sequence analysis revealed a 975-bp ORF encoding a 324-amino-acid polypeptide belonging to the hormone-sensitive lipase (HSL) family IV and showing highest similarity (44%) to the Paenibacillus mucilaginosus esterase/lipase. Recombinant RmEstA was purified to homogeneity: it was 34 kDa by SDS-PAGE and showed optimal pH and temperature of 6.5 and 45°C, respectively. The enzyme was stable to 50°C, under a broad pH range (5.0-10.6). RmEstA exhibited broad substrate specificity toward p-nitrophenol esters and short-acyl-chain triglycerols, with highest activities (1,480 U mg(-1) and 228 U mg(-1)) for p-nitrophenyl hexanoate and tributyrin, respectively. RmEstA efficiently synthesized butyl butyrate (92% conversion yield) when immobilized on AOT-based organogel.. RmEstA has great potential for industrial applications. RmEstA is the first reported esterase from Rhizomucor miehei.

Topics: Amino Acid Sequence; Base Sequence; Butyrates; Cloning, Molecular; Esterases; Esters; Hydrogen-Ion Concentration; Molecular Sequence Data; Nitrophenols; Recombinant Proteins; Rhizomucor; Sequence Homology, Amino Acid; Substrate Specificity; Temperature

Electron exchange between aqueous Fe(II) and structural Fe(III) of iron minerals has been illustrated for understanding the reduction of nitroaromatic compounds (NAC). However, factors influencing Fe(II)-induced the reduction of NAC still remain elusive. In this paper, p-nitrophenol (1.5mM) was selected to explore the effects of pH, the stabilizing ligands (Cl(-), SO4(2-)) of ferrous ions and the extra addition of iron hydroxide on the reduction of NAC via Fe(II) species. The results indicate that the reduction degree of is much lower in SO4(2-) medium than that in Cl(-) medium at pH 7.6. p-Nitrophenol reduction increased in SO4(2-) medium and slightly decreased in Cl(-) medium when Fe hydroxide was extra added. Cl(-) strength (0.01-0.1 mol L(-1)) has no obvious effect on p-NP reduction. SO4(2-) species and its dosage have markedly inhibitory effect on p-NP reduction due to the selective adsorption of SO4(2-) and the formation of sulphated surface complexes on the fresh Fe hydroxide.

Topics: Adsorption; Anions; Chlorides; Chromatography, High Pressure Liquid; Electrons; Environmental Restoration and Remediation; Ferric Compounds; Hydrogen-Ion Concentration; Iron; Ligands; Nitrophenols; Oxidation-Reduction; Sulfates; Surface Properties; Wastewater; Water Pollutants, Chemical; X-Ray Diffraction

para-Nitrophenol (PNP) is a highly toxic compound with threats to mammalian health. The pnpE-encoded γ-hydroxymuconic semialdehyde dehydrogenase catalyzes the reduction of γ-hydroxymuconic semialdehyde to maleylacetate in Pseudomonas sp. strain WBC-3, playing a key role in the catabolism of PNP to Krebs cycle intermediates. However, the catalyzing mechanism by PnpE has not been well understood.. Here we report the crystal structures of the apo and NAD bound PnpE. In the PnpE-NAD complex structure, NAD is situated in a cleft of PnpE. The cofactor binding site is composed of two pockets. The adenosine and the first ribose group of NAD bind in one pocket and the nicotinamide ring in the other.. Six amino acids have interactions with the cofactor. They are C281, E247, Q210, W148, I146 and K172. Highly conserved residues C281 and E247 were identified to be critical for its catalytic activity. In addition, flexible docking studies of the enzyme-substrate system were performed to predict the interactions between PnpE and its substrate γ-hydroxymuconic semialdehyde. Amino acids that interact extensively with the substrate and stabilize the substrate in an orientation suitable for enzyme catalysis were identified. The importance of these residues for catalytic activity was confirmed by the relevant site-directed mutagenesis and their biochemical characterization.

Topics: Amino Acid Sequence; Animals; Apolipoproteins; Bacterial Proteins; Catalytic Domain; Evolution, Molecular; Fatty Acids, Unsaturated; Humans; Maleates; Models, Molecular; Molecular Docking Simulation; Mutagenesis, Site-Directed; NAD; Nitrophenols; Oxidoreductases; Protein Conformation; Protein Structure, Secondary; Protein Structure, Tertiary; Pseudomonas; Sequence Alignment; Substrate Specificity

Monooxygenation is an important route of nitroaromatic compound (NAC) biodegradation and it is widely found for cometabolic transformations of NACs and other aromatic pollutants. We investigated the C and N isotope fractionation of nitrophenol monooxygenation to complement the characterization of NAC (bio)degradation pathways by compound-specific isotope analysis (CSIA). Because of the large diversity of enzymes catalyzing monooxygenations, we studied the combined C and N isotope fractionation and the corresponding (13)C- and (15)N-apparent kinetic isotope effects (AKIEs) of four nitrophenol-biodegrading microorganisms (Bacillus spharericus JS905, Pseudomonas sp. 1A, Arthrobacter sp. JS443, Pseudomonas putida B2) in the pH range 6.1-8.6 with resting cells and crude cell extracts. While the extent of C and N isotope fractionation and the AKIE-values varied considerably for the different organisms, the correlated C and N isotope signatures (δ(15)N vs δ(13)C) revealed trends, indicative of two distinct monooxygenation pathways involving hydroxy-1,4-benzoquinone or 1,2- and 1,4-benzoquinone intermediates, respectively. The distinction was possible based on larger secondary (15)N-AKIEs associated with the benzoquinone pathway. Isotope fractionation was neither masked substantially by nitrophenol speciation nor transport across cell membranes. Only when 4-nitrophenol was biodegraded by Pseudomonas sp. 1A did isotope fractionation become negligible, presumably due to rate-limiting substrate binding steps pertinent to the catalytic cycle of flavin-dependent monooxygenases.

Topics: Arthrobacter; Bacillus; Benzoquinones; Biocatalysis; Biodegradation, Environmental; Carbon Isotopes; Chemical Fractionation; Environmental Pollutants; Kinetics; Metabolic Networks and Pathways; Mixed Function Oxygenases; Nitrogen Isotopes; Nitrophenols; Pseudomonas putida

Enzyme kinetic parameters are usually determined from initial rates nevertheless, laboratory instruments only measure substrate or product concentration versus reaction time (progress curves). To overcome this problem we present a methodology which uses integrated models based on Michaelis-Menten equation. The most severe practical limitation of progress curve analysis occurs when the enzyme shows a loss of activity under the chosen assay conditions. To avoid this problem it is possible to work with the same experimental points utilized for initial rates determination. This methodology is illustrated by the use of integrated kinetic equations with the well-known reaction catalyzed by alkaline phosphatase enzyme. In this work nonlinear regression was performed with the Solver supplement (Microsoft Office Excel). It is easy to work with and track graphically the convergence of SSE (sum of square errors). The diagnosis of enzyme inhibition was performed according to Akaike information criterion.

Topics: Alkaline Phosphatase; Catalysis; Enzyme Inhibitors; Enzymes; Kinetics; Nitrophenols; Organophosphorus Compounds; Software

We isolated strain CERAR5, a Stenotrophomonas sp., from an aquifer contaminated with chlorinated hydrocarbons that utilizes up to 1.0 mM PNP within 62 h in M9 medium as a source of carbon and nitrogen. To assess the potential of this strain for use in bioremediation, we investigated the influence of external sources of carbon and nitrogen on bacterial degradation of PNP following a full factorial design analysis. Glucose, sodium acetate, phenol, sodium nitrate and ammonium chloride were the factors chosen, while per cent removal of PNP, growth of the bacterial strain, and change in pH of the medium were the responses measured. Glucose and acetate had significant positive influence on the removal PNP. In particular, acetate exhibited a significant positive effect on all the three responses measured, clearly suggesting that the addition of acetate greatly contributes to an efficient bioremediation of habitats contaminated with PNP by Stenotrophomonas sp. CERAR5.

Topics: Biodegradation, Environmental; Groundwater; Nitrophenols; Stenotrophomonas

An increasing demand for catalytic Pd nanoparticles has motivated the search for sustainable production methods. An innovative approach uses bacterial cells as support material for synthesizing Pd nanoparticles by reduction of Pd(II) with e.g. hydrogen or formate. Nevertheless, drawbacks of microbially supported Pd catalysts are the low catalytic activity compared to conventional Pd nanocatalysts and the possible poisoning of the catalyst surface by sulfur originating from bacterial proteins. A recent study showed that amine groups were a key component in surface-supported synthesis of Pd nanoparticles, and that abiotic surfaces could support the Pd particle synthesis as efficiently as bacteria. In this study, we explore the possibility of replacing bacteria with amine-functionalized materials, and we compare different functionalization strategies. Pd nanoparticles formed on the support materials were visualized by transmission electron microscopy, and their activity was evaluated by catalysis of p-nitrophenol reduction. Surfaces functionalized with 3-aminopropyltriethoxysilane and chitosan were interesting alternatives to bacterial cells, as the catalytic activity of Pd particles formed on these surfaces was higher than for Pd particles formed on Shewanella oneidensis cells. Smaller Pd nanoparticles generally have better catalytic properties, and previous studies have shown that the particle size can be lowered by increasing the amount of support material used during Pd particle formation. However, increasing the concentration of S. oneidensis cells beyond a certain threshold lead to deactivation of the Pd catalyst. This was not observed for the sulfur-free support materials, implying that such amine-rich materials can provide an excellent support for environmentally friendly synthesis of surface-immobilized Pd nanoparticles.

Topics: Biotechnology; Chitosan; Nanoparticles; Nitrophenols; Palladium

Gold nanoparticles were synthesized by reducing chloroauric acid with a glucan, isolated from an edible mushroom Pleurotus florida, cultivar Assam Florida. Here, glucan acts as reducing as well as stabilizing agent. The synthesized gold nanoparticles were characterized by UV-visible spectroscopy, HR-TEM, XRD, SEM, and FT-IR analysis. The results indicated that the size distribution of gold nanoparticles (Au NPs) changed with the change in concentration of chloroauric acid (HAuCl(4)). The resulting Au NPs-glucan bioconjugates function as an efficient heterogeneous catalyst in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), in the presence of sodium borohydride. The reduction of 4-nitrophenol with Au NPs-glucan bioconjugates followed pseudo-first-order kinetics. The effect of particle size and gold loading on reduction rate of 4-NP was studied with Au NPs-glucan bioconjugates prepared with different concentrations of HAuCl(4). The synthesis of catalytically active Au NPs using a pure mushroom polysaccharide of known structure is reported for the first time.

Topics: Catalysis; Glucans; Gold; Green Chemistry Technology; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Particle Size; Pleurotus; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction

The direct use of macroscopic biopolymer alginate hydrogels (AHs) as a green and effective carrier to stabilize silver nanoparticles (Ag NPs) is presented. The Ag@AHs were characterized by UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The Ag@AHs showed excellent catalytic performance for the reduction of 4-nitrophenol by NaBH4 in aqueous solution, which can be easily separated after catalytic reaction and readily reused for three successive reaction cycles, attributing to the high stability of the Ag NPs supported by AHs. Our findings shed light on the design and fabrication of new heterogeneous catalyst with high performance based on the environmentally benign biopolymer hydrogel.

Topics: Biopolymers; Catalysis; Hydrogel, Polyethylene Glycol Dimethacrylate; Metal Nanoparticles; Microscopy, Electron, Scanning; Models, Chemical; Molecular Structure; Nitrophenols; Silver; Spectrometry, X-Ray Emission; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared

Modified montmorillonite was prepared at different surfactant (HDTMA) loadings through ion exchange. The conformational arrangement of the loaded surfactants within the interlayer space of MMT was obtained by computational modelling. The conformational change of surfactant molecules enhance the visual understanding of the results obtained from characterization methods such as XRD and surface analysis of the organoclays. Batch experiments were carried out for the adsorption of p-chlorophenol (PCP) and different conditions (pH and temperature) were used in order to determine the optimum sorption. For comparison purpose, the experiments were repeated under the same conditions for p-nitrophenol (PNP). Langmuir and Freundlich equations were applied to the adsorption isotherm of PCP and PNP. The Freundlich isotherm model was found to be the best fit for both of the phenolic compounds. This involved multilayer adsorptions in the adsorption process. In particular, the binding affinity value of PNP was higher than that of PCP and this is attributable to their hydrophobicities. The adsorption of the phenolic compounds by organoclays intercalated with highly loaded surfactants was markedly improved possibly due to the fact that the intercalated surfactant molecules within the interlayer space contribute to the partition phases, which result in greater adsorption of the organic pollutants.

Topics: Adsorption; Aluminum Silicates; Cetrimonium; Cetrimonium Compounds; Chlorophenols; Clay; Molecular Dynamics Simulation; Molecular Structure; Nitrophenols; Surface Properties; Surface-Active Agents

In the extrahepatic drug metabolism the intestinal tract can play an important role. These experiments were designed to study the biotransformation of p-nitrophenol (PNP) in the small intestine in the rat. Various segments of the small intestine (proximal and distal jejunum, terminal ileum) were perfused with isotonic solution in vivo containing different concentrations of PNP (20-100-500-1000 μM) and the concentrations of metabolites (PNP-G: p-nitrophenol glucuronide, PNP-S: p-nitrophenol sulfate) were determined in the perfusion medium. It was found a decreasing tendency in the glucuronidation from the proximal to distal segment of the small intestine: e.g. 430 nmol, 240 nmol, and 100 nmol PNP-G appeared in the perfusion medium in the proximal, distal jejunum and in the terminal ileum, respectively, when 500 μM PNP was luminally perfused for 90 minutes. Similar ratio was found at the luminal perfusion of other PNP-concentrations, too. Luminal appearance of sulfoconjugate of PNP was considerably lower and no clear gradient tendency in the formation of PNP-S could be detected in the small intestine from the proximal to distal segment. Our results show that there are considerable differences in drug metabolism in various segments of the small intestine. We have found a gradient conjugating activity from proximal to distal segment of small intestine in the glucuronidation of PNP.

Topics: Animals; Glucuronates; Inactivation, Metabolic; Intestine, Small; Male; Nitrobenzenes; Nitrophenols; Rats; Rats, Wistar

The precise control of nanostructures, assembly processing, and the size of each component is important for the construction of integrated functional nanocomposites. In this paper, we describe a simple two-step method for the synthesis of novel flower-like nanocomposites (AuNPs/NiSiO) composed of well-dispersed and size-controlled Au nanoparticles (AuNPs) immobilized on hierarchically structured layered nickel silicate (NiSiO). The as-prepared AuNPs/NiSiO nanocomposites exhibited excellent catalytic activity in the reduction of 4-nitrophenol (4-NP). The experimental results proved that the size of AuNPs played an important role in enhancing the catalytic activity. In particular, there was no visible decrease in the catalytic activity of the reused catalysts even after being recycled five times. Therefore, the hierarchically nanostructured material can be a promising candidate as the catalytic support.

Topics: Catalysis; Gold; Nanoparticles; Nanostructures; Nickel; Nitrophenols; Oxidation-Reduction; Particle Size; Silicates

A new strategy of reactant-product-dual-template imprinting incorporated with hollow morphology to improve the catalysis efficiency of microspheres was developed. The synthesized capsule can achieve degradation of the reactant and elimination of its product simultaneously.

Topics: Catalysis; Cross-Linking Reagents; Hydrolysis; Microspheres; Molecular Imprinting; Nitrophenols; Paraoxon; Pesticides; Silicon Dioxide; Vinyl Compounds

The electrochemical degradation of p-nitrophenol (PNP) at boron-doped diamond (BDD) and platinum (Pt) anodes was studied by varying the parameters such as Cl(-) concentration, pH of aqueous medium and applied current density. The results obtained were explained in terms of in situ concomitant generation of hydroxyl radicals and chloride based oxidant species. The degradation of PNP was highly promoted in low concentration of NaCl electrolyte (less than 0.10 M), on contrary, the mineralization efficiency was poor at both BDD and Pt anodes with the NaCl concentration up to 0.20 M, which was ascribed to the formation of refractory chlorinated organic compounds. A maximum of 100% and 70% of COD removal was achieved in 5h of electrolysis period using both BDD and Pt anodes under similar experimental conditions. Kinetic study indicated that the degradation of PNP at BDD and Pt anodes followed pseudo-first-order reactions, and the reaction rate constant (k(s)) of the former was observed to be higher than that of the latter. Besides COD, conversion of PNP into various intermediate compounds and their degradations were also monitored. The mechanisms for PNP degradation at BDD and Pt anodes were proposed separately by considering the nature of respective intermediate species and their concentrations.

Topics: Biological Oxygen Demand Analysis; Boron; Diamond; Electrodes; Electrolysis; Hydrogen-Ion Concentration; Nitrophenols; Platinum; Waste Disposal, Fluid; Water Pollutants, Chemical

A robust synthesis of silver nanoparticles (AgNPs) using the peel extract of Punica granatum is reported in this article. The formation of AgNPs was confirmed by the appearance of brownish yellow color and the Surface Plasmon Resonance (SPR) peak at 432 nm. The biogenic AgNPs were found to have the size approximately 30 nm with distorted spherical shape. The high negative zeta potential values of AgNPs revealed their high stability which could be attributed to the capping of AgNPs by the phytoconstituents of the Punica granatum peel. The biogenic AgNPs were also found to function as an effective green catalyst in the reduction of anthropogenic pollutant viz., 4-nitrophenol (4-NP) by solid sodium borohydride, which was evident from the instantaneous color change of bright yellow (400 nm) to colorless (294 nm) solution, after the addition of AgNPs. The catalytic action of biogenic AgNPs in the reduction of 4-NP could be explained on the basis of Langmuir-Hinshelwood model.

Topics: Catalysis; Environmental Pollutants; Green Chemistry Technology; Humans; Lythraceae; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Silver; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared

Platinum-cerium oxide hybrid nanocatalysts (CeO(2)-Pt) were for the first time designed as bionanolabels for highly efficient electrochemical immunosensing of low-abundance proteins coupling nanocatalyst-based redox cycling with in situ signal amplification strategy.

Topics: Carcinoembryonic Antigen; Catalysis; Cerium; Electrochemical Techniques; Immunoassay; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Oxides; Platinum; Polymers; Proteins

Cooperative interactions are frequently observed in the metabolism of drugs and pollutants by cytochrome P450s; nevertheless, the molecular determinants for cooperativity remain elusive. Previously, we demonstrated that steady-state styrene metabolism by CYP2E1 exhibits positive cooperativity. We hypothesized that styrene metabolites have lower affinity than styrene toward CYP2E1 and limited ability to induce cooperative effects during metabolism. To test the hypothesis, we determined the potency and mechanism of inhibition for styrene and its metabolites toward oxidation of 4-nitrophenol using CYP2E1 Supersomes® and human liver microsomes. Styrene inhibited the reaction through a mixed cooperative mechanism with high affinity for the catalytic site (67 µM) and lower affinity for the cooperative site (1100 µM), while increasing substrate turnover at high concentrations. Styrene oxide and 4-vinylphenol possessed similar affinity for CYP2E1. Styrene oxide behaved cooperatively like styrene, but 4-vinylphenol decreased turnover at high concentrations. Styrene glycol was a very poor competitive inhibitor. Among all compounds, there was a positive correlation with binding and hydrophobicity. Taken together, these findings for CYP2E1 further validate contributions of cooperative mechanisms to metabolic processes, demonstrate the role of molecular structure on those mechanisms and underscore the potential for heterotropic cooperative effects between different compounds.

Topics: Binding Sites; Cytochrome P-450 CYP2E1; DNA Adducts; Humans; Hydrophobic and Hydrophilic Interactions; Kinetics; Microsomes, Liver; Nitrophenols; Oxidation-Reduction; Styrene

Polyglycidyl methacrylate (PGMA) microspheres, crosslinked and surface-functionalized by amine, can be used as a solid-state template for the synthesis of gold (Au) crystals in the forms of either nanoparticles (NPs) or plates. It is discovered that the polymer microsphere acts as an internal template to cultivate Au NPs inside the microsphere or an external template to generate the single-crystal plates depending on the critical concentration (Ccr ) of gold ions. The ion-dipole interaction and the structure-dependent solubility of gold induce two distinct gold nanostructures in the presence of the functionalized polymer microspheres. The catalytic activity and long-term storage of the developed gold nanostructures that can be easily scaled-up for mass production through the developed novel methodology is demonstrated.

Topics: Amines; Aminophenols; Catalysis; Cross-Linking Reagents; Gold; Metal Nanoparticles; Microscopy, Electron, Scanning; Microspheres; Nitrophenols; Polymethacrylic Acids; Solubility; Static Electricity

A concise synthesis of Pd nanoparticles encapsulated in a sponge-like carbonaceous support (Pd/C) was achieved by mixing a solution containing water, ethylene glycol and Pd(II) with diphosphorus pentoxide, leading to excellent catalytic performance of Pd/C towards the reduction of the model aromatic nitro compound.

Topics: Carbon; Catalysis; Ethylene Glycol; Kinetics; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Oxygen; Palladium; Phosphorus Compounds; Spectrophotometry, Ultraviolet; Water

Effects of 4-nitrophenol (4NP) on the overall performance of membrane bioreactors (MBRs) were investigated in two bench-scale submerged MBRs. Positive impacts of 4NP on activated sludge production and membrane fouling were demonstrated over 45 days of stable operational period. After addition of 4-nitrophenol, the sludge production could be reduced effectively, but only a slight reduction in chemical oxygen demand removal was obtained. The effluent NH4(+)-N concentrations were almost the same in two MBRs. The transmembrane pressures (TMPs) and resistance R increased with increasing mixed liquor suspended solid concentration at each MBR. The average daily TMP increase rates in the control MBR reactor remained at about 0.23 kPa day(-1) and dropped to about 0.12 kPa day(-1) in the 4NP-MBR. Compared with the control MBR, a wider dispersion and lower peak of floc size, a lower zeta potential, and a lower extracellular polymeric substance concentration were observed in the 4NP-MBR.

Topics: Bioreactors; Membranes, Artificial; Nitrophenols; Sewage

A differential pulse polarography (DPP) for the simultaneous determination of 2-nitrophenol and 4-nitrophenol was proposed. It was found that under optimum experimental conditions (pH = 5, scan rate = 5 mV/s, pulse amplitude = -50 mV), 2-nitrophenol and 4-nitrophenol had well-defined polarographic reduction waves with peak potentials at -317 and -406 mV, respectively. In the mixture of two compounds overlapping polarographic peaks were observed. In this study, support vector regression (SVR) was applied to resolve the overlapped polarograms. Furthermore, a comparison was made between the performance of SVR and partial least square (PLS) on data set. The results demonstrated that SVR is a better well-performing alternative for the analysis and modeling of DPP data than the commonly applied PLS technique. The proposed method was used for the determination of 2-nitrophenol and 4-nitrophenol in industrial waste water.

Topics: Environmental Monitoring; Industrial Waste; Nitrophenols; Polarography; Water Pollutants, Chemical

The ultrasonic degradation of p-nitrophenol (p-NP) in aqueous solution with CCl4 enhancement was studied. The effects of operating parameters such as CCl4 dosage, ultrasonic power, media temperature, the initial concentration of p-NP and initial pH value of the aqueous solution on the degradation of p-NP were investigated, and the enhancement mechanism of CCl4 for p-NP sonolysis was also discussed. The results showed that the sonochemical degradation of p-NP was obviously enhanced by adding CCl4. It attributed to the increase ·OH radicals concentration in the presence of CCl4 as a hydrogen atom scavenger, and the formation of some oxidizing agents such as free chlorine and chlorine-containing radicals. The degradation of p-NP follows a pseudo-first-order kinetics. The degradation rate of p-NP increased with decreasing the temperature, the initial pH value of the solution and decreasing the initial concentration of p-NP. It was also found that p-NP can be mineralized in this process.

Topics: Carbon Tetrachloride; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Solutions; Temperature; Ultrasonics; Water

Strain Yw12, isolated from activated sludge, could completely degrade and utilize methyl parathion as the sole carbon, phosphorus and energy sources for growth in the basic salt media. It could also completely degrade and utilize p-nitrophenol as the sole carbon and energy sources for growth in the minimal salt media. Phenotypic features, physiological and biochemical characteristics, and phylogenetic analysis of 16S rRNA sequence showed that this strain belongs to the genus of Agrobacterium sp. Response surface methodology was used to optimize degradation conditions. Under its optimal degradation conditions, 50 mg l(-1) MP was completely degraded within 2 h by strain Yw12 and the degradation product PNP was also completely degraded within 6 h. Furthermore, strain Yw12 could also degrade phoxim, methamidophos, chlorpyrifos, carbofuran, deltamethrin and atrazine when provided as the sole carbon and energy sources. Enzymatic analysis revealed that the MP degrading enzyme of strain Yw12 is an intracellular enzyme and is expressed constitutively. These results indicated that strain Yw12 might be used as a potential and effective organophosphate pesticides degrader for bioremediation of contaminated sites.

Topics: Agrobacterium; Bacterial Proteins; Biodegradation, Environmental; Hydrolases; Insecticides; Kinetics; Methyl Parathion; Nitrophenols; Phylogeny; Principal Component Analysis; RNA, Bacterial; RNA, Ribosomal, 16S; Sewage; Soil Microbiology; Soil Pollutants; Substrate Specificity

Activity-based protein profiling represents a powerful methodology to probe the activity state of enzymes under various physiological conditions. Here we present the development of a para-nitrophenol phosphonate activity-based probe with structural similarities to the potent agrochemical paraoxon. We demonstrate that this probes labels distinct serine hydrolases with the carboxylesterase CXE12 as the predominant target in Arabidopsis thaliana. The designed probe features a distinct labeling pattern and therefore represents a promising chemical tool to investigate physiological roles of selected serine hydrolases such as CXE12 in plant biology.

Topics: Arabidopsis; Carboxylesterase; Nitrophenols; Organophosphonates; Paraoxon; Plant Proteins; Proteomics

Bimetallic nanoparticles are considered the next generation of nanocatalysts with increased stability and catalytic activity. Bio-supported synthesis of monometallic nanoparticles has been proposed as an environmentally friendly alternative to the conventional chemical and physical protocols. In this study we synthesize bimetallic bio-supported Pd-Au nanoparticles for the first time using microorganisms as support material. The synthesis involved two steps: (1) Formation of monometallic bio-supported Pd(0) and Au(0) nanoparticles on the surface of Cupriavidus necator cells, and (2) formation of bimetallic bio-supported nanoparticles by reduction of either Au(III) or Pd(II) on to the nanoparticles prepared in step one. Bio-supported monometallic Pd(0) or Au(0) nanoparticles were formed on the surface of C. necator by reduction of Pd(II) or Au(III) with formate. Addition of Au(III) or Pd(II) to the bio-supported particles resulted in increased particle size. UV-Vis spectrophotometry and HR-TEM analyses indicated that the previously monometallic nanoparticles had become fully or partially covered by Au(0) or Pd(0), respectively. Furthermore, Energy Dispersive Spectrometry (EDS) and Fast Fourier Transformation (FFT) analyses confirmed that the nanoparticles indeed were bimetallic. The bimetallic nanoparticles did not have a core-shell structure, but were superior to monometallic particles at reducing p-nitrophenol to p-aminophenol. Hence, formation of microbially supported nanoparticles may be a cheap and environmentally friendly approach for production of bimetallic nanocatalysts.

Topics: Aminophenols; Cupriavidus necator; Gold; Kinetics; Metal Nanoparticles; Nanocomposites; Nitrophenols; Oxidation-Reduction; Palladium; Spectrum Analysis

Human carcinogens are formed mainly due to the lifestyle and diet that is followed. It is well known that dietary factors play a crucial role in the aetiology of human cancer. The new attractions of drug discovery using natural products remain an important issue in the current herbal medicine research. The present study aimed to evaluate the antimutagenic activity of the water extracts of Doash leaves against several known mutagens, both direct- and indirect-acting, belonging to different chemical classes. These classes are heterocyclic amines (HAs), polycyclic aromatic hydrocarbons and nitrosamines. The antimutagenic activity will be determined in Salmonella/microsomal system (Ames) using strains of Salmonella Typhimurium. Four Salmonella bacterial strains (TA98, TA97, TA100 and TA1530) were used in the present study. Results obtained showed that Doash extract possesses powerful antimutagenic properties, which impair the deleterious effects of various chemicals used in this study. One possible mechanism involved in this protection is the inhibition of the metabolic activation of chemical carcinogens to their reactive metabolites. We also suggest that the health benefits of Doash could be derived from the additive and synergistic combinations of the various phytochemicals present in Doash leaves. Other studies should also be conducted to determine the active components of Doash leaves, including macronutrients, micronutrients and other phytochemicals. Clinical studies should be performed before any claims that Doash consumption offers chemoprotection against cancer can be made.

Topics: Animals; Antimutagenic Agents; Benz(a)Anthracenes; Hydroxylation; Male; Methylnitronitrosoguanidine; Microsomes, Liver; Mutagens; Mutation; N-Nitrosopyrrolidine; Nitrophenols; Plant Extracts; Plant Leaves; Quinolines; Rats; Rats, Wistar; Salmonella typhimurium; Tea

Epidemiological studies have shown an association between consumption of disinfected drinking water and adverse health outcomes. The chemicals used to disinfect water react with occurring organic matter and anthropogenic contaminants in the source water, resulting in the formation of disinfection by-products (DBPs). The observations that some DBPs are carcinogenic in animal models have raised public concern over the possible adverse health effects for humans. Here, the modulation of liver cytochrome P450-linked monooxygenases (MFO) and the genotoxic effects in erythrocytes of Cyprinus carpio fish exposed in situ to surface drinking water in the presence of disinfectants, such as sodium hypochlorite (NaClO), chlorine dioxide (ClO(2)) and peracetic acid (PAA), were investigated in winter and summer. A complex induction/suppression pattern of CYP-associated MFOs in winter was observed for all disinfectants. For example, a 3.4- to 15-fold increase was recorded of the CYP2B1/2-linked dealkylation of penthoxyresorufin with NaClO (10 days) and PAA (20 days). In contrast, ClO(2) generated the most notable inactivation, the CYP2E1-supported hydroxylation of p-nitrophenol being decreased up to 71% after 10 days' treatment. In summer, the degree of modulation was modest, with the exception of CYP3A1/2 and CYP1A1 supported MFOs (62% loss after 20 days PAA). The micronucleus (MN) induction in fish circulating erythrocytes was also analysed as an endpoint of genotoxic potential in the same fish population. Significant increases of MN induction were detected at the latest sampling time on fish exposed to surface water treated with chlorinate-disinfectants, both in winter (NaClO) and summer (NaClO and ClO(2)), while no effect was observed in fish exposed to PAA-treated water. These results show that water disinfection may be responsible for harmful outcomes in terms of MFO perturbation and DNA damage; if extrapolated to humans, they ultimately offer a possible rationale for the increased urinary cancer risk recorded in regular drinking water consumers.

Topics: Animals; Carps; Chlorine Compounds; Comet Assay; Cytochrome P-450 Enzyme System; Disinfectants; DNA Damage; Drinking Water; Environmental Monitoring; Models, Animal; Nitrophenols; Oxides; Peracetic Acid; Seasons; Sodium Hypochlorite; Water Pollutants, Chemical

The purpose of the research is to investigate the application of bagasse fly ash, a sugar industry solid waste for the synthesis of zeolites and their behavior for the sorption of p-nitrophenol (p-NP).. Zeolitic materials were prepared from bagasse fly ash using alkaline hydrothermal (CZBFA) and fusion (FZBFA) treatment. Comparative batch sorption studies of prepared zeolitic material and virgin material were undertaken to determine their capacities for removal of p-nitrophenol.. PXRD patterns revealed that zeolite P and analcime were the dominant contents of synthesized zeolitic material. Chemical composition, morphology, and crystalline nature of CZBFA and FZBFA were characterized by XRF, FTIR, and SEM. The Langmuir, Freundlich, Dubinin Redushkwich, and Temkin sorption isotherms were applied to compare the sorption nature and capacity of synthesized CZBFA and FZBFA with virgin BFA. For each sorbent-p-NP system, a pseudo-second-order kinetic model described the sorption kinetics accurately. The thermodynamics of the p-NP-sorbent systems exhibit an exothermic sorption process. Intraparticle diffusion model shows that the sorption rate was controlled by film diffusion followed by pore diffusion. Regeneration of sorbents was carried out by desorption studies with HCl, NaOH, and SDS detergent. The column studies were performed for the practical utility of sorbents, and breakthrough curve were obtained, which exhibit higher sorption capacity than batch method.. The sorption capacities of the synthesized zeolites had improved sorption capacities for the sequestration of p-NP and can be utilized as low-cost sorbents for treatment of p-nitrophenolic wastewater.

Topics: Adsorption; Agriculture; Coal Ash; Diffusion; Industrial Waste; Kinetics; Liquid-Liquid Extraction; Microscopy, Electron, Scanning; Models, Chemical; Nitrophenols; Powder Diffraction; Saccharum; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Waste Disposal, Fluid; Water Pollutants, Chemical; X-Ray Diffraction; Zeolites

The measurement of blood cholinesterase (ChE) activities is adopted worldwide for biological monitoring of exposure to organophosphorus insecticides (OPs). Recent development of analytical chemistry has made sensitive quantification possible of non-specific OP metabolites, dialkylphosphates, in urine as a biomarker of low-level OP exposure. In this study, we established a method for quantification of urinary 3-methyl-4-nitrophenol (MNP), a specific metabolite of fenitrothion (FNT), and a parathion metabolite p-nitrophenol (PNP), using gas chromatography-mass spectrometry. The limits of detection of MNP and PNP were 0.3 and 0.5μg/L, respectively. The method enabled the quantification of both free and conjugated metabolites. This method was actually applied to monitor human urine in summer and winter in FNT sprayers (N=29 and 9, respectively) and control workers (N=17 and 29, respectively). Geometric mean total MNP concentrations (μg/gcreatinine) in the FNT sprayers (28.8 in summer and 8.6 in winter) were significantly higher than those of the controls (3.1 in summer and 2.3 in winter) in both seasons. Among the sprayers, total MNP concentrations in summer were significantly higher than in winter. In contrast, no significant difference in total PNP concentrations was observed between FNT sprayers (geometric mean 3.4 in summer and 3.0 in winter) and controls (3.6 in summer and 2.1 in winter). No seasonal difference was observed in each group. In conclusion, the present new method is sensitive enough for biological monitoring of FNT and parathion metabolites even in a non-spraying population.

Topics: Agriculture; Cholinesterases; Chromatography, Liquid; Cresols; Environmental Exposure; Fenitrothion; Gas Chromatography-Mass Spectrometry; Humans; Insecticides; Molecular Structure; Nitrophenols; Occupational Exposure; Seasons; Sensitivity and Specificity; Tandem Mass Spectrometry

We found that the absorption spectra of 2-acetylphenol (2-HAP), 4-acetylphenol (4-HAP), and p-nitrophenol (p-NPh) in water/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane reverse micelles (RMs) at various W(0) (W(0) = [H(2)O]/[surfactant]) values studied changed with time if (-)OH ions were present in the RM water pool. There is an evolution of ionized phenol (phenolate) bands to nonionized phenol absorption bands with time and this process is faster at low W(0) values and with phenols with higher bulk water pK(a) values. That is, in bulk water and at the hydroxide anion concentration used, only phenolate species are observed, whereas in AOT RMs at this fixed hydroxide anion concentration, ionized phenols convert into nonionized phenol species over time. Furthermore, we demonstrate that, independent of the (-)OH concentration used to prepare the AOT RMs, the nonionized phenols are the more stable species in the RM media. We explain our results by considering that strong hydrogen-bonding interactions between phenols and the AOT polar head groups result in the existence of only nonionized phenols at the AOT RM interface. The situation is quite different when the phenols are dissolved in cationic benzyl-n-hexadecyldimethylammonium chloride RMs. Therein, only phenolates species are present at the (-)OH concentrations used. The results clearly demonstrate that the classical definition of pH does not apply in a confined environment, such as in the interior of RMs and challenge the general idea that pH can be determined inside RMs.

Topics: Dioctyl Sulfosuccinic Acid; Heptanes; Hydrogen Bonding; Hydrogen-Ion Concentration; Hydroxides; Ions; Micelles; Nanotechnology; Nitrophenols; Phenol; Water

The degradation of 4-nitrophenol was investigated using a novel electrochemical oxidation system, in which the anodic oxidation at Ti/SnO(2)-Sb(2)O(5)-IrO(2) electrode and the electro-Fenton oxidation with two cathodes were involved. In this system, gas diffusion electrode (GDE) was used to generate H(2)O(2) by O(2) reduction and graphite electrode was employed for the reduction of Fe(3+) regenerating Fe(2+). When the potential values of GDE and graphite cathode were controlled at -0.80 and -0.10 V/SCE respectively, the optimum Fe(2+) concentration for 4-nitrophenol degradation was about 0.10mM, much lower than the concentration of 0.25 mM obtained in the single-cathode system. Due to the combination of electro-Fenton oxidation and anodic oxidation, an effective degradation and a high mineralization current efficiency (MCE) were achieved. After 600 min treatment, 74.5% of the original TOC was removed by the dual-cathode oxidation system. Moreover, it was confirmed that 57.0% of the original nitrogen could be removed in gaseous form from the simulated wastewater. These results indicate that this electrochemical oxidation process might provide an alternative for the degradation of organic pollutants.

Topics: Electrochemistry; Electrodes; Hydrogen Peroxide; Iron; Nitrophenols; Oxidation-Reduction

The use of nitric-acid-activated fly ash (AFA), as heterogeneous Fenton-like catalyst for p-nitrophenol (p-NP) removal from water, was investigated. The physicochemical characteristics of AFA were better than those of raw fly ash (RFA). Under experimental conditions of pH 1.5-5.1, H(2)O(2) dosage 83.3-333 mgL(-1), AFA loaded 5.0-20 gL(-1), and temperature 298-348 K, the p-NP removal rate increased with the increase of H(2)O(2) dosage, AFA loaded and temperature. The highest removal rate (98%) was observed at pH 2.0 when H(2)O(2) dosage 166.5 mgL(-1), AFA loaded 10 gL(-1) and temperature 298 K. However, good p-NP removal efficiency (98.8%) could still be achieved under milder pH (5.1) conditions when enough reaction time (14 h) was applied. The leached iron concentration increased with decrease in pH and with increase in reaction time. The homogenous catalysis caused by leached iron was negligible. The less reaction time and higher AFA load could be selected flexibly for catalytic stability and reusability in actual application. The probable heterogeneous catalytic mechanisms were proposed.

Topics: Catalysis; Coal Ash; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Kinetics; Nitric Acid; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical; Water Purification

A graphene oxide (GO) film coated glassy carbon electrode (GCE) was fabricated for sensitive determination of 4-nitrophenol (4-NP). The GO-based sensor was characterized by scanning electron microscope, atomic force microscopy and electrochemical impedance spectroscopy. The electrochemical behaviors of 4-NP at the GO-film coated GCE were investigated in detail. In 0.1M acetate buffer with a pH of 4.8, 4-NP yields a very sensitive and well-defined reduction peak at the GO-modified GCE. It is found that the GO film exhibits obvious electrocatalytic activity toward the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. Various kinetic parameters such as transfer electron number, transfer proton number and standard heterogeneous rate constant were calculated, and various experimental parameters were also optimized. Under the optimal conditions, the reduction peak current varies linearly with the concentration of 4-NP ranging from 0.1 to 120 μM, and the detection limit is 0.02 μM at the signal noise ratio of 3. Moreover, the fabricated sensor presented high selectivity and long-term stability. This electrochemical sensor was further applied to determine 4-NP in real water samples, and it showed great promise for simple, sensitive, and quantitative detection of 4-NP.

Topics: Electrochemical Techniques; Electrodes; Environmental Monitoring; Graphite; Microscopy, Electron, Scanning; Nitrophenols; Sensitivity and Specificity; Spectroscopy, Fourier Transform Infrared; Water Pollutants, Chemical

Polymer particles with dendrimer@SiO(2)-Ag hierarchical shell were prepared, and their application in the catalytic column for the reduction of 4-nitrophenol (4-NP) was also investigated. The PS microspheres with the carboxyl group were used as the supports for the immobilization of dendrimer@SiO(2)-Ag shell. The polyamidoamine (PAMAM) dendrimer was grafted on the surface of PS microsphere through repetitive Michael addition reaction of methyl acrylate (MA) and amidation of the obtained esters with a large excess of ethylenediamine (EDA) successively. The silver nanoparticles formed inside the PAMAM shell. Then, the silver nanoparticles, which were used as center of nucleation, were coated with SiO(2) shell through improved Stöber method. Moreover, the more silver nanoparticles were dispersed on the surface of SiO(2) shell. The contents of silver element were measured using inductively coupled plasma (ICP-MS). The obtained PS@PAMAM@SiO(2)-Ag nanoparticles were packed in stainless steel column, which has been used effectively for the catalytic reduction of 4-NP. Under column pressures, the rigid SiO(2) shell plays a better role in immobilization of silver nanoparticles than the soft PAMAM shell. This technique for packing catalytic nanoparticles in column improves the efficiency of application with metal catalysts as well as reduces the tedious separation processes in catalytic reaction.

Topics: Catalysis; Dendrimers; Nitrophenols; Oxidation-Reduction; Polyamines; Silicon Dioxide; Silver

Ferrous hydroxide colloids were prepared and characterized as an activator of H(2)O(2) for decomposing organic pollutants, such as Rhodamine B, sulfamonomethoxine (SMM) and 4-nitrophenol (4-NP). As major reactive oxygen species, hydroxyl radicals were confirmed to be generated in the activation of H(2)O(2) by using fluorescent probe technique and electron spin resonance technique. The highly-dispersed colloidal nanoparticles with large specific surface area combined the merits of both homogeneous and heterogeneous activator, leading to fast degradation of organic contaminants. Almost complete decolorization of added RhB (0.02 mM), along with a removal of 64.3% of total organic carbon, was achieved within only 1 min by adding 0.30 mM ferrous hydroxide colloids and 1.20 mM H(2)O(2) at pH 7.0. Based on the contributions from the redox activation and the caged activation, a new mechanism was proposed to explain the enhancing effect of the colloids.

Topics: Colloids; Environmental Pollutants; Environmental Restoration and Remediation; Ferric Compounds; Hydrogen Peroxide; Iron; Nitrophenols; Rhodamines; Sulfamonomethoxine

The aim of the study was to investigate the acclimation of precultivated acetate-fed aerobic granular sludge to a toxic xenobiotic biodegradation. Establishment of p-nitrophenol (PNP) biodegradation in acetate-fed aerobic granular sludge and concomitant changes in the microstructure and bacterial community were determined. Rapid establishment of PNP utilization was observed in the granular sludge when fed with PNP as the sole carbon source. The specific PNP removal was 36-mg h(-1) g(-1) granular biomass at an initial PNP concentration of 50 mg L(-1). The presence of PNP resulted in significant membrane damage in a subpopulation of the bacterial consortium, as shown by BacLight viability staining. This was coincided with a significant decrease in the culturable bacterial diversity of the granular biomass. PCR-DGGE analysis revealed a shift and decrease in number of bands during the establishment of PNP biodegradation. Scanning electron microscopy showed the dominance of rod-shaped bacteria in the PNP-utilizing microbial granules. Our results suggest that acetate-fed granular sludge could be quickly adapted for PNP biodegradation.

Topics: Acetates; Aerobiosis; Bacteria; Biodegradation, Environmental; Environmental Pollutants; Kinetics; Nitrophenols; RNA, Ribosomal, 16S; Sewage

Little is known about the effects of the cardiovascular drug verapamil (VRP) on metabolic processes in fish. Most calcium channel blockers including VRP are metabolized by cytochrome P450 (CYP450) enzymes. In this study we investigated the in vivo effect of VRP on some CYP450-mediated reactions in juvenile rainbow trout (Oncorhynchus mykiss). Fish were exposed to sublethal concentrations of VRP (0.5, 27 and 270 μg l(-1)) for 0, 21, and 42 day. The following CYP450-mediated reactions were studied in hepatic microsomes: O-dealkylation of ethoxyresorufin, methoxyresorufin, and pentoxyresorufin, hydroxylation of coumarin, tolbutamide, and p-nitrophenol, and O-debenzylation of 7-benzyloxy-4-trifluoromethylcoumarin. The amounts of products of these reactions did not differ among fish exposed to different levels of VRP and control fish. This suggests that the levels of VPR used did not alter catalytic activity of the selected CYP450 enzymes. In conclusion, none of the investigated CYP450-mediated reactions has potential as a biomarker to monitor VRP contamination of the aquatic environment.

Topics: Animals; Biomarkers; Calcium Channel Blockers; Coumarins; Cytochrome P-450 Enzyme System; Dose-Response Relationship, Drug; Liver; Microsomes, Liver; Nitrophenols; Oncorhynchus mykiss; Oxazines; Verapamil; Water Pollutants, Chemical

Bioelectrochemical system (BES) for recalcitrant p-nitrophenol (PNP) removal was investigated in this study. Effective removal of PNP at rates up to 9.14 ± 0.48 mol m(-3)d(-1) was achieved at an energy consumption as low as 0.010 ± 0.002 kWh mol(-1) PNP. PNP removal rate was enhanced with negative cathode potential, increased influent PNP concentration and shortened hydraulic retention time (HRT). Although the coulombic efficiencies at the anode did not exceed 40%, coulombic efficiencies for PNP removal at the cathode were above 70% at various cathode potentials. Compared with conventional anaerobic process, the cosubstrate dosage in BES was significantly reduced due to the high coulombic efficiencies at the cathode. p-Aminophenol (PAP) was identified as the dominant product of PNP reduction at the abiotic graphite cathode of BESs. This study demonstrated that the BES had a potential for efficient removal of nitrophenol pollutants from wastewater.

Topics: Chromatography, High Pressure Liquid; Electrochemistry; Nitrophenols; Spectrophotometry, Ultraviolet

We demonstrated a simple, in situ reduction route to the synthesis of two-dimensional graphene oxide/SiO(2) (GSCN) hybrid nanostructures consisting of Au nanoparticles (Au NPs) supported on the both sides of GSCN. The as-prepared GSCN/Au NPs hybrid nanomaterials exhibited good catalytic activity for the reduction of 4-nitrophenol. This approach provided a useful platform based on GO hybrid nanomaterials for the fabrication of GSCN/Au NPs hybrid nanomaterials, which could be very useful in catalytic applications.

Topics: Catalysis; Gold; Graphite; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Oxides; Silicon Dioxide

Topics: Borohydrides; Catalysis; Crystallization; Gold; Metal Nanoparticles; Muramidase; Nitrophenols; Oxidation-Reduction

Well-defined and monodisperse dendritic platinum nanoparticles (DPNs) are successfully prepared by a rapid, one-step, and efficient route with high yield in aqueous solution, wherein neither organic solvents nor surfactants are employed, ensuring the as-made DPNs definitely have "clean" surfaces, allowing them to exhibit high activity for both methanol oxidation and p-nitrophenol reduction. This proposed strategy for simple and facile preparation of "clean" metal nanocatalysts paves the way for accurately evaluating and further improving their intrinsic catalytic activity.

Topics: Catalysis; Metal Nanoparticles; Methanol; Nitrophenols; Oxidation-Reduction; Platinum; Spectrophotometry, Ultraviolet; Water

The aerobic biodegradation of the three dihydroxybenzene isomers (catechol, resorcinol and hydroquinone) by an activated sludge acclimated to consume p-nitrophenol (PNP) was studied through batch respirometric tests. The PNP-degrading biomass was able to consume each isomer as the sole organic carbon source, as well as, mixtures of two or three dihydroxybenzenes. However, the biodegradation rates were significantly different for each isomer and were highly influenced by the simultaneous presence of the other dihydroxybenzenes in binary or ternary mixtures. In general, hydroquinone was the isomer consumed at the fastest rate while the consumption rate of resorcinol was the slowest one. The kinetics of aerobic biodegradation of hydroquinone and catechol were successfully described by a Haldane model. The values of the kinetic coefficients showed that the affinity of PNP-degrading biomass for both isomers was low while catechol caused less substrate inhibition than hydroquinone.

Topics: Aerobiosis; Benzene Derivatives; Biodegradation, Environmental; Kinetics; Nitrophenols; Sewage

The liquid-phase hydrogen peroxide catalytic oxidation of p-nitrophenol was performed with an Fe(III)-resin catalyst. The conversion and mineralization of p-nitrophenol was effectively achieved at mild reaction conditions with the Fe(III)-resin catalyst. It was found that the oxidant concentration, pH, and temperature dominated the degradation rate of p-nitrophenol. The denitration pathway of p-nitrophenol was proposed, in which the concentration of H(2)O(2) and temperature showed strong influence on the conversion of nitrite to nitrate. To study the factors influencing the denitration of p-nitrophenol, a comparable kinetic study was attempted to know the possible denitration pathway of p-nitrophenol. The results of this investigation indicated that denitration was the possible step occurring with the decomposition of p-nitrophenol.

Topics: Catalysis; Denitrification; Ferric Compounds; Hydrogen Peroxide; Hydrogen-Ion Concentration; Kinetics; Nitrates; Nitrites; Nitrophenols; Oxidation-Reduction; Resins, Synthetic; Temperature; Water Pollutants, Chemical

Mixed microbial consortia in the form of aerobic microbial granules (AMG) capable of xenobiotic degradation can be developed from activated sludge or by adaptation of microbial granules pre-grown on labile carbon sources. Both of these approaches were investigated for the cultivation of AMG capable of p-nitrophenol (PNP) biodegradation. Attempts to cultivate AMG from activated sludge using PNP as the sole carbon source were not successful due to poor microbial growth and washout of the inoculated activated sludge. As part of the second approach, parallel sequencing batch reactors (SBRs) were inoculated with pre-grown AMG and operated by feeding both acetate and PNP together (RA), PNP alone (RB) or acetate alone (RC). Acetate/PNP mineralization and nitrification were monitored in the three SBRs. PNP biodegradation was quickly established in both RA and RB. PNP removal rates were found to be 47 and 55 mg g VSS(-1) h(-1) in RA and RB, respectively. PNP biodegradation during the SBR cycle consisted of distinct lag, exponential and deceleration phases. However, with higher concentrations of PNP (>50 mg l(-1)), disintegration of granules was observed in RA and RB. When PNP was the sole carbon source, it inhibited the development of aerobic granules from activated sludge and caused disintegration of pre-cultivated aerobic granules. When PNP was the co-substrate along with acetate, the structural and functional integrity (including nitrification) of the granular sludge was maintained. This report highlights the importance of a labile co-substrate for maintaining the physical and functional integrity of granular sludge, when used for toxic waste degradation.

Topics: Aerobiosis; Bacteria; Base Sequence; Biodegradation, Environmental; Biomass; Bioreactors; Colony Count, Microbial; DNA Primers; Microscopy, Confocal; Nitrophenols; Polymerase Chain Reaction; Sewage

Bone homeostasis is maintained by the balance between osteoblastic bone formation and osteoclastic bone resorption. Osteoclasts are multinucleated cells that are formed by mononuclear preosteoclast fusion. Fat-soluble vitamins such as vitamin D are pivotal in maintaining skeletal integrity. However, the role of vitamin E in bone remodeling is unknown. Here, we show that mice deficient in α-tocopherol transfer protein (Ttpa(-/-) mice), a mouse model of genetic vitamin E deficiency, have high bone mass as a result of a decrease in bone resorption. Cell-based assays indicated that α-tocopherol stimulated osteoclast fusion, independent of its antioxidant capacity, by inducing the expression of dendritic-cell-specific transmembrane protein, an essential molecule for osteoclast fusion, through activation of mitogen-activated protein kinase 14 (p38) and microphthalmia-associated transcription factor, as well as its direct recruitment to the Tm7sf4 (a gene encoding DC-STAMP) promoter. Indeed, the bone abnormality seen in Ttpa(-/-) mice was rescued by a Tm7sf4 transgene. Moreover, wild-type mice or rats fed an α-tocopherol-supplemented diet, which contains a comparable amount of α-tocopherol to supplements consumed by many people, lost bone mass. These results show that serum vitamin E is a determinant of bone mass through its regulation of osteoclast fusion.

Topics: alpha-Tocopherol; Amino Acids; Animals; Apoptosis; Bone and Bones; Bone Resorption; Bromodeoxyuridine; Carrier Proteins; Cell Differentiation; Cell Proliferation; Cells, Cultured; Chromatin Immunoprecipitation; Disease Models, Animal; Gene Expression Regulation; Humans; In Situ Nick-End Labeling; Macrophage Colony-Stimulating Factor; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Microphthalmia-Associated Transcription Factor; Mitogen-Activated Protein Kinase 14; Nitrophenols; Osteoclasts; Osteocytes; RANK Ligand; Rats; RNA, Small Interfering; Signal Transduction; Tomography, X-Ray Computed; Transfection; Vitamin E; Vitamin E Deficiency; Vitamins

We developed novel flow-through surface-enhanced Raman scattering (SERS) platforms using gold nanoparticle (Au-NP) immobilized multihole capillaries for rapid and sensitive vapor detection. The multihole capillaries consisting of thousands of micrometer-sized flow-through channels provide many unique characteristics for vapor detection. Most importantly, its three-dimensional SERS-active micro-/nanostructures make available multilayered assembly of Au-NPs, which greatly increase SERS-active surface area within a focal volume of excitation and collection, thus improving the detection sensitivity. In addition, the multihole capillary's inherent longitudinal channels offer rapid and convenient vapor delivery, yet its micrometer-sized holes increase the interaction between vapor molecules and SERS-active substrate. Experimentally, rapid pyridine vapor detection (within 1 s of exposure) and ultrasensitive 4-nitrophenol vapor detection (at a sub-ppb level) were successfully achieved in open air at room temperature. Such an ultrasensitive SERS platform enabled, for the first time, the investigation of both pyridine and 4-nitrophenol vapor adsorption isotherms at very low concentrations. Type I and type V behaviors of the International Union of Pure and Applied Chemistry isotherm were well observed, respectively.

Topics: Gold; Metal Nanoparticles; Nitrophenols; Pyridines; Spectrum Analysis, Raman; Surface Properties; Volatilization

In this study, we investigated the catalytic properties of N,N-dimethylformamide (DMF)-stabilized gold nanoclusters (AuNCs) in the reduction of 4-nitrophenol (PNP) to 4-aminophenol by NaBH(4), a well known model reaction to be catalyzed by metal surfaces. The DMF-stabilized AuNCs were prepared in DMF by a surfactant-free method. The DMF-stabilized AuNCs showed high catalytic activity even when used in small quantities (∼10(-7) g). The pseudo-first-order rate constant (k(app)) and activation energy were estimated to be 3 × 10(-3) s(-1) and 31 kJ mol(-1), respectively, with 1.0 μM of the gold catalyst at 298 K. The catalytic activity of the DMF-stabilized AuNCs was strongly influenced by the layer of adsorbed DMF on the Au NCs. This layer of adsorbed DMF prohibited the reactants from penetrating to the surface of the AuNCs via the diffusion at the beginning of the reaction, resulting in an induction time (t(0)) before PNP reduction began. Restructuring of the DMF layer (essentially a form of activation) was the key to achieving high catalytic activity. In addition, atomically monodisperse Au(25)(SG)(18)NCs (SG: glutathione) showed higher catalytic activity in the PNP reduction (k(app) = 8 × 10(-3) s(-1)) even with a low catalyst concentration (1.0 μM), and there was no induction time (t(0)) in spite of the strongly binding ligand glutathione. This suggested that the catalytically active surface sites of the Au(25)(SG)(18)NCs were not sterically hindered, possibly because of the unique core-shell-like structure of the NCs. Retaining these open sites on AuNCs may be the key to making the NCs effective catalysts.

Topics: Catalysis; Dimethylformamide; Formamides; Gold; Kinetics; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction

A clone (LP001) expressing a new lipase gene was isolated from a metagenomic library of the Brazilian Atlantic Forest soil. The DNA insert of LP001 was fully sequenced, and 38 ORFs were identified. Comparison of ORFs, %G + C content and gene organization with sequenced bacterial genomes suggested that the fosmid DNA insert belongs to an organism of the Acidobacteria phylum. Protein domain analysis and inactivation by transposon insertion showed that the protein encoded by ORF29 was responsible for the lipase activity and was named LipAAc. The purified LipAAc lipase was capable of hydrolyzing a broad range of substrates, showing the highest activity against p-nitrophenol (pNP) decanoate. The lipase was active over a pH range of 5.0-10.0 and was insensitive to divalent cations. LipAAc is moderately thermostable with optimum temperature between 50 and 60 °C and was thermally activated (80% activity increase) after 1 h incubation at 50 °C. Phylogenetic analysis suggested that the LipAAc is a member of family I of bacterial lipases and clusters with other moderately thermostable lipases of this group. Comparisons of the DNA insert of fosmid LP001 with other acidobacterial genomes and sequence database suggest that lipAAc gene has a fungal origin and was acquired by horizontal transfer.

Topics: Acidobacteria; Bacterial Proteins; Base Composition; Brazil; DNA, Bacterial; Gene Library; Genome, Bacterial; Lipase; Metagenome; Molecular Sequence Data; Nitrophenols; Open Reading Frames; Phylogeny; Sequence Analysis, DNA; Soil Microbiology; Trees

Here we report a facile, surfactant-free and template-free synthesis process of highly uniform dendritic silver nanostructures with high catalytic activity for the reduction of p-nitrophenol. By controlling the concentration of AgNO(3) aqueous solution and the reaction time, various shapes of silver nanodendrites (SNDs) could be obtained easily. The effects of different parameters such as concentrations of the reagents and reaction time on the morphology and structure of as-prepared tree-like nanostructures have also been investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Also, the X-ray photoelectron spectroscopy (XPS) has been used to identify the oxidation state of SNDs. In addition, the catalytic activity of the as-prepared SNDs samples at 200 mM AgNO(3) aqueous solution was evaluated by a redox reaction of p-nitrophenol in the presence of an excess amount of NaBH(4). It was found that the highly symmetrical SNDs with roughly 60-120 nm in stem and branch diameter and 3-12 μm in length obtained after 120 s reaction time do have higher catalytic activity than other SNDs prepared at different reaction time, several times stronger catalytic activity in the sodium borohydride reduction of p-nitrophenol to p-aminophenol, compared to some other silver nanoparticles reported in literature. The crystallinity provided by X-ray diffraction (XRD) analysis indicates that the improvement of the crystallinity is also very crucial for SNDs' catalytic activities. The SNDs are very promising catalytic candidates for the reduction of p-nitrophenol because of easily simple preparation route and high catalytic activity.

Topics: Catalysis; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanostructures; Nitrophenols; Oxidation-Reduction; Photoelectron Spectroscopy; Silver; X-Ray Diffraction

An enzymatic reaction within a mesh-like structure constructed using hyaluronan was investigated in order to understand the influence of specific reaction environments in a living body on the reaction. This mesh-like structure, which mimicked extracellular matrix conditions, was found to accelerate glycohydrolysis by Jack bean α-mannosidase.

Topics: alpha-Mannosidase; Biomimetic Materials; Extracellular Matrix; Fabaceae; Hyaluronic Acid; Kinetics; Magnetic Resonance Spectroscopy; Mannose; Nitrophenols

Ni(x)Co(100-x) (x = 0, 25, 50, 75, and 100) nanoparticles were uniformly in situ grown on reduced graphene oxide (RGO) nanosheets by a coreduction process for the first time. The as-synthesized products were characterized by X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES), and transmission electron microscopy (TEM). It was found that RGO nanosheets can effectively prevent the aggregation of Ni(x)Co(100-x) nanoparticles. The size and morphology of the Ni(x)Co(100-x) nanoparticles on RGO nanosheets can be slightly adjusted by changing the Ni:Co atomic ratio. The magnetic properties of the RGO-Ni(x)Co(100-x) composites were investigated at 300 and 1.8 K, respectively. The results reveal that the composites have ferromagnetic characteristics and show composition dependent magnetic properties. In addition, these RGO-Ni(x)Co(100-x) nanocomposites also exhibit enhanced catalytic activities toward the reduction of 4-nitrophenol (4-NP) by NaBH(4) as compared with bare Ni(x)Co(100-x) alloy, and the RGO-Ni(25)Co(75) shows the highest catalytic activity among the obtained nanocomposites. This general and facile coreduction route can be extended to synthesize other alloy nanostructures on RGO nanosheets with various morphologies and functions, and provides a new opportunity for the application of graphene-based materials.

Topics: Catalysis; Cobalt; Graphite; Magnetics; Nanoparticles; Nickel; Nitrophenols; Oxidation-Reduction; Oxides

The degradation and detoxification towards the duckweed Lemna minor of 4-nitrophenol (4NP) was studied by means of bench-scale constructed wetlands (CWs), TiO(2)-photocatalysis and Fenton + photoFenton reactions. The main goal of this work was to compare the three treatment techniques to evaluate their possible combination for the efficient, low cost treatment of 4NP effluents. In CWs, adsorption on the substrate of 4NP was found to achieve 34-45%. Low concentrations (up to 100 ppm) of 4NP were successfully treated by CWs in 8-12 h. The microbial degradation of 4NP started after a lag phase which was longer with higher initial concentrations of the pollutant. The greatest degradation rate was found to occur at initial concentrations of 4NP between 60 and 90 ppm. Solar TiO(2)-photocatalysis was faster than the CWs. The greatest removals in terms of mass of 4NP removed after 6 h of irradiation were found to occur at 4NP concentrations of about 200 ppm. Fenton reaction provided complete 4NP degradation up to 500 ppm in only 30 min but TOC was removed by only about 40%. The resulting toxicities were below 20% for initial 4NP concentrations below 300 ppm. It was the Fenton + photoFenton combination (180 min in total) that provided TOC reductions up to 80% and negative L. minor growth inhibition for almost all the 4NP concentrations tested. The combination of solar TiO(2)-photocatalysis (6 h) with CWs (16 h) was able to completely treat and detoxify 4NP effluents with concentrations as high as 200 ppm of the organic.

Topics: Biodegradation, Environmental; Catalysis; Light; Nitrophenols; Oxidation-Reduction; Plants; Titanium; Water Microbiology; Wetlands

In this study, a facile one-step redox polymerization method for the preparation of highly dispersed palladium (Pd)/polypyrrole (PPy) nanocapsules has been demonstrated. During the polymerizaion process, the formation of RB-PdCl(4)(2-) complex via an electrostatic interaction plays a key role for the preparation of Pd/PPy composite nanocapsules. The well-dispersed Pd nanocrystals with small sizes of 2-4 nm embedded in PPy nanocapsules exhibited a good catalytic activity during the catalytic reduction of p-nitrophenol into p-aminophenol by NaBH(4) in aqueous solution. The kinetic apparent rate constant (k(app)) was about 8.87×10(-3) s(-1). Moreover, the as-prepared Pd/PPy composite nanocapsules exhibited a good reusability, which could be repeatedly used for the reduction of p-nitrophenol with a high catalytic activity for at least 10 successive cycles.

Topics: Aminophenols; Catalysis; Nanocapsules; Nitrophenols; Organometallic Compounds; Oxidation-Reduction; Palladium; Particle Size; Polymerization; Polymers; Pyrroles; Surface Properties

Molecularly imprinted polymers were grafted on the surface of multiwalled carbon nanotubes (MWCNT) using the hydrolysis product of paraoxon 4-nitrophenol as template, 4-vinyl pyridine (4-VPy) as the functional monomer and divinylbenzen (DVB) as the crosslinker. The binding experiments of 4-nitrophenol indicated that the MWCNT based molecularly imprinted polymers (MWCNT-MIP) have much higher adsorption ability than the MWCNT based non-imprinted polymers (MWCNT-NIP). At the same time we found that the adsorption of 4-nitrophenol can help to increase the hydrolytic rate of paraoxon, which indicates that there is an obvious catalyzing effect on the hydrolysis of paraoxon for this kind of materials. Furthermore, the 4-nitrophenol left in the paraoxon hydrolysis medium is only 0.01056 mM for MWCNT-MIP in the catalytic experiment of paraoxon we made (the initial concentration of paraoxon is 0.5 mM and MWCNT-MIP is 4 mg), which indicates that this kind of MWCNT based imprinted polymers can not only catalyze the hydrolysis of paraoxon but also eliminate the poisonous organism product 4-nitrophenol.

Topics: Adsorption; Catalysis; Hydrolysis; Insecticides; Molecular Imprinting; Nanotubes, Carbon; Nitrophenols; Paraoxon; Polymers; Water Pollutants, Chemical; Water Pollution

Cytochrome P450 (P450) enzymes are mixed-function oxidases that catalyze the metabolism of xenobiotics and endogenous biochemicals. Selective inhibitors are needed to accurately distinguish the contributions of individual P450 enzymes in the metabolism of drugs and the activation of procarcinogens in human tissues, but very frequently these enzymes have substantial overlapping selectivity. We evaluated a chemically diverse set of nine previously identified CYP2A6 inhibitors to determine which are able to discriminate between human CYP2A enzymes CYP2A6 and the 94%-identical CYP2A13 enzyme. Inhibitor binding to recombinant purified enzyme was evaluated, and affinities were determined. K(i) values were determined for inhibition of p-nitrophenol 2-hydroxylation, a reaction accomplished by CYP2A13 and CYP2A6 with more similar catalytic efficiencies (k(cat)/K(m) 0.19 and 0.12 μM⁻¹ · min⁻¹, respectively) than hydroxylation of the classic substrate coumarin (0.11 and 0.53 μM⁻¹ · min⁻¹, respectively). Of the nine compounds assayed, only tranylcypromine and (R)-(+)-menthofuran had a greater than 10-fold preference for CYP2A6 inhibition versus CYP2A13 inhibition. Most compounds evaluated [tryptamine, 4-dimethylaminobenzaldehyde, phenethyl isothiocyanate, β-nicotyrine, (S)-nicotine, and pilocarpine] demonstrated only moderate or no preference for inhibition of one CYP2A enzyme over the other. However, 8-methoxypsoralen has a 6-fold lower K(i) for CYP2A13 than for CYP2A6. This information is useful to inform reinterpretation of previous data with these inhibitors and to guide future studies seeking to determine which human CYP2A enzyme is responsible for the in vivo metabolism of compounds in human tissues expressing both enzymes.

Topics: Aryl Hydrocarbon Hydroxylases; Binding, Competitive; Catalysis; Coumarins; Cytochrome P-450 CYP2A6; Dose-Response Relationship, Drug; Enzyme Inhibitors; Humans; Hydroxylation; Ligands; Models, Biological; Molecular Structure; Monoterpenes; Nitrophenols; Protein Binding; Recombinant Proteins; Substrate Specificity; Tranylcypromine

The development of new synthesis methods for monodispersed nanocrystals using cheap and nontoxic chemicals, environmentally benign solvents and renewable materials remains a challenge to the scientific community. Most of the current methods involve known protocols which may be potentially harmful to either environment or human health. Recent research has been focused on green synthesis methods to produce new nanomaterials, ecofriendly and safer with sustainable commercial viability. The present work reports the green synthesis of gold nanoparticles using the aqueous extract of fenugreek (Trigonella foenum-graecum) as reducing and protecting agent. The pathway is based on the reduction of AuCl(4)(-) by the extract of fenugreek. This method is simple, efficient, economic and nontoxic. Gold nanoparticles having different sizes in the range from 15 to 25 nm could be obtained by controlling the synthesis parameters. The nanoparticles have been characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles is evident from clear lattice fringes in the HRTEM images, bright circular spots in the SAED pattern and peaks in the XRD pattern. FTIR spectrum indicates the presence of different functional groups present in the biomolecule capping the nanoparticles. The synthesized gold nanoparticles show good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH(4). The catalytic activity is found to be size-dependent, the smaller nanoparticles showing faster activity.

Topics: Catalysis; Colloids; Gold; Green Chemistry Technology; Hydrogen-Ion Concentration; Metal Nanoparticles; Nitrophenols; Particle Size; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Trigonella; X-Ray Diffraction

The nontarget effects, in terms of biochemical changes induced by p-nitrophenol (PNP) in three soil microalgae, Chlorella sp., Chlorococcum sp., and Heterochlamydomonas sp., and the PNP removal efficiency of these isolates, were determined. On exposure to 20 mg L(-1) PNP, Chlorella sp. showed greater activity of peroxidase, superoxide dismutase, and glutathione reductase as well as high contents of proline and carotenoids. While Heterochlamydomonas sp. exhibited higher levels of catalase and protein, Chlorococcum sp. produced greater amounts of malondialdehyde, a measure of lipid peroxidation, in the presence of PNP. Chlorella sp. tolerated PNP by producing large quantities of antioxidants coupled with less lipid peroxidation, while Chlorococcum sp. was susceptible, as evidenced by low antioxidant production and high lipid peroxidation. During 7-d exposure, Chlorella sp., Heterochlamydomonas sp., and Chlorococcum sp. were able to remove 39, 18, and 4% of 20 mg L(-1) PNP, respectively. The present results indicate that proline, carotenoids and malondialdehyde are the potential biomarkers for assessing PNP toxicity toward microalgae, and their response could be considered for differentiating tolerant and susceptible strains. Moreover, there is a clear correlation between PNP removal and antioxidant synthesis in microalgae on exposure to the pollutant.

Topics: Antioxidants; Catalase; Chlorella; Chlorophyta; Environmental Pollutants; Glutathione Peroxidase; Glutathione Reductase; Lipid Peroxidation; Malondialdehyde; Microalgae; Nitrophenols; Peroxidase; Soil; Superoxide Dismutase

A new phytochemical method for the synthesis of gold nanoparticles is reported. The essential oils extracted from the fresh leaves of Anacardium occidentale are used for the reduction of auric acid to Au nanoparticles (NPs). The formation and morphology of synthesized NPs are investigated with the help of UV-visible, TEM and FTIR spectroscopy. The NPs synthesized at room temperature are mono-dispersed and hexagonal in shape with an average size of 36 nm while those prepared at higher temperature are composed of a mixture of anisotropic particles. The UV-visible absorption spectra of these anisotropic NPs show asymmetry in the longer wavelength side. The quantity of oil is an important criterion modulating the shape of NPs. Possible biochemical mechanism leading to the formation of NPs is studied using FTIR spectroscopy. The potential of synthesized Au NPs as catalyst is explored for the hydrogenation of p-nitro phenol to p-amino phenol at room temperature.

Topics: Anacardium; Catalysis; Colloids; Gold; Metal Nanoparticles; Nitrophenols; Oils, Volatile; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Surface Plasmon Resonance; Temperature

In this work, we report a facile method to generate core-shell structured Fe(3)O(4)@SiO(2)-Ag magnetic nanocomposite by an in situ wet chemistry route with the aid of polyvinylpyrrolidone as both reductant and stabilizer. This method can effectively prevent Ag nanoparticles from aggregating on the silica surface, thus resulting highly dispersed and small-sized Ag nanoparticles. The as-prepared nanocomposite is composed of a central magnetite core with a strong response to external fields, an interlayer of SiO(2), and numerous highly dispersed Ag nanoparticles with a narrow size distribution. Furthermore, the Fe(3)O(4)@SiO(2)-Ag nanocomposite showed high performance in the catalytic reduction of 4-nitrophenol and could be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 15 times.

Topics: Catalysis; Ferrosoferric Oxide; Magnets; Nanocomposites; Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Silicon Dioxide; Silver

A new fluorescent biosensor has been designed to screen α-glucosidase inhibitors (AGIs) sensitively by utilizing signal amplification effect of conjugated polymers. The fluorescence of cationic poly(fluorenylene phenylene) (PFP) was quenched in the presence of para-nitrophenyl-α-d-glucopyranoside and α-glucosidase, and turned on upon addition of AGIs. Thus, a new method was developed for AGIs screening based on the fluorescence turn-off/turn-on. The IC(50) values obtained for inhibitors were compared with that reported using absorption spectroscopy. All results present the new method is more sensitive and promising in screening AGIs and inhibitors of other enzymes whose hydrolysis product is 4-nitrophenol.

Topics: alpha-Glucosidases; Biosensing Techniques; Cations; Diabetes Mellitus; Fluorenes; Fluorescent Dyes; Glucosides; Humans; Hydrolysis; Inhibitory Concentration 50; Kinetics; Nitrophenols; Nitrophenylgalactosides; Polymers; Quaternary Ammonium Compounds; Spectrophotometry

The fabrication of nanostructured bimetallic materials through electrochemical routes offers the ability to control the composition and shape of the final material that can then be effectively applied as (electro)-catalysts. In this work a clean and transitory hydrogen bubble templating method is employed to generate porous Cu-Au materials with a highly anisotropic nanostructured interior. Significantly, the co-electrodeposition of copper and gold promotes the formation of a mixed bimetallic oxide surface which does not occur at the individually electrodeposited materials. Interestingly, the surface is dominated by Au(I) oxide species incorporated within a Cu(2)O matrix which is extremely effective for the industrially important (electro)-catalytic reduction of 4-nitrophenol. It is proposed that an aurophilic type of interaction takes place between both oxidized gold and copper species which stabilizes the surface against further oxidation and facilitates the binding of 4-nitrophenol to the surface and increases the rate of reaction. An added benefit is that very low gold loadings are required typically less than 2 wt% for a significant enhancement in performance to be observed. Therefore the ability to create a partially oxidized Cu-Au surface through a facile electrochemical route that uses a clean template consisting of only hydrogen bubbles should be of benefit for many more important reactions.

Topics: Cations; Copper; Electrochemical Techniques; Gold; Hydrogen; Nanostructures; Nanotechnology; Nitrophenols; Oxidation-Reduction; Porosity; Spectrum Analysis; Surface Properties

Only limited information is available on the design and synthesis of functional materials for preventing corrosion of metal nanostructures. In the nanometer regime, even noble metals are subject to chemical attack. Here, the corrosion behavior of noble metal nanoparticles coated with a conjugated polymer nanolayer was explored for the first time. Specifically, electrochemical corrosion and sulfur tarnishing behaviors were examined for Ag-polypyrrole (PPy) core-shell nanoparticles using potentiodynamic polarization and spectrophotometric analysis, respectively. First, the Ag-PPy nanoparticles exhibited enhanced resistance to electrochemically induced corrosion compared to their exposed silver counterparts. Briefly, a neutral PPy shell provided the highest protection efficiency (75.5%), followed by sulfate ion- (61.3%) and dodecylbenzenesulfonate ion- (53.6%) doped PPy shells. However, the doping of the PPy shell with chloride ion induced an adverse effect (protection efficiency, -120%). Second, upon exposure to sulfide ions, the Ag-PPy nanoparticles preserved their morphology and colloidal stability while the bare silver analog underwent significant structural deformation. To further understand the function of the PPy shell as a protection layer for the silver core, the catalytic activity of the nanostructures was also evaluated. Using the reduction of 4-nitrophenol as a representative example of a catalytic reaction, the rate constant for that reduction using the PPy encased Ag nanoparticles was found to be 1.1 × 10(-3) s(-1), which is approximately 33% less than that determined for the parent silver. These results demonstrate that PPy can serve as both an electrical and chemical barrier for mitigating undesirable chemical degradation in corrosive environments, as well as provide a simple physical barrier to corrosive substances under appropriate conditions.

Topics: Catalysis; Dose-Response Relationship, Drug; Electrochemistry; Ions; Kinetics; Materials Testing; Microscopy, Electron, Transmission; Nanoparticles; Nanostructures; Nanotechnology; Nitrophenols; Polymers; Potentiometry; Pyrroles; Silver; Spectrophotometry, Ultraviolet; Temperature

Organophosphorus (OP) and pyrethroid (PYR) compounds are the most widely used insecticides. OPs and PYRs are developmental neurotoxicants. Understanding the extent of exposure in the general population and especially in young children is important for the development of public health policy on regulation and use of these chemicals. Presented here are the results of the first investigation into the extent of environmental exposure to neurotoxic insecticides in preschool children in South Australia (SA). Children were enrolled from different areas of SA and assigned into urban, periurban and rural groups according to their residential address. Residential proximity to agricultural activity, parental occupational contact to insecticides and use of insecticides within the household were investigated as potential indirect measures of exposure. We used liquid chromatography/tandem mass spectrometry to measure the following metabolites of OPs and PYRs in urine samples as direct indicators of exposure: dialkylphosphates, p-nitrophenol, 3-methyl-4-nitrophenol, 3,5,6-trichloro-2-pyridinol, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid, 2-methyl-3phenylbenzoic acid and 3-phenoxybenzoic acid. Results were analysed to assess factors affecting the risk and level of exposure. Results were also compared to the published data in similar age groups from US and German studies. The results of this study demonstrate that there was widespread chronic exposure to OPs and and PYRs in SA children. OP metabolites were detected more commonly than PYR. Exposure to more than one chemical and contemporaneous exposure to chemicals from both OP and PYR groups was common in the study population. There were some differences in risks and levels of exposure between the study groups. Exposure to some restricted use of chemicals, for example, fenitrothion, was higher in periurban and rural children. There was no difference among the study groups in exposure to chlorpyrifos, used commonly in agriculture and in domestic settings and most frequently found OP pesticide in food in Australia. South Australian children appear to have higher levels of exposure compared their peers in US and Germany.

Topics: Agriculture; Benzoates; Child; Child, Preschool; Chlorpyrifos; Cross-Sectional Studies; Environmental Exposure; Environmental Pollutants; Female; Humans; Male; Nitrophenols; Organophosphorus Compounds; Pesticides; Pyrethrins; Rural Population; South Australia

We investigated the biodegradation of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP) in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol (NP). We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria: 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NP-degrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP (0.5 mmol/L) as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water.

Topics: 2,4-Dinitrophenol; Araceae; Bacteria; Biodegradation, Environmental; Glucose; Molecular Sequence Data; Nitrophenols; Rhizosphere; Rivers; RNA, Ribosomal, 16S

Titanium dioxide (TiO2) nanoparticles were prepared by sol gel route. The preparation parameters were optimized in the removal of 4-nitrophenol (4-NP). All catalysts were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). An artificial neural network model (ANN) was developed to predict the photocatalytic removal of 4-NP in the presence of TiO2 nanoparticles prepared under desired conditions. The comparison between the predicted results by designed ANN model and the experimental data proved that modeling of the removal process of 4-NP using artificial neural network was a precise method to predict the extent of 4-NP removal under different conditions.

Topics: Catalysis; Crystallization; Nanoparticles; Neural Networks, Computer; Nitrophenols; Temperature; Time Factors; Titanium; Ultraviolet Rays; X-Ray Diffraction

In molecular imprinting the porogen plays a decisive role, as it not only affects the physical properties of the resulting polymer including its porosity, the specific surface area, and the swelling behavior, but also governs the stability of the prepolymerization complex, which in turn decisively determines the recognition properties of the resulting molecularly imprinted polymer (MIP). In this study, the influence of the porogen on the selectivity of MIPs was investigated. Therefore, bulk MIPs against 4-nitrophenol using 4-vinylpyridine (4-VP) as functional monomer and ethylene glycol dimethacrylate (EDMA) as crosslinker were prepared in acetonitrile and chloroform. The recognition properties of both MIPs were evaluated during chromatographic studies using the respective porogenic solvents as mobile phase for both MIPs. Along with the characterization of the morphology of the obtained polymers via SEM and BET analysis, the beneficial nature of chloroform as porogen for imprinting 4-NP was experimentally demonstrated and verified by findings obtained from complementary molecular dynamics simulations. Moreover, the application of chloroform as mobile phase for the MIP prepared in acetonitrile and vice versa clearly demonstrated the dependence of the resulting recognition properties on the selection of the mobile phase.

Topics: Acetonitriles; Chloroform; Models, Molecular; Molecular Dynamics Simulation; Molecular Imprinting; Nitrophenols; Particle Size; Polymers; Porosity; Surface Properties

In this work, a solid phase extraction sequential injection methodology for the determination of alkaline phosphatase activity in dynamic water systems was developed. The determination of the enzymatic activity was based on the spectrophotometric detection of a coloured product, p-nitrophenol, at 405 nm. The p-nitrophenol is the product of the catalytic decomposition of p-nitrophenyl phosphate, a non-coloured substrate. Considering the low levels expected in natural waters and exploiting the fact of alkaline phosphatase being a metalloprotein, the enzyme was pre-concentrated in-line using a NTA Superflow resin charged with Zn(2+) ions. The developed sequential injection method enabled a quantification range of 0.044-0.441 unit mL(-1) of enzyme activity with a detection limit of 0.0082 unit mL(-1) enzyme activity (1.9 μmol L(-1) of pNP) and a determination rate of 17 h(-1). Recovery tests confirmed the accuracy of the developed sequential injection method and it was effectively applied to different natural waters and to plant root extracts.

Topics: Alkaline Phosphatase; Animals; Cattle; Flow Injection Analysis; Fresh Water; Ion Exchange Resins; Limit of Detection; Nitrophenols; Organophosphorus Compounds; Phosphorus; Plant Extracts; Plant Roots; Plants; Solid Phase Extraction; Spectrophotometry; Zinc

Polystyrene (PS)/gold (Au) core-shell nanocomposites with tunable size, high stability, and excellent catalytic activity have been synthesized by a facile method that combines the ionic self-assembly with the in situ reduction. The composition and stoichiometry, as well as its morphology and optical properties of these nanocomposites have been examined and verified by various characterization techniques. The size and the coverage of gold nanoparticles (NPs) can be simply tailored by changing the amount of 3-aminopropyltrimethoxysilane (APTES), the functionalization time, the protonation time, and the amount of chloroauric acid (HAuCl(4)). The continuous red shifts of the localized surface plasmon resonance absorption of the Au NPs on the PS spheres are observed. Importantly, the obtained Au NPs with controllable and uniform size on the surfaces of amino-functionalized PS spheres exhibit excellent size-dependent catalytic properties for the reduction of 4-nitrophenol (4-NP) by NaBH(4).

Topics: Catalysis; Gold; Nanocomposites; Nanoparticles; Nitrophenols; Oxidation-Reduction; Polystyrenes; Propylamines; Silanes

Bioaugmentation with an enriched microbial population was applied in an aerobic sequencing batch reactor (SBR) receiving transient or continuous shock loads of p-nitrophenol (PNP). The effect of the amount of biomass added for bioaugmentation was assessed by using two different dosages (2% or 5% w/w of the total biomass in the seeded SBR). In both cases, total PNP removal was achieved during the transient PNP shock load occurring after bioaugmentation. However, after a long PNP starvation period the only experiment still showing total PNP removal during a second PNP shock load was the one where a dosage of 5% w/w was applied. The results suggested that the dosage is a key factor for the implementation of a successful bioaugmentation strategy. In addition, the performance of a bioaugmented SBR receiving a continuous PNP shock load was enhanced when compared to a non-bioaugmented SBR.

Topics: Aerobiosis; Bacteria; Batch Cell Culture Techniques; Biodegradation, Environmental; Biomass; Bioreactors; In Situ Hybridization, Fluorescence; Microscopy, Confocal; Nitrophenols

The development of new synthesis methods for monodispersed nanocrystals using cheap and nontoxic chemicals, environmentally benign solvents and renewable materials remains a challenge to the scientific community. The present work reports a new green method for the synthesis of gold nanoparticles. Four different ayurvedic arishtams are used for the reduction of Au(3+) to Au nanoparticles. This method is simple, efficient, economic and nontoxic. Gold nanoparticles having different sizes in the range from 15 to 23 nm could be obtained. The nanoparticles have been characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles is evident from bright circular spots in the SAED pattern and peaks in the XRD pattern. The synthesized gold nanoparticles show good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH(4). The synthesized nanoparticles are found to exhibit size dependent catalytic property, the smaller nanoparticles showing faster activity.

Topics: Absorption; Catalysis; Colloids; Gold; Medicine, Ayurvedic; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Pharmaceutical Preparations; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Time Factors; X-Ray Diffraction

Various metal ions are present in industrial wastewater. In this study, the role of Cu(2+) in pollutant degradation by laccase and the effect of common metal ions such as Na(+), K(+), Ca(2+), Mg(2+), Zn(2+), Hg(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Fe(3+), and Al(3+) on the degradation velocity of the laccase-Cu(2+) synergistic system using 4-nitrophenol as the target pollutant were investigated. The results show that the laccase-Cu(2+) system achieved a higher degradation velocity than the system without Cu(2+). The activity of the laccase-Cu(2+) synergistic system was inhibited when a monovalent metal ion (Na(+) or K(+)) was added into the system regardless of the concentration. The addition of relatively low concentrations of any divalent metal ions also resulted in inhibition of the activity. However, increasing concentrations of Ca(2+) or Fe(2+) increased the rate of degradation of 4-nitrophenol by the laccase-Cu(2+) system, whereas increasing concentrations of other divalent metal ions suppressed the system. The inhibition effect of the added trivalent metal ions (Al(3+) or Fe(3+)) was significant during the entire process, indicating that these trivalent metal ions can be a serious obstacle to the activity of the laccase-Cu(2+) synergistic system.

Topics: Calcium; Cations, Divalent; Cobalt; Copper; Enzyme Activation; Laccase; Magnesium; Manganese; Mercury; Models, Theoretical; Nickel; Nitrophenols; Zinc

The TiO(2)/ZnO nanofibers embedded by Au nanoparticles (TiO(2)/ZnO/Au NFs) were fabricated by combining the electrospinning technique (for TiO(2)/ZnO nanofibers) and an in situ reduction approach (for Au nanoparticles). X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electronmicroscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy, were used to characterize the as-synthesized nanofibers. The results showed that small Au nanoparticles (Au NPs) were well dispersed on the TiO(2)/ZnO nanofibers (TiO(2)/ZnO NFs). And, the TiO(2)/ZnO/Au nanofibers showed high charge separation efficiency under ultraviolet excitation, as evidenced by photoluminescence spectra. The photocatalytic studies revealed that the TiO(2)/ZnO/Au NFs exhibited enhanced photocatalytic efficiency of photodegradation of Methyl orange (MO) and 4-nitrophenol (4-NP) compared with the pure TiO(2) nanofibers, ZnO nanofibers and TiO(2)/ZnO NFs under ultraviolet excitation, which might be attributed to the high separation efficiency of photogenerated electron-hole pairs based on the photosynergistic effect among the three components of TiO(2), ZnO and Au. And, the TiO(2)/ZnO/Au NFs could be easily separated and recycled due to their one-dimensional nanostructural property.

Topics: Azo Compounds; Catalysis; Coloring Agents; Gold; Metal Nanoparticles; Nanofibers; Nitrophenols; Photolysis; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Zinc Oxide

Direct fabrication of core-shell or yolk-shell functional nanomaterials via a facile template-free method remains a challenge. In this work, we present a novel approach that involves straightforward chemical transformation and thermal treatment of the infinite coordination polymer particles to obtain composition-tunable CeO(2) yolk-shell structures. Uniform CeO(2) yolk-shell hollow spheres with a high surface area are promising support materials for tiny gold nanoparticles (ca. 4 nm), forming Au-CeO(2) nanocomposites which exhibit a remarkable catalytic activity and high stability for the reduction of p-nitrophenol. A possible mechanism for the formation of CeO(2) yolk-shell microspheres is also proposed.

Topics: Catalysis; Cerium; Gold; Metal Nanoparticles; Nanocomposites; Nitrophenols; Oxidation-Reduction; Polymers; Surface Properties

Fluorescent nanoaggregates of pentacenequinone derivative serve as reactors for the preparation of palladium nanoparticles in aqueous medium. Further, the combination of catalytic quantities of palladium nanoparticles with NaBH(4) smoothly reduces 4-nitrophenol to 4-aminophenol in aqueous medium.

Topics: Aminophenols; Molecular Structure; Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Particle Size; Quinones; Spectrometry, Fluorescence; Surface Properties

Responsive catalytic hybrid nanogels with Au nanoparticle cores and a polyvinylpyrrolidone (PVP) based gel shell are prepared through a novel one-pot approach. The embedded Au nanoparticles demonstrate both a pH-modulated catalytic activity and anti-aggregation properties upon recycling.

Topics: Catalysis; Gels; Gold; Nanoparticles; Nitrophenols; Oxidation-Reduction; Povidone; Protons

A catalytic system for deglycosylation of isoflavone in black soybean milk was established. β-Glucosidase which was covalently immobilized onto the glass microspheres exhibited a significant efficiency for the conversion of pNPG to p-nitrophenol over other carriers. The optimum temperature for pNPG hydrolysis was 40 °C, and complete reaction can be reached in 30 min. Operational reusability was confirmed for more than 40 batch reactions. Moreover, the storage stability verification demonstrated that the glass microsphere catalytic system was capable of sustaining its highest catalytic activity for 40 days. The kinetic parameters, including rate constant (K) at which isoflavone glycosides deglycosylation were determined, the time (τ(50)) in which 50% of isoflavone glycosides deglycosylation was reached, and the time (τ(complete)) required to achieve complete isoflavone glycosides deglycosylation, were 0.35 ± 0.04 min(-1), 2.04 ± 0.25 min, and 30 min (for daidzin) and 0.65 ± 0.03 min(-1), 1.19 ± 0.08 min, and 20 min (for genistin), respectively. HPLC results revealed that this enzyme system took only 30 min to reach complete isoflavone deglycosylation and the aglycone content in the total isoflavones in black soymilk was enriched by 51.42 ± 0.17% under a 30 min treatment by the glass microsphere enzymatic system.

Topics: beta-Glucosidase; Enzyme Stability; Enzymes, Immobilized; Food, Fortified; Glass; Glycosides; Glycosylation; Hydrolysis; Isoflavones; Kinetics; Microspheres; Nitrophenols; Soy Milk

Enzymatic assays need robust, rapid colorimetric methods that can follow ongoing reactions. For this, we developed a highly accurate, multi-wavelength detection method that could be used for several systems. Here, it was applied to the detection of para-nitrophenol (pNP) in basic and acidic solutions. First, we confirmed by factor analysis that pNP has two forms, with unique spectral characteristics in the 240 to 600 nm range: Phenol in acidic conditions absorbs in the lower range, whereas phenolate in basic conditions absorbs in the higher range. Thereafter, the method was used for the determination of species concentration. For this, the intensity measurements were made at only two wavelengths with a microtiter plate reader. This yielded total dye concentration, species relative abundance, and solution pH value. The method was applied to an enzymatic assay. For this, a chromogenic substrate that generates pNP after hydrolysis catalyzed by a lipase from the fungus Yarrowia lipolytica was used. Over the pH range of 3-11, accurate amounts of acidic and basic pNP were determined at 340 and 405 nm, respectively. This method surpasses the commonly used single-wavelength assay at 405 nm, which does not detect pNP acidic species, leading to activity underestimations. Moreover, alleviation of this pH-related problem by neutralization is not necessary. On the whole, the method developed is readily applicable to rapid high-throughput of enzymatic activity measurements over a wide pH range.

Topics: Coloring Agents; Enzyme Assays; Fungal Proteins; Hydrogen-Ion Concentration; Hydrolysis; Lipase; Nitrophenols; Spectrophotometry, Ultraviolet

Here we report the cell surface display of organophosphorus hydrolase (OPH) and green fluorescent protein (GFP) fusion by employing the N- and C-terminal domains of ice nucleation protein (INPNC) as an anchoring motif. An E. coli-Pseudomonas shuttle vector, pNOG33, coding for INPNC-OPH-GFP was constructed for targeting the fusion onto the cell surface of p-nitrophenol (PNP)-degrading P. putida JS444. The surface localization of INPNC-OPH-GFP was verified by cell fractionation, Western blot, proteinase accessibility, and immunofluorescence microscopy. Furthermore, the functionality of the surface-exposed OPH-GFP was demonstrated by OPH assays and fluorescence measurements. Surface display of macromolecular OPH-GFP fusion (63 kDa) neither inhibited cell growth nor affected cell viability. These results suggest that INP is an useful tool for the presentation of heterologous proteins on cell surfaces of indigenous microbes. The engineered P. putida JS444 degraded organophosphates (OPs) as well as PNP rapidly and could be easily monitored by fluorescence. Parathion (100 mg kg⁻¹) could be degraded completely within 15 days in soil inoculated with the engineered strain. These merits make this engineered strain an ideal biocatalyst for in situ bioremediation of OP-contaminated soil.

Topics: Aryldialkylphosphatase; Bacterial Outer Membrane Proteins; Bacterial Proteins; Biodegradation, Environmental; Cell Membrane; Gene Expression; Green Fluorescent Proteins; Nitrophenols; Protein Engineering; Protein Transport; Pseudomonas; Pseudomonas putida; Recombinant Fusion Proteins

Nitrobenzene is a synthetic compound, more than 95% of which is used in the production of aniline. Nitrobenzene has been demonstrated to be substantially metabolized to p-Nitrophenol, p-Aminophenol and p-Nitroaniline in food animals (e.g., bovines, fowls). There have been no studies on the acute toxicity and the mutagenesis of the mixture of the three metabolites mentioned above. The aim of the present study is to testify the acute toxicity and the mutagenesis of the three metabolites mixture. Seventy Kunming mice (half male, half female) received an intragastric administration exposure to metabolites-containing suspension of 750, 638, 542, 461, 392, 333 mg kg(-1) body weight and 0.5% sodium carboxymethyl cellulose (control), followed by a 14-day observation. The medial lethal dose (LD(50)) concentration for nitrobenzene metabolites mixture in this study was 499.92 mg/kg. Their mutagenic toxicology was studied through micronucleus and sperm abnormality test. Kunming mice were twice intragastrically exposed to 1/5 LD(50), 1/10 LD(50), 1/20 LD(50) mg kg(-1) nitrobenzene metabolites-containing suspension spaced 24-h apart. Cyclophosphamide, pure water and sodium carboxymethyl cellulose served as doses of the positive group, the negative group and the solvent control group, respectively. The incidence of micronucleus and sperm abnormality increased significantly in the 1/5 LD(50) and 1/10 LD(50) group compared with the negative and solvent control group. A dose-related increase in the incidence of micronucleus and sperm abnormality was noted. In conclusion, the three metabolites mixture of nitrobenzene was secondary toxicity and mutagenic substances in mice.

Topics: Aminophenols; Aniline Compounds; Animals; Body Weight; Bone Marrow Cells; Female; Lethal Dose 50; Male; Mice; Micronucleus Tests; Mutagenesis; Mutagens; Nitrobenzenes; Nitrophenols; Spermatozoa; Toxicity Tests, Acute

A novel actinobacterium, designated PNP1(T), was isolated from a wastewater treatment plant at a pesticide factory by selective enrichment with para-nitrophenol. The strictly aerobic strain PNP1(T) grew with para-nitrophenol as the sole carbon and energy source. Metabolism of para-nitrophenol resulted in the stoichiometric release of nitrite. When incubated with both para-nitrophenol and acetate, para-nitrophenol was degraded and utilized as growth substrate prior to acetate. When grown on acetate (in the absence of ammonium) both nitrite and nitrate served as nitrogen sources, nitrate being quantitatively reduced to nitrite which accumulated in cultures during aerobic growth. Cells were coccoid and stained Gram-positive, were non-motile and did not form endospores. Colonies of strain PNP1(T) on agar medium were bright yellow, circular and smooth. The dominant menaquinone was MK-8(H(2)) (54%) and the major cellular fatty acid was anteiso C15:0 (75%). Strain PNP1(T) grew optimally at 27°C, at pH 8-8.5, at salinities 3% (w/v) NaCl, yet exhibited a substantial halotolerance with growth occurring at salinities up to 17% (w/v) NaCl. In addition to para-nitrophenol, a range of sugars, short chain fatty acids and alcohols served as electron donors for growth. The DNA G + C mol% was 68%. The genotypic and phenotypic properties suggest that strain PNP1(T) represents a novel species of the actinobacterial genus Citricoccus for which the name Citricoccus nitrophenolicus is proposed. It is the first member of this genus that has been reported to hydrolyze and grow on para-nitrophenol. The type strain is PNP1(T) (=DSM 23311(T) = CCUG 59571(T)).

Topics: Acetates; Actinobacteria; Base Composition; Molecular Sequence Data; Nitrates; Nitrites; Nitrophenols; Waste Disposal, Fluid; Water Microbiology

Application of the microwave-enhanced catalytic degradation (MECD) method on the abatement of 4-nitrophenol (4-NP) using nickel oxide was studied. A mix-valenced nickel oxide was prepared from nickel nitrate aqueous solution through a precipitation with sodium hydroxide and an oxidation by sodium hypochlorite with/without microwave-assisted heating. They were characterized by X-ray (XRD), infrared spectroscopy (IR), temperature programmed reduction (TPR), and transmission electron micrographs (TEM). Their catalytic activities towards the degradation of 4-NP were investigated through continuous bubbling of air during the liquid phase and evaluated quantitatively with high pressure liquid chromatography (HPLC). Also, the effect of the kinds of catalyst, temperature, pH, initial concentration, and dosage of catalyst on the efficiency of 4-NP degradation was investigated. The results showed that the 4-NP was completely degraded using the high efficiency MECD method within 15 min under [H(+)] = 1.0M, T = 40 °C, and C = 200 ppm over nickel oxide.

Topics: Catalysis; Chromatography, High Pressure Liquid; Gas Chromatography-Mass Spectrometry; Hydrogen Bonding; Hydrogen-Ion Concentration; Microscopy, Electron, Transmission; Microwaves; Nanoparticles; Nickel; Nitrophenols; Oxidation-Reduction; Spectrophotometry, Infrared; Temperature; X-Ray Diffraction

In this study, the acute toxicities of nitrobenzene (NB) and para nitrophenol (p-NP) were investigated in a high rate sequential anaerobic migrating blanket (AMBR)/aerobic completely stirred tank reactor (CSTR) using Microtox and Daphnia magna tests. After sequential anaerobic and aerobic treatments, the inhibitions in the Microtox bacteria decreased from an initial 78.10-48.20% and 4.00%, respectively, in wastewater containing 40.00 mg/L p-NP. The inhibitions of the influent wastewater containing 60.00 mg/L NB decreased from 72.10% to 45.30% and to 4.00% after anaerobic and aerobic treatment, respectively. The acute toxicity removals were 94% and 93% in the effluent of the whole sequential system, for p-NP and NB, respectively. The acute toxicity in the influent was dependent on the parent NB and p-NP concentrations and ons their physicochemical properties such as hydrophobicity, octanol/water partition coefficient and vapour density for both Microtox bacteria and Daphnia magna while the toxicity in the effluent of the anaerobic reactor was strongly dependent on the metabolites of p-NP (p-amino phenol, phenol, NH(4)-N) and NB (aniline) for Microtox test. This effluent was not toxic to Daphnia magna.

Topics: Aerobiosis; Anaerobiosis; Animals; Daphnia; Nitrobenzenes; Nitrophenols; Photobacterium

This work describes a simple synthetic route to induce chitosan (CHI) gelation by the in situ formation of gold nanoparticles (AuNPs). AuNPs were obtained by thermal treatment (e.g., 40 and 80 °C) of CHI aqueous solutions containing HAuCl(4) and in the absence of further reducing agents. The CHI hydrogels resulting after AuNP formation were submitted to unidirectional freezing and subsequent freeze-drying via ISISA (ice-segregation-induced self-assembly) process for the preparation of CHI scaffolds. The study of AuNP-CHI scaffolds by SEM and confocal fluorescence microscopy revealed a morphological structure characteristic of the hydrogel nature of the samples subjected to the ISISA process. Interestingly, not only the morphology but also the dissolution and swelling degree of the resulting CHI scaffolds were strongly influenced by the strength of the hydrogels obtained by the in situ formation of AuNP. We have also studied the catalytic activity AuNP-CHI scaffolds in the reduction of p-nitrophenol. The negligible dissolution and low swelling degree obtained in certain AuNP-CHI scaffolds allowed them to be used for more than four cycles with full preservation of the reaction kinetics.

Topics: Catalysis; Chitosan; Gold; Hot Temperature; Hydrogels; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Porosity

Gold nanotubes of small particle sizes down to 5 nm and high aspect ratios were synthesized in ion track etched polycarbonate following a rational reaction design. 4-(Dimethylamino)pyridine (DMAP) was employed to adjust the electroless deposition by interfering with the autocatalytically active gold surface. Modification of the pH value and DMAP concentration led to a wide range of products which were characterized by SEM, TEM, and EDS. Filigree nanotubes of 10-15 nm wall thickness and 5.0 ± 2.1 nm grain size were obtained as well as robust and free-standing structures proving homogeneous deposition along the whole template length of 30 μm. Template-supported gold nanotubes were applied in the UV-vis monitored reduction of 4-nitrophenol by sodium borohydride under pseudo-first-order conditions. They proved to be a reliable microfluidic system of excellent catalytic activity coming up with an apparent rate constant of 1.3 × 10(-2) s(-1). Despite a high flow rate, the reaction showed 99% conversion after a distance of just 60 μm.

Topics: 4-Aminopyridine; Borohydrides; Gold; Indicators and Reagents; Nanotubes; Nitrophenols; Surface Properties

We present a simple template-free method for the synthesis of interconnected hierarchical porous palladium nanostructures by controlling the aggregation of nanoparticles in organic media. The interaction between the nanoparticles is tuned by varying the dielectric constant of the medium consistent with DLVO calculations. The reaction products range from discrete nanoparticles to compact porous clusters with large specific surface areas. The nanoclusters exhibit hierarchical porosity and are found to exhibit excellent activity towards the reduction of 4-nitrophenol into 4-aminophenol and hydrogen oxidation. The method opens up possibilities for synthesizing porous clusters of other functional inorganics in organic media.

Topics: Aminophenols; Catalysis; Electrochemical Techniques; Hydrogen; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Porosity

Examining the relationship between biodiversity and functional stability (resistance and resilience) of activated sludge bacterial communities following disturbance is an important first step towards developing strategies for the design of robust biological wastewater treatment systems. This study investigates the relationship between functional resistance and biodiversity of dominant bacterial taxa by subjecting activated sludge samples, with different levels of biodiversity, to toxic shock loading with cupric sulfate (Cu[II]), 3,5-dichlorophenol (3,5-DCP), or 4-nitrophenol (4-NP). Respirometric batch experiments were performed to determine the functional resistance of activated sludge bacterial community to the three toxicants. Functional resistance was estimated as the 30 min IC(50) or the concentration of toxicant that results in a 50% reduction in oxygen utilization rate compared to a referential state represented by a control receiving no toxicant. Biodiversity of dominant bacterial taxa was assessed using polymerase chain reaction-terminal restriction fragment length polymorphism (PCR-T-RFLP) targeting the 16S ribosomal RNA (16S rRNA) gene. Statistical analysis of 30 min IC(50) values and PCR-T-RFLP data showed a significant positive correlation (P < 0.05) between functional resistance and microbial diversity for each of the three toxicants tested. To our knowledge, this is the first study showing a positive correlation between biodiversity of dominant bacterial taxa in activated sludge and functional resistance. In this system, activated sludge bacterial communities with higher biodiversity are functionally more resistant to disturbance caused by toxic shock loading.

Topics: Bacteria; Biodiversity; Bioreactors; Chlorophenols; Copper Sulfate; DNA, Bacterial; Nitrophenols; Oxygen; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; RNA, Ribosomal, 16S; Sewage

There are a number of publications in the literature that might indicate a connection between pH and the kinetics of the aerobic p-nitrophenol (PNP) biodegradation. In this study two hypotheses were postulated to elucidate the kinetics dependence on pH: (i) the substrate inhibition does not depend on the pH value, therefore the half-saturation coefficient and the substrate inhibition constant will be the same at any pH and (ii) the substrate inhibition depends on the pH value, therefore the half-saturation coefficient and the substrate inhibition constant will have a different value depending on the pH. A PNP-degrading activated sludge was used to carry out three batch respirometric experiments at different pH values: 6.5±0.1, 7.0±0.1, 8.0±0.1. The ability to describe the experimental results with the kinetic models derived from both postulated hypotheses was quantitatively evaluated through the norm of the prediction error array. The time course of specific oxygen uptake rate and PNP concentration was satisfactorily described by a Haldane kinetics that includes the pH effect, based on the PNP acid-base equilibrium, on the kinetic parameters. The results suggest that the nonionised form of PNP is the real substrate and also the inhibitor of the aerobic PNP biodegradation.

Topics: Aerobiosis; Algorithms; Biodegradation, Environmental; Biomass; Calibration; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Nonlinear Dynamics; Oxygen; Sewage; Solutions; Water

A bacterial consortium with the ability to degrade methyl parathion and p-nitrophenol, using these compounds as the only carbon source, was obtained by selective enrichment in a medium with methyl parathion. Samples were taken from Moravia, Medellin; an area that is highly contaminated, owing to the fact that it was used as a garbage dump from 1974 to 1982. Acinetobacter sp, Pseudomonas putida, Bacillus sp, Pseudomonas aeruginosa Citrobacter freundii, Stenotrophomonas sp, Flavobacterium sp, Proteus vulgaris, Pseudomonas sp, Acinetobacter sp, Klebsiella sp and Proteus sp were the microorganisms identified within the consortium. In culture, the consortium was able to degrade 150 mg L⁻¹ of methyl-parathion and p-nitrophenol in 120 h, but after adding glucose or peptone to the culture, the time of degradation decreased to 24 h. In soil, the consortium was also able to degrade 150 mg L⁻¹ of methyl parathion in 120 h at different depths and also managed to decrease the toxicity.

Topics: Bacteria; Biodegradation, Environmental; Kinetics; Methyl Parathion; Microbial Consortia; Nitrophenols; Soil Microbiology; Soil Pollutants

A novel, enzyme-free amperometric immunoassay of biomarkers with sensitive enhancement was designed by using gold nanoflower-labeled detection antibodies toward the catalytic reduction of p-nitrophenol and redox cycling of p-aminophenol on a graphene-based Au(111) platform.

Topics: Aminophenols; Antibodies; Biomarkers; Biosensing Techniques; Catalysis; Electrochemical Techniques; Ferrous Compounds; Gold; Graphite; Immunoassay; Metallocenes; Nanostructures; Nitrophenols; Oxidation-Reduction

4-Nitrophenol (4-NP) is a toxic compound formed in soil by the hydrolysis of organophosphorous pesticides, such as parathion. We previously reported the presence of the 4-NP degradation gene cluster (nphRA1A2) in Rhodococcus sp. strain PN1, which encodes a two-component 4-NP hydroxylase system that oxidizes 4-NP into 4-nitrocatechol. In the current study, another gene cluster (npsC and npsRA2A1B) encoding a similar 4-NP hydroxylase system was cloned from strain PN1. The enzymes from this 4-NP hydroxylase system (NpsA1 and NpsA2) were purified as histidine-tagged (His-) proteins and then characterized. His-NpsA2 showed NADH/FAD oxidoreductase activity, and His-NpsA1 showed 4-NP oxidizing activity in the presence of His-NpsA2. In the 4-NP oxidation using the reconstituted enzyme system (His-NpsA1 and His-NpsA2), hydroquinone (35% of 4-NP disappeared) and hydroxyquinol (59% of 4-NP disappeared) were detected in the presence of ascorbic acid as a reducing reagent, suggesting that, without the reducing reagent, 4-NP was converted into their oxidized forms, 1,4-benzoquinone and 2-hydroxy-1,4-benzoquinone. In addition, in the cell extract of recombinant Escherichia coli expressing npsB, a typical spectral change showing conversion of hydroxyquinol into maleylacetate was observed. These results indicate that this nps gene cluster, in addition to the nph gene cluster, is also involved in 4-NP degradation in strain PN1.

Topics: Bacterial Proteins; Benzoquinones; Catechols; Cloning, Molecular; Escherichia coli; Genes, Bacterial; Hydroquinones; Multigene Family; Nitrophenols; Oxidation-Reduction; Oxygenases; Rhodococcus; Sequence Analysis, DNA; Substrate Specificity

Greener synthesis of nanogold-biocomposite by fungus, Cylindrocladium floridanum was reported in this study. Results revealed that when cultured in static condition for a period of 7d, the fungus accumulated gold nanoparticles on the surface of the mycelia. Bionanocomposites with Au nanocrystals were characterized by UV-Vis spectroscopy, XRD, SEM, EDX and high-resolution TEM. The SPR band of UV-Vis spectrum at 540 nm confirmed the presence of gold nanoparticles on the surface of the fungal mycelia. The fcc (111)-oriented crystalline nature of particles was identified by XRD pattern. The synthesized particles are spherical in shape as evidenced by TEM image. The biocomposites with Au nanoparticles function as an efficient heterogeneous catalyst in the degradation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), in the presence of reducing agent, sodium borohydride which was reflected by UV-Vis spectra of the catalytic reaction kinetics. The reduction of 4-nitrophenol follows pseudo-first-order kinetic model with the reaction rate constant of 2.67 × 10(-2)min(-1) with 5.07 × 10(-6)mol/dm(3) of gold at ca. 25 nm. The rate of the reaction was increased by increasing the concentration of gold nanoparticles from 2.54 × 10(-6) to 12.67 × 10(-6)mol/dm(3) (∼ 25 nm) and with reduced size from 53.2 to 18.9 nm respectively. This is the first report on fungal-matrixed gold(0) nanocomposites heterogeneously catalyzing the reduction of the toxic organic pollutant, 4-nitrophenol that enable the recovery and recycling of AuNPs catalysts.

Topics: Ascomycota; Biodegradation, Environmental; Catalysis; Gold; Kinetics; Metal Nanoparticles; Mycelium; Nanocomposites; Nitrophenols

A simple and fast dynamically coated capillary electrophoretic method was developed for the characterization and inhibition studies of alkaline phosphatases(EC 3.1.3.1). An inside capillary enzymatic reaction was performed, and hydrolysis of the substrate 4-nitrophenylphosphate to 4-nitrophenol was measured. Fused-silica capillary surface was dynamically modified with polycationic polybrene coating. By reversal of the electroosmotic flow (EOF), analysis time was reduced up to 3 min as the anionic analytes were migrated in the same direction as the EOF. Furthermore, the sensitivity of the method was increased using electroinjection through high-field amplified injection. The baseline separation of 4-nitrophenylphosphate and 4-nitrophenol was achieved by employing 50 mM sodium phosphate as the running buffer (pH 8.5), 0.0025% polybrene, and a constant voltage of -15 kV, and the products were detected at 322 nm. Under the optimized conditions, a good separation with high efficiency was achieved. The new method was applied to study enzyme kinetics and inhibitor screening. K(m) and K(i) values obtained with the new CE method were compared well with the standard spectrophotometric method. Dynamic coating of fused-silica capillary gave fast and reproducible separation of substrate and product. The method can be easily optimized for inhibition studies of other isozymes.

Topics: Alkaline Phosphatase; Electrophoresis, Capillary; Enzyme Inhibitors; Enzymes, Immobilized; Kinetics; Nitrophenols; Organophosphorus Compounds; Protein Array Analysis

We herein report O-glycosidation reactions promoted via silver N-heterocyclic carbene complexes formed in situ in ionic liquids. Seven different room temperature ionic liquids were screened for the glycosidation reaction of 4-nitrophenol with tetra-O-acetyl-α-d-galactopyranosyl bromide. Good to excellent yields were obtained using Ag-NHC complexes derived from imidazolium halide salts to promote the glycosidation reaction, whereas yields considered moderate to low were obtained without use of the silver carbene complex. Anion metathesis of the ionic liquids with inexpensive alkylammonium halides also resulted in silver N-heterocyclic carbene formation and subsequent O-glycosidation in the presence of silver carbonate. Effective utility of this methodology has been demonstrated with biologically relevant acceptors (including flavones and steroids) where O-β-glycoside products were obtained selectively in moderate to good yields. We have also demonstrated that the Ag-NHC complex is a superior promoter to traditionally used silver carbonate for the glycosidation of polyphenolic acceptors. The ionic liquids used in the study could be recycled three times without apparent loss in activity.

Topics: Galactosides; Glycosides; Imidazoles; Ionic Liquids; Methane; Nitrophenols; Nuclear Magnetic Resonance, Biomolecular; Silver

The mutual effects of metal cations (Cu2+, Pb2+, Zn2+, and Cd2+) and p-nitrophenol (NP) on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2+, Pb2+, and Zn2+ diminished the adsorption and increased the desorption of NP remarkably, while Cd2+ had no such effect. In contrast, NP diminished the adsorption of Cu2+, Pb2+, and Zn2+ onto ash, however, this suppression effect depended on the initial concentrations of metal cations. NP had no effect on Cd2+ adsorption on ash. Fourier transform infrared (FT-IR) and X-ray absorption spectroscopic (XAS) studies suggested the following mechanisms responsible for the metal suppression effect on NP adsorption: (1) large hydrated Cu2+, Pb2+, and Zn2+ shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; (2) Cu2+, Pb2+, and Zn2+ may block the micropores of ash, resulting in decreased adsorption of NP; (3) complexation of Cu2+, Pb2+, and Zn2+ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a "soft acid", Cd2+ is less efficient in the complexation of oxygen-containing acid groups than Cu2+, Pb2+, and Zn2+. Thus, Cd2+ had no effect on the adsorption of NP on wheat ash.

Topics: Adsorption; Biodegradation, Environmental; Cations; Copper; Hydrogen-Ion Concentration; Kinetics; Lead; Magnetic Resonance Spectroscopy; Metals, Heavy; Nitrophenols; Reference Standards; Spectroscopy, Fourier Transform Infrared; Triticum; X-Ray Absorption Spectroscopy; Zinc

Pollution free catalyst is an attractive area of current interest. The p-Aminophenol is one of the most significant catalyst, because it involves the manufacture of various pharmaceuticals. Crosslinked poly(styrene)-co-poly(4-vinylimidazole) (PSPVIM) was prepared by varying the crosslinked monomer ratio as 2% and 10% respectively. The 2 (w%) of DVB, 25 (w%) of N-VIm as functional monomer and 73 (w%) of styrene as support monomer as organic phase and gelatin, boric acid and polyvinyl alcohol as aqueous phase was used to prepare cross-linked poly(styrene)-co-poly(N-vinyl imidazole) (PVIM) beads (Type-I). Similarly, Type II beads were also prepared by fixing the 10% as a cross linking ratio (DVB). The immobilization of Ag NPs onto the PS-VIm polymer matrix was performed using AgNO3 as a metal precursor solution. The k(obs) determined from UV-Vis results, reveals that the degree of reduction of 4-nitrophenol using Type-I catalysts is more effective than Type-II catalyst due to lower immobilization of AgNPs at higher cross-linked bead matrix. It was found that on increasing the amount of catalyst i.e., type-I PS-PVIm-AgNPs, the rate constant also increases. Therefore, PS-PVIm-AgNPs (Type-I) heterogeneous catalyst is superior for the reduction of 4-NP.

Topics: Catalysis; Crystallization; Environment; Macromolecular Substances; Materials Testing; Molecular Conformation; Nanostructures; Nanotechnology; Nitrophenols; Particle Size; Surface Properties

Three kinds of molecularly imprinted polymers (MIPs) were obtained with surface molecular imprinting technique on functionalized potassium tetratitanate whisker (F-PTW). The results of adsorption experiments indicated that MIP prepared using PTW modified with N-(2-aminoethyl)-3-(trimethoxysilyl)propylamine (AAPTS) (F-PTW A) as support [MIP(1)] was superior to the other two polymers, then MIP(1) was selected to analyze the 4-nitrophenol (4-NP) adsorption process from aqueous solution in this study. AAPTS offered hydrophilic exterior that allowed to self-assemble with the template 4-NP through intermolecular interaction rather than based on the interactions between the functional monomers and template. Equilibrium adsorption data were analyzed by the Langmuir and Freundlich isotherm models at various temperatures. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model, intraparticle diffusion equation, initial adsorption rate, half-adsorption time. A diffusion-controlled process as the essential adsorption rate-controlling step was also proposed. The performance of such imprinted polymer was further demonstrated by high-performance liquid chromatography, and the results showed that the selectivity of MIP(1) exhibited higher affinity for template 4-NP over competitive phenolic compounds than that of non-imprinted polymer NIP(1). MIP(1) could be reused four times without significant loss in the adsorption capacity.

Topics: Adsorption; Hydrogen-Ion Concentration; Molecular Imprinting; Nitrophenols; Particle Size; Polymers; Solutions; Surface Properties; Titanium; Water

A novel packed bed reactor (PBR) was designed with cross flow aeration at multiple ports along the depth to improve the hydrodynamic conditions of the reactor, and the biodegradation efficiency of Arthrobacter chlorophenolicus A6 on p-nitrophenol (PNP) removal in PBR at different PNP loading rates were evaluated. The novel PBR was designed to improve the hydrodynamic features such as mixing time profile (t(m95)), oxygen mass transfer coefficient (k(L)a), and overall gas hold up capacity (ɛ(G)) of the reactor. PNP concentration in the influent was varied between 600 and 1400 mg l(-1) whereas the hydraulic retention time (HRT) in the reactor was varied between 18 and 7.5h. Complete removal of PNP was achieved in the reactor up to a PNP loading rate of 2787 mg l(-1)d(-1). More than 99.9% removal of PNP was achieved in the reactor for an influent concentration of 1400 mg l(-1) and at 18 h HRT. In the present study, PNP was utilized as sole source of carbon and energy by A. chlorophenolicus A6. Furthermore, the bioreactor showed good compatibility in handling shock loading of PNP.

Topics: Arthrobacter; Biodegradation, Environmental; Bioreactors; Carbon; Equipment Design; Nitrophenols; Time Factors

Two N-terminally truncated variants of the esterase E34Tt from Thermus thermophilus HB27 (YP_004875.1) were expressed in Kluyveromyces lactis. Production and biochemical properties of both recombinant proteins were investigated. The esterase activity was greatly increased compared to the wild-type strain. In particular, the extracellular production of the ΔN16 variant (KLEST-3S) was 50-fold higher than that obtained with T. thermophilus HB27. Response surface methodology was applied to describe the pH and temperature dependence of both activity and stability. When compared with the wild type esterase, the optimal temperature of reaction decreased 35 and 15 °C for ΔN16 and ΔN26, respectively. KLEST-3S showed a maximum of activity at pH 7.5 and 47.5 °C, and maximal stability at pH 8.1 and 65 °C. KLEST-5A (ΔN26) did not show an absolute maximum of activity. However, best results were obtained at 40 °C and pH 8.5. KLEST-5A showed also a lower stability. In the presence of a surfactant, both proteins showed lower stability at 85 °C (t(½)< 5 min) than the wild-type enzyme (t(½)=135 min). However, in the absence of detergent, the stability of KLEST-3S was higher (t(½)=230 min, at 85 °C) than that of the mutant KLEST-5A (12 min) or the wild type enzyme (19 min). Minor differences were observed in the substrate specificity. Our results suggest that the N-terminal segment is critical for maintaining the hyperthermophilic function and stability.

Topics: Amino Acid Sequence; Analysis of Variance; Cloning, Molecular; Esterases; Glycosylation; Hydrogen-Ion Concentration; Kluyveromyces; Molecular Sequence Data; Nitrophenols; Protein Processing, Post-Translational; Protein Stability; Recombinant Fusion Proteins; Temperature; Thermus thermophilus

We examined the degradation of amaranth, a representative azo dye, by Bjerkandera adusta Dec 1. The degradation products were analyzed by high performance liquid chromatography (HPLC), visible absorbance, and electrospray ionization time-of-flight mass spectroscopy (ESI-TOF-MS). At the primary culture stage (3 days), the probable reaction intermediates were 1-aminonaphthalene-2,3,6-triol, 4-(hydroxyamino) naphthalene-1-ol, and 2-hydroxy-3-[2-(4-sulfophenyl) hydrazinyl] benzenesulfonic acid. After 10 days, the reaction products detected were 4-nitrophenol, phenol, 2-hydroxy-3-nitrobenzenesulfonic acid, 4-nitrobenzene sulfonic acid, and 3,4'-disulfonyl azo benzene, suggesting that no aromatic amines were created. Manganese-dependent peroxidase activity increased sharply after 3 days culture. Based on these results, we herein propose, for the first time, a degradation pathway for amaranth. Our results suggest that Dec 1 degrades amaranth via the combined activities of peroxidase and hydrolase and reductase action.

Topics: 1-Naphthylamine; Amaranth Dye; Benzenesulfonates; Biodegradation, Environmental; Chromatography, High Pressure Liquid; Color; Coloring Agents; Coriolaceae; Culture Media; Environmental Pollution; Fungal Proteins; Hydrolases; Nitrophenols; Oxidoreductases; Peroxidases; Phenol; Spectrometry, Mass, Electrospray Ionization; Water Pollutants, Chemical

The study investigated the kinetics of p-nitrophenol hydroxylase (PNPH) in hepatic microsomes obtained from Atlantic salmon (Salmo salar). The selective inhibitors for some major mammalian cytochrome P450 (CYP450) were used to investigate the potential inhibitory effect on enzymes involved in p-nitrophenol hydroxylation. The following inhibitors were used: α-naphtoflavone (CYP1A), ellipticine (CYP1A1), furafylline (CYP1A2), 8-methoxypsoralen (8MOP, CYP2A6), 4-methylpyrazole (4MP, CYP2A6/2E1), diallyl sulfide (DAS, CYP2E1), and ketoconazole (CYP3A4). Additionally, the natural steroids 17-beta-oestraiol (E2) and testosterone were investigated as potential inhibitors of PNPH activity. It was found that formation of 4-nitrocatechol from p-nitrophenol followed monophasic kinetics with K(m) = 0.17 ± 0.03 mM and V(max) = 21.8 ± 1.05 pmol/min/mg. PNPH activity was competitively inhibited by diallyle sulfide with the K(i) value of 285.1 ± 94.2 μM μM and uncompetitively by ellipticine with K(i) value of 65.7 ± 7.8 μM. Moreover, E2 showed an ability to reduce PNPH activity through the mechanism-based inhibition mode. Our results suggest that hepatic microsomes from Atlantic salmon possess CYP2E1-like activity. However, specific isoform-mediated PNPH activity should be identified.

Topics: Animals; Biotransformation; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Hydroxylation; Kinetics; Microsomes, Liver; Nitrophenols; Salmo salar; Xenobiotics

In this work, we have synthesized eccentric Au@TiO(2) core-shell nanostructures and demonstrated their multiple reuse in the catalytic reduction of 4-nitrophenol.

Topics: Catalysis; Gold; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Titanium

A descriptor based computational model was developed for cytochrome P450 2E1 (CYP2E1) based on inhibition constants determined for inhibition of chlorzoxazone, or 4-nitrophenol, metabolism. An empirical descriptor for type II binding was developed and tested for a series of CYP2E1 inhibitors. Inhibition constants where measured for 51 different compounds. A fast 2-dimensional predictive model was developed based on 40 compounds, and tested on 8 compounds of diverse structure. The trained model (n=40) had an r(2) value of 0.76 and an RMSE of 0.48. The correlation between the predicted and actual pK(i) values of the test set of compounds not included in the model gives an r(2) value of 0.78. The features that described binding include heme coordination (type II binding), molecular volume, octanol/water partition coefficient, solvent accessible surface area, and the sum of the atomic polarizabilities. The heme coordination parameter assigns an integer between 0 and 6 depending on structure, and is a new descriptor, based on simple quantum chemical calculations with correction for steric effects. The type II binding parameter was found to be important in obtaining a good correlation between predicted and experimental inhibition constants increasing the r(2) value from 0.38 to 0.77.

Topics: Chlorzoxazone; Cytochrome P-450 CYP2E1; Heme; Iron; Kinetics; Nitrogen; Nitrophenols; Protein Binding; Quantum Theory; Solvents; Substrate Specificity

Organoclays were synthesised through ion exchange of a single surfactant for sodium ions, and characterised by a range of method including X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The change in surface properties of montmorillonite and organoclays intercalated with the surfactant, tetradecyltrimethylammonium bromide (TDTMA) were determined using XRD through the change in basal spacing and the expansion occurred by the adsorbed p-nitrophenol. The changes of interlayer spacing were observed in TEM. In addition, the surface measurement such as specific surface area and pore volume was measured and calculated using BET method, this suggested the loaded surfactant is highly important to determine the sorption mechanism onto organoclays. The collected results of XPS provided the chemical composition of montmorillonite and organoclays, and the high-resolution XPS spectra offered the chemical states of prepared organoclays with binding energy. Using TGA and FT-IR, the confirmation of intercalated surfactant was investigated. The collected data from various techniques enable an understanding of the changes in structure and surface properties. This study is of importance to provide mechanisms for the adsorption of organic molecules, especially in contaminated environmental sites and polluted waters.

Topics: Adsorption; Aluminum Silicates; Clay; Nitrophenols; Surface Properties; Surface-Active Agents; Trimethyl Ammonium Compounds

A HPLC method was developed for the determination of mangiferin in rat plasma and aqueous humor. 4-Nitrophenol was used as internal standard. Analysis was performed on a Cosmosil ODS C18 analytical column (4.6 mm x 250 mm, 5 microm) with mobile phase consisting of methanol-water (40: 60) with 2% glacial acetic acid at a flow rate of 1.0 mL x min(-1). The calibration curve of mangiferin in rat plasma and aqueous humor showed excellent linear behaviors over the investigated concentration of 0. 50-250.00 mg x L(-1) in plasma and 0.10-10.00 mg x L(-1) in aqueous humor, respectively, and the correlation coefficients were all above 0.995 4. The intra-day and inter-day precisions for all samples were measured to be below 12%. The limit of quantitation was 0.10 mg x L(-1) and low enough for the determination of mangiferin in all samples. The validated method has been successfully applied to preliminary pharmacokinetics study of mangiferin in rat plasma and aqueous humor.

Topics: Animals; Aqueous Humor; Chromatography, High Pressure Liquid; Female; Male; Nitrophenols; Rats; Rats, Wistar; Reproducibility of Results; Sensitivity and Specificity; Xanthones

A molecularly imprinted polymer (MIP), obtained by precipitation polymerisation with 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as cross-linker, and bisphenol-A (BPA) as template, was prepared. The binding site configuration of the BPA-MIP was examined using Scatchard analysis. Moreover, the behaviour of the BPA-MIP for the extraction of several phenolic compounds (bisphenol-A, bisphenol-F, 4-nitrophenol, 3-methyl-4-nitrophenol) and phenoxyacid herbicides such as 2,4-D, 2,4,5-T and 2,4,5-TP has been studied in organic and aqueous media in the presence of other pesticides in common use. It was possible to carry out the selective preconcentration of the target analytes from the organic medium with recoveries of higher than 70%. In an aqueous medium, hydrophobic interactions were found to exert a remarkably non-specific contribution to the overall binding process. Several parameters affecting the extraction efficiency of the BPA-MIP were evaluated to achieve the selective preconcentration of phenols and phenoxyacids from aqueous samples. The possibility of using the BPA-MIP as a selective sorbent to preconcentrate these compounds from other samples such as urine and river water was also explored.

Topics: Benzhydryl Compounds; Binding Sites; Cresols; Environmental Pollutants; Herbicides; Humans; Nitrophenols; Particle Size; Phenols; Polymerization; Polymers; Pyridines; Rivers; Solid Phase Extraction; Urine

In the presence of large excesses of borohydride salts, gold monolayer protected-clusters can be grown to larger sizes simply by controlling the amount of reducing agent added to smaller clusters. In addition, gold monolayer clusters can be used as catalysts for reduction reactions by sodium borohydride; results suggest such catalysts have sterically constrained active sites.

Topics: Borohydrides; Catalysis; Gold; Lithium Compounds; Metal Nanoparticles; Nitrophenols; Reducing Agents; Salts

Ixodes scapularis, commonly known as the blacklegged or deer tick, is the main vector of Lyme disease in the United States. Recent progress in transcriptome research has uncovered hundreds of different proteins expressed in the salivary glands of hard ticks, the majority of which have no known function, and include many novel protein families. We recently identified transcripts coding for two putative cytosolic sulfotransferases in these ticks which recognized phenolic monoamines as their substrates. In this current study, we characterize the genetic expression of these two cytosolic sulfotransferases throughout the tick life cycle as well as the enzymatic properties of the corresponding recombinant proteins. Interestingly, the resultant recombinant proteins showed sulfotransferase activity against both neurotransmitters dopamine and octopamine.. The two sulfotransferase genes were coded as Ixosc SULT 1 & 2 and corresponding proteins were referred as Ixosc Sult 1 and 2. Using gene-specific primers, the sulfotransferase transcripts were detected throughout the blacklegged tick life cycle, including eggs, larvae, nymphs, adult salivary glands and adult midgut. Notably, the mRNA and protein levels were altered upon feeding during both the larval and nymphal life stages. Quantitative PCR results confirm that Ixosc SULT1 was statistically increased upon blood feeding while Ixosc SULT 2 was decreased. This altered expression led us to further characterize the function of these proteins in the Ixodid tick. The sulfotransferase genes were cloned and expressed in a bacterial expression system, and purified recombinant proteins Ixosc Sult 1(R) and 2(R) showed sulfotransferase activity against neurotransmitters dopamine and octopamine as well as the common sulfotransferase substrate p-nitrophenol. Thus, dopamine- or octopamine-sulfonation may be involved in altering the biological signal for salivary secretion in I. scapularis.. Collectively, these results suggest that a function of Ixosc Sult 1 and Sult 2 in Ixodid tick salivary glands may include inactivation of the salivation signal via sulfonation of dopamine or octopamine.

Topics: Animals; Blood; Cloning, Molecular; Dopamine; Feeding Behavior; Gene Expression Regulation, Enzymologic; Ixodes; Life Cycle Stages; Neurotransmitter Agents; Nitrophenols; Nymph; Octopamine; Recombinant Proteins; Salivary Glands; Sequence Homology, Amino Acid; Signal Transduction; Sulfotransferases

To determine the existence of p-nitrophenol (PNP)-lowering bacteria in intestine of Japanese coastal fish, the gastro-intestinal contents were incubated in Brain Heart Infusion (BHI) broth and minimal medium (MM) broths containing 1 mmol/L PNP at 30 °C for 7 days. Among 26 samples of 19 fish species, 17 samples showed a decrease in PNP of 0.5-0.8 mmol/L in BHI broth, but no decrease was shown in MM broth. Eighteen PNP-lowering bacterial strains were isolated from four fishes. All of the strains were identified as Lactococcus lactis subsp. lactis. Three L. lactis strains JS1-3 isolated from Japanese seabass Lateolabrax japonicus showed the highest PNP-lowering activity (0.44 mmol/L). Optimum temperature and pH for the growth and PNP decreasing corresponded with the marine environment. These results suggested that marine fishes have PNP decreasing bacteria in their intestine. These bacteria might protect host fish from toxicities of PNP and PNP related compounds.

Topics: Animals; Fishes; Hydrogen-Ion Concentration; Intestinal Mucosa; Intestines; Japan; Lactococcus lactis; Marine Biology; Nitrophenols; Temperature

Vibrational spectra of the organic nonlinear optical crystallized dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol have been recorded and analyzed. The spectral interpretation has been done based on the density functional theory using the standard B3LYP/LANL2DZ basis set. Total energy distribution is calculated using the scaled quantum mechanic program. Natural bond orbital analysis is also used to explain the inter and intra molecular hydrogen bonding. The relative second harmonic efficiency of the compound is found to be 15 times greater than that of KDP. The effect of intermolecular hydrogen bonding between the phenolate ion of 4-nitrophenol with N-atom of pyridine ring is sufficiently more, enhancing the β value which is the required property of a system to be NLO active.

Topics: 4-Aminopyridine; Computational Biology; Dimethylamines; Hydrogen Bonding; Models, Molecular; Molecular Conformation; Nitrophenols; Polarography; Spectrum Analysis, Raman; Stereoisomerism; Vibration

Cardanol, a well known hazardous byproduct of the cashew industry, has been used as starting material for the synthesis of useful differently substituted "cardanol-based" porphyrins and their zinc(II), copper(II), cobalt(II) and Fe(III) complexes. Novel composites prepared by impregnation of polycrystalline TiO₂ powder with an opportune amount of "cardanol-based" porphyrins, which act as sensitizers for the improvement of the photo-catalytic activity of the bare TiO₂, have been used in the photodegradation in water of 4-nitrophenol (4-NP), which is a toxic and bio-refractory pollutant, dangerous for ecosystems and human health.

Topics: Catalysis; Molecular Structure; Nitrophenols; Phenols; Photochemistry; Porphyrins; Titanium; Water

Carbon nanofibers/silver nanoparticles (CNFs/AgNPs) composite nanofibers were fabricated by two steps consisting of the preparation of the CNFs by electrospinning and the hydrothermal growth of the AgNPs on the CNFs. The as-prepared nanofibers were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, resonant Raman spectra, thermal gravimetric and differential thermal analysis, and X-ray photoelectron spectroscopy, respectively. The results indicated that not only were AgNPs (25-50 nm) successfully grown on the CNFs but also the AgNPs were distributed without aggregation on the CNFs. Further more, by adjusting the parameters in hydrothermal processing, the content of silver supported on the CNFs could be easily controlled. The catalytic activities of the CNFs/AgNPs composite nanofibers to the reduction of 4-nitrophenol (4-NP) with NaBH(4) were tracked by UV-visible spectroscopy. It was suggested that the CNFs/AgNPs composite nanofibers exhibited high catalytic activity in the reduction of 4-NP, which might be attributed to the high surface areas of AgNPs and synergistic effect on delivery of electrons between CNFs and AgNPs. And, the catalytic efficiency was enhanced with the increasing of the content of silver on the CNFs/AgNPs composite nanofibers. Notably, the CNFs/AgNPs composite nanofibers could be easily recycled due to their one-dimensional nanostructural property.

Topics: Carbon; Catalysis; Electrochemical Techniques; Metal Nanoparticles; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanofibers; Nanotechnology; Nitric Acid; Nitrophenols; Oxidation-Reduction; Particle Size; Silver; Spectrum Analysis; Surface Properties; Thermogravimetry; X-Ray Diffraction

Desorption behaviors of loaded 4-nitrophenol (4-NP) on hyper-cross-linked polymer resin NDA-701 were studied. The molar ratio of NaOH and 4-NP desorbed (M(NAOH/4-NP)) selection experiments were carried out at two different reaction temperature(303 K and 333 K). Desorption kinetics characteristic of4-NP on NDA-701 in the batch and fixed-bed mode were examined at different reaction temperature and M(NaOH/4-NP) values. The results showed that optimal M(NaOH/4-NP) values were 1.2 and 100% 4-NP could be desorbed from NDA-701 at two different temperature. When the M(NaOH/4-NP) was lower than 1.2, the desorption efficiency increases with the increase of temperature, but the function of temperature decrease with increasing of M(NaH/4-NP) values for desorption ratio. The information indicated that desorption thermodynamic characteristic of NDA-701 was controlled by M(NaOH/4-NP) values. Desorption kinetics in the alkaline system can be well described by pseudo-second-order kinetic model, and desorption rate is increased with the increase of desorption temperatures, the k2 value increase from 0.010 g x (mmol x min)(-1) to 0.035 g x (mmol x min)(-1) when desorption temperature increase from 303 K to 333 K. Nevertheless, higher M(NaOH/4-NP) values could not promote desorption rate if only M(NaOH/4-NP) value was larger than the optimal molar ratio of NaOH and 4-NP. When M(NaOH/4-NP) values increase from 1.2 to 5.0, the k2 value increase from 0.038 g x (mmol x min)(-1) to 0.044 g x (mmol x min)(-1) merely at 333 K. the results indicated that desorption kinetic characteristic of NDA-701 was controlled by temperature. NDA-701 can be completely recovered using 2 times Bed Volume of 2% NaOH solution at the temperature of 333 K, comparing with field application, implying that more energy and cost can be saved in comparison with the actual desorption process in the industry.

Topics: Adsorption; Ion Exchange Resins; Kinetics; Nitrophenols; Polymers; Resins, Synthetic; Thermodynamics; Waste Disposal, Fluid; Water Pollutants, Chemical

The possible impacts on nitrogen-cycle in a p-nitrophenol (PNP) polluted soil and the effectiveness of wastewater sludge amendments in restoring nitrification potential and urease activity were evaluated by an incubation study. The results indicated that PNP at 250 mg/kg soil inhibited urease activity, nitrification potential, arginine ammonification rate and heterotrophic bacteria counts to some extents. After exposure to PNP, the nitrification potential of the tested soil was dramatically reduced to zero over a period of 30 days. Based on the findings, nitrification potential was postulated as a simple biochemical indicator for PNP pollution in soils. Nitrogen-cycling processes in soils responded positively to the applications of wastewater sludges. A sludge application rate of 200 tons/ha was sufficient for successful biostimulation of these nitrogen processes. The microbial activities in sludge-amended, heavy PNP-polluted soils seemed to recover after 30-45 days, indicating the effectiveness of sludge as a useful soil amendment.

Topics: Analysis of Variance; Arginine; Biodegradation, Environmental; Environmental Restoration and Remediation; Heterotrophic Processes; Nitrification; Nitrogen; Nitrogen Cycle; Nitrophenols; Sewage; Soil; Soil Pollutants; Urease; Waste Disposal, Fluid

A lipase-based assay for detection of specific DNA sequences has been developed. Lipase from Candida antarctica was conjugated to DNA and captured on magnetic beads in a sandwich assay, in which the binding was dependent on the presence of a specific target DNA. For amplification and to generate a detectable readout the captured lipase was applied to an optical assay that takes advantage of the enzymatic activity of lipase. The assay applies p-nitrophenol octanoate (NPO) as the substrate and in the presence of lipase the ester is hydrolyzed to p-nitrophenolate which has a strong absorbance at 405 nm. The method provides detection a detection limit of 200 fmol target DNA and it was able to distinguish single base mismatches from the fully complementary target.

Topics: Base Pair Mismatch; Biosensing Techniques; Candida; DNA; Fungal Proteins; Lipase; Nitrophenols; Sensitivity and Specificity

Yeast cells displaying organophosphorus hydrolase (OPH), which was anchored using a lectin-like cell-wall protein (Flo1p), were used as a biocatalyst for the detection of organophosphorus compounds (OPs). The concentration of p-nitrophenol produced by the hydrolysis of the OPs paraoxon was calculated from the absorbance change at 415 nm during a 30-min reaction. The apparent Michaelis-Menten constant (K'(m)) for surface-displayed OPH was estimated to be approximately 50 µM, which is consistent with the value of purified OPH, and shows that cell-surface expression is a useful strategy to overcome the mass-transport resistance of substrates across the cell membrane. Notably, the long-term storage stability of the enzyme activity exceeded 40 days when cells displaying OPH were preserved at temperatures below -4 °C. A fiber-optic biosensing system was also constructed using a commercial optical-fiber detection device and yeast cells with surface-displayed OPH. A linear relationship was obtained for paraoxon concentrations of up to 50 ppm (182 µM), with a detection sensitivity of 0.0043 A.U. per ppm (R(2) = 0.9574) and a detection limit of 5 ppm (18 µM).

Topics: Aryldialkylphosphatase; Biocatalysis; Biosensing Techniques; Hydrolysis; Kinetics; Nitrophenols; Organophosphorus Compounds

Organoclays are increasingly being used to remediate both contaminated soils and waste water. The present study was attempted to elucidate the structural evolution of bentonite based organoclays prepared from a commercially available, low-cost alkyl ammonium surfactant Arquad(®) 2HT-75. XRD, FTIR, SEM and zeta potential measurement were used to characterise the organoclays. In particular, the relationship between surface charge characteristics of the organoclays and their ability to remediate organic contaminants such as phenol and p-nitrophenol was investigated. The investigation revealed that the arrangement and conformation of surfactant molecules in the bentonite became more regular, ordered and solid-like as of Arquad(®) 2HT-75 loading increased. This also led to the formation of a positive zeta potential on the surface of organobentonites prepared with 3.57:1 and 4.75:1 surfactant-clay (w/w) ratio. The zeta potential values decreased with increasing pH of the suspension. The adsorption data of phenol and p-nitrophenol were best fitted to Freundlich isotherm model. The adsorption was controlled by multiple mechanisms of partitioning, physico-sorption and chemisorption. The outcomes of this study are useful for the synthesis of low cost organobentonite adsorbents for the remediation of ionisable organic contaminants such as phenol and p-nitrophenol from waste water.

Topics: Adsorption; Bentonite; Environmental Restoration and Remediation; Microscopy, Electron, Scanning; Nitrophenols; Organic Chemicals; Phenol; Spectroscopy, Fourier Transform Infrared; Surface Properties; X-Ray Diffraction

In this paper, we reported a simple, aqueous-phase route to the synthesis of two-dimensional graphene/SnO(2) composite nanosheets (GSCN) hybrid nanostructures consisting of 5 nm Pt nanoparticles supported on the both sides of GSCN. Functional two-dimensional GSCN were obtained through the reduction of graphene oxide (GO) using SnCl(2) in the presence of polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA). The main advantages of this preparation are that the reduction of GO, the formation of SnO(2) and the functionalization of GSCN were achieved simultaneously through one-pot reaction. GSCN/Pt ternary hybrid nanomaterials were generated by in situ reduction of negatively charged PtCl(6)(2-) precursors adsorbed on the positively charged surface of GSCN through electrostatic attraction. The as-synthesized GSCN/Pt ternary hybrid nanomaterials exhibited high cycle stabilization during the catalytic reduction of p-nitrophenol into p-aminophenol by NaBH(4). Additionally, our approach is expected to extend to other hybrid nanomaterials. We believe that the obtained GSCN/Pt ternary hybrid nanomaterials have great potential for applications in other field, such as electrochemical energy storage, sensors, and so on.

Topics: Allyl Compounds; Aminophenols; Borohydrides; Catalysis; Graphite; Nanostructures; Nitrophenols; Oxidation-Reduction; Platinum; Quaternary Ammonium Compounds; Tin Compounds

The reaction of intracellular Ca(2+) to different agonist stimuli in primary hepatocytes from rainbow trout (Oncorhynchus mykiss) as well as the permanent fish cell line RTL-W1 was investigated systematically. In addition to "classical" agonists such as phenylephrine and ATP, model environmental toxicants like 4-nitrophenol and 3,4-dichloroaniline were used to elucidate possible interactions between toxic effects and Ca(2+) signaling. We report Ca(2+) oscillations in response to several stimuli in RTL-W1 cells and to a lesser extent in primary hepatocytes. Moreover, these Ca(2+) oscillations are amplitude-encoded in contrast to their mammalian counterpart. Bioinformatics and computational analysis were employed to identify key players of Ca(2+) signaling in fish and to determine likely causes for the experimentally observed differences between the Ca(2+) dynamics in fish cells compared to those in mammalian liver cells.

Topics: Adenosine Triphosphate; Aniline Compounds; Animals; Calcium; Calcium Signaling; Cell Line; Cells, Cultured; Environmental Pollutants; Hepatocytes; Nitrophenols; Oncorhynchus; Phenylephrine

Nonthermal discharge plasma and TiO(2) photocatalysis are two techniques capable of organic pollutants removal in soil. In the present study, a pulsed discharge plasma-TiO(2) catalytic (PDPTC) technique by combining the two means, where catalysis of TiO(2) is driven by the pulsed discharge plasma, is proposed to investigate the remediation of p-nitrophenol (PNP) contaminated soil. The experimental results showed that 88.8% of PNP was removed within 10 min of treatment in PDPTC system and enhancing pulse discharge voltage was favorable for PNP degradation. The mineralization of PNP and intermediates generated during PDPTC treatment was followed by UV-vis spectra, denitrification, total organic carbon (TOC), and CO(x) selectivity analyses. Compared with plasma alone system, the enhancement effects on PNP degradation and mineralization were attributed to more amounts of chemically active species (e.g., O(3) and H(2)O(2)) produced in the PDPTC system. The main intermediates were identified as hydroquinone, benzoquinone, catechol, phenol, benzo[d][1, 2, 3]trioxole, acetic acid, formic acid, NO(2)(-), NO(3)(-), and oxalic acid. The evolution of the main intermediates with treatment time suggested the enhancement effect of the PDPTC system. A possible pathway of PNP degradation in soil in such a system was proposed.

Topics: Environmental Restoration and Remediation; Models, Chemical; Nitrophenols; Photochemistry; Soil Pollutants; Titanium

The present study reports the kinetics of p-nitrophenol (PNP) biodegradation by Arthrobacter chlorophenolicus A6 in batch shake flasks for initial PNP concentrations in the range of 25-225 mg l(-1). Results of batch growth kinetics of A. chlorophenolicus A6 at various initial PNP concentrations revealed that the culture followed substrate inhibition kinetics with estimated decay coefficient value of 0.0132 h(-1). Biokinetic constants involved in the process were estimated by fitting the experimental data to several substrate inhibition kinetics models available from the literature. Among the models tested, Webb model fitted the experimental data best with the least root mean square error value, and the estimated model constants values were μ = 0.161 h(-1), K (i) = 128 mg l(-1), K (s) = 60.15 mg l(-1), and K = 100 mg l(-1). In addition, observed and theoretical yield coefficients, maintenance energy, and specific growth rate of the culture at various initial PNP concentrations were also investigated in the study.

Topics: Arthrobacter; Biodegradation, Environmental; Kinetics; Nitrophenols

A pulsed discharge plasma-TiO(2) catalytic (PDPTC) system was developed to investigate the degradation of p-nitrophenol (PNP) in soil. The effects of TiO(2) amount, soil pH and air moisture on PNP degradation were evaluated, and PNP degradation processes were predicted with Gaussian 03W combined with density functional theory (DFT). Experimental results showed that 88.8% of PNP could be smoothly removed in 10 min in the PDPTC system with the specific energy density of 694 J g(soil)(-1), compared with 78.1% in plasma alone system. The optimum TiO(2) amount was 2% in the present study, and higher TiO(2) amount exhibited an inhibitive effect. Alkaline soil was favorable for PNP removal. The increase of air moisture to a certain extent could enhance PNP removal. A DFT calculation presented that there was a high preference for the -ortho and -para positions with respect to the functional -OH group of PNP molecule for OH radicals attack. The main intermediates were hydroquinone, benzoquinone, catechol, phenol, benzo[d][1,2,3]trioxole, acetic acid, formic acid, NO(2)(-), NO(3)(-) and oxalic acid. The generation of hydroxylated intermediates, NO(2)(-) and NO(3)(-) suggested that the experimental results were consistent with those of the theoretical prediction.

Topics: Catalysis; Chromatography, High Pressure Liquid; Humidity; Mass Spectrometry; Nitrophenols; Plasma Gases; Soil Pollutants

In the present investigation, the silver-bionanocomposite with fcc structured Ag-nanocrystals was synthesized using the fungus, Cylindrocladium floridanum through a novel, environmentally benign biological process. Silver-bionanocomposite was systematically characterized by UV-Vis spectroscopy, XRD, SEM, EDX, and TEM techniques. TEM analysis of mycelia confirmed the presence of silver nanoparticles (AgNPs) on the outer surface of the cell wall and inner of cytoplasmic membrane of the fungus, when cultured in aqueous solution of AgNO3 at 30 °C for a period of 7 days in static condition. Additionally, it was observed that bionanocomposite with AgNPs functions as an efficient heterogeneous catalyst in the degradation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), in the presence of reducing agent, sodium borohydride which was reflected by UV-Vis spectra of the catalytic reaction kinetics. This is the first report of the silver-bionanocomposite using fungus, Cy. floridanum, heterogeneously catalyzing the reduction of a toxic pollutant, 4-NP to 4-AP.

Topics: Absorption; Ascomycota; Biocatalysis; Biodegradation, Environmental; Biomass; Environmental Pollutants; Humans; Kinetics; Metal Nanoparticles; Nanocomposites; Nitrophenols; Oxidation-Reduction; Particle Size; Silver; Spectrophotometry, Ultraviolet

Well-dispersed Ag@Pd supported on magnetite nanoparticles have been obtained through a simple colloidal impregnation method. The as-synthesised nanocomposite exhibits greatly enhanced catalytic reactivity and reusability towards 4-nitrophenol hydrogenation.

Topics: Catalysis; Ferrosoferric Oxide; Hydrogenation; Magnetite Nanoparticles; Nitrophenols; Oxidation-Reduction; Palladium; Povidone; Silver; Surface Properties

In this paper, we develop a cost-effective and simple route for the synthesis of Au nanoparticles (AuNPs) decorated graphene oxide (GO) nanosheets using polyoxyethylene sorbitol anhydride monolaurate (TWEEN 20) as a stabilizing agent for GO as well as a reducing and immobilizing agent for AuNPs. The AuNPs assemble on the surface of TWEEN-functionalized GO by the in situ reduction of HAuCl(4) aqueous solution. The morphologies of these composites were characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). It is found that the resultant AuNPs decorated GO nanosheets (AuNPs/TWEEN/GO) exhibit remarkable catalytic performance for hydrazine oxidation. This hydrazine sensor has a fast amperometric response time of less than 3s. The linear range is estimated to be from 5 μM to 3 mM (r=0.999), and the detection limit is estimated to be 78 nM at a signal-to-noise ratio of 3. The AuNPs/TWEEN/GO composites also exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the GO supports also enhance the catalytic activity via a synergistic effect.

Topics: Catalysis; Chlorides; Gold; Gold Compounds; Graphite; Limit of Detection; Metal Nanoparticles; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Polysorbates; Spectrophotometry, Ultraviolet; Surface-Active Agents; Water

A simple, green method is described for the synthesis of Gold (Au) and Silver (Ag) nanoparticles (NPs) from the stem extract of Breynia rhamnoides. Unlike other biological methods for NP synthesis, the uniqueness of our method lies in its fast synthesis rates (~7 min for AuNPs) and the ability to tune the nanoparticle size (and subsequently their catalytic activity) via the extract concentration used in the experiment. The phenolic glycosides and reducing sugars present in the extract are largely responsible for the rapid reduction rates of Au(3+) ions to AuNPs. Efficient reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of AuNPs (or AgNPs) and NaBH(4) was observed and was found to depend upon the nanoparticle size or the stem extract concentration used for synthesis.

Topics: Aminophenols; Borohydrides; Catalysis; Euphorbiaceae; Gold; Green Chemistry Technology; Kinetics; Metal Nanoparticles; Microscopy, Electron, Transmission; Nanotechnology; Nitrophenols; Oxidation-Reduction; Particle Size; Plant Extracts; Plant Stems; Silver; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis; Surface Plasmon Resonance

In this study, to investigate the application of heterogeneous photocatalysis in the removal of organic contaminants from aqueous media a novel tubular continuous-flow photoreactor with supported TiO2-P25 on glass plates was designed and constructed. The photoreactor comprises six quartz tubes and a UV lamp which was placed in the center of the quartz tubes. 4-nitrophenol (4-NP) as a most refractory pollutant was chosen as a probe pollutant to examine the photoreactor efficiency for environmental cleaning applications. Results of experiments show that the removal efficiency of 4-NP in this photoreactor is a function of photoreactor length, gas and liquid flow rates and 4-NP initial concentration. Kinetics analysis indicates that degradation of 4-NP in continuous-mode can be modeled with the Langmuir-Hinshelwood (L-H) model (k(L-H) = 1.5 mg L(-1) min(-1), K(ads) = 0.11 mg(-1) L). A design equation was obtained with a combination of L-H modified equation and tubular reactor design equation. This equation can be used for estimation of 4-NP concentration in different photoreactor lengths under various operational parameters. Mineralization study was followed through total organic carbon (TOC) analysis and measurement of nitrite and nitrate as final degradation products.

Topics: Carbon; Kinetics; Nanoparticles; Nitrates; Nitrites; Nitrophenols; Oxidation-Reduction; Titanium; Water Pollutants, Chemical; Water Pollution; Water Purification

Lichens belonging to the order Peltigerales display strong activity of multi-copper oxidases (e.g. tyrosinase) as well as heme-containing peroxidases. The lichen peroxidase was purified to homogeneity from the thallus of Leptogium saturninum (LsaPOX) by fast protein liquid chromatography and then partially characterized. The oligomeric protein occurs as both 79 kDa dimeric and 42 kDa monomeric forms, and displayed broad substrate specificity. In addition to an ability to oxidize classic peroxidase substrates (e.g. 2,6-dimethoxyphenol), the enzyme could convert recalcitrant compounds such as synthetic dyes (e.g. Azure B and Reactive Blue 5), 4-nitrophenol and non-phenolic methoxylated aromatics (e.g. veratryl alcohol). Comparing LsaPOX with a basidiomycete dye-decolorizing (DyP)-type peroxidase from Auricularia auricula-judae showed that the lichen enzyme has a high-redox potential, with oxidation capabilities ranging between those of known plant and fungal peroxidases. Internal peptide fragments show homology (up to 60%) with putative proteins from free-living ascomycetes (e.g. Penicillium marneffei and Neosartorya fischeri), but not to sequences of algal or cyanobacterial peptides or to known fungal, bacterial or plant peroxidases. LsaPOX is the first heme peroxidase purified from an ascomyceteous lichen that may help the organism to successfully exploit the extreme micro-environments in which they often grow.

Topics: Ascomycota; Chromatography, High Pressure Liquid; Heme; Lichens; Monophenol Monooxygenase; Nitrophenols; Oxidation-Reduction; Peroxidase; Sequence Analysis, Protein; Substrate Specificity

Cytosolic sulfotransferases (SULTs) are mammalian enzymes that detoxify a wide variety of chemicals through the addition of a sulfate group. Despite extensive research, the molecular basis for the broad specificity of SULTs is still not understood. Here, structural, protein engineering and kinetic approaches were employed to obtain deep understanding of the molecular basis for the broad specificity, catalytic activity and substrate inhibition of SULT1A1. We have determined five new structures of SULT1A1 in complex with different acceptors, and utilized a directed evolution approach to generate SULT1A1 mutants with enhanced thermostability and increased catalytic activity. We found that active site plasticity enables binding of different acceptors and identified dramatic structural changes in the SULT1A1 active site leading to the binding of a second acceptor molecule in a conserved yet non-productive manner. Our combined approach highlights the dominant role of SULT1A1 structural flexibility in controlling the specificity and activity of this enzyme.

Topics: Arylsulfotransferase; Binding Sites; Catalysis; Catalytic Domain; Coumarins; Crystallography, X-Ray; Humans; Kinetics; Models, Molecular; Mutagenesis, Site-Directed; Mutation; Nitriles; Nitrophenols; Protein Binding; Protein Conformation; Static Electricity; Substrate Specificity

One new tetralone, monaspurpurone (1), was isolated from the EtOH extract of a yellow mutant of the fungus Monascus purpureus BCRC 38113 (Eurotiaceae) grown on rice, along with five known compounds, β-sitosteryl palmitate (2), ergosterol (3), ankaflavin (4), monascin (5) and p-nitrophenol (6). They were characterised on the basis of spectral analysis and comparison with literature data. All the isolates were also evaluated for the scavenging properties towards the DPPH in TLC autographic and spectroscopic assays.

Topics: Biphenyl Compounds; Chromatography, Thin Layer; Ergosterol; Flavins; Free Radical Scavengers; Heterocyclic Compounds, 3-Ring; Molecular Structure; Monascus; Nitrophenols; Oryza; Palmitates; Picrates; Sitosterols; Spectrum Analysis; Tetralones

Due to increasing human requirements, newer chemical species are being observed in the effluent streams with higher loadings such that efficacy of conventional treatment techniques is decreased and a combination of advanced oxidation processes is implemented for enhanced treatment ability and better energy efficiency. In the present work, the efficacy of combination of sonochemistry and Fenton chemistry has been investigated for wastewater treatment considering p-nitrophenol as model pollutant at pilot scale operation. Degradation of p-nitrophenol has been investigated under various operating conditions based on the use of ultrasound, Fenton process, ultrasound and H(2)O(2), ultrasound and Fe, ultrasound and FeSO(4), ultrasound and conventional Fenton process and ultrasound and advanced Fenton process. Two different initial concentrations of 0.5 and 1% of p-nitrophenol have been used for the experiments. In conventional Fenton and advanced Fenton process, two loadings of FeSO(4) and Fe powder 0.5 and 1g/l and three ratios of FeSO(4):H(2)O(2) and Fe:H(2)O(2) (1:5, 1:7.5 and 1:10) were investigated respectively. In all the systems investigated, maximum extent of degradation (66.4%) was observed for 0.5% p-nitrophenol concentration (w/v) using a combination of ultrasound and advanced Fenton process. The novelty of the work is in terms of investigating the efficacies of combined advanced oxidation processes based on the use of cavitation and Fenton chemistry at pilot scale operation and tries to establish the missing design related information for large scale operation of wastewater treatment.

Topics: Ferrous Compounds; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Nitrophenols; Oxidation-Reduction; Powders; Ultrasonics; Water Pollutants, Chemical; Water Purification

The parathion degradation under ultrasonic irradiation in aqueous solution was investigated. The results indicate that at the conditions in question, degradation rate of parathion decreased with increasing initial concentration and decreasing power. The optimal frequency for parathion degradation was 600 kHz. The free radical reactions predominate in the sonochemical degradation of parathion and the reaction zones are predominately at the bubble interface and, to a much lesser extent, in bulk solution. The gas/liquid interfacial regions are the real effective reaction sites for sonochemical degradation of parathion. The reaction can be well described as a gas/liquid heterogeneous reaction which obeys a kinetic model based on Langmuir-Hinshelwood model. The main pathways of parathion degradation by ultrasonic irradiation were also proposed by qualitative and quantitative analysis of organic and inorganic byproducts. It is indicated that the N(2) in air takes part in the parathion degradation through the formation of NO(2) under ultrasonic irradiation. Parathion is decomposed into paraoxon and 4-nitrophenol in the first step via two different pathways, respectively, which is in agreement with the theoretical molecular orbital (MO) calculations.

Topics: Chemistry; Free Radical Scavengers; Free Radicals; Gases; Hydroxyl Radical; Kinetics; Models, Chemical; Nitrogen; Nitrophenols; Paraoxon; Parathion; Sonication; Ultrasonics; Water Pollutants, Chemical; Water Purification

Dearomatization levels during electrochemical oxidation of p-methoxyphenol (PMP) and p-nitrophenol (PNP) have been determined through UV-Vis spectroscopy using solid phase extraction (UV-Vis/SPE). The results show that the method is satisfactory to determine the ratio between aromatic compounds and aliphatic acids and reaction kinetics parameters during treatment of wastewater, in agreement with results obtained from numerical deconvolution of UV-Vis spectra. Analysis of solutions obtained from electrolysis of substituted phenols on antimony-doped tin oxide (SnO(2)--Sb) showed that an electron acceptor substituting group favored the aromatic ring opening reaction, preventing formation of intermediate quinone during oxidation.

Topics: Anisoles; Antimony; Electrodes; Electrolysis; Hydrocarbons, Aromatic; Nitrophenols; Oxidation-Reduction; Solid Phase Extraction; Solutions; Spectrophotometry, Ultraviolet; Tin Compounds

We have evaluated the catalytic properties of Au-based nanostructures (including nanocages, nanoboxes, and solid nanoparticles) using a model reaction based on the reduction of p-nitrophenol by NaBH(4). From the average reaction rate constants at three different temperatures, we determined the activation energy, the entropy of activation, and the pre-exponential factor for each type of Au nanostructure. The kinetic data indicate that the Au-based nanocages are catalytically more active than both the nanoboxes and nanoparticles probably due to their extremely thin but electrically continuous walls, the high content of Au, and the accessibility of both inner and outer surfaces through the pores in the walls. In addition, a compensation effect was observed in this Au-based catalytic system, which can be primarily interpreted by a model based on kinetic regime switching.

Topics: Adsorption; Borohydrides; Catalysis; Gold; Kinetics; Materials Testing; Metal Nanoparticles; Metals; Models, Chemical; Nanotechnology; Nitrophenols; Temperature; Thermodynamics

Indications for tonsillectomy in recurrent tonsillitis are defined according to the number of episodes of acute bacterial infections in a year. However, little is known about the tonsil immune competence status in patients presenting with recurrent tonsillitis with either hypertrophied or atrophied tonsils, or in patients presenting with obstructive sleep apnoea. In this study we examined the tonsil immune status in children with 3-5 acute recurrent infections a year and in children with obstructive sleep apnoea by comparing the activity of tonsil and adenoid tissue nonspecific alkaline and acid phosphatase.. Specific activity of tonsil and adenoid tissue nonspecific alkaline and acid phosphatase was investigated in children who underwent tonsillectomy and adenoidectomy for recurrent infection (72 children) and for obstructive sleep apnoea (10 children). Tissue enzyme activities were measured using p-nitrophenylphosphate as a substrate. Tissue samples were examined by the haematoxylin-eosin histological technique. Statistical analyses were performed using SPSS v. 16 software.. The tissue nonspecific alkaline phosphatase activity was similar in hypertrophied tonsils in the recurrent infection group and in the obstructive sleep apnoea group (3.437+/-1.226 and 3.978+/-0.762 U/mg of protein, respectively). The enzyme activity in both hypertrophied tonsil groups was significantly higher as compared to atrophied tonsils in the recurrent tonsillitis group, p=0.021 and p=0.006, respectively. The enzyme activity was significantly higher in the adenoids compared to the tonsils from all three groups. Contrary to this, no significant differences were noticed for tonsil and adenoid acid phosphatase activities among the groups.. Similar acid phosphatase activity in all three groups implies that all three groups have preserved antigen presenting cell activity. In patients with hypertrophied tonsils similar tissue nonspecific alkaline phosphatase activity suggests preserved B cell tonsil immune activity, regardless of the pathology. Patients with atrophied tonsils had significantly lower alkaline phosphatase activity, indicating relative tonsil B cell immune deficiency. Thus, different immunological status in patients presenting with hypertrophied vs. atrophied tonsils could point to a different underlying pathophysiologic mechanism of the disease.

Topics: Adenoidectomy; Adenoids; Alkaline Phosphatase; Atrophy; B-Lymphocytes; Child; Child, Preschool; Female; Humans; Hydrogen-Ion Concentration; Hypertrophy; Macrophages; Male; Nasal Obstruction; Nitrophenols; Palatine Tonsil; Recurrence; Sleep Apnea, Obstructive; Tonsillectomy; Tonsillitis

Metal nanoparticle-chitosan (NPs-chitosan) bioconjugates were formed by exposure of chitosan to an aqueous solution of metal salts under thermal treatment. The metal nanoparticles that are formed strongly bound to chitosan, which encouraged us to investigate their catalytic performance. It was demonstrated that the metal NPs-chitosan bioconjugates functioned as effective catalysts for the reduction of 4-nitrophenol in the presence of NaBH(4), which was monitored by means of spectrophotometry as a function of reaction time. The silver NPs-chitosan bioconjugates exhibited excellent catalytic activity and were reusable for up to seven cycles. In contrast, the gold NPs-chitosan catalyst displayed poor catalytic activity, even in the second cycle. A highlight of our approach is that chitosan simultaneously acts as an active support for the synthesis and assembly of nanoparticles, and the resultant bioconjugates bear the advantage of easy separation from the reaction medium.

Topics: Animals; Biocompatible Materials; Catalysis; Chitosan; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction

SEIRA, SERS, TPD and DFT were used to study 4-nitrophenol (4NP), 3-nitrophenol (3NP) and 2-nitrophenol (2NP) adsorption on nanoscale silver films/powder. SERS and DFT demonstrated that 4NP adsorbed as the 4-nitrophenolate ion. SEIRA results revealed that a 4NP multilayer condensed differently using deposition solvents with and without polar bonds. 3NP and 2NP adsorption were not altered by the polar properties of the solvent. The nanoscale properties of the silver films/powder were shown to impact how the polar properties of the deposition solvent altered nitrophenol adsorption. In the SEIRA spectra of 4NP and 3NP a C=O stretch was observed above 1700cm(-1) using a highly volatile n-pentane deposition solvent. No other solvent yielded such a peak for 4NP or 3NP adsorption including n-heptane. 2NP had a C=O stretch regardless of deposition solvent. A C=O stretch confirmed nitrophenol ionization in the monolayer and pointed toward the significance of resonance in NP adsorption. 2NP never formed a multilayer at high exposures as demonstrated using TPD and SEIRA. Results of this work will have environmental implications and will aid biochemical and industrial applications where phenolic compounds are employed.

Topics: Adsorption; Isomerism; Models, Molecular; Nanostructures; Nitrophenols; Silver; Spectrum Analysis

Silver and gold nanoparticles have been grown on calcium alginate gel beads using a green photochemical approach. The gel served as both a reductant and a stabilizer. The nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray (EDS), and selected area electron diffraction (SAED) analyses. The particles are spherical, crystalline, and the size ranges for both Ag and Au nanoparticles are <10 nm. It is noticed from the sorption experiment that the loading of gold on calcium alginate beads is much more compared to that of Ag. The effectiveness of the as-prepared dried alginate-stabilized Ag and Au nanoparticles as a solid phase heterogeneous catalyst has been evaluated, for the first time, on the well-known 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP) in the presence of excess borohydride. The reduction was very efficient and followed zero-order kinetics for both Ag and Au nanocomposites. The effects of borohydride, initial 4-NP concentration, and catalyst dose were evaluated. The catalyst efficiency was examined on the basis of turnover frequency (TOF) and recyclability. The catalytic efficiency of alginate-based Ag catalyst was much more compared to that of the Au catalyst. The as-prepared new solid-phase biopolymer-based catalysts are very efficient, stable, easy to prepare, eco-friendly, and cost-effective, and they have the potential for industrial applications.

Topics: Alginates; Aminophenols; Calcium; Catalysis; Gels; Gold; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Photochemistry; Silver; Surface Properties

A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD(5)/COD(Cr) of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods.

Topics: Biodegradation, Environmental; Edetic Acid; Iron; Microwaves; Nitrophenols; Oxidation-Reduction; Solutions; Water Pollutants, Chemical; Water Purification

Photocatalytic degradation of 4-nitrophenol was investigated using Fe-doped (1, 3, 5 and 8 wt.% Fe) TiO(2) catalysts under UV light irradiation in aqueous dispersions in the presence of H(2)O(2). Photocatalysts with the lowest Fe content (1%) showed a considerably better behavior with respect to the unloaded TiO(2) and the catalysts with higher Fe contents. Photocatalytic degradation was studied under different conditions such as amounts of 1% Fe-TiO(2) catalyst, H(2)O(2) dose and initial pH of 4-NP solution. The results indicated that about 67.53% total organic carbon of a solution containing 20 mg L(-1) 4-NP was removed at pH 6.17 by using 4.9 mM of H(2)O(2) and 0.4 g L(-1) of the catalyst in a 2-L batch photo-reactor, the complete degradation of 4-NP occurring after 60 min. It was also observed that catalytic behavior could be reproduced in consecutive experiments without a considerable decrease of the UV/Fe-TiO(2)/H(2)O(2) process efficiency.

Topics: Catalysis; Hydrogen Peroxide; Iron; Nitrophenols; Photolysis; Titanium; Ultraviolet Rays

The 4-nitrophenol (PNP) in diesel exhaust particles (DEP) has been identified as a vasodilator and is a known degradation product of the insecticide parathion. In this study, the protective effect of quercetin, a potent oxygen free radical scavenger and metal chelator, against the oxidative damage of PNP on cultured testicular cells was studied in male embryonic chickens. Testicular cells from Day 18 embryos were cultured in serum-free McCoy's 5A medium and challenged with quercetin (1.0 microg/ml) alone or in combinations with PNP (10(-7)-10(-5) M) for 48 h. The oxidative damage was estimated by measuring cell viability, content of malondialdehyde (MDA), activity of superoxide dismutase (SOD) and glutathione peroxidation (GSH-Px) activity. The results showed that exposure to PNP (10(-5) M) induced condensed nuclei, vacuolated cytoplasm and a decrease in testicular cell viability and spermatogonial cell number. Exposure to PNP induced lipid peroxidation by elevation of the content of MDA. Exposure to PNP also decreased GSH-Px activity and SOD activity. However, simultaneous supplementation with quercetin restored these parameters to the same levels as the control. Consequently, PNP induced oxidative stress in spermatogonial cells, and dietary quercetin may attenuate the reproductive toxicity of PNP to restore the intracellular antioxidant system in the testicular cells of embryonic chickens.

Topics: Animal Feed; Animals; Antioxidants; Cell Count; Cells, Cultured; Chick Embryo; Chickens; Drug Interactions; Glutathione Peroxidase; Lipid Peroxidation; Male; Malondialdehyde; Nitrophenols; Oxidative Stress; Quercetin; Reproduction; Spermatogonia; Superoxide Dismutase; Testis; Tetrazolium Salts; Thiazoles; Vehicle Emissions

A kinetic model consisting of first-order desorption and biodegradation processes was developed to describe the bioregeneration of phenol- and p-nitrophenol-loaded powdered activated carbon (PAC) and pyrolyzed rice husk (PRH), respectively. Different dosages of PAC and PRH were loaded with phenol or p-nitrophenol by contacting with the respective phenolic compound at various concentrations. The kinetic model was used to fit the phenol or p-nitrophenol concentration data in the bulk solution during the bioregeneration process to determine the rate constants of desorption, k(d), and biodegradation, k. The results showed that the kinetic model fitted relatively well (R(2)>0.9) to the experimental data for the phenol- and p-nitrophenol-loaded PAC as well as p-nitrophenol-loaded PRH. Comparison of the values of k(d) and k shows that k is much greater than k(d). This indicates clearly that the desorption process is the rate-determining step in bioregeneration and k(d) can be used to characterize the rate of bioregeneration. The trend of the variation of the k(d) values with the dosages of PAC or PRH used suggests that higher rate of bioregeneration can be achieved under non-excess adsorbent dosage condition.

Topics: Adsorption; Biodegradation, Environmental; Charcoal; Kinetics; Models, Chemical; Nitrophenols; Phenols

A bacterial strain Rhodococcus imtechensis RKJ300 (= MTCC 7085(T) = JCM 13270(T)) was isolated from pesticide-contaminated soil of Punjab by the enrichment technique on minimal medium containing 4-nitrophenol. Strain RKJ300 is capable of utilizing 4-nitrophenol, 2-chloro-4-nitrophenol, and 2,4-dinitrophenol as sole sources of carbon and energy. The strain involved both oxidative and reductive catabolic mechanisms for initial transformation of these compounds. In the case of 2-chloro-4-nitrophenol, colorimetric analysis indicated that nitrite release was followed by stoichiometric elimination of chloride ions. Experiments using whole cells and cell-free extracts showed chlorohydroquinone and hydroquinone as the intermediates of 2-chloro-4-nitrophenol degradation. This is the first report of degradation on 2-chloro-4-nitrophenol by a bacterium under aerobic condition to the best of our knowledge. However, pathways for degradation of 4-nitrophenol and 2,4-dinitrophenol were similar to those reported in other strains of Rhodococcus. Laboratory-scale soil microcosm studies demonstrated that the organism was capable of degrading a mixture of nitrophenols simultaneously, indicating its applicability toward in situ bioremediation of contaminated sites. The fate of the augmented strain as monitored by the plate-counting method and hybridization technique was found to be fairly stable throughout the period of microcosm experiments.

Topics: 2,4-Dinitrophenol; Biodegradation, Environmental; Environmental Pollutants; Molecular Structure; Nitrophenols; Rhodococcus; Soil Microbiology

In order to investigate nitro-substitutent's effect on degradation of phenols at boron-doped diamond (BDD) anodes, cyclic voltammetries of three nitrophenol isomers: 2-nitrophenol (2NP), 3-nitrophenol (3NP) and 4-nitrophenol (4NP) were studied, and their bulk electrolysis results were compared with phenol's (Ph) under alkaline condition. The voltammetric study showed nitrophenols could be attacked by hydroxyl radicals and nitro-group was released from the aromatic ring. Results of bulk electrolysis showed degradation of all phenols were fit to a pseudo first-order equation and followed in this order: 2NP>4NP>3NP>Ph. Molecular structures, especially carbon atom charge, significantly influenced the electrochemical oxidation of these isomers. Intermediates were analyzed during the electrolysis process, and were mainly catechol, resorcinol, hydroquinone, and carboxylic acids, such as acetic acid and oxalic acid. A simple degradation pathway was proposed. Moreover, a linear increasing relationship between degradation rates and Hammett constants of the studied phenols was observed, which demonstrated that electrochemical oxidation of these phenols was mainly initiated by electrophilic attack of hydroxyl radicals at BDD anodes.

Topics: Boron; Diamond; Electrochemical Techniques; Electrodes; Electrolysis; Environmental Restoration and Remediation; Hydroxyl Radical; Nitrophenols; Oxidation-Reduction; Phenols

In this study, the capability of Ralstonia eutropha H16 to degrade p-nitrophenol with or without a supplementary substrate (glucose or yeast extract) was investigated. Using PNP as the sole energy and carbon source, the biodegradation behavior of the bacterium was modeled by applying a modified form of the Monod equation that considers substrate inhibition, as suggested in the literature (mu=(mu(m)S/k(s) +S)(1-(S/S(m)(n)). PNP at a 6 mg/L initial level was degraded within 20h under the defined incubation conditions (shaking at the reciprocal mode, pH 7 and temperature of 30 degrees C) however the biodegradation was enhanced when yeast extract included in the test medium (50% reduction in the time for complete degradation). When glucose was used instead of yeast extract in the test medium R. eutropha growth was not supported by this carbohydrate and PNP was degraded in about 14h indicating degradation time reduced by 1/3. Comparison of R. eutropha growth pattern showed that biomass formation was insignificant when the bacterium grew in the test medium containing only PNP or PNP plus glucose. But by use of yeast extract considerable biomass formation was observed (OD(546)=0.35 versus 0.1). The presence of organic pollutants in natural ecosystems at low levels frequently occurs in form of mixture with other compounds. The findings of the present work were discussed in terms of secondary substrate utilization for R. eutropha at low PNP level.

Topics: Biodegradation, Environmental; Biomass; Carbon; Culture Media; Cupriavidus necator; Glucose; Kinetics; Nitrophenols

Electrode kinetic data for the electro-reduction of 4-nitrophenol in aqueous solution are compared for bulk silver macro-electrodes and arrays of silver nanoparticles of size 15-50 nm. The electrode kinetics and mechanism change qualitatively and quantitatively.

Topics: Electrodes; Kinetics; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Silver; Surface Properties

The synergistic effect of gamma radiation with hydrogen peroxide (H(2)O(2)) for p-nitrophenol (PNP) decomposition in aqueous solution was evaluated. The PNP solution with initial concentration of 50mg/L was irradiated in the presence of extra H(2)O(2) at initial concentration of 0, 20, 40, and 80 mg/L. The experimental results showed that the decomposition of PNP conformed to the pseudo-first-order reaction kinetics under the applied conditions. When initial H(2)O(2) concentration was in the range of 0-80 mg/L, higher concentration of H(2)O(2) was more effective for the decomposition, mineralization and nitrogen release of PNP. However, the removal of total organic carbon (TOC) and total nitrogen (TN) was not as effective as that of PNP. Ammonia and nitrate were detected as the main inorganic nitrogen products of PNP decomposition without extra H(2)O(2), whereas nitrate was considered as a final inorganic nitrogen product with extra H(2)O(2) in the initial concentration range of 0-80 mg/L. Major decomposition products, including organic acids were identified by LC/MS and IC. Possible pathways for PNP decomposition by gamma radiation in aqueous solution were proposed.

Topics: Ammonia; Gamma Rays; Hydrogen Peroxide; Kinetics; Nitrates; Nitrophenols; Organic Chemicals; Solutions; Water Pollutants, Chemical; Water Purification

Human cytochrome P450 (P450) enzymes metabolize a variety of endogenous and xenobiotic compounds, including steroids, drugs, and environmental chemicals. In this study, we examine the possibility that bacterial P450 BM3 (CYP102A1) mutants with indole oxidation activity have the catalytic activities of human P450 enzymes. Error-prone polymerase chain reaction was carried out on the heme domain-coding region of the wild-type gene to generate a CYP102A1 DNA library. The library was transformed into Escherichia coli for expression of the P450 mutants. A colorimetric colony-based method was adopted for primary screening of the mutants. When the P450 activities were measured at the whole-cell level, some of the blue colonies, but not the white colonies, possessed apparent oxidation activity toward coumarin and 7-ethoxycoumarin, which are typical human P450 substrates that produce fluorescent products. Coumarin is oxidized by the CYP102A1 mutants to produce two metabolites, 7-hydroxycoumarin and 3-hydroxycoumarin. In addition, 7-ethoxycoumarin is simultaneously oxidized to 7-hydroxycoumarin by O-deethylation reaction and to 3-hydroxy,7-ethoxycoumarin by 3-hydroxylation reactions. Highly active mutants are also able to metabolize several other human P450 substrates, including phenacetin, ethoxyresorufin, and chlorzoxazone. These results indicate that indigo formation provides a simple assay for identifying CYP102A1 mutants with a greater potential for human P450 activity. Furthermore, our computational findings suggest a correlation between the stabilization of the binding site and the catalytic efficiency of CYP102A1 mutants toward coumarin: the more stable the structure in the binding site, the lower the energy barrier and the higher the catalytic efficiency.

Topics: Amino Acid Substitution; Bacterial Proteins; Biocatalysis; Carbon; Chlorzoxazone; Coumarins; Cytochrome P-450 Enzyme System; Enzyme Stability; Escherichia coli; Heme; Humans; Indigo Carmine; Indoles; Kinetics; Molecular Dynamics Simulation; NADPH-Ferrihemoprotein Reductase; Nitrophenols; Oxazines; Oxidation-Reduction; Phenacetin; Protein Engineering; Recombinant Proteins; Transformation, Genetic; Umbelliferones

Organophosphorus hydrolase (OPH) hydrolyzes organophosphorus esters. We constructed the yeast-displayed OPH using Flo1p anchor system. In this system, the N-terminal region of the protein was fused to Flo1p and the fusion protein was displayed on the cell surface. Hydrolytic reactions with paraoxon were carried out during 24 h of incubation of OPH-displaying cells at 30 degrees C. p-Nitrophenol produced in the reaction mixture was detected by HPLC. The strain with highest activity showed 8-fold greater OPH activity compared with cells engineered using glycosylphosphatidylinositol anchor system, and showed 20-fold greater activity than Escherichia coli using the ice nucleation protein anchor system. These results indicate that Flo1p anchor system is suitable for display of OPH in the cell surface-expression systems.

Topics: Aryldialkylphosphatase; Chromatography, High Pressure Liquid; Membrane Proteins; Nitrophenols; Paraoxon; Recombinant Fusion Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Temperature; Time Factors

The effect of p-nitrophenol (PNP) concentration with or without glucose and yeast extract on the growth and biodegradative capacity of Ralstonia eutropha was examined. The chemical constituents of the culture medium were modeled using a response surface methodology. The experiments were performed according to the central composite design arrangement considering PNP, glucose and yeast extract as the selected variables whose influences on the degradation was evaluated (shaking in reciprocal mode, temperature of 30 degrees C, pH 7 and test time of about 9 h). Quadratic polynomial regression equations were used to quantitatively explain variations between and within the models (responses: the biodegradation capacity and the biomass formation). The coefficient of determination was high (R(adjusted)(2) = 0.9783), indicating the constructed polynomial model for PNP biodegradative capacity explains the variation between the regressors fairly well. A PNP removal efficiency of 74.5% occurred within 9 h (15 mg/L as the initial concentration of PNP with use of yeast extract at 0.5 g/L).

Topics: Biodegradation, Environmental; Culture Media; Cupriavidus necator; Kinetics; Models, Statistical; Nitrophenols

A rod-shaped, gram-negative bacterium Stenotrophomonas sp. SMSP-1 was isolated from the sludge of a wastewater treating system of a pesticide manufacturer. Strain SMSP-1 could hydrolyze methyl parathion to p-nitrophenol (PNP) and dimethyl phosphorothioate but could not degrade PNP further. Strain SMSP-1 was able to hydrolyze other organophosphate pesticides, including fenitrothion, ethyl parathion, fenthion, and phoxim, but not chlorpyrifos. A 4395-bp DNA fragment, including an organophosphorus hydrolase encoding gene ophc2, was cloned from the chromosome of strain SMSP-1 using the shotgun technique. Its sequence analysis showed that ophc2 was associated with a typical mobile element ISPpu12 consisting of tnpA (encoding a transposase), lspA (encoding a lipoprotein signal peptidase), and orf1 (encoding a CDF family heavy metal/H(+) antiporter). The ophc2 gene was effectively expressed in E. coli. This is the second report of cloning the ophc2 gene and the first report of this gene from the genus of Stenotrophomonas.

Topics: Amino Acid Sequence; Bacterial Proteins; Base Sequence; Biodegradation, Environmental; Cloning, Molecular; Escherichia coli; Gene Expression Regulation, Bacterial; Genes, Bacterial; Methyl Parathion; Molecular Sequence Data; Nitrophenols; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Stenotrophomonas

Microbial degradation studies have pointed toward the occurrence of two distinct PNP catabolic pathways in Gram positive and Gram negative bacteria. The former involves 4-nitrocatechol (4-NC), 1,2,4-benzenetriol (BT), and maleylacetate (MA) as major degradation intermediates, whereas the later proceeds via formation of 1,4-benzoquinone (BQ) and hydroquinone (HQ). In the present study we identified a Gram negative organism viz. Burkholderia sp. strain SJ98 that degrades PNP via 4NC, BT, and MA. A 6.89 Kb genomic DNA fragment of strain SJ98 that encompasses seven putatively identified ORFs (orfA, pnpD, pnpC, orfB, orfC, orfD, and orfE) was cloned. PnpC is benzenetriol dioxygenase belonging to the intradiol dioxygenase superfamily, whereas PnpD is identified as maleylacetate reductase, a member of the Fe-ADH superfamily showing NADH dependent reductase activity. The in vitro activity assays carried out with purified pnpC and pnpD (btd and mar) gene products transformed BT to MA and MA to beta-ketoadipate, respectively. The cloning, sequencing, and characterization of these genes along with the functional PNP degradation studies ascertained the involvement of 4-NC, BT, and MA as degradation intermediates of PNP pathway in this strain. This is one of the first conclusive reports for 4-NC and BT mediated degradation of PNP in a Gram negative organism.

Topics: Biodegradation, Environmental; Blotting, Southern; Burkholderia; Catechols; Chromatography, Gas; Cloning, Molecular; DNA, Bacterial; Electrophoresis, Polyacrylamide Gel; Genetic Vectors; Mass Spectrometry; Molecular Weight; Nitrophenols; Phylogeny; Reverse Transcriptase Polymerase Chain Reaction; Sequence Analysis, DNA

Microcalorimetry, high-performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS) have been used to conduct a thermodynamic investigation of the hydrolysis reactions {1-naphthyl acetate(aq) + H(2)O(l) = 1-naphthol(aq) + acetate(aq)}, {4-nitrophenyl acetate(aq) + H(2)O(l) = 4-nitrophenol(aq) + acetate(aq)}, and {4-nitrophenyl α-L-arabinofuranoside(aq) + H(2)O(l) = L-arabinose(aq) + 4-nitrophenol(aq)}. Calorimetrically determined enthalpies of reaction Δ(r)H(cal) were measured for all three reactions. However, since the positions of equilibrium for all of these reactions were found to lie very far to the right, it was only possible to set lower limits for the values of the apparent equilibrium constants K'. A chemical equilibrium model, together with pKs and standard enthalpies of reaction Δ(r)H° for the H(+) binding reactions of the reactants and products, was then used to calculate the values of Δ(r)H° for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. The values of Benson estimates of Δ(r)H° for the chemical reference reactions that correspond to the first of the above two reactions were, in all cases, within 16 kJ·mol(-1) of the results obtained in this study. Thermochemical network calculations led to Δ(f)H° = -286.4 kJ·mol(-1) for 1-naphthyl acetate(aq) and Δ(f)H° = -364.9 kJ·mol(-1) for 4-nitrophenyl acetate(aq).

Topics: Acetates; Arabinose; Glycosides; Hydrolysis; Molecular Structure; Naphthols; Nitrophenols; Thermodynamics

Polymeric sorbent materials that incorporate beta-cyclodextrin (CD) have been prepared and their sorption behavior toward two model agrochemical contaminant compounds, p-nitrophenol (PNP) and methyl chloride examined. The sorption of PNP was studied in aqueous solution using ultraviolet-visible (UV-Vis) spectroscopy, whereas the sorption of methyl chloride from the gas phase was studied using a Langmuir adsorption method. The sorption results for PNP in solution were compared between granular activated carbon (GAC), modified GAC, CD copolymers, and CD-based mesoporous silica hybrid materials. Nitrogen porosimetry at 77 K was used to estimate the surface area and pore structure properties of the sorbent materials. The sorbents displayed variable surface areas as follows: copolymers (36.2-157 m(2)/g), CD-silica materials (307-906 m(2)/g), surface modified GAC (657 m(2)/g), and granular activated carbon (approximately 10(3) m(2)/g). The sorption capacities for PNP and methyl chloride with the different sorbents are listed in descending order as follows: GAC > copolymers > surface modified GAC > CD-silica hybrid materials. In general, the differences in the sorption properties of the sorbents were related to the following: (i) surface area of the sorbent, (ii) CD content and accessibility, (iii) and the chemical nature of the sorbent material.

Topics: Adsorption; Agrochemicals; beta-Cyclodextrins; Charcoal; Methyl Chloride; Nitrophenols; Silicon Dioxide; Water Pollution, Chemical; Water Purification

The cytosolic sulfotransferases (SULTs) in vertebrates catalyze the sulfonation of endogenous thyroid/steroid hormones and catecholamine neurotransmitters, as well as a variety of xenobiotics, using 3'-phosphoadenosine 5'-phosphosulfate (PAPS) as the sulfonate donor. In this study, we determined the structures of SULT1A2 and an allozyme of SULT1A1, SULT1A1 *3, bound with 3'-phosphoadenosine 5'-phosphate (PAP), at 2.4 and 2.3A resolution, respectively. The conformational differences between the two structures revealed a plastic substrate-binding pocket with two channels and a switch-like substrate selectivity residue Phe247, providing clearly a structural basis for the substrate inhibition. In SULT1A2, Tyr149 extends approximately 2.1A further to the inside of the substrate-binding pocket, compared with the corresponding His149 residue in SULT1A1 *3. Site-directed mutagenesis study showed that, compared with the wild-type SULT1A2, mutant Tyr149Phe SULT1A2 exhibited a 40 times higher K(m) and two times lower V(max) with p-nitrophenol as substrate. These latter data imply a significant role of Tyr149 in the catalytic mechanism of SULT1A2.

Topics: Arylsulfotransferase; Catalysis; Crystallography, X-Ray; Humans; Mutagenesis, Site-Directed; Mutation; Nitrophenols; Phosphoadenosine Phosphosulfate; Protein Conformation; Substrate Specificity; Tyrosine

Our previous studies have shown that major metabolites of nitrobenzene in bovine and fowl were p-nitrophenol, p-aminophenol, and p-nitroaniline. There are few reports about the subacute toxicity of the three metabolites. The aim of this study was to investigate the subacute toxicity of these compounds. A suspension containing three metabolites at 50, 25, and 5 mg kg(-1) body weight was administrated introgastrically to Sprague-Dawley rats of both sexes for 4 weeks. All four groups survived to the end of the 4-week treatment period. Compared to the control group, there was a significant difference in body-weight increases in rats administered nitrobenzene metabolites at 50 and 25 mg kg(-1) (P < 0.01). ALT, AST, ALP, T-CHO, TP, albumin, and creatinine were significantly increased in the 50-mg kg(-1) group and tended to increase in the 25-mg kg(-1) group, compared with controls. There was no significant difference in glucose between treatment groups and controls. RBC counts and concentration of Hb decreased significantly in the 50- and 25-mg kg(-1) groups, compared with controls, whereas WBC and Ret counts increased in the 50- and 25-mg kg(-1) groups and LYM only in the 50-mg kg(-1) group. There were no significant differences in MONO and neutrophil counts, compared with controls. Methemoglobin concentrations were significantly increased on day 21 of treatment in the 50-mg kg(-1) group and on day 28 in the 25- and 50-mg kg(-1) groups. The subacute toxicity was characterized by lesions affecting the liver, kidneys, spleen, cerebellum, and hematopoietic system.

Topics: Administration, Oral; Alanine Transaminase; Alkaline Phosphatase; Aminophenols; Aniline Compounds; Animals; Aspartate Aminotransferases; Blood Cell Count; Body Weight; Cholesterol; Creatinine; Female; Male; Methemoglobin; Nitrobenzenes; Nitrophenols; Organ Size; Random Allocation; Rats; Rats, Sprague-Dawley; Serum Albumin

The degradation mechanism of p-nitrophenol (p-NP) exposed to 254 nm UV light was studied in the presence and the absence of oxygen respectively via both steady-state photolysis and time-resolved laser flash photolysis (LFP) experiments. It has been confirmed that p-NP can be photo-ionized to produce its radical cation (p-NP(+)) and hydrated electron (e(aq)(-)) with a quantum yield of 0.52. In neutral solution p-NP(+) will be quickly deprotonated to form its phenoxyl radical (p-NP) which will react with oxygen to promote the breakage of benzene ring of p-NP. The degradation efficiency of p-NP exposed to 254 nm UV is as low as commonly reported. However, oxygen could improve the photo-degradation efficiency, which is due to the reaction of oxygen with p-NP. The reaction between oxygen and p-NP has been experimentally confirmed both in LFP and in pulse radiolysis.

Topics: Nitrophenols; Photochemistry; Spectrophotometry, Ultraviolet; Ultraviolet Rays

The degradation kinetics of p-nitrophenol (p-NP) exposed to 254/185 nm UV light were studied in two modes, i.e., 254 nm UV light intensity enhanced mode and normal mode. It was observed that the extra 254 nm UV light source accelerated the degradation process both in the presence and the absence of oxygen. Considering that hydroxyl radical (*OH) is the dominant factor that causes the degradation of p-NP, the enhanced degradation that occurred in the presence of the extra light source was attributed to the synergistic effect between *OH attack and the primary reactions initiated by 254 nm UV light. The synergistic effect has been confirmed by 266 nm laser flash photolysis (LFP) experiments. It is demonstrated that the phenoxy radical generated from the photoionization of p-NP is capable of reacting with *OH. On the basis of these results, it should be noted that UV light could cause more severe damage to p-NP attacked by *OH in aqueous solution.

Topics: Hydroxyl Radical; Kinetics; Nitrophenols; Oxidants; Oxygen; Ultraviolet Rays

A 9.2-kb DNA fragment encoding the enzymes of a p-nitrophenol (PNP) catabolic pathway from Pseudomonas putida DLL-E4 was cloned and sequenced. Ten open reading frames (ORFs) were found and five ORFs were functionally verified. The pnpA and pnpC gene products were purified to homogeneity by Ni-NTA chromatography. PnpA is a flavin adenine dinucleotide-dependent single-component PNP 4-monooxygenase which converts p-nitrophenol to para-benzoquinone in the presence of NADH and FAD. PnpC is a 1,2,4-trihydroxybenzene (BT) 1,2-dioxygenase which converts BT to maleylacetate. The hydroquinone (HQ) dioxygenase (PnpC1C2) multi-component protein complex was expressed in Escherichia coli via plasmid pET-pnpC1C2 containing pnpC1 and pnpC2. This complex converts HQ to gamma-hydroxymuconic semialdehyde. pnpR is a lysR-type regulator gene. PnpR is a positive regulator involved in HQ degradation in pnp gene cluster. These results demonstrate that a pathway encoded by the pnp gene cluster is involved in degradation of HQ and BT in P. putida DLL-E4.

Topics: Biodegradation, Environmental; Catechols; Chromatography, High Pressure Liquid; Cloning, Molecular; Dioxygenases; Electrophoresis, Polyacrylamide Gel; Gene Deletion; Gene Expression Regulation, Bacterial; Genes, Bacterial; Mass Spectrometry; Molecular Sequence Data; Multigene Family; Nitrophenols; Pseudomonas putida; Sequence Analysis, DNA; Substrate Specificity; Transcription, Genetic

The objective of this research was to evaluate the treatment ofp-nitrophenol (PNP) as a sole organic carbon source using a sequencing batch reactor (SBR) with the addition of adsorbent. Two types of adsorbents, namely powdered activated carbon (PAC) and pyrolysed rice husk (PRH) were used in this study. Two identical SBRs, each with a working volume of 10 L, were operated with fill, react, settle, draw and idle periods in the ratio of 2:8:1:0.75:0.25 for a cycle time of 12 h. The results showed that, without the addition of adsorbent, increasing the influent PNP concentration to 200 mg/L resulted in the deterioration of chemical oxygen demand (COD) removal efficiency and PNP removal efficiency in the SBRs. Improvement in the performance of the SBR was observed with the addition of PAC. When the dosage of 1.0 g PAC/cycle was applied, COD removal of 95% and almost complete removal of PNP were achieved at the influent PNP concentration of 300 mg/L. The kinetic study showed that the rates of COD and PNP removal can be described by the first-order kinetics. The enhancement of performance in the PAC-supplemented SBR was postulated to be due to the initial adsorption of PNP by the freshly added and the bioregenerated PAC, thus reducing the inhibition on the microorganisms. The PRH was found to be ineffective because of its relatively low adsorption capacity for PNP, compared with that of PAC.

Topics: Adsorption; Biodegradation, Environmental; Biomass; Bioreactors; Carbon; Environmental Monitoring; Kinetics; Nitrophenols; Oryza; Oxygen; Powders; Time Factors; Waste Disposal, Fluid; Water Pollutants, Chemical

Many heme enzymes show remarkable versatility and atypical kinetics. The fungal extracellular enzyme chloroperoxidase (CPO) characterizes a variety of one and two electron redox reactions in the presence of hydroperoxides. A structural counterpart, found in mammalian microsomal cytochrome P450 (CYP), uses molecular oxygen plus NADPH for the oxidative metabolism (predominantly hydroxylation) of substrate in conjunction with a redox partner enzyme, cytochrome P450 reductase. In this study, we employ the two above-mentioned heme-thiolate proteins to probe the reaction kinetics and mechanism of heme enzymes. Hitherto, a substrate inhibition model based upon non-productive binding of substrate (two-site model) was used to account for the inhibition of reaction at higher substrate concentrations for the CYP reaction systems. Herein, the observation of substrate inhibition is shown for both peroxide and final substrate in CPO catalyzed peroxidations. Further, analogy is drawn in the "steady state kinetics" of CPO and CYP reaction systems. New experimental observations and analyses indicate that a scheme of competing reactions (involving primary product with enzyme or other reaction components/intermediates) is relevant in such complex reaction mixtures. The presence of non-selective reactive intermediate(s) affords alternate reaction routes at various substrate/product concentrations, thereby leading to a lowered detectable concentration of "the product of interest" in the reaction milieu. Occam's razor favors the new hypothesis. With the new hypothesis as foundation, a new biphasic treatment to analyze the kinetics is put forth. We also introduce a key concept of "substrate concentration at maximum observed rate". The new treatment affords a more acceptable fit for observable experimental kinetic data of heme redox enzymes.

Topics: Benzothiazoles; Benzylisoquinolines; Biocatalysis; Chloride Peroxidase; Cytochrome P-450 Enzyme System; Diclofenac; Heme; Hydroxylation; Kinetics; Models, Biological; Nitrophenols; Oxidation-Reduction; Peroxides; Picolines; Pyrogallol; Sulfonic Acids; Thiazoles

Significant improvement in biodegradation performance has been demonstrated arising from the reduction of cytotoxicity provided by the sequestering of 4-nitrophenol (4NP) within Hytrel polymer beads added to a two-phase partitioning bioreactor (TPPB) operating in sequencing batch reactor (SBR) mode. This reduced toxicity is particularly apparent as the feed substrate concentration is increased; in fact it was shown that at a feed of 1000 mg/L 4NP, the inhibitory effect of the substrate completely prevents degradation from occurring in a single-phase system, whereas at only a 5% polymer loading, rapid and compete biodegradation is achieved. Different polymer/aqueous phase ratios were used to detoxify varying feed concentrations, and degradation rates were enhanced through the use of increased polymer loadings. As demonstrated in oxygen uptake experiments, the addition of polymers also reduces the maximum demand for oxygen, relative to single-phase operation, and smoothes the demand for oxygen throughout the degradation process. Polymer regeneration has also been further characterized by quantifying the number of methanol washes required to achieve satisfactory 4NP residuals, and the addition of a small amount of cosolvent has been shown to dramatically increase the rate of bioregeneration to produce beads ready for reuse.

Topics: Bioreactors; Nitrophenols; Polymers

We report a novel system to analyze atmospheric nitrophenols (NPs). Rain or air sample extracts (1 mL) are preconcentrated on a narrow bore (2 mm) aliphatic anion exchanger. In the absence of strong retention of NPs exhibited by aromatic ion exchangers, retained NPs are eluted as a plug by injection of 100 microL of 0.1 M Na(2)SO(4) on to a short (2 x 50 mm) reverse phase C-18 column packed with 2.2 mum particles. The salt plug passes through the C-18 column unretained while the NPs are separated by an ammonium acetate buffered methanol-water eluent, compatible with mass spectrometry (MS). The eluted NPs are measured with a long path Teflon AF-based liquid core waveguide (0.15 x 1420 mm) illuminated by a 403 nm light emitting diode and detected by a monolithic photodiode-operational amplifier. The waveguide is rendered chemically active by suspending it over concentrated ammonia that permeates into the lumen. The NPs ionize to the yellow anion form (lambda(max) approximately 400 nm). The separation of 4-nitrophenol, 2,4-dinitrophenol, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenol, and 2-nitrophenol (these are the dominant NPs, typically in that order, in both rain and air of Houston and Arlington, TX, confirmed by tandem MS) takes just over 5 min with respective S/N = 3 limits of detection (LODs) of 60, 12, 30, 67, and 23 pg/mL compared to MS/MS LODs of 20, 49, 11, 20, and 210 pg/mL. Illustrative air and rain data are presented.

Topics: 2,4-Dinitrophenol; Air; Air Pollutants; Chromatography, Liquid; Cresols; Mass Spectrometry; Nitrophenols; Rain; Spectrophotometry

We present an analytical technique for determination of ligand-selector equilibrium binding constants. The method is based on the measurements of effective molecular diffusion coefficient of the ligand during Poiseuille flow through a long (approximately 25 m), thin (0.254 mm +/- 0.05 mm ID) capillary with and without the selector. The data are analyzed using the Taylor dispersion theory. Bovine Serum Albumin (BSA) and cyclodextrin (CD) were taken as model selectors. We have tested our method on the following selector-ligand complexes: BSA with warfarin, propranolol, noscapine, salicylic acid, and riboflavin, and cyclodextrin with 4-nitrophenol. The results are in good agreement with data from the literature and with our own results obtained within classical chromatography. This method works equally well for uncharged and charged compounds.

Topics: Adrenergic beta-Antagonists; Animals; Anticoagulants; Antitussive Agents; Cattle; Chromatography, High Pressure Liquid; Cyclodextrins; Diffusion; Ligands; Nitrophenols; Noscapine; Pharmaceutical Preparations; Photosensitizing Agents; Propranolol; Riboflavin; Salicylic Acid; Serum Albumin, Bovine; Warfarin

A three-phase hollow fiber liquid-phase microextraction method coupled with CE was developed and used for the determination of partition coefficients and analysis of selected nitrophenols in water samples. The selected nitrophenols were extracted from 14 mL of aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally backextracted into 40.0 microL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under the following optimum conditions: donor solution, 0.05 M H(3)PO(4), pH 3.0; organic solvent, 1-octanol; acceptor solution, 40 microL of 0.1 M NaOH, pH 12.0; agitation rate, 1050 rpm; extraction time, 15 min. Under optimized conditions, the calibration curves for the analytes were linear in the range of 0.05-0.30 mg/L with r(2)>0.9900 and LODs were in the range of 0.01-0.04 mg/L with RSDs of 1.25-2.32%. Excellent enrichment factors of up to 398-folds were obtained. It was found that the partition coefficient (K(a/d)) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol and 2,6-dinitrophenol and that the individual partition coefficients (K(org/d) and K(a/org)) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the analysis of water samples.

Topics: 1-Octanol; 2,4-Dinitrophenol; Chromatography, Liquid; Electrophoresis, Capillary; Limit of Detection; Nitrophenols; Solvents; Uncoupling Agents; Water

Liquid-phase decomposition of 4-nitrophenol (4-NP) and formation of hydrogen peroxide (H(2)O(2)) induced by contact glow discharge electrolysis (CGDE) were investigated. Experimental results showed that the decays of 4-NP and total organic carbon (TOC) obeyed the first-order and pseudo-first-order reaction kinetics, respectively. The major intermediate products were 4-nitrocatechol, hydroquinone, benzoquinone, hydroxyhydroquinone, organic acids and nitrite ion. The final products were carbon dioxide and nitrate ion. The initial formation rate of H(2)O(2) decreased linearly with increasing initial concentration of 4-NP. Addition of iron ions, especially ferric ion, to the solution significantly enhanced the 4-NP removal due to the additional hydroxyl radical formation through Fenton's reaction. A reaction pathway is proposed based on the degradation kinetics and the distribution of intermediate products.

Topics: Carbon Dioxide; Catechols; Electrolysis; Environmental Restoration and Remediation; Hydrogen Peroxide; Kinetics; Nitrates; Nitrophenols; Quinones; Water Pollutants, Chemical

Photocatalytic oxidation mediated by TiO(2) is a promising oxidation process for degradation of organic pollutants, but suffers from the decreased photocatalytic efficiency attributed to the recombination of photogenerated electrons and holes. Thus, a cost-effective supply of external electrons is an effective way to elevate the photocatalytic efficiency. Here we report a novel bioelectrochemical system to effectively reduce p-nitrophenol as a model organic pollutant with utilization of the energy derived from a microbial fuel cell. In such a system, there is a synergetic effect between the electrochemical and photocatalytic oxidation processes. Kinetic analysis shows that the system exhibits a more rapid p-nitrophenol degradation at a rate two times the sum of rates by the individual photocatalytic and electrochemical methods. The system performance is influenced by both external resistor and electrolyte concentration. Either a lower external resistor or a lower electrolyte concentration results in a higher p-nitrophenol degradation rate. This system has a potential for the effective degradation of refractory organic pollutants and provides a new way for utilization of the energy generated from conversion of organic wastes by microbial fuel cells.

Topics: Bioelectric Energy Sources; Electrochemical Techniques; Electrolytes; Nitrophenols; Photochemistry; Water Pollutants, Chemical

The electrochemical degradation of p-nitrophenol (PNP) under different conditions was investigated. The electrochemical behavior of PNP and its reduction product p-aminophenol (PAP) on stainless steel cathode and Ti/Pt anode through cyclic voltammetry were observed. Electrochemical degradation process was performed in an undivided cell and 92% PNP was removed corresponding to a 22% total organic carbon removal. A divided cell was also used and it was found that PNP degradation was mainly attributed to cathodic reduction, while anodic oxidation was responsible for PNP removal due to the reaction with hydroxyl radicals and surface oxide generated on the anode. The sequential electrolytic processes, reduction-oxidation and oxidation-reduction, were compared in the divided cell. In the case of reduction-oxidation process, the total organic carbon removal reached 40%, but PNP removal was the same with the undivided cell. A black deposit was found in the effluent and identified by Fourier transform infrared spectroscopy as a polymer of PAP produced by the 1,4-addition reaction of quinoneimine. Intermediates left in the solution such as hydroquinone, p-benzoquinone and PAP were determined by high performance liquid chromatography. Whereas, the oxidation-reduction process proved unsatisfying.

Topics: Electrochemical Techniques; Electrodes; Electrolysis; Environmental Pollutants; Molecular Structure; Nitrophenols; Time Factors

Sorption properties of an iron surfactant-modified pillared montmorillonite (Fe-SMPM) toward two organic pollutants, basic yellow 28 dye (BY28) and 4-nitrophenol (4-NP), were studied at different pH values in both single component and binary pollutant systems. The pseudo-first-order model fits well with the kinetic data obtained in single component studies and sorption capacities of both BY28 and 4-NP increased with the pH value. A sorption synergetic mechanism was observed in binary systems; 4-nitrophenol adsorption was enhanced by the presence of BY28 in the mixture and increased with dye concentrations. Isotherms were described using the Freundlich model in single component systems and the Sheindorf-Rebhun-Sheintuch (SRS) model, an extended Freundlich model, in binary mixtures systems. Hydrophobic interactions between the surfactant-modified pillared clay and the pollutants were suggested to explain the sorption mechanisms.

Topics: Adsorption; Aluminum Silicates; Azo Compounds; Bentonite; Clay; Coloring Agents; Iron; Kinetics; Molecular Structure; Nitrophenols; Organic Chemicals

The preparation of carbon nanotube (CNT)/PdO nanoparticles and graphene oxide (GO)/PdO nanoparticle hybrids via a general aqueous solution strategy is reported. The PdO nanoparticles are generated in situ on the CNTs and GO by a one-step "green" synthetic approach in aqueous Pd(NO(3))(2) solution under ambient conditions without adding any additional chemicals. The production of PdO is confirmed by energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. The morphologies of the resulting CNT/PdO and GO/PdO nanohybrids are characterized by transmission and/or scanning transmission electron microscopy. PdO nanoparticles with an average size of 2-3 nm in diameter are decorated evenly along the surfaces of CNTs and GO. This synthesis strategy is demonstrated to be compatible for 1) CNTs with different modifications, including pristine, oxidized, and polymer-functionalized CNTs; 2) different types of CNTs, including single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multiwalled carbon nanotubes (MWCNTs); and 3) different shapes of carbon materials, including tubular CNTs and planar GO. The as-prepared CNT/PdO and GO/PdO nanohybrids can be transformed into CNT/Pd and GO/Pd nanohybrids by reduction with NaBH(4), and can then be used as a heterogeneous catalyst in the catalytic reduction of 4-nitrophenol.

Topics: Carbon; Catalysis; Green Chemistry Technology; Nanoparticles; Nanotubes, Carbon; Nitrophenols; Palladium; Water

Diatoms (unicellular algae) form porous silica walls (frustule) with intricate, hierarchically organized three-dimensional (3D) structures with micro- to nanoscale dimensions. This paper presents the fabrication of self-supporting gold microstructures with complex 3D morphologies by using electroless gold deposition onto a diatom silica substrate, followed by the substrate removal by acid dissolution. It was demonstrated that gold diatom replicas with distinct micro- to nanoscale structures can be created by a simple and scalable process based on electroless gold deposition. Excellent catalytic properties (catalytic rate constant k = 23.5 +/- 1 x 10(-2) min(-1)) of prepared gold replica catalysts were confirmed for the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH(4) as the reductant. This synthetic approach is general and flexible, and it is envisaged that it can be applied for the preparation of a wide range of different metals (Pt, Pd, Ag, Ni, etc.) offering more efficient catalytic, optical, or magnetic properties.

Topics: Aminophenols; Borohydrides; Catalysis; Diatoms; Gold; Metal Nanoparticles; Nitrophenols; Oxidation-Reduction; Particle Size; Porosity; Silicon Dioxide; Surface Properties

Glycosyltransferases are involved in biosynthesis of both protein-bound and non-bound glycans that have multiple and important biological functions in all species. A variety of methods for assaying glycosyltransferase activity have been developed driven by the specific interests and type of information required by researchers. In this work, a novel colorimetric assay for the glycosyltransferase-catalyzed reaction was established. Compared with measuring the newly formed product, which might not exhibit visible absorption, the unreacted acceptor could be readily detected by measuring the visible absorption of the hydrolysis product. In the assay, 4-nitrophenyl-beta-D-glycoside (glycosyl-beta-pNP) is used as the glycosyl acceptor, which can be hydrolyzed by a special exoglycosidase to release the p-nitrophenol before glycosylation reactions. Absorbance change of the p-nitrophenolate corresponds to unreacted glycosyl acceptor that accompanied the glycosyl transfer. The assay is demonstrated to be useful in the initial characterization of recombinant glycosyltransferases for their kinetic parameters, optimal metal cofactor, and pH value. It provides a simple, sensitive, and quantitative method for assessing glycosyltransferase activity and is thus expected to have broad applications including automated high-throughput screening.

Topics: Bacterial Proteins; Colorimetry; Enzyme Assays; Glycosylation; Glycosyltransferases; Hydrolysis; Kinetics; Nitrophenols

In this paper, Mn-doped ZnS quantum dots (QDs) capped by a molecularly imprinted polymer (MIP) were synthesized. The results showed a high selectivity of the MIP-capped Mn-doped ZnS QDs toward the template molecule (4-nitrophenol) by QD fluorescence quenching. The application of MIP-capped Mn-doped ZnS QDs to the chemiluminescence (CL) system was also studied using a KIO(4)-H(2)O(2) system. This application combines the good selectivity of MIP with the high sensitivity of CL. The linear range of this CL system is from 0.1 to 40 microM, and the detection limit (DL) for 4-nitrophenol in the water can reach 76 nM. The method was also used in the real water samples, and the recoveries can fall in the range of 91-96%.

Topics: Fresh Water; Luminescent Measurements; Manganese; Molecular Imprinting; Nitrophenols; Polymers; Quantum Dots; Spectrophotometry, Ultraviolet; Sulfides; Zinc Compounds

An efficient Fe(2)O(3)-pillared rectorite (Fe-R) clay was successfully developed as a heterogeneous catalyst for photo-Fenton degradation of organic contaminants. X-ray diffraction analysis and high-resolution transmission electron microscope analysis clearly showed the existence of the Fe(2)O(3) nanoparticles in the Fe-R catalyst. The catalytic activity of the Fe-R catalyst was evaluated by the discoloration and chemical oxygen demand (COD) removal of an azo-dye rhodamine B (RhB, 100 mg/L) and a typical persistent organic pollutant 4-nitrophenol (4-NP, 50 mg/L) in the presence of hydrogen peroxide (H(2)O(2)) under visible light irradiation (lambda > 420 nm). It was found that the discoloration rate of the two contaminants was over 99.3%, and the COD removal rate of the two contaminants was over 87.0%. The Fe-R catalyst showed strong adsorbability for the RhB in the aqueous solution. Moreover, the Fe-R catalyst still showed good stability for the degradation of RhB after five recycles. Zeta potential and Fourier transform infrared spectroscopy were used to examine the photoreaction processes. Finally, a possible photocatalytic mechanism was proposed.

Topics: Aluminum Silicates; Catalysis; Color; Environmental Pollutants; Ferric Compounds; Hydrogen Peroxide; Iron; Light; Microscopy, Electron, Transmission; Minerals; Nitrophenols; Organic Chemicals; Oxygen; Rhodamines; Spectrophotometry, Ultraviolet; X-Ray Diffraction

In this paper, a comparison is provided between liquid-liquid and liquid-solid partitioning systems applied to the removal of high concentrations of 4-nitrophenol. The target compound is a typical representative of substituted phenols found in many industrial effluents while the biomass was a mixed culture operating as a conventional Sequencing Batch Reactor and acclimatized to 4-nitrophenol as the sole carbon source. Both two-phase systems showed enhanced performance relative to the conventional single phase bioreactor and may be suitable for industrial application. The best results were obtained with the polymer Hytrel which is characterized by higher partition capability in comparison to the immiscible liquid solvent (2-undecanone) and to the polymer Tone™. A model of the two systems was formulated and applied to evaluate the relative magnitudes of the reaction, mass transfer and diffusion characteristic times. Kinetic parameters for the Haldane equation, diffusivity and mass transfer coefficients have been evaluated by data fitting of batch tests for liquid-liquid and liquid-solid two phase systems. Finally, preliminary results showed the feasibility of polymer regeneration to facilitate polymer reuse by an extended contact time with the biomass.

Topics: Bacteria; Biomass; Bioreactors; Ketones; Kinetics; Nitrophenols; Solvents; Water

The mechanism of 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) adsorption on perfil-natural mineral taken from Bulgarian deposits, in a fixed-bed column was investigated. The single component experiments were conducted at constant initial sorbate concentration, volumetric flow rate, temperature and pH. The effect of adsorbent bed depth (Z 1, 2, 3, 6 cm) and sorbate nature on the adsorption capacity, mass transfer parameters and mechanisms was studied. The equilibrium behaviour of the system 4-NP-perfil was described by Langmuir, Freundlich and Redlich-Peterson models. The single resistance Thomas model, including Reynolds-Richards and Walter solutions, and the two-resistance Arnold model were applied for mathematical modeling of the experimental data. The comparative analyses indicated that external mass transfer was the rate limiting mechanism during the initial adsorption stages, while intraparticle diffusion was dominant in the middle and high concentration ranges. The effect of axial dispersion on the dynamics of adsorption was evaluated.

Topics: 2,4-Dinitrophenol; Adsorption; Kinetics; Models, Theoretical; Nitrophenols; Solutions; Water Pollutants, Chemical; Water Purification

p-Nitrophenol (PNP) is a difficultly decomposed organic pollutant under solar light in the absence of strong oxidants. This study shows that under artificial solar light PNP can be effectively degraded by a Cu(2)O/TiO(2) p-n junction network which is fabricated by anodizing Cu(0) particles-loaded TiO(2) nanotubes (NTs). The network is composed of p-type Cu(2)O nanowires on the top surface and Cu(2)O nanoparticles on the inner walls of the n-type TiO(2) NT arrays. The Cu(2)O/TiO(2) network shows much higher degradation rate (1.97 μg/min cm(2)) than the unmodified TiO(2) NTs (0.85 μg/min cm(2)). The enhanced photocatalytic acitivity can be attributed to the extended absorption in the visible resulting from the Cu(2)O nanowire networks and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Cu(2)O/TiO(2) p-n junction interface.

Topics: Catalysis; Chromatography, High Pressure Liquid; Copper; Environmental Pollutants; Gas Chromatography-Mass Spectrometry; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanowires; Nitrophenols; Photochemistry; Spectrophotometry, Ultraviolet; Titanium

A simple, green, one-pot synthesis of gold nanoparticles was achieved through the reaction of an aqueous mixture of potassium tetrachloroaurate(III) and the macrocycle cucurbit[7]uril in the presence of sodium hydroxide at room temperature without introducing any kind of traditional reducing agents and/or external energy. The as-prepared gold nanoparticles showed catalytic activity for the reduction reaction of 4-nitrophenol in the presence of NaBH(4), which has been established by visual inspection and UV/Vis spectroscopy. This report is the first for the preparation of gold nanoparticles using cucurbit[7]uril in aqueous media through chemical reduction without employing conventional reducing agents and/or external energy.

Topics: Borohydrides; Catalysis; Gold; Macrocyclic Compounds; Metal Nanoparticles; Nitrophenols; Reducing Agents; Silver; Sodium Hydroxide; Spectrophotometry, Ultraviolet; Temperature

The open reading frame PA3859 of Pseudomonas aeruginosa encodes an intracellular carboxylesterase belonging to a group of microbial enzymes (EC 3.1.1.1) that catalyze the hydrolysis of aliphatic and aromatic esters with a broad substrate specificity. With few exceptions, for this class of enzymes, belonging to the α/β-hydrolase fold superfamily, very little information is available regarding their biochemical activity and in vivo function. The X-ray crystal structure of recombinant PA3859 has been determined for two crystal forms (space groups P2(1) and P2(1)2(1)2). The kinetic properties of the enzyme were studied using p-nitrophenyl esters as substrates and data fitted to a surface dilution mixed micelle kinetic model. Enzymatic assays and computational docking simulations, pinpointed the enzyme's preference for esters of palmitic and/or stearic acids and provided insights into the enzyme-substrate favorable binding modes.

Topics: Algorithms; Bacterial Proteins; Biocatalysis; Carboxylesterase; Catalytic Domain; Computer Simulation; Crystallography, X-Ray; Fatty Acids; Hydrolysis; Kinetics; Models, Molecular; Nitrophenols; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Pseudomonas aeruginosa; Substrate Specificity

Sorption properties of surface modified activated carbon (AC) with p-nitrophenol (PNP) and methylene blue (MB) in aqueous solution were investigated. The calculated surface areas for AC and surface modified AC were compared using nitrogen sorption and a dye-based method. The surface areas of AC and the surface modified AC with glutaraldehyde (AC-β-CD) (1:10:10⁹) and 1,4-phenylene diisocyanate (ACPDICD) measured by nitrogen sorption were 1,269 m²/g, 103 m²/g, and 95 m²/g, respectively (Langmuir model) and 956 m²/g, 74 m²/g, and 69 m²/g (BET model), respectively. However, the calculated surface areas for the dye-based method (PNP; pH 6.00) for AC, AC-β-CD(1:10:10⁹), and ACPDICD was 1,035 m²/g, 814 m²/g, and 76 m²/g (Langmuir model), respectively and 1,491 m²/g, 1,669 m²/g, and 92 m²/g (BET model), respectively. The corresponding surface areas for the dye-based method (MB; pH 8.40) for AC-β-CD(1:10:10⁹) and ACPDICD was 263 m²/g and 171 m²/g (Langmuir model), respectively and 1019 m²/g and 182 m²/g (BET model), respectively. The sorption capacity (Q(m)) and binding affinity characteristics [K(F)(L/g), K(L)(g/mol), and K(BET)(L/g)] were estimated at room temperature at equilibrium conditions using several sorption isotherm models.

Topics: Adsorption; beta-Cyclodextrins; Charcoal; Methylene Blue; Nitrophenols

Fe(III) supported on resin (Fe(III)-resin) as an effective catalyst for peroxide oxidation was prepared and applied for the degradation of p-nitrophenol (PNP). Catalytic wet peroxide oxidation (CWPO) experiments with hydrogen peroxide as oxidant were performed in a batch rector with p-nitrophenol as the model pollutant. Under given conditions (PNP concentration 500 mg/L, H(2)O(2) 0.1 M, 80°C, resin dosage 0.6% g/mL), p-nitrophenol was almost completely removed, corresponding to an 84% of COD removal. It was found that the reaction temperature, oxidant concentration. and initial pH of solution significantly affected both p-nitrophenol conversion and COD removal by oxidation. It can be inferred from the experiments that Fe(III) supported on resin was an effective catalyst in the mineralization of p-nitrophenol. In an acidic environment of oxidation, the leaching test showed that there was only a slight leaching effect on the activity of catalytic oxidation. It was also confirmed by the aging test of catalysts in the oxidation.

Topics: Biological Oxygen Demand Analysis; Catalysis; Cation Exchange Resins; Chlorides; Ferric Compounds; Hydrogen Peroxide; Hydrogen-Ion Concentration; Microscopy, Electron, Scanning; Nitrophenols; Oxidation-Reduction; Surface Properties; Water Pollutants, Chemical; Water Purification

A laboratory scale anaerobic migrating blanket reactor (AMBR) was operated at different HRTs (1-10.38 days) in order to determine the para-nitrophenol (p-NP) and COD removal kinetic constants. The reactor was fed with 40 mg L(-1)p-NP and 3000 mg L(-1) glucose-COD. Modified Stover-Kincannon and Grau second-order kinetic models were applied to the experimental data. The predicted p-NP and COD concentrations were calculated using the kinetic constants. It was found that these data were in better agreement with the observed ones in the modified Stover-Kincannon compared to Grau second-order model. The kinetic constants calculated according to Stover-Kincannon model are as follows: the saturation value constant (K(B)) and maximum utilization rate constants (R(max)) were found as 31.55 g CODL(-1)day(-1), 29.49 g CODL(-1)day(-1) for COD removal and 0.428 g p-NPL(-1)day(-1), 0.407 g p-NPL(-1)day(-1) for p-NP removal, respectively (R(2)=1). The values of (a) and (b) were found to be 0.096 day and 1.071 (dimensionless) with high correlation coefficients of R(2)=0.85 for COD removal. Kinetic constants for specific gas production rate were evaluated using modified Stover-Kincannon, Van der Meer and Heerrtjes and Chen and Hasminoto models. It was shown that Stover-Kincannon model is more appropriate for calculating the effluent COD, p-NP concentrations in AMBR compared to the other models. The maximum specific biogas production rate, G(max), and proportionality constant, G(B), were found to be 1666.7 mL L(-1) day(-1) and 2.83 (dimensionless), respectively in modified Stover-Kincannon gas model. The bacteria had low Haldane inhibition constants (K(ID)=14 and 23 mg L(-1)) for p-NP concentrations higher than 40 mg L(-1) while the half velocity constant (K(s)) increased from 10 to 60 and 118 mg L(-1) with increasing p-NP concentrations from 40 to 85 and 125 mg L(-1).

Topics: Anaerobiosis; Biodegradation, Environmental; Biomass; Bioreactors; Equipment Design; Gases; Hydrogen-Ion Concentration; Industrial Waste; Kinetics; Models, Theoretical; Nitrophenols; Oxygen; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

Rhodococcus sp. CN6, isolated from a pesticide industry's effluent-sediment, was able to completely degrade and utilize 100mg/L p-nitrophenol (PNP) as the sole carbon, nitrogen and energy sources for growth in the minimal salt media (MSM) within 12h. To study the applicability of the strain for bioremediation of PNP, its degradation potential was examined in the presence of different supplemented carbon and nitrogen sources in MSM with 100mg/L PNP. Dextrin was experienced as the best supplemented carbon source used by the strain CN6 during degrading PNP. Addition of ammonium nitrate could also increase the PNP degradation rate. Preliminary studies on the surface characters of Rhodococcus sp. CN6 were undertaken for the sake of exploring its high efficiency on the degradation of PNP. Microbial adherence to hydrocarbons (MATH) assays illuminated that the strain CN6 was of higher hydrophobicity while grown on higher concentration of PNP. The results suggested that the strain CN6 could be used as a potential and efficient PNP degrader for the bioremediation of contaminated sites.

Topics: Biodegradation, Environmental; Dextrins; Hydrophobic and Hydrophilic Interactions; Kinetics; Nitrates; Nitrophenols; Rhodococcus

The behavior of a modified carbon paste electrode (CPE) for para-nitrophenol detection by cyclic and square wave voltammetry (SWV) was studied. The electrode was built by incorporating the hydroxyapatite (HAP) to carbon paste. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the voltammetric quantification. During the preconcentration step, para-nitrophenol was adsorbed onto hydroxyapatite surface. The influence of various experimental parameters on the HAP-CPE response was investigated (i.e. pH, carbon paste composition, accumulation time). Under the optimized conditions, the reduction peak shows that the peak height was found to be directly proportional to the para-nitrophenol concentration in the range comprised between 2x10(-7) mol L(-1) and 1x10(-4) mol L(-1). With this, it was possible to determine detection limit (DL), which resulted in 8x10(-9) mol L(-1) for peak 1. The proposed electrode (HAP-CPE) presented good repeatability, evaluated in term of relative standard deviation (R.S.D.=2.87%) for n=7 and was applied for para-nitrophenol determination in water samples. The average recovery for these samples was 86.2%.

Topics: Apatites; Calibration; Carbon; Electrochemical Techniques; Electrodes; Hydrogen-Ion Concentration; Nitrophenols; Rivers; Time Factors

Tissue iron overload constitutes a major health problem for people who require regular blood transfusions, such as those with beta-thalassemia major. Deferiprone is a hydroxypyridinone iron chelator used therapeutically to remove this excess iron and prevent tissue damage. Deferiprone is metabolized by UDP-glucuronosyltransferases (UGTs) into deferiprone 3-O-glucuronide (DG), but a systematic evaluation of the contribution of individual human UGTs and the impact of genetic variations of UGTs have not been conducted. Sixteen human UGT1A and UGT2B were studied for deferiprone glucuronidation, and their clearances were compared in human tissue samples. DG was measured by liquid chromatography coupled with mass spectrometry. DG was primarily produced in vitro by UGT1A6, and a second glucuronide metabolite was discovered. UGT1A6, as well as liver and kidney human microsomes, had similar kinetic profiles and clearance (Cl(int) = 1.4-3.0 mul/min/mg), but clearance by intestinal microsomes was much lower (0.04 mul/min/mg). Binding of deferiprone to microsomal preparations was not significant. Genetic variants of UGT1A6 had K(m) values similar to the reference protein (UGT1A6*1), but their V(max) values were reduced by 25 to 70%. The UGT1A6 splice variant isoform 2, detected in the liver and kidney, had no transferase activity for deferiprone. When UGT1A6_i2 was coexpressed with the classic UGT1A6_i1 isoform, velocity was reduced for deferiprone but remained similar for 4-nitrophenol or serotonin glucuronidation. In conclusion, deferiprone glucuronidation seems to depend almost totally on UGT1A6, especially in the liver. Genetic variations and differences in the expression of splice variants represent a potential source of variation in deferiprone metabolism.

Topics: Cells, Cultured; Deferiprone; Genetic Variation; Glucuronides; Glucuronosyltransferase; Humans; Kinetics; Microsomes; Nitrophenols; Pyridones; Recombinant Proteins; Serotonin; Substrate Specificity

A novel magnetically recoverable Au nanocatalyst was fabricated by the simple adsorption-reduction of Au(III) ions on chitosan-coated iron oxide magnetic nanocarrier. Au nanoparticles with a mean diameter of 3.14 nm were well loaded on the surface of magnetic nanocarrier because chitosan layer provided an effective driving force in the formation and stabilization of Au nanoparticles. The resultant magnetically recoverable Au nanocatalyst exhibited excellent catalytic activity to the reduction of 4-nitrophenol (4-NP) with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increasing the amount of Au nanocatalyst, decreasing the initial 4-NP concentration, and increasing the temperature. Also, the kinetic data suggested that this catalytic reaction was diffusion controlled owing to the presence of chitosan layer. In addition, catalyst reuse showed no trace of deactivation or poisoning during the catalytic and separation processes, revealing the stable nature and good catalytic ability of this nanocatalyst.

Topics: Borohydrides; Catalysis; Chitosan; Conservation of Natural Resources; Gold; Kinetics; Magnetics; Metal Nanoparticles; Nitrophenols; Reducing Agents

This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (lambda>400 nm), compared with TiO2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.

Topics: Catalysis; Electrochemical Techniques; Electrodes; Light; Nanotubes; Nitrophenols; Photolysis; Salicylic Acid; Titanium

The adsorption and degradation of 4,6-o-dinitrocresol (DNOC) and p-nitrophenol (PNP) in SWy-2 montmorillonite clay slurry were investigated. The pH and type of cation of the slurry were varied. Results showed that adsorption of DNOC and PNP increased at lower pH values, and when pH < pKa(4.4) of DNOC, DNOC was almost completely adsorbed on the clay under given experimental conditions. The specific cation also had a significant effect on adsorption, which was dramatically enhanced in the presence of K+ and NH4+, compared with the presence of Na+ or Ca2+. Anodic Fenton treatment (AFT) degradation of DNOC and PNP in the clay slurry was studied, and it was found that DNOC degradation rates were greatly affected by the initial pH and the types of electrolytes. Due to the higher adsorption, the degradation rate substantially decreased in the clay slurry system in the presence of K+ and low pH, with a large amount of DNOC residue remaining after 60 min treatment. AFT degradation of PNP was completed within 30 min treatment. Based on LC-MS data, a DNOC degradation pathway was proposed. Overall, the results showed the inhibition effect of adsorption on the degradation of nitroaromatic compounds in montmorillonite clay slurry by AFT, providing important implications for water and soil remediation.

Topics: Adsorption; Aluminum Silicates; Bentonite; Chromatography, Liquid; Clay; Dinitrocresols; Electrodes; Electrolytes; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Mass Spectrometry; Nitrogen; Nitrophenols; Sewage; Temperature; Time Factors; X-Ray Diffraction

A novel in vitro human reconstructed skin micronucleus (RSMN) assay has been developed using the EpiDerm 3D human skin model [R. D. Curren, G. C. Mun, D. P. Gibson, and M. J. Aardema, Development of a method for assessing micronucleus induction in a 3D human skin model EpiDerm, Mutat. Res. 607 (2006) 192-204]. The RSMN assay has potential use in genotoxicity assessments as a replacement for in vivo genotoxicity assays that will be banned starting in 2009 according to the EU 7th Amendment to the Cosmetics Directive. Utilizing EpiDerm tissues reconstructed with cells from four different donors, intralaboratory and interlaboratory reproducibility of the RSMN assay were examined. Seven chemicals were evaluated in three laboratories using a standard protocol. Each chemical was evaluated in at least two laboratories and in EpiDerm tissues from at least two different donors. Three model genotoxins, mitomycin C (MMC), vinblastine sulfate (VB) and methyl methanesulfonate (MMS) induced significant, dose-related increases in cytotoxicity and MN induction in EpiDerm tissues. Conversely, four dermal non-carcinogens, 4-nitrophenol (4-NP), trichloroethylene (TCE), 2-ethyl-1,3-hexanediol (EHD), and 1,2-epoxydodecane (EDD) were negative in the RSMN assay. Results between tissues reconstructed from different donors were comparable. These results indicate the RSMN assay using the EpiDerm 3D human skin model is a promising new in vitro genotoxicity assay that allows evaluation of chromosome damage following "in vivo-like" dermal exposures.

Topics: Animal Testing Alternatives; Epidermis; Glycols; Humans; Laboratories; Methyl Methanesulfonate; Micronucleus Tests; Mitomycin; Mutagens; Nitrophenols; Reproducibility of Results; Skin; Skin Irritancy Tests; Tissue Engineering; Trichloroethylene; Vinblastine

In order to obtain an acidity scale in room-temperature ionic liquid solutions, the protonation equilibrium of sodium p-nitrophenolate in [bm(2)im][NTf(2)] and in [bmpyrr][NTf(2)], at 298 K, has been studied by means of spectrophotometric titration. Carboxylic acids differing in both structure and in water solution strength have been used. Data collected indicate that in the analyzed ionic liquid solutions carboxylic acids are less dissociated than in water solution. Furthermore, by virtue of a mutual interaction, the studied equilibrium seems to be affected by both the nature of the ionic liquids and the carboxylic acids.

Topics: Carboxylic Acids; Hydrogen-Ion Concentration; Ionic Liquids; Molecular Structure; Nitrophenols; Solutions; Water

We report here, for the first time, a single-step method for the synthesis of 4-nitrophenyl ferulate (4NPF), a spectrophotometric substrate for the assay of feruloyl esterases by dehydrative coupling of ferulic acid and 4-nitrophenol.

Topics: Carboxylic Ester Hydrolases; Coumaric Acids; Nitro Compounds; Nitrophenols

The polymeric adsorbents were synthesized from 2-dimethylaminoethyl methacrylate (DMA) and [2-(methacryloyloxy)ethyl]dimethylhexadecylammonium bromide (DMAC(16)) monomers in the presence of ethylene glycol dimethacrylate (EDMA) cross-linking monomer using suspension polymerization technique and their adsorption efficiencies in the removal of p-nitrophenol from aqueous solutions were investigated. DMAC(16) monomer was prepared by means of modification of DMA monomer with 1-bromohexadecane. Adsorption experiments were carried out in a batch system and the experimental parameters were evaluated with respect to pH, agitation time, temperature and initial p-nitrophenol concentration. It was observed that the adsorbent poly[2-(methacryloyloxy)ethyl]dimethylhexadecylammonium bromide (p-DMAC(16)) prepared from DMAC(16) monomer was more effective in the removal of p-nitrophenol than the adsorbent poly(2-dimethylaminoethyl methacrylate) (p-DMA) prepared from DMA monomer. The effective pH ranges for the adsorption of p-nitrophenol onto p-DMAC(16) and p-DMA were 2-12 and 3-9, respectively. Langmuir and Freundlich adsorption models were used to describe the isotherms and find isotherm constants. The Langmuir model was well agreed with experimental data for both adsorbents. The pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models were used to understand the mechanism of the adsorption process and it fitted very well the pseudo-second-order kinetic model for each adsorbent. Thermodynamic parameters such as activation energy and changes of free energy, enthalpy, and entropy were also evaluated for the adsorption of p-nitrophenol onto each adsorbent. Additionally, reusability of the adsorbents was investigated and the results showed that both adsorbents can be employed many times without a significant loss in their adsorption capacities for the removal of p-nitrophenol from water.

Topics: Adsorption; Hydrogen-Ion Concentration; Kinetics; Methacrylates; Nitrophenols; Solutions; Surface Properties; Thermodynamics; Time Factors; Water

Pseudomonas sp. strain WBC-3 utilizes para-nitrophenol (PNP) as a sole source of carbon, nitrogen, and energy. In order to identify the genes involved in this utilization, we cloned and sequenced a 12.7-kb fragment containing a conserved region of NAD(P)H:quinone oxidoreductase genes. Of the products of the 13 open reading frames deduced from this fragment, PnpA shares 24% identity to the large component of a 3-hydroxyphenylacetate hydroxylase from Pseudomonas putida U and PnpB is 58% identical to an NAD(P)H:quinone oxidoreductase from Escherichia coli. Both PnpA and PnpB were purified to homogeneity as His-tagged proteins, and they were considered to be a monomer and a dimer, respectively, as determined by gel filtration. PnpA is a flavin adenine dinucleotide-dependent single-component PNP 4-monooxygenase that converts PNP to para-benzoquinone in the presence of NADPH. PnpB is a flavin mononucleotide-and NADPH-dependent p-benzoquinone reductase that catalyzes the reduction of p-benzoquinone to hydroquinone. PnpB could enhance PnpA activity, and genetic analyses indicated that both pnpA and pnpB play essential roles in PNP mineralization in strain WBC-3. Furthermore, the pnpCDEF gene cluster next to pnpAB shares significant similarities with and has the same organization as a gene cluster responsible for hydroquinone degradation (hapCDEF) in Pseudomonas fluorescens ACB (M. J. Moonen, N. M. Kamerbeek, A. H. Westphal, S. A. Boeren, D. B. Janssen, M. W. Fraaije, and W. J. van Berkel, J. Bacteriol. 190:5190-5198, 2008), suggesting that the genes involved in PNP degradation are physically linked.

Topics: Benzoquinones; Chromatography, Affinity; Chromatography, Gel; Cloning, Molecular; Coenzymes; Dimerization; DNA, Bacterial; Gene Order; Genes, Bacterial; Hydroquinones; Molecular Sequence Data; Multigene Family; NADP; Nitrophenols; Oxygenases; Pseudomonas; Quinone Reductases; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Synteny

Pseudomonas sp. strain WBC-3 utilizes methyl parathion (O,O-dimethyl O-p-nitrophenol phosphorothioate) or para-nitrophenol as the sole source of carbon, nitrogen and energy. A gene encoding methyl parathion hydrolase (MPH) had been characterized previously and found to be located on a typical class I composite transposon that comprised IS6100 (Tnmph). In this study, the transposability of this transposon was confirmed by transposition assays in two distinct mating-out systems. Tnmph was demonstrated to transpose efficiently in a random manner in Pseudomonas putida PaW340 by Southern blot and in Ralstonia sp. U2 by sequence analysis of the Tnmph insertion sites, both exhibiting MPH activity. The linkage of the mph-like gene with IS6100, together with the transposability of Tnmph, as well as its capability to transpose in other phylogenetically divergent bacterial species, suggest that Tnmph may contribute to the wide distribution of mph-like genes and the adaptation of bacteria to organophosphorus compounds.

Topics: Blotting, Southern; Conjugation, Genetic; DNA Transposable Elements; DNA, Bacterial; Gene Transfer, Horizontal; Methyl Parathion; Nitrophenols; Phosphoric Monoester Hydrolases; Pseudomonas; Recombination, Genetic; Sequence Analysis, DNA

Oxidative degradation of p-nitrophenol (PNP) was investigated with NaNO(2) as the catalyst and dioxygen as the oxidizing agent in the presence of trichlorophenol (TCP). Although degradation of PNP alone was proved to be inefficient toward the NaNO(2)-mediated oxidative degradation system, when PNP in combination with TCP was used as the substrate, NaNO(2) showed relatively high catalytic activity for eradicating both PNP and TCP with molecular oxygen. Reaction conditions to the degradation system, e.g., temperatures, reaction time, pH, NaNO(2) and TCP concentrations were optimized. PNP could be highly efficiently degraded in the NaNO(2)/TCP/O(2) system (more than 99% removal for PNP) and the TOC removal of the mixture of PNP and TCP could reach 71% at 150 degrees C, 0.5 MPa oxygen pressure. Degradation products were determined, and 93% carbon atom was clarified. A plausible overall mechanism for the formation of active species is described, in which peroxylnitrite was believed to be a dominating active intermediate being responsible for destroying the substrates, PNP and TCP. The novel NaNO(2)-based concurrent oxidation system for PNP and TCP provides a potential application in treatment of multi-component industrial effluents.

Topics: Catalysis; Chlorophenols; Hydrogen-Ion Concentration; Models, Chemical; Molecular Structure; Nitrophenols; Oxygen; Sodium Nitrite

Kinetics of p-nitrophenol (PNP) adsorption onto layered double oxides (LDO) during its hydration into layered double hydroxides (LDH) was studied. Results indicate that the adsorption of PNP onto LDO is a spontaneous endothermic process. The adsorption isotherms correlate well with the Freundlich type model. Results suggest that the adsorption of PNP onto LDO is an entropy-increasing process, and it appears to be in agreement with pseudo-second-order kinetics. Intra-particle diffusion was found to take part in the adsorption processes, and it might be the primary rate-limiting step for the sorbing capacity of LDO to PNP. Results from X-ray diffraction and Fourier transform infrared indicate that PNP molecules are probably taken into the interlayer of the structure during the hydration of LDO into the LDH. Activated carbon was used as a benchmark material in evaluating the sorbing capacity of LDO to PNP. The sorbing capacity of LDO to PNP (32 mg PNP/g LDO) was well below activated carbon (659 mg PNP/g carbon); however, the sorbing process of LDO to PNP is also a unique synthetic process for LDH, which has been used in removing specific anionic species, such as bioagents and pharmaceutical intermediates from waters.

Topics: Adsorption; Kinetics; Microscopy, Electron, Transmission; Models, Chemical; Nitrophenols; Oxides; Thermodynamics; Time Factors

A series of anion-cation modified palygorskites were prepared by microwave irradiation, and characterized with FT-IR. Compared with natural palygorskite, the p-nitrophenol sorption capacity with anion-cation modified palygorskite was significantly improved. The maximum sorption capacity (137.74 mg g(-1)) was obtained with the mass ratio 1:4 and 3:10 of hexadecyltrimethylammonium bromide to sodium dodecyl sulfate and the surfactant to palygorskite of at 313 K. The sorption equilibrium was in accordance with the Langmuir isothermal sorption equations. Thermodynamic function calculated showed that the sorption was a spontaneous and exothermic process. Free energy of the sorption increased with the increase of the temperature. The sorption of p-nitrophenol followed the pseudo-second-order process (sorption rate constant: 0.00453 mg(-1)min(-1)).

Topics: Adsorption; Anions; Cations; Cetrimonium; Cetrimonium Compounds; Kinetics; Magnesium Compounds; Nitrophenols; Silicon Compounds; Sodium Dodecyl Sulfate; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Surface-Active Agents; Thermodynamics

The bioregeneration efficiencies of powdered activated carbon (PAC) and pyrolyzed rice husk loaded with phenol and p-nitrophenol were quantified by oxygen uptake measurements using the respirometry technique in two approaches: (i) simultaneous adsorption and biodegradation and (ii) sequential adsorption and biodegradation. It was found that the applicability of the simultaneous adsorption and biodegradation approach was constrained by the requirement of adsorption preceding biodegradation in order to determine the initial adsorbent loading accurately. The sequential adsorption and biodegradation approach provides a good estimate of the upper limit of the bioregeneration efficiency for the loaded adsorbent in the simultaneous adsorption and biodegradation processes. The results showed that the mean bioregeneration efficiencies for PAC loaded with phenol and p-nitrophenol, respectively, obtained using the two approaches were in good agreement.

Topics: Adsorption; Biodegradation, Environmental; Charcoal; Nitrophenols; Oryza; Oxygen

The spectral shifts in the visible electronic absorption spectra of three amino-nitro-benzene derivatives in different solvents were correlated with the macroscopic parameters (refractive index and electric permittivity) of the solvents. The wavenumbers in the maximum of the visible charge transfer absorption band of o-nitro-aniline, 4-amino-3-nitrophenol and 3-amino-4-nitrophenol depend linearly on the Baur-Nicol function of electric permittivity. This dependence allows to estimate the electric polarizability in the electronic excited states if the electric polarizability in the ground state of the spectrally active molecule is determined by other procedures, such as by quanto-mechanical calculations.

Topics: Aniline Compounds; Benzene Derivatives; Coloring Agents; Humans; Molecular Structure; Nitrophenols; Solvents; Spectrum Analysis

This study investigated the molecular mechanism by which Bax inhibitor 1 (BI1) abrogates the accumulation of reactive oxygen species (ROS) in the endoplasmic reticulum (ER). Electron uncoupling between NADPH-dependent cytochrome P450 reductase (NPR) and cytochrome P450 2E1 (P450 2E1) is a major source of ROS on the ER membrane. ER stress produced ROS accumulation and lipid peroxidation of the ER membrane, but BI1 reduced this accumulation. Under ER stress, expression of P450 2E1 in control cells was upregulated more than in BI1-overexpressing cells. In control cells, inhibiting P450 2E1 through chemical or siRNA approaches suppressed ROS accumulation, ER membrane lipid peroxidation and the resultant cell death after ER stress. However, it had little effect in BI1-overexpressing cells. In addition, BI1 knock down also increased ROS accumulation and expression of P450 2E1. In a reconstituted phospholipid membrane containing purified BI1, NPR and P450 2E1, BI1 dose-dependently decreased the production of ROS. BI1 bound to NPR with higher affinity than P450 2E1. Furthermore, BI1 overexpression reduced the interaction of NPR and P450 2E1, and decreased the catalytic activity of P450 2E1, suggesting that the flow of electrons from NPR to P450 2E1 can be modulated by BI1. In summary, BI1 reduces the accumulation of ROS and the resultant cell death through regulating P450 2E1.

Topics: Apoptosis Regulatory Proteins; Cell Death; Cell Line, Tumor; Chlorzoxazone; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Endoplasmic Reticulum; Enzyme Inhibitors; Humans; Hydroxylation; Kinetics; Lipid Peroxidation; Membrane Proteins; NADPH-Ferrihemoprotein Reductase; Nitrophenols; Oxidative Stress; Reactive Oxygen Species; RNA Interference; RNA, Small Interfering; Substrate Specificity; Transfection

Removal and recovery of aromatic pollutants from water by solid adsorbents have been of considerable concern recently. Relatively limited information is available on desorption kinetics and isotherms aspects. In the present study, batch desorption experiments of loaded 4-nitrophenol on a hyper-cross-linked polymer resin NDA-701, a polymeric adsorbent Amberlite XAD-4 and a granular activated carbon GAC-1 were carried out to study the effects of reaction temperature and pore-size distribution of adsorbents. 4-Nitrophenol desorbed rapidly in the early stages, followed by a much slower release, which was described well by a first-order two-component four-parameter model. The adsorption and desorption equilibrium isotherms were well described by Freundlich equation and the apparent adsorption-desorption hysteresis (hysteresis index) for 4-nitrophenol followed an order as: NDA-701 approximately XAD-4<

Topics: Adsorption; Kinetics; Nitrophenols; Polymers; Thermodynamics

From blue to red: While four pi-conjugated nitrophenolates absorb within a relatively narrow region in solution, they cover the entire visible spectrum when isolated in vacuo [picture: see text]. The work combines gas- and solution-phase spectroscopy and provides the first benchmark of theoretical excitation energies for nitrophenolates.

Topics: Gases; Hydroxybenzoates; Nitrophenols; Solutions; Spectrum Analysis; Vacuum

We report the crystal structure of mouse sulfotransferase, mSULT1D1, complexed with donor substrate 3'-phosphoadenosine 5'-phosphosulfate and accepter substrate p-nitrophenol. The structure is the first report of the native Michaelis complex of sulfotransferase. In the structure, three proposed catalytic residues (Lys48, Lys106, and His108) were in proper positions for engaging in the sulfuryl transfer reaction. The data strongly support that the sulfuryl transfer reaction proceeds through an S(N)2-like in-line displacement mechanism.

Topics: Animals; Catalysis; Catalytic Domain; Crystallography, X-Ray; Histidine; Lysine; Mice; Nitrophenols; Phosphoadenosine Phosphosulfate; Protein Conformation; Sulfotransferases

Human exposure to methyl parathion can be assessed by measuring the concentration of its metabolite paranitrophenol (PNP) in urine. Our biologic monitoring study in Chiang Mai, Thailand, measured PNP and dialkylphosphate metabolites (i.e., dimethylphosphate [DMP] and dimethylthiophosphate [DMTP]) of methyl parathion in urine samples collected from 136 farmers (age 20 to 65 years) and 306 school children (age 10 to 15 years) in 2006. Participants came from two topographically different areas: one was colder and mountainous, whereas the other was alluvial with climate fluctuations depending on the monsoon season. Both children and farmers were recruited from each area. Despite methyl parathion's prohibited use in agriculture in 2004, we detected PNP in >90% of all samples analyzed. We applied a nonparametric correlation test (PNP vs. DMP and DMTP) to determine whether the PNP found in most of the samples tested resulted from exposures to methyl parathion. DMP (Spearman's rho = 0.601 [p = 0.001] for farmers and Spearman's rho = 0.263 [p <0.001] for children) and DMTP (Spearman's rho = 0.296 [p = 0.003] for farmers and Spearman's rho = 0.304 [p<0.001] for children) were positively correlated with PNP, suggesting a common source for the three analytes, presumably methyl parathion or related environmental degradates. Although we found a modest correlation between the metabolites, our findings suggest that despite the prohibition, at least a portion (approximately 25% to 60%) of the PNP detected among farmers and children in Thailand may be attributed to exposure from continued methyl parathion use.

Topics: Adolescent; Adult; Aged; Agriculture; Child; Cross-Sectional Studies; Environmental Exposure; Humans; Insecticides; Methyl Parathion; Middle Aged; Molecular Structure; Nitrophenols; Occupational Exposure; Statistics, Nonparametric; Thailand; Young Adult

A procedure has been developed for simultaneous determination of the activities of alpha-D- and beta-D-mannosidase in the biological fluids from the quantity of free 4-nitrophenol. The latter is released via enzymatic degradation of substrates of 4-nitrophenyl-alpha-D-mannose and 4-nitrophenyl-beta-D-mannose in individual incubation tests.

Topics: Adolescent; Adult; alpha-Mannosidase; Animals; Asthenozoospermia; beta-Mannosidase; Child; Duodenitis; Gastritis; Humans; Male; Nitrophenols; Rats; Spermatozoa; Young Adult

In previous studies, we found that 4-nitrophenol (PNP) isolated from diesel exhaust particles exhibited both estrogenic and anti-androgenic activities. This compound is also a degradation product of the insecticide parathion. Here, we investigated the in vivo effect of PNP on reproductive function in immature male rats. Twenty-eight-day-old rats were injected subcutaneously with PNP (0.01, 0.1, 1, or 10 mg/kg) daily for 14 days. Plasma concentrations of luteinizing hormone (LH) were significantly lower in all PNP dosage groups than in the control group, and follicle-stimulating hormone (FSH) was significantly decreased in rats treated with 0.1, 1, or 10 mg/kg PNP. However, plasma concentrations of testosterone were significantly increased by 10 mg/kg PNP, and plasma concentrations of immunoreactive (ir)-inhibin were also significantly increased in the 0.1, 1, and 10 mg/kg PNP groups. Plasma concentrations of prolactin were significantly increased by 10 mg/kg PNP, and plasma concentrations of corticosterone were significantly increased in all treatment groups. These findings clearly show that PNP influences the hypothalamic-pituitary-gonadal axis in immature male rats, with decreased secretion of LH and FSH and increased secretion of testosterone and inhibin. PNP, therefore, appears to disrupt endocrine activity in the immature male reproductive system.

Topics: Age Factors; Animals; Corticosterone; Follicle Stimulating Hormone; Gonadal Steroid Hormones; Infertility, Male; Inhibins; Luteinizing Hormone; Male; Nitrophenols; Prolactin; Rats; Rats, Wistar; Testosterone; Vehicle Emissions

The design, synthesis, characterization and application of biologically synthesized nanomaterials have become an important branch of nanotechnology. In this paper, we report the extracellular synthesis of gold nanoparticles using Barbated Skullcup (BS) herb (a dried whole plant of Scutellaria barbata D. Don) as the reducing agent. After exposing the gold ions to BS herb extract, rapid reduction of gold ions is observed leading to the formation of gold nanoparticles in solution. UV-vis spectrum of the aqueous medium containing gold nanoparticles showed a peak at around 540 nm. Transmission electron microscopy (TEM) micrograph analysis of the gold nanoparticles indicated that they were well-dispersed and ranged in size 5-30 nm. When the gold nanoparticles were modified on the glassy carbon electrode (GCE), it could enhance electronic transmission rate between the electrode and the p-nitrophenol.

Topics: Electrochemistry; Electrodes; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Particle Size; Plant Extracts; Scutellaria; Spectrophotometry, Ultraviolet

The study of digestive enzymes, especially in important pests like Chilo suppressalis Walker (Lepidoptera: Pyralidae), which are a key constraint on rice production in a wide area of the globe and also in Iran, could be a successful procedure in the development of a safe and useful control strategy. Glycosidase are a type of digestive enzymes which have a critical role in the final stages of carbohydrate digestion; they hydrolyze alpha-D-(1,4)-glucose linkage such as p-nitrophenyl-alpha-D-glucoside in di and oligosaccharide components. Laboratory reared 4th instar larvae were randomly selected; midgut and salivary gland were removed by dissection under a stereo microscope and glucosidase activities were assayed by Ferreira and Terra's procedures. The activities of alpha- and beta-glucosidase in the midgut and salivary gland were 0.009, 0.0063, 0.005 and 0.003 micromol/min/mg protein, respectively. The optimal pH and temperature for enzyme activity were determined to be 9 and 45 degrees C for the glucosidases measured, values which are in agreement with other reports, especially in lepidopteran insects, which give values between 8-12 and 20-50 degrees C. The enzyme activity increased with the addition of NaCl, MgCl(2) and CaCl(2) and decreased due to the use of different concentrations of KCl, Urea, EDTA, SDS and Urea both in midgut and the salivary glands. Control of pests by using resistant varieties is one of the most important practices that are dependent on inhibitors in plants. Hence, characterization of digestive enzymes, especially the effect of inhibitors on enzyme activity, could be useful, on the one hand for a better understanding of enzyme roles in the nutrition physiology of insects, and on the other hand to reach safe and useful controls of insect pests.

Topics: alpha-Glucosidases; Animals; beta-Glucosidase; Digestive System; Enzyme Activators; Enzyme Inhibitors; Glycoside Hydrolase Inhibitors; Hydrogen-Ion Concentration; Kinetics; Larva; Lepidoptera; Nitrophenols; Salivary Glands; Temperature

The study regards para-nitrophenol (p-NP) removal by a mixed culture in a batch reactor under aerobic conditions performed at low ratio substrate (p-NP) to p-NP degrading microorganisms (0.09 < I(0)/(X(B,PNP))(0) < 0.80 g COD(PNP)g VSS(-1)). p-NP biodegradation was modelled with a dual-biomass kinetic including Haldane formalism. The purpose was to examine the effect of operating conditions of acclimation phases in the kinetic parameters estimated by respirometric measurements. The experiments were conducted with a series of successive additions of p-NP and a biogenic substrate (Ss) in different proportions (0 < R = Ss/I < 6.6). To place emphasis on decisive role played by frequency and amount of p-NP supply, a parallel was drawn with continuous processes, characterising acclimation cycles by different organic loading rate (207 < OLR < 1490 mg COD(PNP) l(-1) d(-1)). During acclimation, results showed progressively decreasing half saturation constant (K(s)(PNP)) values (11.4-1.21 mg CODl(-1)) whereas inhibition coefficient K(I)(PNP) increased (72.4-289 mg CODl(-1)), as the specific degradation rate increased. The inverse behaviour was observed during starvation periods. At the end of acclimation, higher values of growth yield (0.39 < Y(PNP) < 0.63 mg COD(X) mg COD(PNP)(-1)) and maximum growth rate (1.09 < mu(max)(PNP) < 2.01 d(-1)) were obtained for cycles with low R.

Topics: Acclimatization; Animals; Bacteria; Biodegradation, Environmental; Biomass; Eukaryota; Flocculation; Kinetics; Models, Biological; Nitrophenols; Oxygen; Reproducibility of Results; Time Factors

A soil bacterium strain, capable of using p-nitrophenol (PNP) as its sole source of carbon and energy, was isolated by enrichment on minimal salt medium (MSM). On the basis of a phylogenetic analysis of 16S rRNA gene sequences the bacterium is a species of Arthrobacter, closely related to Arthrobacter ureafaciens DSM 20126. This strain has an unusually high substrate tolerance for PNP degradation in MSM. Greatest degradation of PNP was observed at 30 degrees C and under slightly alkaline pH (pH 7-9) conditions. Effective degradation rates slowed as the concentration of PNP was increased. Addition of glucose from 0.1% to 0.5% generally enhanced the degradation of PNP at high concentration (400 mg/l) although acidification as a result of glucose metabolism had a negative effect on PNP depletion. Biodegradation of PNP at high concentration was greatly accelerated by beta-cyclodextrin at a concentration of 0.5%, indicating that beta-cyclodextrin could be a promising addictive for effective PNP bioremediation.

Topics: Arthrobacter; beta-Cyclodextrins; Biodegradation, Environmental; Carbon; Culture Media; Hydrogen-Ion Concentration; Nitrophenols; Temperature

Organophosphorous hydrolase (OPH) was expressed onto the surface of a Stenotrophomonas species (LZ-1), capable of simultaneously degrading 4-substituted phenols, using the N- and C-terminal domains of ice nucleation protein (INPNC) as an anchoring motif for the first time. The engineered strain LZ-1 could degrade p-nitrophenyl-substituted organophosphates as well as their hydrolytic product, PNP, rapidly. Especially, addition of 4-CP (below 0.8 mM) significantly accelerated the complete degradation of above organophosphates (47.1, 34.0, and 40% reduction of time of paraoxon, parathion, and methyl-parathion, respectively) through the accelerated degradation of PNP due to enhanced cell growth supported by 4-CP as the carbon source. OPH could be surface-displayed at a high level without inhibition of cell growth and OPH activity in the presence of 4-CP. In soil samples, strain LZ-1 could also remove these compounds successfully. Functional display of heterologous proteins on the surface of indigenous bacteria could provide a promising technology for effective bioremediation of sites contaminated with mixed organic pollutants.

Topics: Aryldialkylphosphatase; Bacterial Outer Membrane Proteins; Genetic Engineering; Membrane Proteins; Nitrophenols; Organophosphates; Pesticides; Phenols; Recombinant Fusion Proteins; Stenotrophomonas

The biological treatment of a high-strength p-nitrophenol (PNP) wastewater in an aerobic Sequencing Batch Reactor (SBR) has been studied. A specific operational strategy was applied with the main aim of developing a K-strategist PNP-degrading activated sludge. The enrichment of a K-strategist microbial population was performed using a non-acclimated biomass coming from a municipal WWTP as inoculum, and following a feeding strategy in which the PNP-degrading biomass was under endogenous conditions during more than 50% of the aerobic reaction phase. Hundred per cent of PNP removal was achieved in the whole operating period with a maximum specific PNP loading rate of 0.26 g PNP g(-1)VSS d(-1). A kinetic characterization of the obtained PNP-degrading population was carried out using respirometry assays in specifically designed batch tests. With the experimental data obtained a kinetic model including substrate inhibition has been used to describe the time-course of the PNP concentration and specific oxygen uptake rate (SOUR), simultaneously. The kinetic parameters obtained through optimization, validated with an additional respirometric test, were k(max)=1.02 mg PNP mg(-1) COD d(-1), K(s)=1.6 mg PNP L(-1) and K(i)=54 mg PNP L(-1). The values obtained for the K(s) and k(max) are lower than those reported in the literature for mixed populations, meaning that the biomass is a K-strategist type, and therefore demonstrating the success of the operational strategy imposed to obtain such a K-strategist population. Moreover, our measured K(i) value is higher than those reported by most of the bibliographic references; therefore the acclimated activated sludge used in this work was evidently more adapted to PNP inhibition than the other reported cultures.

Topics: Bacteria; Biodegradation, Environmental; Bioreactors; Models, Biological; Nitrophenols; Water Pollutants, Chemical; Water Purification

To compare N-acetyl-beta-hexosaminidase (HEX) activity in the serum and urine of smokers as well as non-smokers with renal cancer, and healthy people.. To assess hexosaminidase activity the level of p-nitrophenol released from p-nitrophenol derivatives was measured.. The activity of enzyme was significantly higher in cancer group, with the highest activity in non-smokers.. Cigarette smoking can inhibit, by the influence on HEX activity, catabolism of oligosaccharide chains in cancer tissues.

Topics: beta-N-Acetylhexosaminidases; Biomarkers, Tumor; Humans; Kidney Neoplasms; Nitrophenols; Oligosaccharides; Risk Factors; Smoking

The surface of zeolite was modified by cationic beta-cyclodextrin (CCD), which was synthesized with 2, 3-epoxypropyltrimethylammonium chloride (ETMAC) and beta-cyclodextrin (beta-CD), to prepare a novel and effective sorbent for removal of p-nitrophenol (p-NP) from aqueous solution. FTIR, SEM and EDS were used to characterize the surface modification. It was found that CCD, which was synthesized at different conditions such as the mole ratio of ETMAC against beta-CD and pH, made an impact on sorption capacity of p-NP on CCD-modified zeolite (CCDMZ). Given ETMAC: beta-CD = 7:1 and pH = 13, the cationic process of beta-CD might be optimum for CCD to bond to zeolite surfaces. In addition, CCD concentration and modification time affected sorption capacity of p-NP on CCDMZ too. The sorption of p-NP on CCDMZ, activated zeolite (AZ) and natural zeolite (NZ) was investigated by contact time, initial p-NP concentration and sorption isotherms with the batch sorption experiments. The results showed that the sorption of p-NP on CCDMZ satisfactorily fitted the known Langmuir model and the sorption capacity of CCDMZ was higher than that of AZ and NZ although the contact time of CCDMZ appeared to be shorter than other two.

Topics: Adsorption; beta-Cyclodextrins; Cations; Chemistry Techniques, Analytical; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Quaternary Ammonium Compounds; Spectroscopy, Fourier Transform Infrared; Surface Properties; Temperature; Time Factors; Water; Water Purification; Zeolites

By using a molecularly imprinted polymer (MIP) as a recognition element, the design and construction of a high selective voltammetric sensor for para-nitrophenol was formed. Para-nitrophenol selective MIP and a non-imprinted polymer (NIP) were synthesized, and then used for carbon paste (CP) electrode preparation. The MIP-CP electrode showed greater recognition ability in comparison to the NIP-CP. It was shown that electrode washing after para-nitrophenol extraction led to enhanced selectivity, without noticeably decreasing the sensitivity. Some parameters affecting sensor response were optimized and a calibration curve was plotted. A dynamic linear range of 8x10(-9) to 5x10(-6) mol L(-1) was obtained. The detection limit of the sensor was calculated as 3x10(-9) mol L(-1). Thus, this sensor was used successfully for the para-nitrophenol determination in different water samples.

Topics: Electrodes; Molecular Imprinting; Nitrophenols

Single-walled carbon nanohorn (SWCNH) was developed as new adsorbent for solid-phase extraction using 4-nitrophenol as representative. The unique exoteric structures and high surface area of SWCNH allow extracting a large amount of 4-nitrophenol over a short time. Highly sensitive determination of 4-nitrophenol was achieved by linear sweep voltammetry after only 120s extraction. The calibration plot for 4-nitrophenol determination is linear in the range of 5.0x10(-8) M-1.0x10(-5) M under optimum conditions. The detection limit is 1.1x10(-8) M. The proposed method was successfully employed to determine 4-nitrophenol in lake water samples, and the recoveries of the spiked 4-nitrophenol were excellent (92-106%).

Topics: Adsorption; Calibration; Carbon; Fresh Water; Nitrophenols; Solid Phase Extraction; Water Pollutants, Chemical

Several cytosolic sulfotransferase enzyme isoforms are functional in placenta but there is limited information available on the utility of cultured trophoblast cells for studying sulfation. The trophoblast cell layer constitutes the rate-determining barrier for trans-placental transfer. The objective of this work was to examine the mRNA expression and enzyme activities of four sulfotransferase isoforms reported to be functional in human placenta (SULT1A1, SULT1A3, SULT1E1, and SULT2A1) in primary cytotrophoblast cells and the trophoblast-like BeWo cell line. Reverse transcription polymerase chain reaction (RT-PCR) was performed to determine mRNA expression. Enzyme activities were assessed using the following substrates: 4-nitrophenol for SULT1A1, dopamine for SULT1A3, 17beta-estradiol for SULT1E1, and dehydroepiandrosterone for SULT2A1. For 4-nitrophenol and dopamine sulfation, apparent K(m) values, response to inhibitors (2,6-dichloro-4-nitrophenol and sodium chloride), and thermal stability profiles indicated that 4-nitrophenol and dopamine sulfation in BeWo cells were being mediated by SULT1A1 and SULT1A3, respectively. SULT1A1 and SULT1A3 were also functional in the cytotrophoblast cells. Both at the protein and at the mRNA levels, SULT1A1 was more abundant in BeWo cells in comparison to the primary cytotrophoblast cells. SULT1E1 and SULT2A1 mRNA were not detected in the cytotrophoblasts. SULT1E1 mRNA was weakly expressed in BeWo but there was negligible functional activity. Although SULT2A1 mRNA was abundantly expressed in BeWo, Western blot and enzyme activities revealed that the protein is not expressed in BeWo cells. The results suggest that the BeWo cells and the cytotrophoblast cells can be used to examine the roles of SULT1A1 and SULT1A3 in placental metabolism.

Topics: Arylsulfotransferase; Cell Line, Tumor; Choriocarcinoma; Dopamine; Female; Humans; Isoenzymes; Nitrophenols; Placenta; Pregnancy; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sodium Chloride; Substrate Specificity; Sulfotransferases; Trophoblasts

Experiments have been performed with a semicontinuous batch reactor to compare the degradation efficiency of nitrobenzene in aqueous solution by the ultrasonic processes of single field, opposite dual fields, and orthogonal dual fields. Ultrasound with dual fields can improve the degradation efficiency of nitrobenzene compared to that of single field, and the improvement phenomenon is even more pronounced in the orthogonal dual-field system. The degradation reactions of nitrobenzene in the three processes all follow the pseudofirst-order kinetic model. The mechanism investigation indicates the degradation proceeds via hydroxyl radical (*OH) oxidation. The enhancement efficiency of orthogonal dual fields is attributed to an obvious synergetic effect, which accelerates the *OH initiation from 0.28 micromol L(-1) min(-1) for a single field to 0.98 micromol L(-1) min(-1) compared with 0.42 micromol L(-1) min(-1) for opposite dual fields, resulting in rapid formation of an increased diversity of byproducts and an advanced degree of mineralization of total organic carbon (TOC). The introduction of an ultrasonic field placed in the different spatial position causes a variable kinetic order during the removal of TOC. The degradation byproducts are identified by gas chromatography mass spectrometry and ion chromatography, including p-, m-nitrophenol, malonic acid, nitrate ion, 4-nitrocatechol, phenol, maleic acid, oxalic acid, hydroquinone, 1,2,3-trihydroxy-5-nitrobenzene, and acetic acid.

Topics: Acetic Acid; Carbon; Catechols; Chromatography, Gas; Hydroquinones; Hydroxyl Radical; Ions; Kinetics; Maleates; Malonates; Nitrates; Nitrobenzenes; Nitrophenols; Oxalic Acid; Ultrasonics; Water

Here we report an a novel approach, the marriage of photocatalytic degradation and electrochemical oxidation, to wastewater remediation based on the use of bifunctional electrodes. To illustrate this innovative technique, TiO2/Ti/ Ta2O5-IrO2 bifunctional electrodes were prepared using a facile thermal decomposition technique and employed in this study. The TiO2 photocatalyst was coated on one side of the Ti substrate, while the Ta2O5-IrO2 electrocatalytic thin film was coated on the other side. The fabricated bifunctional electrodes were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The performance of the bifunctional electrodes was tested using both 4-nitrophenol (4-NPh) and 2-nitrophenol (2-NPh) as model pollutants. Our study demonstrates that the prepared bifunctional electrodes exhibit high efficiency for both 4-NPh and 2-NPh degradation. In the degradation of 4-NPh a rate constant of 1.06 x 10(-2) min(-1) was created and a rate constant of 1.93 x 10(-2) min(-1) was produced for 2-NPh by the combination of the photochemical and electrochemical oxidation on the novel bifunctional electrodes, quadruple the rate constant created by the individual photochemical and photoelectrochemical methods. The innovative approach described in this study provides a very promising and energy efficient environmentally friendly technology for water purification and waste effluent treatment.

Topics: Catalysis; Electrochemistry; Electrodes; Microscopy, Electron, Scanning; Nitrophenols; Photochemistry; Platinum; Time Factors; Titanium; Waste Disposal, Fluid; Water Pollutants; Water Purification

The present work reports the preparation of activated carbon fiber (ACF) from Kenaf natural fibers. Taguchi experimental design method was used to optimize the preparation of ACF using K(2)HPO(4). Optimized conditions were: carbonization at 300 degrees C, impregnation with 30%w/v K(2)HPO(4) solution and activation at 700 degrees C for 2h with the rate of achieving the activation temperature equal to 2 degrees C min(-1). The surface characteristics of the ACF prepared at optimized conditions were also studied using pore structure analysis, scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Pore structure analysis shows that micropores constitute the most of the porosity of the prepared ACF. The ability of the ACF prepared at optimized conditions to adsorb phenol and p-nitrophenol from aqueous solution was also investigated. The equilibrium data of phenol and p-nitrophenol adsorption on the prepared ACF were well fitted to the Langmuir isotherm. The maximum adsorption capacities of phenol and p-nitrophenol on the prepared ACF are 140.84 and 136.99 mg g(-1), respectively. The adsorption process follows the pseudo-first-order kinetic model.

Topics: Adsorption; Biodegradation, Environmental; Carbon; Carbon Fiber; Charcoal; Hibiscus; Kinetics; Nitrogen; Nitrophenols; Phenols; Phosphates; Potassium Compounds; Temperature; Time Factors

Porous alumina membranes are attractive materials for the construction of biosensors and also have utility for the production of immobilised enzyme bioreactors. Microsomes from rat liver were adsorbed onto alumina membrane activated by silane. Microsomal membranes were pumped through the channels where they became immobilised by binding to amine groups on the surface of the alumina membrane. In an effort to gain a quantitative understanding of the effects of microsomal film growth on enzyme activity, we compared the para-nitrophenol (pNP) hydroxylase activity of the microsomes by varying the amount of microsomes fixed in alumina microchannels. The alumina membrane was placed in a fluidic device at a fast flow that afforded short residence time (seconds) to obtain transformation of pNP to 4-nitrocatechol (pNC), which was detected by LC-MS/MS. This enabled the use of this bioreactor where CYP2E1 activity is low and tissue sources are limiting. The microsomes, successfully immobilised on the alumina membranes, were used to produce stable biocatalytic reactors that can be used repeatedly over a period of 2 months.

Topics: Adsorption; Aluminum Oxide; Animals; Bioreactors; Catechols; Cytochrome P-450 CYP2E1; Enzymes, Immobilized; Gold; Hydroxylation; Male; Membranes, Artificial; Microsomes, Liver; Nitrophenols; Rats; Rats, Sprague-Dawley; Time Factors

The objective of this study is to evaluate the performance of sequencing batch biofilm reactors (SBBRs) and sequencing batch reactor (SBR) in the simultaneous removal of p-nitrophenol (PNP) and ammoniacal nitrogen. SBBRs involved the use of polyurethane sponge cubes and polyethylene rings, respectively, as carrier materials. The results demonstrate that complete removal of PNP was achievable for the SBR and SBBRs up to the PNP concentration of 350 mg/l (loading rate of 0.368 kg/m3 d). At this loading rate, the average ammoniacal nitrogen removal efficiency for the SBR and SBBR (with polyethylene rings) was reduced to 86% and 96%, respectively. However, the SBBR (with polyurethane sponge cubes) still managed to achieve an almost 100% ammoniacal nitrogen removal. Based on the results, the performance of the SBBRs was better than that of SBR in PNP and ammoniacal nitrogen removal. The results of the gas chromatography mass spectroscopy, high-performance liquid chromatography and ultraviolet-visible analyses indicate that complete mineralization of PNP was achieved in all of the reactors.

Topics: Biofilms; Bioreactors; Equipment Design; Kinetics; Nitrogen Compounds; Nitrophenols; Quinones; Sewage; Spectrum Analysis; Waste Disposal, Fluid; Water Purification

We compared the Arthrobacter chlorophenolicus proteome during growth on 4-chlorophenol, 4-nitrophenol, or phenol at 5 and 28 degrees C, both for the wild-type and a mutant strain with mass spectrometry based proteomics. A label-free workflow employing spectral counting identified 3749 proteins across all growth conditions, representing over 70% of the predicted genome and 739 of these proteins form the core proteome. Statistically significant differences were found in the proteomes of cells grown under different conditions including differentiation of hundreds of unknown proteins. The 4-chlorophenol-degradation pathway was confirmed, but not that for phenol.

Topics: Arthrobacter; Bacterial Proteins; Chlorophenols; Chromatography, Liquid; Electrophoresis, Gel, Two-Dimensional; Nitrophenols; Phenols; Proteome; Tandem Mass Spectrometry; Temperature

An extraction-preconcentration procedure based on the use of a molecularly imprinted polymer (MIP) as selective sorbent has been developed for the determination of several phenolic compounds (bisphenol-A, bisphenol-F and 4-nitrophenol) and phenoxyacid herbicides (2,4-D, 2,4,5-T and 2,4,5-TP) in honey samples. Liquid chromatography with diode array detection (LC-DAD) and electrospray ionisation-ion trap mass spectrometry (LC-IT-MS) were used for the separation, identification and quantification of these analytes. The molecularly imprinted polymer was obtained by precipitation polymerisation with bisphenol-A (BPA) as template and 4-vinylpyridine as the functional monomer. The behaviour of this sorbent was compared with those of other materials frequently used in SPE. The selectivity of the BPA-MIP for the target analytes was tested in samples containing other pesticides in common use. The recoveries achieved for all six compounds were in the 81-96% range. By applying the proposed procedure prior to LC-IT-MS, the limits of detection achieved in commercial honey samples were in the 0.1-3.8 ng g(-1) range, with relative standard deviations of 12-24%.

Topics: 2,4-Dichlorophenoxyacetic Acid; 2,4,5-Trichlorophenoxyacetic Acid; Benzhydryl Compounds; Chromatography, Liquid; Herbicides; Honey; Molecular Imprinting; Nitrophenols; Phenols; Polymers; Pyridines; Tandem Mass Spectrometry

A low cost and accurate method for the detection and analytical determination of the activity of the enzyme alpha-L-fucosidase (AFU) was developed. The method was based upon measuring the fluorescence intensity of the complex ion associate of the ion associate of rhodamine-B and the compound 2-chloro-4-nitrophenol (RB(+)CNP(-)) at 580 nm in phosphate buffer (pH 5) against the reagent blank. The influence of the different parameters, e.g. pH, incubation time, temperature, 2-chloro-4-nitrophenol concentration, foreign ions and surfactants that control the fluorescence intensity of the produced ion associate was critically investigated. The correlation between the fluorescence activity of the enzyme AFU by the developed procedures and the standard method was positive and highly significant in patients and controls (r(2)=0.99, p<0.001). The developed method is simple and proceeds without practical artifacts compared to the standard method.

Topics: alpha-L-Fucosidase; Hepatitis B, Chronic; Hepatitis C, Chronic; Humans; Hydrogen-Ion Concentration; Ions; Nitrophenols; Reproducibility of Results; Rhodamines; Spectrometry, Fluorescence

This study reports a material that is based on the concept of ionic liquid analogue: a slightly crosslinked polymer-supported imidazolium trifluoroacetate salt (IL-CF(3)COO(-)) that favorably combines the properties of ionic liquids (ILs) and the advantages of a solid support. The ionic liquid-supported material was evaluated for the first time as a solid-phase extraction (SPE) sorbent for selectively and quantitatively extracting pharmaceuticals from aqueous samples. The novel IL-CF(3)COO(-) was evaluated under reversed-phase (RP), weak anion exchange (WAX), strong anion exchange (SAX) and strong cation exchange (SCX) SPE procedures, and we found that SAX conditions are the most suitable for investigating the behaviour of the IL-CF(3)COO(-) material. Under SAX conditions, the IL-CF(3)COO(-) material was capable of selectively and quantitatively extracting a group of acidic compounds from aqueous samples, while washing basic analytes that were also present in the sample. The SPE method using IL-CF(3)COO(-) material was used to analyse 1000 ml of different aqueous samples (ultrapure, tap and river) with complete recovery of the acidic compounds studied. Moreover, the method provided clean chromatogram and high recoveries when percolating complex real samples, such as 1000 ml of river water and 250 ml of effluent wastewater from a sewage treatment plant spiked at low levels with the analytes studied.

Topics: Adsorption; Carbamazepine; Chromatography, High Pressure Liquid; Fresh Water; Imidazoles; Ionic Liquids; Molecular Structure; Nalidixic Acid; Nitrophenols; Rivers; Salicylic Acid; Sewage; Solid Phase Extraction

Dendritic Ag/Au bimetallic nanostructures have been synthesized via a galvanic replacement reaction (GRR) of Ag dendrites in a chlorauric acid (HAuCl4) solution. After short periods of time, one obtains structures with protruding flakes; these will mature into very porous structures with little Ag left over. The morphological, compositional, and crystal structural changes involved with reaction time t were analyzed by using scanning and transmission electron microscopy (SEM and TEM, respectively), energy-dispersive X-ray spectrometry (EDX), and X-ray diffraction. High-resolution TEM combined with EDX and selected area electron diffraction confirmed the replacement of Ag with Au. A proposed formation mechanism of the original Ag dendrites developing pores while growing Au flakes cover this underlying structure at longer reaction times is confirmed by exploiting surface-enhanced Raman scattering (SERS). Catalytic reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) is strongly enhanced, implying promising applications in catalysis.

Topics: Borohydrides; Catalysis; Dendrites; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nitrophenols; Oxidation-Reduction; Silver; Spectrophotometry, Ultraviolet; Spectrum Analysis, Raman; X-Ray Diffraction

The present study has demonstrated the enhanced performance of a two-phase bioreactor, operating with polymers as a partitioning phase, as an alternative to both single phase biotreatment and to the use of an immiscible organic solvent partitioning phase, to deliver a toxic substrate (4-nitrophenol, or 4NP) to a microbial consortium in batch and repeated batch mode. Three commercial polymers were tested, Hytrel, Tone, and Elvax, and were shown to have superior properties related to the use of a consortium, including complete biocompatibility with the biomass and nonbiodegradability. Repeated kinetic tests performed with short reaction times demonstrated the accumulation of 4NP within the polymers in the range of 6-8 mg/g polymer, which reduced polymer performance in subsequent batch operations. Hytrel gave the best performance with residuals of up to 4 mg/g polymer showing no reduction in subsequent use, while for the other polymers a 4NP value lower than 2 mg/g polymer was required to have acceptable performance during repeated polymer use. Polymer reuse without affecting the process efficiency was confirmed with regeneration tests. A conventional methanol extraction method, as well as biological regeneration of the polymers by prolonged contact with the biomass, were assessed for their ability to remove the residual 4NP. Parallel kinetic tests performed with newand regenerated polymers showed a complete overlap of the 4NP concentration profiles indicating that a simple biological regeneration method provides a means of completely restoring polymer performance for repeated batch operation.

Topics: Absorption; Bacteria; Biodegradation, Environmental; Conservation of Natural Resources; Kinetics; Nitrophenols; Polyesters; Polymers; Polyvinyls; Time Factors

The interaction of 3,4 dinitrophenol (DNP) with cyclic ketones, lactones, and lactams was investigated by UV-visible spectroscopy and density functional theory (DFT) methods. Equilibrium constants K(HB) for 1:1 hydrogen bonded complexes were determined in solution in CCl(4) and C(6)H(12). For the entire range of studied bases, the pK(HB) scale, varying between 2.92 for beta-propiolactone to 5.53 for 1-methyl-epsilon-caprolactam, indicates that the basicity increases with the ring size. Geometries, energies, and vibrational characteristics of complexes were obtained by means of DFT calculations. For lactones and lactams, the energy difference between the two most stable conformers, cis and trans, with respect to the ring oxygen (nitrogen) atom, is relatively small, suggesting that the complex observed in solution is probably an equilibrium mixture of both forms. The good correlation between Gibbs free energies in solution and in the gas phase, computed at the B3LYP/6-311++G(3df,2p) level of theory, confirms the reliability of our results. The electron density of the complexes has been analyzed by means of the atoms in molecules (AIM) theory and the natural bond orbital (NBO) method have been used to characterize the orbital interactions. Our theoretical survey shows that the 1:1 complexes are stabilized by a network of conventional and/or nonconventional intermolecular hydrogen bonds.

Topics: Dinitrobenzenes; Hydrogen Bonding; Ketones; Lactams; Lactones; Models, Molecular; Molecular Conformation; Nitrophenols; Phenols; Quantum Theory; Thermodynamics

Our previous studies showed that administration of a subtoxic dose of acetaminophen (APAP) to female rats increased generation of carbon monoxide from dichloromethane, a metabolic reaction catalyzed mainly by cytochrome P450 (CYP) 2E1. In this study we examined the changes in metabolism and toxicity of APAP upon repeated administration. An intraperitoneal dose of APAP (500 mg/kg) alone did not increase aspartate aminotransferase, alanine aminotransferase, or sorbitol dehydrogenase activity in serum, but was significantly hepatotoxic when the rats had been pretreated with an identical dose of APAP 18 h earlier. The concentrations and disappearance of APAP and its metabolites in plasma were monitored for 8 h after the treatment. APAP pretreatment reduced the elevation of APAP-sulfate, but increased APAP-cysteine concentrations in plasma. APAP or APAP-glucuronide concentrations were not altered. Administration of a single dose of APAP 18 h before sacrifice increased microsomal CYP activities measured with p-nitrophenol, p-nitroanisole, and aminopyrine as probes. Expression of CYP2E1, CYP3A, and CYP1A proteins in the liver was also elevated significantly. The results suggest that administration of APAP at a subtoxic dose may result in an induction of hepatic CYP enzymes, thereby altering metabolism and toxicological consequences of various chemical substances that are substrates for the same enzyme system.

Topics: Acetaminophen; Alanine Transaminase; Aminopyrine; Analgesics, Non-Narcotic; Animals; Anisoles; Aspartate Aminotransferases; Cysteine; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP3A; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Injections, Intraperitoneal; L-Iditol 2-Dehydrogenase; Liver; Microsomes, Liver; Nitrophenols; Rats; Rats, Sprague-Dawley

The survival of and interactions between a Pseudomonas putida strain labelled with a red fluorescent protein gene (WT-rfp) and its green fluorescent protein gene-labelled rpoS(-) mutant (KO-gfp) were examined. The generation times of the planktonic WT-rfp and KO-gfp in trypticase soy broth were not significantly different (i.e., p > 0.05) from each other at 30 degrees C. However, the biovolume of the KO-gfp biofilm was about 7 times larger than its WT-rfp counterpart after 48 h of growth. Furthermore, the presence of WT-rfp suppressed the biofilm development of KO-gfp significantly in co-culture biofilms. In planktonic conditions, the pre-carbon-starved WT-rfp achieved a 3-fold greater survival than the pre-carbon-starved KO-gfp in 0.85% saline after a 13-day incubation. In a 1:1 ratio co-culture, the pre-carbon-starved WT-rfp outcompeted the pre-carbon-starved KO-gfp by 20-fold. However, the survival of WT-rfp and KO-gfp were not significantly different from each other in biofilm conditions. Additionally, 11.4% and 61.2% of the WT-rfp and KO-gfp biofilms, respectively, remained intact after washing in 0.2% SDS for 60 min. In conclusion, the rpoS had a significant impact on survival and competitiveness of planktonic P. putida, and on biofilm development, being implicated in competitive suppression of biofilm development in co-culture biofilms and decreased biofilm cohesiveness.

Topics: Bacterial Adhesion; Bacterial Proteins; Base Sequence; Biodegradation, Environmental; Biofilms; Carbon; DNA Primers; Ecosystem; Gene Deletion; Genes, Bacterial; Green Fluorescent Proteins; Luminescent Proteins; Mutation; Nitrophenols; Plankton; Plasmids; Pseudomonas putida; Recombinant Proteins; Red Fluorescent Protein; Sigma Factor

The kinetics and mechanisms of p-nitrophenol (PNP) biodegradation by Pseudomonas aeruginosa HS-D38 were investigated. PNP could be used by HS-D38 strain as the sole carbon, nitrogen and energy sources, and PNP was mineralized at the maximum concentration of 500 mg/L within 24 h in an mineral salt medium (MSM). The analytical results indicated that the biodegradation of PNP fit the first order kinetics model. The rate constant kPNP is 2.039 x 10(-2)/h in MSM medium, KPNP+N is 3.603 x 10(-2)/h with the addition of ammonium chloride and KPNP+C is 9.74 x 10(-3)/h with additional glucose. The addition of ammonium chloride increased the degradation of PNP. On the contrary, the addition of glucose inhibited and delayed the biodegradation of PNP. Chemical analysis results by thin-layer chromatography (TLC), UV-Vis spectroscopy and gas chromatography (GC) techniques suggested that PNP was converted to hydroquinone (HQ) and further degraded via 1,2,4-benzenetriol (1,2,4-BT) pathway.

Topics: Biodegradation, Environmental; Kinetics; Nitrophenols; Pseudomonas aeruginosa

This article attempts to discern the physical (or mechanistic) features of the sonochemical degradation of two major and ubiquitous nitroaromatic pollutants, viz. nitrobenzene and p-nitrophenol. The fundamental physical phenomenon behind sonochemical degradation of pollutants is radial motion of cavitation bubbles. This study implements a dual approach to the problem, i.e. results of the experiments under different conditions have been coupled to a mathematical model that addresses physics and chemistry of the cavitation bubbles. Various experimental techniques applied in this study influence important physical parameters related to cavitation phenomenon in the liquid medium such as extent of radical production from the bubble, thickness of the liquid shell surrounding the bubble that gets heated up during transient collapse, the concentration of the pollutant in the interfacial region and extent of radical scavenging in the medium. Concurrent analysis of the experimental and simulation results reveal that overall degradation of the pollutant achieved for a given combination of experimental conditions is a function of competing (and sometimes conflicting) effect of these parameters. A semi-quantitative account of the relative influence of these parameters and the interrelations between them is presented.

Topics: Algorithms; Models, Theoretical; Nitrobenzenes; Nitrophenols; Ultrasonics; Waste Disposal, Fluid; Water Pollutants, Chemical

A novel-immobilized enzyme strategy created by magnetic nanospheres for monitoring enzyme activity and screening inhibitors followed by high performance liquid chromatography (HPLC) has been demonstrated. Through the reaction of the aldehyde groups with amine groups, alpha-glycosidase was simply and stably immobilized onto magnetic nanospheres by the cross-linking agent glutaraldehyde. In order to profiling the activity of the immobilized alpha-glucosidase, the natural substrate was hydrolyzed by it and the yield of product was determined by HPLC. Compared with traditional bioassay approach, the prepared immobilized alpha-glucosidase displays a high activity and stability which allows it to be easily reused for 10 times. Enzyme inhibition assays by known inhibitor glucobay and three candidate traditional Chinese medicines (TCMs) were then investigated using a similar methodology. This assay was able to readily detect the change of the immobilized enzyme activity based on measuring a decrease of product formation using HPLC. The approach is general and offers many attractive advantages including easy product isolation, inexpensive cost, and high efficiency in terms of reagent consumption.

Topics: alpha-Glucosidases; Chromatography, High Pressure Liquid; Enzyme Inhibitors; Enzymes, Immobilized; Magnetics; Nanospheres; Nitrophenols

The objectives of the paper are to verify the potentialities of a sequential two phase partitioning bioreactor in degrading xenobiotics and to evaluate the kinetic parameters for modelling the system. The target compound investigated was the 4-nitrophenol. Preliminary tests were carried out to define the solvent most appropriate for the compound. Among the three investigated solvents 1-undecanol, 2-undecanon and oleyl alcohol, the 2-undecanon was chosen because of the higher partition coefficient of 30 and the negligible formation of emulsions. Moreover, the tested solvent showed satisfactory "biocompatibility" characteristics for the biomass with minor effects on the intrinsic kinetics. Parallel batch kinetic tests were then performed with the conventional one phase and the two phase systems. In the two phase system the biomass is exposed for all the time to 4NP concentrations that are significantly lower if compared to the conventional system and, for the highest concentration (450 mg/l) in the two phase system a reduction of the reaction time is observed depending on the biomass concentration. Kinetic parameters were also evaluated in both cases by fitting of the experimental data with a modified form of the Haldane equation.

Topics: Biodegradation, Environmental; Bioreactors; Industrial Waste; Kinetics; Models, Theoretical; Nitrophenols; Waste Disposal, Fluid; Water Pollutants, Chemical; Xenobiotics

The objectives of this work were to demonstrate the potential of a two-phase sequencing batch reactor in degrading xenobiotics and to evaluate the kinetic parameters leading to a mathematical model of the system. 4-Nitrophenol (4NP), a typical representative of substituted phenols, was selected as the target xenobiotic; this compound has never been remediated in a two-phase bioreactor before. Partition tests were conducted to determine the most appropriate partitioning solvent, and among the three investigated solvents (1-undecanol, 2-undecanone and oleyl alcohol), 2-undecanone was chosen because of its favourable partition coefficient and its negligible emulsion-forming tendencies. Moreover, the selected solvent showed satisfactory biocompatibility characteristics with respect to the biomass, with only minor effects on the intrinsic microbial kinetics. Kinetic tests were then performed in a sequencing batch reactor (2-l volume) operated in both conventional one- and two-phase configurations, with the two-phase system showing a significant improvement in the process kinetics in terms of reduced inhibition and increased maximum removal rate. The obtained kinetic parameters suggest that the two-phase sequencing batch system may find full-scale application, as the maximum removal rate k(max) (approximately 3 mg 4NP mgVSS(-1) day(-1)) is of the same order of magnitude of heterotrophic bacteria operating in wastewater treatment plants.

Topics: Bacteria; Bioreactors; Biotransformation; Kinetics; Models, Theoretical; Nitrophenols; Solvents; Water Purification

Arthrobacter sp. Y1, capable of metabolizing p-nitrophenol (PNP) as the sole carbon, nitrogen and energy source was isolated from activated sludge. The bacterium could tolerate concentrations of PNP up to 600 mg L(- 1), and degradation of PNP was achieved within 120 h of incubation. PNP and its metabolites were analyzed by high performance liquid chromatography (HPLC). The metabolite formed indicated that the organism followed the 4-nitrocathechol (4-NC) pathway for metabolism of this compound. The relevant degrading-enzyme was extracellular. Addition of other carbon source (glucose 0 approximately 30 g L(- 1)) led to accelerated degradation. If the glucose concentration exceeded 30 g L(- 1), however, degradation was repressed. Spectrophotometry assay of the nitrite and genotoxic study showed that strain Y1 could detoxify PNP. Therefore, the present study may provide a basis for the development of the bioremediation strategies to remedy the pollutants in the environment.

Topics: Arthrobacter; Biodegradation, Environmental; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Glucose; Nitrophenols; Sewage

Surface display of the active proteins on living cells has enormous potential in the degradation of numerous toxic compounds. Here, we report the codisplay of organophosphorus hydrolase (OPH) and enhanced green fluorescent protein (GFP) on the cell surface of Escherichia coli by use of the truncated ice nucleation protein (INPNC) and Lpp-OmpA fusion systems. The surface localization of both INPNC-OPH and Lpp-OmpA-GFP was demonstrated by Western blot analysis, immunofluorescence microscopy, and a protease accessibility experiment. Anchorage of GFP and OPH on the outer membrane neither inhibits cell growth nor affects cell viability, as shown by growth kinetics of cells and stability of resting cultures. The engineered E. coli can be applied in the form of a whole-cell biocatalyst and can be tracked by fluorescence during bioremediation. This strategy of codisplay should open a new dimension for the display of multiple functional moieties on the surface of a bacterial cell. Furthermore, a coculture comprised of the engineered E. coli and a natural p-nitrophenol (PNP) degrader, Ochrobactrum sp. strain LL-1, was assembled for complete mineralization of organophosphates (OPs) with a PNP substitution. The coculture degraded OPs as well as PNP rapidly. Therefore, the coculture with autofluorescent and mineralizing activities can potentially be applied for bioremediation of OP-contaminated sites.

Topics: Aryldialkylphosphatase; Bacterial Outer Membrane Proteins; Blotting, Western; Coculture Techniques; Enzymes; Escherichia coli; Escherichia coli Proteins; Green Fluorescent Proteins; Microbial Viability; Microscopy, Fluorescence; Molecular Sequence Data; Nitrophenols; Ochrobactrum; Organophosphates; Peptide Hydrolases; Recombinant Fusion Proteins; RNA, Ribosomal, 16S; Sequence Analysis, DNA

The cyclization of 2-(hydroxypropyl)-4-nitrophenyl phosphate (HpPNP) catalyzed by the dinuclear zinc complex of 1,3-bis(1,4,7-triazacyclonon-1-yl)-2-hydroxypropane (1) proceeds by a transition state that is different from that of the uncatalyzed reaction. Kinetic isotope effects (KIEs) measured in the nucleophilic atom and in the leaving group show that the uncatalyzed cyclization has a transition state (TS) with little phosphorus-oxygen bond fission to the leaving group ((18)k(lg) = 1.0064 +/- 0.0009 and (15)k = 1.0002 +/- 0.0002) and that nucleophilic bond formation occurs in the rate-determining step ((18)k(nuc) = 1.0326 +/- 0.0008). In the catalyzed reaction, larger leaving group isotope effects ((18)k(lg) = 1.0113 +/- 0.0005 and (15)k = 1.0015 +/- 0.0005) and a smaller nucleophile isotope effect ((18)k(nuc) = 1.0116 +/- 0.0010) indicate a later TS with greater leaving group bond fission and greater nucleophilic bond formation. These observed nucleophile KIEs are the combined effect of the equilibrium effect on deprotonation of the 2'-hydroxyl nucleophile and the KIE on the nucleophilic step. An EIE of 1.0245 for deprotonation of the hydroxyl group of HPpNP was obtained computationally. The different KIEs for the two reactions indicate that the effective catalysis by 1 is accompanied by selection for an altered transition state, presumably arising from the preferential stabilization by the catalyst of charge away from the nucleophile and toward the leaving group. These results demonstrate the potential for a catalyst using biologically relevant metal ions to select for an altered transition state for phosphoryl transfer.

Topics: Catalysis; Cations, Divalent; Cyclization; Kinetics; Nitrogen Isotopes; Nitrophenols; Organophosphates; Organophosphorus Compounds; RNA; Uridine; Zinc

The adsorption characteristics of phenol, p-chlorophenol and p-nitrophenol in wastewater by activated carbon fiber (ACF) were studied. The surface properties of ACF were characterized by scanning electron microscopy (SEM). The thermodynamic characteristics and mechanism of phenol, p-chlorophenol and p-nitrophenol adsorption on ACF were investigated by using the bottle-point technique. The results showed that the adsorption speed was fast, and ACF had good adsorption properties when pH < 7. On the same condition, the order of removal efficiency were: phenol (87%) < p-chlorophenol (96%) < p-nitrophenol (99%). All the adsorptions are physical adsorption, and the adsorption process were spontaneous exothermic reaction. All the adsorption isotherms can be well represented by Dubinin-Radushkevich equation and the sorption process were spontaneous exothermic reaction.

Topics: Adsorption; Charcoal; Chlorophenols; Nitrophenols; Phenol; Water Pollutants, Chemical

Heterogeneous photocatalysis on metal oxide semiconductor particles is an advanced oxidation technology (AOT), which has been effective means of removing organic pollutants from water streams as it utilizes ultraviolet light with semiconductors acting as photocatalyst and leads to complete mineralization of pollutants to environmentally harmless compounds. In the present investigation, the photo-catalyzed degradation studies of p-Nitrophenol (PNP) were carried out in laboratory scale immersion well UV photo-reactor using semiconductor photo-catalyst TiO2 in suspension. For this purpose, low pressure 12 W mercury lamp was used and the effect of (i) time of irradiation, (ii) dose of TiO2, (iii) initial concentration of PNP and (iv) the addition of H2O2 to the system was studied to arrive at optimum process parameters for the complete degradation and decolorization of PNP. Simple UV irradiation could not achieve significant degradation of PNP. But UV+aeration+TiO2+ H2O2 combination achieved almost complete degradation of PNP. The spectrophotometric analysis showed that the rate of degradation of PNP was very fast in initial two hours and the maximum degradation was achieved in 5 hours. The degradation was found to increase in the order UV < UV + aeration < UV + aeration + TiO2 < UV + aeration + TiO2+ H2O2, and the degradation was found to be almost 100% for UV + aeration + TiO2 + H2O2, 91% for UV + aeration + TiO2, 43% for UV + aeration and only 26% for UV irradiation.

Topics: Catalysis; Nitrophenols; Oxidation-Reduction; Photochemistry; Titanium; Ultraviolet Rays; Water; Water Pollutants, Chemical; Water Purification

Infrared spectroscopy has been used to study the adsorption of para-nitrophenol on mono-, di- and tri-alkyl surfactant intercalated montmorillonite. Organoclays were obtained by the cationic exchange of mono-, di- and tri-alkyl chain surfactants for sodium ions [hexadecyltrimethylammonium bromide (HDTMAB), dimethyldioctadecylammonium bromide (DDOAB), methyltrioctadecylammonium bromide (MTOAB)] in an aqueous solution with Na-montmorillonite. Upon formation of the organoclay, the properties change from strongly hydrophilic to strongly hydrophobic. This change in surface properties is observed by a decrease in intensity of the OH stretching vibrations assigned to water in the cation hydration sphere of the montmorillonite. As the cation is replaced by the surfactant molecules, the para-nitrophenol replaces the surfactant molecules in the clay interlayer. Bands attributed to CH stretching and bending vibrations change for the surfactant intercalated montmorillonite. Strong changes occur in the HCH deformation modes of the methyl groups of the surfactant. These changes are attributed to the methyl groups locking into the siloxane surface of the montmorillonite. Such a concept is supported by changes in the SiO stretching bands of the montmorillonite siloxane surface. This study demonstrates that para-nitrophenol will penetrate into the untreated clay interlayer and replace the intercalated surfactant in surfactant modified clay, resulting in the change of the arrangement of the intercalated surfactant.

Topics: Adsorption; Aluminum Silicates; Clay; Nitrophenols; Silicon Dioxide; Spectrophotometry, Infrared; Surface-Active Agents; Vibration

The adsorption of 4-nitrophenol using commercially available Amberlite IRA-900 modified with metal phthalocyanines (MPc) was investigated. The metallophthalocyanines immobilised onto the surface of Amberlite IRA-900 include Fe (FePcS4), Co (CoPcS4) and Ni (NiPcS4) tetrasulphophthalocyanines, and differently sulphonated phthalocyanine mixtures of Fe (FePcSmix), Co (CoPcSmix) and Ni (NiPcSmix). Adsorption rates were fastest for the modified adsorbents at a loading of 1x10(-3)g MPc/g Amberlite, at pH 9. The highest amount of 4-NP removal was obtained on FePcSmix modified Amberlite IRA-900 with Qt=42.9mmolg(-1) and adsorption efficiency of 86%. The recovery efficiency of 4-NP within 150min was 76%. Using the Langmuir-Hinshelwood kinetic model, the complexes showed an order of 4-nitrophenol adsorption to be as follows: CoPcSmix>NiPcS4>NiPcSmix>FePcS4>FePcSmix>CoPcS4. The MPc modified Amberlite IRA-900 was used repeatedly, following removal of 4-NP by nitric acid, without any significant loss of activity.

Topics: Adsorption; Chromatography, High Pressure Liquid; Indoles; Isoindoles; Kinetics; Nitrophenols; Resins, Synthetic; Spectrum Analysis

This work combined selective adsorption and bioaugmentation to treat mixed wastewater of nitrobenzene and p-nitrophenol. The mixed wastewater of nitrobenzene (217 mg/L) and p-nitrophenol (500 mg/L) was adjusted its pH to 8 and then passed through the adsorption column at 100 mL/h. In effluent the nitrobenzene concentration was less than 4 mg/L. Without the toxic inhibition of nitrobenzene, p-nitrophenol in effluent could be degraded within 60 h through bioaugmentation. About 23 mg/g of nitrobenzene adsorbed the dry resin HU-05 could be desorbed and degraded through bioaugmentation. During this process the adsorption capacity of the resin HU-05 was recovered partly. The recovered extent was limited by nitrobenzene bioavailability. The performance of the resin HU-05 kept stably in the recycle experiments of 60 days.

Topics: Adsorption; Biodegradation, Environmental; Bioreactors; Biotechnology; Hydrogen-Ion Concentration; Industrial Waste; Nitrobenzenes; Nitrophenols; Polymers; Resins, Plant; Waste Disposal, Fluid; Water Microbiology; Water Pollutants, Chemical; Water Purification

Carbon-supported copper (Cu/GAC) catalyst was prepared by conventional impregnation method and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The sizes of Cu particles dispersing on the surface of GAC were 0.3-1.5 microm, which could be penetrated by microwave so that Cu/GAC catalyst could absorb microwave energy effectively. The catalysis of Cu/GAC in microwave assisted catalytic oxidation of p-nitrophenol (PNP) in aqueous solution was investigated through a fixed bed reactor under ambient pressure and continuous flow mode. PNP removal reached 91.8% under optimized conditions, corresponding to 88% of TOC removal. It showed a higher PNP degradation and total organic carbon (TOC) removal for Cu/GAC catalyst than GAC alone, and Cu/GAC catalyst kept on a high catalysis and a good stability for a long time run, which indicated that GAC structure and catalytic capacity were improved by the load of Cu.

Topics: Adsorption; Carbon; Catalysis; Copper; Microwaves; Nitrophenols; Oxidation-Reduction; Solutions; Water Pollutants, Chemical; Water Purification

HDTMA+-pillared montmorillonites were obtained by pillaring different amounts of the surfactant hexadecyltrimethylammonium bromide (HDTMAB) into sodium montmorillonite (Na-Mt) in an aqueous solution. The optimum conditions and batch kinetics of sorption of p-nitrophenol from aqueous solutions are reported. The solution pH had a very important effect on the sorption of p-nitrophenol. The maximum p-nitrophenol absorption/adsorption occurs when solution pH (7.15-7.35) is approximately equal to the pKa (7.16) of the p-nitrophenol ion deprotonation reaction. X-ray diffraction analysis showed that surfactant cations had been pillared into the interlayer and the p-nitrophenol affected the arrangement of surfactant. With the increased concentration of surfactant cations, the arrangement of HDTMA+ within the clay interlayer changes and the sorption of p-nitrophenol increases. HDTMA+-pillared montmorillonites are more effective than Na-Mt for the adsorption of p-nitrophenol from aqueous solutions. The Langmuir, Freundlich and dual-mode sorption were tested to fit the sorption isotherms.

Topics: Adsorption; Bentonite; Hydrogen-Ion Concentration; Kinetics; Nitrophenols; Quaternary Ammonium Compounds; Solutions; Surface Properties; Water Pollutants, Chemical; Water Purification; X-Ray Diffraction

This study investigates the influence of variables on the removal efficiency of solution containing 4-NP (4-nitrophenol) by D. C. electrocoagulation (EC). The efficiency of different electrode connections and materials (steel 310, Fe, Al, graphite and steel 304) for 4-NP removal is compared. Current density, time of electrolysis, interelectrode distance, supporting electrolyte concentration and stirring rate of the solution were the variables that mostly influenced the 4-NP removal. Initially, a simple electrochemical cell was prepared with an anode and a cathode. Then the effect of each variable was studied separately using aqueous 4-NP in a batch mode. For a solution of 20 mg/L 4-NP+300 mg/L NaCl with chemical oxygen demand (COD) of approximately 40 mg O2/L, almost up to 99% 4-NP and 65% COD were removed, when the pH was about 9, time of electrolysis was approximately 10 min, current density was 100 A m(-2), interelctrode distance was 15 mm and stirring rate was 400 rpm. In the second series of experiments, the efficiency of EC cells with monopolar electrodes in series and parallel connections and an EC cell with bipolar electrodes was compared with that of a simple electrochemical cell. The best results obtained when steel 310 and Fe are used as anodes and employing Al and graphite as anodes would not be satisfactory. Also findings show that the types of sacrificial electrodes are not very significant in the removal of 4-NP. In the real wastewater obtained from Tabriz petrochemical plant 52% removal could be achieved after 10 min with using steel 310 as anode and steel 304 as cathode.

Topics: Electrodes; Electrolysis; Iron; Nitrophenols; Sodium Chloride; Solutions; Steel; Temperature; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

In order to design and operate a fixed-bed reactor, accurate modeling is important. For a single component system, the determination of intraparticle diffusivity is rather easy. However, the calculations of multi-component systems are normally complicated and very time-consuming. Therefore, an alternative simple determination procedure using the shallow bed technique is proposed in this research to determine the intraparticle diffusivities for multi-component systems. Ternary component systems of phenol (PH), benzoic acid (BA), and p-nitro-phenol (PNP) were investigated as model components. This study illustrated that adsorption uptake curves of different components in ternary systems can be converted into one typical characteristic curve (theoretical uptake curve, TUC) by using a set of dimensionless groups. By matching the dimensionless experimental uptake curve (DEUC) with TUC, diffusivities of PH, BA and PNP were determined as 8.00 x 10(-8), 5.92 x 10(-8) and 5.05 x 10(-8)cm2 s(-1), respectively. These values are in good agreement with simulated experimental values. This study demonstrated that the shallow bed technique can be used to simultaneous determination of intraparticle diffusivities from multi-component systems.

Topics: Benzoic Acid; Diffusion; Nitrophenols; Particle Size; Phenol

pH and the presence of compounds have a great effect on the sorption of organic contaminants. In this study, batch equilibrium experiments were carried out to investigate the influence of pH on the sorption of p-nitrophenol (PNP) onto sediment in the presence of Pb(NO3)2 and cetylpyridinium chloride (CPC) cationic surfactant. Results indicated that in the multi-solute system with PNP, Pb(NO3)2 and CPC, the sorption of PNP increased with the increasing pH and the amount of sorbed PNP at equilibrium was much higher than in the single-solute system. This can be attributed to the presence of Pb(NO3)2 and CPC. It is believed that the main reason for that was the larger sorption of CPC at higher pH allowing higher sorption of PNP. The results are believed to provide a useful insight into describing the transport and fate of PNP in natural environments.

Topics: Adsorption; Cetylpyridinium; Geologic Sediments; Hydrogen-Ion Concentration; Lead; Nitrates; Nitrophenols; Water Pollutants, Chemical

Quotation and calculation accuracy can play a key role in a scientific paper. This comment mainly presents the possible errors in an article by Akçay et al., including the questionable expression of Polanyi potential (epsilon) in the Dubinin-Radushkevich (DR) equation used by the authors and the discrepancies in adsorption thermodynamic parameters study.

Topics: Adsorption; Bentonite; Chlorophenols; Kinetics; Nitrophenols; Phenol; Solutions; Water

The trans-sialidase from Trypanosoma cruzi catalyzes the transfer of a sialic acid moiety from sialylated donor substrates to the terminal galactose moiety of lactose and lactoside acceptors to yield alpha-(2,3)-sialyllactose or its derivatives with net retention of anomeric configuration. Through kinetic analyses in which the concentrations of two different donor aryl alpha-sialoside substrates and the acceptor substrate lactose were independently varied, we have demonstrated that this enzyme follows a ping-pong bi-bi kinetic mechanism. This is supported for both the native enzyme and a mutant (D59A) in which the putative acid/base catalyst has been replaced by the demonstration of the half-reaction in which a sialyl-enzyme intermediate is formed. Mass spectrometric analysis of the protein directly demonstrates the formation of a covalent intermediate, while the observation of release of a full equivalent of p-nitrophenol by the mutant in a pre-steady state burst provides further support. The active site nucleophile is confirmed to be Tyr342 by trapping of the sialyl-enzyme intermediate using the D59A mutant and sequencing of the purified peptic peptide. The role of D59 as the acid/base catalyst is confirmed by chemical rescue studies in which activity is restored to the D59A mutant by azide and a sialyl azide product is formed.

Topics: Alanine; Animals; Aspartic Acid; Azides; Catalysis; Glycoproteins; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; N-Acetylneuraminic Acid; Neuraminidase; Nitrophenols; Substrate Specificity; Trypanosoma cruzi; Tyrosine

Dinitrosyl iron complexes (DNIC) with thiolate ligands and S-nitrosothiols, which are NO and NO+ donors, share the earlier demonstrated ability of nitrite for inhibition of catalase. The efficiency of inhibition sharply (by several orders in concentration of these agents) increases in the presence of chloride, bromide, and thiocyanate. The nitro compounds tested--nitroarginine, nitroglycerol, nitrophenol, and furazolidone--gained the same inhibition ability after incubation with ferrous ions and thiols. This is probably the result of their transformation into DNIC. None of these substances lost the inhibitory effect in the presence of the well known NO scavenger oxyhemoglobin. This fact suggests that NO+ ions rather than neutral NO molecules are responsible for the enzyme inactivation due to nitrosation of its structures. The enhancement of catalase inhibition in the presence of halide ions and thiocyanate might be caused by nitrosyl halide formation. The latter protected nitrosonium ions against hydrolysis, thereby ensuring their transfer to the targets in enzyme molecules. The addition of oxyhemoglobin plus iron chelator o-phenanthroline destroying DNIC sharply attenuated the inhibitory effect of DNIC on catalase. o-Phenanthroline added alone did not influence this effect. Oxyhemoglobin is suggested to scavenge nitrosonium ions released from decomposing DNIC, thereby preventing catalase nitrosation. The mixture of oxyhemoglobin and o-phenanthroline did not affect the inhibitory action of nitrite or S-nitrosothiols on catalase.

Topics: Catalase; Cysteine; Enzyme Inhibitors; Glutathione; Iron; Kinetics; Nitrites; Nitro Compounds; Nitrogen Compounds; Nitrogen Oxides; Nitrophenols; S-Nitrosothiols

Thermostable esterase gene was cloned (Est-AF) from extremophilic microorganisms, Archaeoglobus fulgidus DSM 4304. The protein analysis result showed that Est-AF is monomer with total 247 amino acids and molecular weight of estimated 27.5 kDa. It also showed repeating units G-X-S-X-G (GHSLG) (residues 86 approximately 90) which is reported as active site of known esterases, and the putative catalytic triad composed of Ser88, Asp198 and His226. The esterase activity test with various acyl chain length of rho-nitrophenol resulted that Est-AF showed highest specific activity with rho-nitrophenylbutyrate (pNPC4) and rapidly decrease with rho-nitrophenyl ester contain more than 8 carbon chain. These results represent that cloned enzyme is verified as a carboxylesterase but not a lipase because esterase activity is decreased with rho-nitrophenyl ester contains more than 8 carbon chains but lipase activity does not affected with carbon chain length. Optimum temperature of esterase reaction with rho-nitrophenylbutyrate (pNPC4) was 80 degrees C. When ketoprofen ethyl ester was used as a substrate, activity of Est-AF showed the highest value at 70 degrees C, and 10% of activity still remains after 3 h of incubation at 90 degrees C. This result represents Est-AF has high thermostability with comparison of other esterases that have been reported. However, Est-AF showed low enantioselectivity with ketoprofen ethyl ester. Optimum pH of Est-AF is between pH 7.0 and pH 8.0. Km value of ketoprofen ethyl ester is 1.6 mM and, Vmax is 1.7 micromole/mg protein/min. Est-AF showed similar substrate affinity but slower reaction with ketoprofen ethyl ester compare with esterase from mesophilic strain P. fluorescens.

Topics: Amino Acid Sequence; Archaeal Proteins; Archaeoglobus fulgidus; Carboxylesterase; Cloning, Molecular; Enzyme Stability; Kinetics; Molecular Sequence Data; Nitrophenols; Organic Chemicals; Sequence Alignment; Sequence Analysis, Protein; Surface-Active Agents; Temperature

The esterase, phosphatase, and sulfatase activities of carbonic anhydrase (CA, EC 4.2.1.1) isozymes, CA I, II, and XIII with 4-nitrophenyl esters as substrates was investigated. These enzymes show esterase activity with 4-nitrophenyl acetate as substrate, with second order rate constants in the range of 753-7706M(-1)s(-1), being less effective as phosphatases (k(cat)/K(M) in the range of 14.89-1374.40M(-1)s(-1)) and totally ineffective sulfatases. The esterase/phosphatase activities were inhibited by sulfonamide CA inhibitors, proving that the zinc-hydroxide mechanism responsible for the CO(2) hydrase activities of CAs is also responsible for their esterase/phosphatase activity. CA XIII was the most effective esterase and phosphatase. CA XIII might catalyze other physiological reactions than CO(2) hydration, based on its relevant phosphatase activity.

Topics: Carbonic Anhydrase I; Carbonic Anhydrase II; Carbonic Anhydrases; Catalysis; Cytosol; Esterases; Esters; Humans; Isoenzymes; Nitrophenols; Phosphoric Monoester Hydrolases; Substrate Specificity; Sulfatases

A wavelet-based latent variable regression (WLVR) method was developed to perform simultaneous quantitative analysis of overlapping spectrophotometric signals. The quality of the noise removal was improved by combining wavelet thresholding with principal component analysis (PCA). A method for selecting the optimum threshold was also developed. Eight error functions were calculated for deducing the number of factor. The latent variables were made by projecting the wavelet-processed signals onto orthogonal basis eigenvectors. Two-programs WMRA and WLVR, were designed to perform wavelet thresholding and simultaneous multicomponent determination. Experimental results showed the WLVR method to be successful even where there was severe overlap of spectra.

Topics: 2,4-Dinitrophenol; Indicators and Reagents; Least-Squares Analysis; Models, Theoretical; Multivariate Analysis; Nitrophenols; Principal Component Analysis; Regression Analysis; Signal Processing, Computer-Assisted; Software; Spectrophotometry; Spectrophotometry, Ultraviolet

The salivary glands of insect's vectors are target organs to study the vectors-pathogens interactions. Rhodnius prolixus an important vector of Trypanosoma cruzi can also transmit Trypanosoma rangeli by bite. In the present study we have investigated ecto-phosphatase activity on the surface of R. prolixus salivary glands. Ecto-phosphatases are able to hydrolyze phosphorylated substrates in the extracellular medium. We characterized these ecto-enzyme activities on the salivary glands external surface and employed it to investigate R. prolixus-T. rangeli interaction. Salivary glands present a low level of hydrolytic activity (4.30+/-0.35 nmol p-nitrophenol (p-NP)xh(-1)xgland pair(-1)). The salivary glands ecto-phosphatase activity was not affected by pH variation; and it was insensitive to alkaline inhibitor levamisole and inhibited approximately 50% by inorganic phosphate (Pi). MgCl2, CaCl2 and SrCl2 enhanced significantly the ecto-phosphatase activity detected on the surface of salivary glands. The ecto-phosphatase from salivary glands surface efficiently releases phosphate groups from different phosphorylated amino acids, giving a higher rate of phosphate release when phospho-tyrosine is used as a substrate. This ecto-phosphatase activity was inhibited by carbohydrates as d-galactose and d-mannose. Living short epimastigotes of T. rangeli inhibited salivary glands ecto-phosphatase activity at 75%, while boiled parasites did not. Living long epimastigote forms induced a lower, but significant inhibitory effect on the salivary glands phosphatase activity. Interestingly, boiled long epimastigote forms did not loose the ability to modulate salivary glands phosphatase activity. Taken together, these data suggest a possible role for ecto-phosphatase on the R. prolixus salivary glands-T. rangeli interaction.

Topics: Animals; Calcium Chloride; Carbohydrates; Down-Regulation; Enzyme Activators; Enzyme Inhibitors; Host-Parasite Interactions; Hydrogen-Ion Concentration; Levamisole; Magnesium Chloride; Male; Nitrophenols; Phosphoric Monoester Hydrolases; Rhodnius; Salivary Glands; Strontium; Trypanosoma

Methyl parathion (MP), a highly toxic organophosphorus pesticide, was widely used for agriculture crop protection. During the production of MP and the process of MP-containing wastewater treatment, MP can release into the atmosphere and will do great harm to adjacent communities. A consortium comprised of an engineered microorganism and a natural p-nitrophenol (PNP) degrader was assembled for complete mineralization of MP. We genetically engineered Escherichia coli BL21 (DE3) enabling the overexpression of methyl parathion hydrolase (MPH). In addition, we isolated Ochrobactrum sp. strain LL-1 that utilized PNP, a product of MP hydrolysis, as the sole carbon, nitrogen, and energy source. The coculture effectively hydrolyzed 0.2 mM MP and prevented the accumulation of PNP in suspended culture. A laboratory-scale bioreactor containing the dual-species consortium was developed for the treatment of artificial off-gas containing MP. The bioreactor maintained over 98% of average MP removal efficiency over a 75 day period, and PNP produced from hydrolysis of MP was degraded completely, indicating that complete mineralization of MP was achieved. The strategy of linking degrading consortium to a bioreactor may provide an alternative to physicochemical abatement technologies for the treatment of waste-gas streams containing MP as well as other PNP-substituted organophosphates.

Topics: Air Pollutants; Bioreactors; Escherichia coli; Hydrolases; Insecticides; Methyl Parathion; Molecular Sequence Data; Nitrophenols; Ochrobactrum; RNA, Ribosomal, 16S; Sequence Analysis, RNA

Diesel exhaust is believed to consist of thousands of organic constituents and is a major cause of urban pollution. We recently reported that a systematic separation procedure involving successive solvent extractions, followed by repeated column chromatography, resulted in the isolation of vasodilatory active nitrophenols. These findings indicated that the estimation of the amount of nitrophenols in the environment is important to evaluate their effect on human health. The isolation procedure, however, involved successive solvent extractions followed by tedious, repeated chromatography, resulting in poor fractionation and in a significant loss of accuracy and reliability. Therefore, it was crucial to develop an alternative, efficient, and reliable analytical method. Here, we describe a facile and efficient acid-base extraction procedure for the analysis of nitrophenols.. Diesel exhaust particles (DEP) were collected from the exhaust of a 4JB1-type engine (ISUZU Automobile Co., Tokyo, Japan). Gas chromatography-mass spectrometry (GC-MS) analysis was performed with a GCMS-QP2010 instrument (Shimadzu, Kyoto, Japan).. A solution of DEP in 1-butanol was extracted with aqueous NaOH to afford a nitrophenol-rich oily extract. The resulting oil was methylated with trimethylsilyldiazomethane and subsequently subjected to GC-MS analysis, revealing that 4-nitrophenol, 3-methyl-4-nitrophenol, 2-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol were present in significantly higher concentrations than those reported previously.. Simple acid-base extraction followed by the direct analysis of the resulting extract by GC-MS gave only broad peaks of nitrophenols with a poor detection limit, while the GC-MS analysis of the sample pretreated with (trimethylsilyl)diazomethane gave satisfactorily clear chromatograms with sharp peaks and with a significantly lowered detection limit (0.5 ng/ml, approximately 100 times).. The present method involving an acid-base extraction, in situ derivatization, and GC-MS analysis has shown to be a simple, efficient, and reliable method for the isolation and identification of the chemical substances in DEP.

Topics: Air Pollutants; Biphenyl Compounds; Cities; Cresols; Diazomethane; Gas Chromatography-Mass Spectrometry; Humans; Japan; Methylation; Nanoparticles; Nitrophenols; Particulate Matter; Trimethylsilyl Compounds; Vehicle Emissions

Micelle-supported gold composites with a polystyrene core and a poly(4-vinyl pyridine)/Au shell are synthesized using NaBH(4) to reduce a mixture of micelle and HAuCl(4) in acidic aqueous solution (pH approximately 2). The template micelle with a polystyrene core and a poly(4-vinyl pyridine) shell is formed by self-assembly of block copolymer polystyrene-block-poly(4-vinyl pyridine). The gold nanoparticles coated onto the surfaces of the composites possess an average diameter of about 15 nm. The composites are applied to catalyze the reduction of p-nitrophenol in the presence of NaBH(4), and the results indicate that the kinetic constant of the reaction increases when the composite concentration and the reaction temperature increase. In addition, research results also indicate that composites with high content of gold show higher catalytic activity and higher catalytic efficiency.

Topics: Catalysis; Coated Materials, Biocompatible; Gold; Magnetic Resonance Spectroscopy; Metal Nanoparticles; Micelles; Nitrophenols; Oxidation-Reduction; Polystyrenes; Polyvinyls

In this study, attention was focused on substituted phenols because of their widespread presence in industrial effluents originating from many different sources: they are major constituents of wastewater from coal conversion processes, coke ovens, petroleum refineries and petrochemical industries, resin and fibreglass manufacturing and herbicide production. Moreover, for their characteristics of toxicity to humans and aquatic life (1 mgl(-1) is enough to detect the effects), they are included in the USEPA list of priority pollutants. Toxicity is higher in substituted phenols and is dependent on the nature and numbers of substituent groups. Objective of the present paper is to give a contribution to the modelling of phenolic mixture biodegradation by kinetic studies in which the different compounds are followed separately: this can be easily attained with an experimental apparatus such as the Sequencing Batch Reactor (SBR). Two substituted phenols, 4-nitrophenol (4NP) and 3,4-dimethylphenol (3,4DMP), were utilized as substrates and their degradation kinetics were investigated to evaluate the process parameters both in single compound and in mixture tests.. Single compound and mixture kinetic tests have been carried out during the reaction phase of the working cycle of the SBR reactor. The single substrates and their mixture were utilized as sole carbon and energy sources. Moreover, in order to verify data reproducibility, all kinetic tests have been carried out in at least two replicates under the same operating conditions.. Kinetic data showed the presence of substrate inhibition, to model this experimental evidence the Haldane equation, that is usually employed for substrate inhibited kinetics, was rearranged in a different form with parameters which have a precise meaning in relation to the process kinetics and, at the same time, make the integration procedure easier. The derivation of the equation is shown in an Appendix at the end of the paper. Kinetic parameters obtained are suitable for application. It was observed that the 4-nitrophenol removal rate in single compound tests is significantly higher than the 3,4-dimethylphenol removal rate in the whole range of investigated concentrations (up to 80 mg COD l(-1)). A faster 4-nitrophenol biodegradation was also observed in mixture tests. Moreover, it is worth noting that the two compounds were simultaneously degraded and no diauxic growth was observed. The comparison between single compound and mixture degradation kinetics showed that the 4-nitrophenol degradation rate was comparable in the two cases while a significantly beneficial effect (by increase by about 80% of the maximum removal rate) was detected for 3,4-dimethylphenol degradation in the mixture.. Results of this study showed that the biodegradation kinetics of substituted phenols in mixture can be significantly different from that observed in single compound tests: in fact, the presence of a faster degradable compound (the 4NP) seems to exert a positive effect on the removal of a slower degradable compound (the 3,4DMP). The higher removal rate detected for 4NP, both in single compound and mixture tests, confirmed the key role of the biomass acclimatization in determining the biodegradation kinetics of xenobiotic compounds. The experimental approach and the original method applied for data analysis are of general validity and can be extended to the investigation of different classes of compounds.. A relevant aspect related to the process applicability is the demonstrated possibility of easily adapting an enriched culture grown on a specific xenobiotic (in our case the 4NP) for the removal of similar single compounds or in mixtures. When biological process are considered for xenobiotic removal, this suggests a possible strategy of developing enriched cultures on target compounds that can be efficiently utilized on more complex matrices with reduced start up and acclimatization periods.

Topics: Biodegradation, Environmental; Bioreactors; Kinetics; Nitrophenols; Waste Management; Water Pollutants, Chemical; Xylenes

Sera from AIH (autoimmune hepatitis) type 2 patients contain an autoantibody against the UGT1A subtype, called anti-LKM3. Previously, we reported that sera in AIH type 1 patients contained autoantibodies against drug-metabolizing enzymes (Shinoda et al. (2004) Autoimmunity, 37, 473). In this report, we showed that AIH-1 sera did not react with some peptides in the C-terminal half of the UGT1A subtype but reacted with a peptide P1(33-42) among several common peptides in the N-terminal half of the UGT1A subtype. This result suggests that the P1 site (33-42) presents on the outside of the UGT1A molecule to be recognized by lymphocytes of the immune system to produce an autoantibody. To detect a key recognition site on peptide P1(33-42), we studied the reactivity of two peptides, M1(28-37) and M2(38-47), containing the N-terminal and C-terminal half of peptide P1. Peptide M2 did not react with AIH-1 serum but peptide M1 did. Thus, the common peptide sequence 33-37 in the positive peptide M1(28-37) and P1(33-42) is a key recognition sequence. Next, we studied the reactivity of some other synthetic peptides, in which some amino acids in the sequence 33-37 in peptide M1 changed to Ala. The peptides changing to Ala (PQ33-34AA) or (DGS35-37AAA) did not react with AIH-1 sera. Meanwhile, these AIH sera did not inhibit the glucuronidation of p-nitrophenol by UGT1A6, suggesting that the key sequence 33-37 might not be contained in active sites of glucuronidation by UGT1A6. In conclusion, sera from AIH-1 patients reacted with the amino acids in the sequence 33-37 (PQDGS) of the N-terminal of UGT1A6.

Topics: Amino Acid Sequence; Autoantibodies; Enzyme-Linked Immunosorbent Assay; Female; Glucuronides; Glucuronosyltransferase; Hepatitis, Autoimmune; Humans; Lymphocytes; Middle Aged; Nitrophenols; Peptides

The photooxidative degradation of 4-nitrophenol (4-NP) was studied in the UV/H2O2 process. The effects of applied H2O2 dose, initial 4-NP concentration and UV light intensity have been studied. Degradation was complete in 13 min and follows apparent first-order kinetics. The removal efficiency of 4-NP depends on the operational parameters and increases as the initial concentration of H2O2 and light intensity are increased but it decreases when the initial concentration of 4-NP is increased. From HPLC analysis, major intermediate products were hydroxyl derivatives of 4-NP as a result of photooxidative hydroxylation.

Topics: Chromatography, High Pressure Liquid; Hydrogen Peroxide; Kinetics; Nitrophenols; Oxidation-Reduction; Photolysis; Ultraviolet Rays; Water Purification

The adsorption of p-nitrophenol (PNP) onto activated carbon fiber (ACF) was investigated in simulated wastewater in a batch system to evaluate the effects of solution pH, presence of sodium chloride, adsorbent doses and temperature. It was found that PNP adsorption amount depended on pH, sodium chloride content, adsorbent doses and temperature. Langmuir and Freundlich models were applied to describe the adsorption isotherms. Freundlich model agreed with experimental data well, indicating the possibility of more than just one monomolecular layer of coverage. SEM photographs of ACF before and after adsorption revealed that it was in part with multimolecular layers of coverage on ACF surfaces. The change of free energy, enthalpy, and entropy of adsorption were also evaluated for the adsorption process. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The experimental data fitted very well the pseudo-second-order kinetic model. Attempts were made to desorb PNP from ACF using dilute NaOH solution and water, and desorption efficiency was obtained to the extent of 92.7% with 0.025 M NaOH and water at 368 K.

Topics: Adsorption; Charcoal; Hydrogen-Ion Concentration; Kinetics; Microscopy, Electron, Scanning; Nitrophenols; Sodium Chloride; Temperature; Textiles; Thermodynamics; Waste Disposal, Fluid

Novel aryl beta-d-galactopyranosides were synthesized employing phase-transfer catalysis, and assayed as potential galactose donors in the presence of beta-galactosidase from bovine testes using pNP-Gal as a reference. The aglycones were represented mainly by nitrophenols containing halogens, hydroxymethyl, aldehyde, carboxyl, ester or amino functions. An unusual intermolecular acetyl migration onto the benzylic alcohol group was observed during galactosylation of hydroxymethylnitrophenols. Pyridyl glycosides were obtained by reaction with the corresponding silver pyridinolates. Glycosides of halo-, hydroxymethyl- or methoxycarbonyl-nitrophenols as leaving groups gave virtually the same yields of transglycosylation products. A minor increase was achieved with nitrosalicylaldehyde as leaving group, whereas carboxy or amino derivatives gave very low or no yield of the transglycosylation product. Commercially available donors such as resorufinyl and 4-methylumbelliferyl beta-d-galactopyranosides exhibited a lower transglycosylation potential than these novel pNP-Gal derivatives.

Topics: Animals; beta-Galactosidase; Cattle; Chromatography, High Pressure Liquid; Glycosylation; Male; Nitrophenols; Nitrophenylgalactosides; Nuclear Magnetic Resonance, Biomolecular; Testis

Aqueous 4-nitrophenol solutions containing TiO2 or Al2O3 nanoparticles were irradiated with electron beam. 4-Nitrophenol was decomposed by the ionizing radiation process in the absence of the nanoparticles. The addition of TiO2 or Al2O3 (2 g l(-1)) before irradiation improved the removal of 4-nitrophenol, total organic carbon (TOC) but also nitrogen (TN). To identify the origin of the loss (catalysis or simply adsorption), TiO2 or Al2O3 nanoparticles were added after irradiation. Experiments show that the effect of the presence of TiO2 or Al2O3 during irradiation is just due to adsorption.

Topics: Adsorption; Aluminum Oxide; Chromatography, High Pressure Liquid; Electrons; Nanoparticles; Nitrophenols; Radiation, Ionizing; Titanium; Water Pollutants, Chemical; Water Pollution

The degradation of 4-nitrophenol by electro-Fenton (E-Fenton) method was carried out in batch recirculation mode. The effect of operating conditions such as electrical current, Fenton's reagent dosage, Fe(II) to H(2)O(2) molar ratio, and H(2)O(2) feeding time on the efficiency of E-Fenton process was investigated. It was found that E-Fenton method showed the synergetic effect on COD removal. The increase of Fenton's reagent dosage, Fe(II) to H(2)O(2) molar ratio, and the electrical current would lead to the increase of COD removal efficiency. Continuous addition of hydrogen peroxide was more effective than the addition of hydrogen peroxide in a single step and there existed an optimal H(2)O(2) feeding time for COD removal. The reaction system was modeled as a plug flow reactor (PFR) in series with a continuous stirred tank reactor (CSTR), and the pseudo-first order rate constant of COD removal was determined from the model based on the experimental data.

Topics: Electrochemistry; Hydrogen Peroxide; Iron; Nitrophenols; Oxidation-Reduction; Water Pollutants, Chemical; Water Purification

Ionic permselectivity of DNA films has been investigated by the analysis of the electrochemical response of methylene blue (MB) as a function of pH and ionic strength on DNA-modified electrodes in aqueous p-nitrophenol (p-NP) and phosphate buffers. We have observed a linear Pourbaix diagram in p-NP buffer indicating that the reduction of MB occurs with a two-electron plus one-proton reaction. Interestingly, in phosphate buffer the Pourbaix diagram is curved and this suggests that the thermodynamics of MB incorporated in the film depend also on the ratio of mono- versus divalent anions in the bulk. This result indicates that DNA films do not behave as pure ion-exclusion films, but instead there is a differential permselectivity that depends on the identity of the anions. Based on this consideration of the ionic distribution in the films, we provide a new method for the analysis of the DNA surface coverage based on AC impedance of an anionic species, ferricyanide. The methodology is of particular value in analyzing DNA hybridization and dehybridization. This approach presents an advantage compared to standard ruthenium hexammine assays since our methodology is insensitive to film morphology, and is highly sensitive to the amount of negative charge on the surface.

Topics: Buffers; Chromatography, High Pressure Liquid; DNA; Electrochemistry; Electrodes; Ferrocyanides; Hydrogen-Ion Concentration; Indicators and Reagents; Membranes, Artificial; Methylene Blue; Nitrophenols; Oligonucleotides; Phosphates; Ruthenium Compounds; Thermodynamics

Arthrobacter chlorophenolicus is a previously described Gram-positive bacterium capable of degrading high concentrations of several phenolic compounds under optimal mesophilic (28 degrees C) as well as psychrophilic (5 degrees C) conditions. However, the exact mechanisms by which this organism is able to tolerate such extremes in temperature and high levels of toxic compounds are currently not known. In this study, we monitored changes in the fatty acid composition of the cell membrane under different extreme growth conditions. Arthrobacter chlorophenolicus adapts to differences in temperature and phenol concentrations by altering the anteiso/iso ratio of fatty acids in the cell membrane to different extents. According to the different physico-chemical properties of those two species of branched fatty acids, the bacteria showed an increased amount of anteiso fatty acids when grown under psychrophilic conditions to decrease the viscosity of their membranes. On the other hand, at higher growth temperatures as well as in the presence of toxic concentrations of phenol, 4-chlorophenol and 4-nitrophenol, the cells adapted their membrane by a dose-dependent decrease in the anteiso/iso ratio, leading to a more rigid membrane and counteracting the fluidity increase caused by the higher temperature and the organic solvents.

Topics: Adaptation, Physiological; Arthrobacter; Cell Membrane; Chlorophenols; Chromatography, Gas; Fatty Acids; Membrane Fluidity; Nitrophenols; Phenols; Temperature

Heavy metals and surfactants have a significant effect on the sorption of organic contaminants. In this study, batch equilibrium experiments were carried out to investigate the influence of Pb(NO(3))(2) on the sorption of p-nitrophenol (PNP) onto sediments in the presence of cationic surfactant cetylpyridinium chloride (CPC). Results indicated that in the complex system containing PNP, Pb(NO(3))(2) and CPC, the sorption of PNP decreased with increasing concentration of Pb(NO(3))(2) due primarily to competing for adsorption sites. Likewise, partitioning of PNP in adsorbed surfactant layers and micelles decreased with increasing level of Pb(NO(3))(2). Moreover, the influence of different metal ions (Pb(2+), Cd(2+), Zn(2+)) was examined and results indicated that the presence of heavy metals inhibited the sorption of PNP in the order: Pb(2+)>Cd(2+)>Zn(2+). The competitive effect of the heavy metals was in agreement with the hydration energy and hydrated radius. The results are believed to provide a useful insight into describing the transport and fate of PNP in natural environments.

Topics: Adsorption; Cations, Divalent; Cetylpyridinium; Geologic Sediments; Metals, Heavy; Models, Chemical; Nitrophenols; Surface-Active Agents; Water Pollutants, Chemical

The cyclization of the RNA model 2-hydroxypropyl p-nitrophenyl phosphate (HPNPP, 1) promoted by Zn2+ alone and the 1,5,9-triazacyclododecane complex of Zn2+ (Zn2+:[12]aneN3) is studied in ethanol in the presence of 0.5 equiv of -OEt/Zn2+ to investigate the effect of a low polarity/dielectric medium on a metal-catalyzed reaction of biological relevance. Ethanol exerts a medium effect that promotes strong binding of HPNPP to Zn2+, followed by a dimerization to form a catalytically active complex (HPNPP:Zn2+)2 in which the phosphate undergoes cyclization with a rate constant of kcat = 2.9 s(-1) at s(s)pH 7.1. In the presence of the triaza ligand:Zn2+ complex, the change from water to methanol and then to ethanol brings about a mechanism where two molecules of the complex, suggested as EtOH:Zn2+:[12]aneN3 and its basic form, EtO-:Zn2+:[12]aneN3, bind to HPNPP and catalyze its decomposition with a rate constant of kcat of 0.13 s(-1) at s(s)pH 7.1. Overall, the acceleration exhibited in these two situations is 4 x 10(14)-fold and 1.7 x 10(12)-fold relative to the background ethoxide-promoted reactions at the respective s(s)pH values. The implications of these findings are discussed within the context of the idea that enzymatic catalysis is enhanced by a reduced effective dielectric constant within the active site.

Topics: Biomimetics; Catalysis; Cyclization; Ethanol; Methanol; Molecular Structure; Nitrophenols; Organometallic Compounds; Organophosphates; Organophosphorus Compounds; Oxidation-Reduction; Sensitivity and Specificity; Zinc

This work deals with a new abiotic oxidation process designed as a suitable pre-treatment step within a biological depuration of wastewater containing phenol or its derivatives (o-cresol, 2-chlorophenol and p-nitrophenol) or aniline. The reaction was carried out in a stirred tank reactor at 20 degrees C and atmospheric pressure in presence of the organic compound, 150mgl(-1), zero valent iron particles (10g), ethylenediamine tetraacetic acid (EDTA, 101mgl(-1)) and air. The experimental results show that 85% of phenol conversion can be achieved after 360min. 2-Chlorophenol was found to be more easily degradable and it is completely eliminated after 300min. The oxidation of o-cresol and aniline behaved more closely to phenol obtaining after 360min 70% and 68% of conversion respectively. p-Nitrophenol was a very refractory compound, giving only 28% of conversion after 360min. Moreover, the influence of some operating variables was studied over the following ranges: temperature from 20 to 50 degrees C, initial phenol concentration from 150 to 1000mgl(-1), EDTA concentration from 50 to 200mgl(-1) and iron particles from 5 to 20g. As expected, temperature strongly enhances phenol conversion. Also, an increase of the catalyst to phenol ratio or the iron or EDTA to phenol ratio improves the reaction rate. A preliminary kinetic analysis of the data shown that the rate of phenol disappearance is not first order with respect to the phenol.

Topics: Aniline Compounds; Atmospheric Pressure; Catalysis; Chlorophenols; Cresols; Edetic Acid; Environmental Restoration and Remediation; Iron; Nitrophenols; Oxidation-Reduction; Phenols; Temperature; Water Purification

Previous studies [Transfusion 2005;45:384] showed that certain chemical compounds containing sulfur-reactive groups can inhibit Fcgamma receptor (FcgammaR)-mediated phagocytosis in vitro. These studies, however, did not prove that only sulfur functionality-induced reactivity was efficacious. In an effort to develop a drug-based approach for the future treatment of immune-mediated cytopenias, these earlier findings have now been extended and this chemically induced interference with FcgammaR-mediated phagocytosis of anti-D-coated red cells (RBCs) was examined to assess the optimal structural requirements for the inhibitory effect.. Chemical compounds were purchased or synthesized and used for the assessment of which chemical moiety(-ies) were required for successful inhibition of in vitro phagocytosis of anti-D-coated RBCs with a monocyte monolayer assay.. Using compounds having similar structures but differences in reactive moieties, it was proved that the only chemical moiety that was required for inhibition of FcgammaR-mediated phagocytosis in vitro was a disulfide bond. It is also shown, however, that a p-nitrophenyl group provides significant enhancement to the inhibitory effect of disulfide-containing compounds. Involvement of carbonyl and hydroxyl functional groups was also able to be ruled out.. Our results confirm and extend previous studies that suggested that only those compounds that target free sulfhydryl groups on the monocyte-macrophage are most effective at blocking phagocytosis of antibody-coated RBCs in vitro. It is also shown that p-nitrophenyl substituent groups have an enhancing effect on the efficacy of disulfide bond-containing compounds. These findings should aid in the design of a drug-based approach for the future treatment of immune cytopenias.

Topics: Antibodies; Disulfides; Erythrocytes; Humans; In Vitro Techniques; Macrophages; Nitrobenzenes; Nitrophenols; Phagocytosis; Receptors, IgG; Structure-Activity Relationship; Sulfhydryl Compounds

In vitro alkaline elution is a sensitive and specific short term assay which measures DNA strand breakage in a mammalian test system (primary rat hepatocytes). This lab has previously demonstrated the performance of the assay with known genotoxic and non-genotoxic compounds. The methodology employed has relatively low sample throughput and is labor-intensive, requiring a great deal of manual processing of samples in a format that is not amenable to automation. Here, we present an automated version of the assay. This high-throughput alkaline elution assay (HT-AE) was made possible through 3 key developments: (1) DNA quantitation using PicoGreen and OliGreen fluorescent DNA binding dyes; (2) design and implementation of a custom automation system; and (3) reducing the assay to a 96-well plate format. The assay can now be run with 5-50mg of test compound. HT-AE was validated in a similar manner as the original assay, including assessment of non-genotoxic and non-carcinogenic compounds and evaluation of cytotoxicity to avoid confounding effects of toxicity-associated DNA degradation. The validation test results from compounds of known genotoxic potential were used to set appropriate criteria to classify alkaline elution results for genotoxicity.

Topics: Animals; Biological Assay; Cell Survival; Cells, Cultured; Chlorophenols; Chlorpheniramine; DNA; DNA Damage; Dose-Response Relationship, Drug; Hepatocytes; Hydrogen-Ion Concentration; In Vitro Techniques; Male; Mutagenicity Tests; Mutagens; Nitrophenols; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Sensitivity and Specificity; Toxicity Tests

Simulated solar UV/TiO(2) photocatalysis was efficient to detoxify a mixture of 100 mgphenoll(-1) and 50 mgp-nitrophenol (PNP) l(-1) and allow the subsequent biodegradation of the remaining pollutants and their photocatalytic products under photosynthetic aeration with Chlorella vulgaris. Photocatalytic degradation of phenol and PNP was well described by pseudo-first order kinetics (r(2)>0.98) with removal rate constants of 1.9x10(-4) and 2.8x10(-4)min(-1), respectively, when the pollutants were provided together and 5.7x10(-4) and 9.7x10(-4)min(-1), respectively, when they were provided individually. Photocatalytic pre-treatment of the mixture during 60 h removed 50+/-1% and 62+/-2% of the phenol and PNP initially present but only 11+/-3% of the initial COD. Hydroquinone, nitrate and catechol were identified as PNP photocatalytic products and catechol and hydroquinone as phenol photocatalytic products. Subsequent biological treatment of the pre-treated samples removed the remaining contaminants and their photocatalytic products as well as 81-83% of the initial COD, allowing complete detoxification of the mixture to C. vulgaris. Similar detoxification efficiencies were recorded after biological treatment of the irradiated mixture with activated sludge microflora or with an acclimated consortia composed of a phenol-degrading Alcaligenes sp. and a PNP-degrading Arthrobacter sp., although the acclimated strains biodegraded the remaining pollutants faster. Biological treatment of the non-irradiated mixture was inefficient due to C. vulgaris inhibition.

Topics: Alcaligenes; Arthrobacter; Catalysis; Chlorella vulgaris; Chlorophyll; Lepidium sativum; Nitrophenols; Phenol; Photosynthesis; Plant Stems; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Water Pollutants, Chemical

Water purification is of extreme importance to modern society. Organoclays through adsorption of recalcitrant organics provides one mechanism for the removal of these molecules. The organoclay was synthesised through ion exchange with dimethyldioctadecylammonium bromide labeled as DDOAB of formula (CH3(CH2)17)2NBr(CH3)2. Paranitrophenol (pnp) was adsorbed on the organoclay at a range of concentrations according to the cation exchange capacity (CEC) of the host montmorillonite. The paranitrophenol in solution was analysed by a UV-260 spectrophotometer at 317 nm, with detection limits being 0.05 mg/L. The expansion of the montmorillonite was studied by a combination of X-ray diffraction and transmission electron microscopy. Upon adsorption of the paranitrophenol the basal spacing decreased. The thermal stability of the organoclay was determined by a combination of thermogravimetry and infrared emission spectroscopy. The surfactant molecule DDOAB combusts at 166, 244, and 304 degrees C and upon intercalation into Na-montmorillonite is retained up to 389 degrees C thus showing the organoclay is stable to significantly high temperatures well above the combustion/decomposition temperature of the organoclay.

Topics: Adsorption; Bentonite; Microscopy, Electron, Transmission; Nitrophenols; Particle Size; Quaternary Ammonium Compounds; Sensitivity and Specificity; Surface Properties; Temperature; X-Ray Diffraction

A simple, novel and sensitive spectrophotometric method was described for simultaneous determination of nitrophenol isomers mixtures. All factors affecting on the sensitivity were optimized and the linear dynamic range for determination of nitrophenol isomers were found. The simultaneous determination of nitrophenol mixtures by using spectrophotometric methods is a difficult problem, due to the spectral interferences. The partial least squares modeling was used for the multivariate calibration of the spectrophotometric data. The orthogonal signal correction was used for preprocessing of data matrices and the prediction results of model, with and without using orthogonal signal correction, were statistically compared. The experimental calibration matrix was designed by measuring the absorbance over the range 300-520 nm for 21 samples of 1-20, 1-20 and 1-10 microg ml(-1) of m-nitrophenol, o-nitrophenol and p-nitrophenol, respectively. The RMSEP for m-nitrophenol, o-nitrophenol and p-nitrophenol with and without OSC were 0.3682, 0.5965, 0.3408 and 0.7351, 0.9962, 1.0055, respectively. The proposed method was successfully applied for the determination of m-nitrophenol, o-nitrophenol and p-nitrophenol in synthetic and real matrix samples such as water.

Topics: Industrial Waste; Least-Squares Analysis; Nitrophenols; Rivers; Spectrophotometry; Water Pollutants, Chemical; Water Supply

A bacterium capable of utilizing p-nitrophenol (PNP) as the sole nitrogen, carbon, and energy source was isolated from mangrove sediment. This bacterium was confirmed based on 16S rDNA sequence analysis and taxonomic analysis as being a member of the genus Rhodococcus and was designated strain Ns. The strain Ns could tolerate high concentrations of PNP up to 1.5 mmol/L and complete degradation was achieved in four days at 30 degrees C in the dark under aerobic conditions. Biodegradation of PNP quickly occurred at optimal pH above 5.0, and at least 5 per thousand salinity. Bacterial growth on PNP was observed with the simultaneous production of 4-nitrocatechol, which was also degraded by the same bacterium, as a degradation intermediate, Moreover, Rhodococcus sp. Ns was able to also deplete 2-nitrophenol(ONP) as the sole source of carbon, nitrogen and energy, but not 3-nitrophenol. The experimental results show that bacteria indigenous to the natural wetland sediment are capable of complete degradation of PNP and ONP.

Topics: Biodegradation, Environmental; Nitrophenols; Rhizophoraceae; Rhodococcus

Curcumin glucosyltransferase (CaUGT2) isolated from cell cultures of Catharanthus roseus exhibits unique substrate specificity. To identify amino acids involved in substrate recognition and catalytic activity of CaUGT2, a combination of domain swapping and site-directed mutagenesis was carried out. Exchange of the PSPG-box of CaUGT2 with that of NtGT1b (a phenolic glucosyltransferase from tobacco) led to complete loss of enzyme activity in the resulting recombinant protein. However, replacement of Arg378 of the NtGT1b PSPG-box with cysteine, the corresponding amino acid in CaUGT2, restored the catalytic activity of the chimeric enzyme. Further site-directed mutagenesis revealed that the size of the amino acid side-chain in that particular site is critical to the catalytic activity of CaUGT2.

Topics: Amino Acid Sequence; Amino Acid Substitution; Arginine; Catalysis; Catalytic Domain; Catharanthus; Curcumin; Cysteine; Glucosyltransferases; Kinetics; Molecular Sequence Data; Molecular Structure; Mutagenesis, Site-Directed; Nitrophenols; Phylogeny; Plant Proteins; Sequence Homology, Amino Acid; Substrate Specificity

The electrochemical oxidative removal of p-chlorophenol and p-nitrophenol was studied by cyclic voltammetry (CV) and constant current electrolysis on commercially available graphite and titanium substrate insoluble anodes (TSIA). The effect of cationic cetyl trimethylammonium bromide (CTAB), anionic sodium dodecyl sulphate (SDS) and non-ionic polyoxyethylene(23)lauryl ether (Brij-35) surfactants, which prevent adherent film formation on the electrode surface were also studied. CV experiments indicate that p-chlorophenol exhibits a relatively higher tendency for film formation on graphite and that sodium chloride is a better medium for the destruction of phenols. The electrochemical oxidation of phenols under galvanostatic conditions in chloride medium with CTAB enhanced the detoxification process with significantly lower fouling effects on TSIA. The surfactants, however, did not improve phenol removal on graphite under identical experimental conditions. A charge of 2.5F per mol was found to be sufficient to achieve 44-48% removal of phenol on both the electrodes in the absence of the surfactants. A 55-65% removal was achieved in the presence of the cationic surfactant on the TSIA electrode. Phenol was removed as a low molecular weight polymer (MW approximately 4450).

Topics: Chlorophenols; Electrochemistry; Electrodes; Nitrophenols; Surface-Active Agents

Chromogenic mono- and diferuloyl-butanetriol analogs were prepared by chemical syntheses and their efficiency was evaluated as substrates for feruloyl esterases from Aspergillus niger.

Topics: Animals; Aspergillus niger; Carboxylic Ester Hydrolases; Cattle; Chromatography, Thin Layer; Chromogenic Compounds; Hydrolysis; Kinetics; Magnetic Resonance Spectroscopy; Models, Chemical; Nitrophenols; Protein Binding; Serum Albumin, Bovine; Substrate Specificity; Time Factors

Pseudomonas pseudomallei EBN-10 strain, previously isolated from a local pharmaceutical industry's wastewater, was spontaneously adapted to higher p-nitrophenol (PNP) levels, which then was subjected to gamma ray-induced mutagenesis; the efficient isolates hence obtained were designated as EBN-11 and EBN-12, respectively. EBN-12 mutant strain could completely mineralize PNP (100 mg/L) on the minimal media in 24 h while, the parent strain utilized only 6% of it. Addition of glucose as co-substrate further increased the PNP degradation rate; however, phenol inclusion inhibited the degradation process. Ammonium sulphate was experienced as the best of the nitrogen sources used by EBN-12 mutant strain, while degrading PNP.

Topics: Burkholderia pseudomallei; Culture Media; Kinetics; Mutation; Nitrophenols

Silver nanoshell coated cationic polystyrene beads have been synthesized at room temperature through immobilization of specific silver precursor ions followed by wet chemical reduction technique. Electrostatic field force has been taken into consideration for the immobilization of precursor ions onto the resin beads. The as-synthesized particles were characterized by XRD, XPS, SEM, EDX, and FTIR studies. The silver coated resin beads have been exploited as a solid phase catalyst to reduce 4-nitrophenol in presence of sodium borohydride. The detailed kinetics of the reduction process was monitored under varied experimental conditions. At the end of the reaction, the catalyst particles remain active, get separated from the product, 4-aminophenol and can be recycled for a number of times after the quantitative reduction of 4-nitrophenol. The activity of the solid-catalyst particles has been examined towards the reduction of other nitrophenols e.g., o-, m-nitrophenol and also for 2,4,6-trinitrophenol. The synthesis of anthranilic acid from o-nitrobenzoic acid has also been achieved using the composite materials as catalyst. The synthesis of the solid phase catalyst particles, their application and detailed kinetic aspects of the reduction of 4-nitrophenol have been reported.

Topics: Borohydrides; Catalysis; Coated Materials, Biocompatible; Crystallization; Macromolecular Substances; Materials Testing; Molecular Conformation; Nanostructures; Nanotechnology; Nitrophenols; Particle Size; Polystyrenes; Silver; Surface Properties

Water purification is of extreme importance worldwide. p-Nitrophenol was used as a test chemical to design and test an organoclay for the removal of p-nitrophenol from an aqueous solution. Synthesis of the organoclay with methyltrioctadecylammonium bromide [CH(3)(CH(2))(17)](3)NBr(CH(3)) labeled as MTOAB results in multiple expansions of the montmorillonite clay from 1.24 nm to a maximum of 5.20 nm as is evidenced by the XRD patterns. Thermal analysis shows strong bonding of the surfactant to the clay siloxane layers and the interaction of the p-nitrophenol with the clay surfaces. It is proposed that the p-nitrophenol penetrates the siloxane layer of the clay and bonds through the ditrigonal space of the siloxane hexagonal units to the inner OH units. Such a concept is supported by the observation of an additional infrared band at 3652 cm(-1) for the organoclay. Shifts in the p-nitrophenol OH stretching vibrations mean a strong interaction of the p-nitrophenol molecule. Significant changes in the siloxane stretching bands are also observed.

Topics: Adsorption; Aluminum Silicates; Bentonite; Bromides; Chemistry, Physical; Clay; Nitrophenols; Quaternary Ammonium Compounds; Sodium; Spectrophotometry, Infrared; Surface Properties; Temperature; Thermogravimetry; X-Ray Diffraction

A biosensing system based on alpha-glucosidase (AG) activity was developed by using bismuth film modified glassy carbon electrode (BiFE). AG enzyme was immobilized on the BiFE by means of gelatin membrane and the activity was measured by the following of liberated 4-nitrophenol from the 4-nitrophenyl-alpha-D-glucopyranoside (PNPGP) which is the synthetic substrate of the enzyme at the working potential of -950 mV. The proposed system was used as an AG based biosensing system. Experimental data showed that the response current of 4-nitrophenol obtained at the BiFE was linear in concentration range between 0.033 and 0.33 mM of PNPGP. Before examining the analytical characteristics, pH optimization of the AG-biosensor was also performed. Furthermore, the proposed method was applied to analyze two different AG inhibitors (Amaryl and Acorbose) which are important in Noninsulin-dependent diabetes mellitus (NIDDM).

Topics: alpha-Glucosidases; Biosensing Techniques; Bismuth; Electrochemistry; Electrodes; Enzyme Inhibitors; Enzymes, Immobilized; Glycoside Hydrolase Inhibitors; Hydrogen-Ion Concentration; Nitrophenols; Sulfonylurea Compounds

Porcine microsomes are able to hydroxylate chlorzoxazone and p-nitrophenol, the most commonly used human test substrates for CYP2E1. However, in pigs, CYP2E appears not to be the only enzyme involved in the hydroxylation of chlorzoxazone and p-nitrophenol, as the enzyme capacity and immunochemical level of the apoprotein do not correlate. The present study shows that the hydroxylation of chlorzoxazone and p-nitrophenol is inhibited 50-65% by anti-human CYP2A6, suggesting that these substrates are metabolized almost equally well by CYP2A and CYP2E in pigs. To find an alternative probe to porcine CYP2E, bupropion, another human substrate, was examined. Incubation with bupropion concentrations ranging from 0.05 to 20 mM and with various inhibitors revealed that this substrate is metabolized by both CYP2A and CYP2E. At the high substrate concentration (5 mM), however, the CYP2A6 inhibition decreased compared to inhibition percentages found using the low substrate concentration (0.5 mM). The opposite was found for CYP2E, as inhibition studies with antibodies and diethyldithiocarbamate indicate that it catalysed a negligible part of the reaction at the low substrate concentration and up to 84% at the high concentration. Thus, hydroxylation of bupropion follows the same pattern in pigs as in human beings and the activity measured in pigs is comparable with the human counterpart. Furthermore, bupropion is a more specific substrate for CYP2E than chlorzoxazone and p-nitrophenol although not perfect.

Topics: Animals; Bupropion; Chlorzoxazone; Cytochrome P-450 CYP2E1; Female; Hydroxylation; Male; Microsomes, Liver; Nitrophenols; Substrate Specificity; Swine; Swine, Miniature

In the present study we prepared a hyper-cross-linked polymeric adsorbent (NDA-701) possessing a uniquely bimodal pore size distribution for 4-nitrophenol (4-NP) adsorption from water. A macroporous polymeric adsorbent Amberlite XAD-4 and a granular activated carbon GAC-1 were chosen for comparison. NDA-701 exhibited better mechanical strength and higher capacity of 4-NP than XAD-4, which possibly resulted from its hyper-cross-linking nature and micropore structure, respectively. 4-NP adsorption isotherm onto NDA-701 is well described by the Freundlich model, and its better kinetics performance than GAC-1 resulted from its macropore structure. After adsorption NDA-701 was amenable to an entire regeneration by using NaOH solution as regenerant, whereas only approximately 75% regeneration efficiency was observed for GAC-1. Results of continuous fixed-bed runs in pilot and industrial scale demonstrated that NDA-701 is capable of completely removing 4-NP from chemical effluent with no capacity loss, and 4-NP can be readily recovered by further treatment of the concentrated regenerant solution. It is attractive that the value of the recovered 4-NP from chemical wastewater will even engender a surplus after countervailing all the operation cost during field application.

Topics: Adsorption; Kinetics; Microscopy, Electron, Scanning; Nitrophenols; Polymers; Thermodynamics

The npd gene cluster, which encodes the enzymes of a p-nitrophenol catabolic pathway from Arthrobacter sp. strain JS443, was cloned and sequenced. Three genes, npdB, npdA1, and npdA2, were independently expressed in Escherichia coli in order to confirm the identities of their gene products. NpdA2 is a p-nitrophenol monooxygenase belonging to the two-component flavin-diffusible monooxygenase family of reduced flavin-dependent monooxygenases. NpdA1 is an NADH-dependent flavin reductase, and NpdB is a hydroxyquinol 1,2-dioxygenase. The npd gene cluster also includes a putative maleylacetate reductase gene, npdC. In an in vitro assay containing NpdA2, an E. coli lysate transforms p-nitrophenol stoichiometrically to hydroquinone and hydroxyquinol. It was concluded that the p-nitrophenol catabolic pathway in JS443 most likely begins with a two-step transformation of p-nitrophenol to hydroxy-1,4-benzoquinone, catalyzed by NpdA2. Hydroxy-1,4-benzoquinone is reduced to hydroxyquinol, which is degraded through the hydroxyquinol ortho cleavage pathway. The hydroquinone detected in vitro is a dead-end product most likely resulting from chemical or enzymatic reduction of the hypothetical intermediate 1,4-benzoquinone. NpdA2 hydroxylates a broad range of chloro- and nitro-substituted phenols, resorcinols, and catechols. Only p-nitro- or p-chloro-substituted phenols are hydroxylated twice. Other substrates are hydroxylated once, always at a position para to a hydroxyl group.

Topics: Arthrobacter; Bacterial Proteins; Cloning, Molecular; Escherichia coli; Genes, Bacterial; Kinetics; Molecular Sequence Data; Multigene Family; Nitrophenols; Oxygenases; RNA, Bacterial; RNA, Ribosomal, 16S; Substrate Specificity

In the present study we investigate the biochemical properties of the members of NPP family in synaptosomes prepared from rat heart left ventricles. Using p-nitrophenyl-5'-thymidine monophosphate (p-Nph-5'-TMP) as substrate for E-NPPs in rat cardiac synaptosomes, we observed an alkaline pH dependence, divalent cation dependence and the K ( M ) value corresponded to 91.42 +/- 13.97 microM and the maximal velocity (V ( max )) value calculated was 63.79 +/- 3.59 nmol p-nitrophenol released/min/mg of protein (mean +/- SD, n = 4). Levamisole (1 mM), was ineffective as inhibitor of p-Nph-5'-TMP hydrolysis in pH 8.9 (optimum pH for the enzyme characterized). Suramin (0.25 mM) strongly reduced the hydrolysis of p-Nph-5'-TMP by about 46%. Sodium azide (10 and 20 mM) and gadolinium chloride (0.3 and 0.5 mM), E-NTPases inhibitors, had no effects on p-Nph-5'-TMP hydrolysis. RT-PCR analysis of left ventricle demonstrated the expression of NPP2 and NPP3 enzymes, but excluded the presence of NPP1 member. By quantitative real-time PCR we identified the NPP3 as the enzyme with the highest expression in rat left ventricle. The demonstration of the presence of the E-NPP family in cardiac system, suggest that these enzymes could contribute with the fine-tuning control of the nucleotide levels at the nerve terminal endings of left ventricles that are involved in several cardiac pathologies.

Topics: Animals; Antineoplastic Agents; Enzyme Inhibitors; Heart Ventricles; Hydrolysis; Male; Nitrophenols; Phosphoric Diester Hydrolases; Pyrophosphatases; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sodium Azide; Suramin; Synaptosomes; Thymidine Monophosphate

A range of compounds were evaluated as probes for the indirect detection of inorganic ions using CE and light-emitting diodes (LEDs) as the light source. Emphasis was placed on examining probes likely to absorb strongly in the UV-Vis region near 350-430 nm as compounds, which absorb at longer wavelengths tend to be bulkier and adsorb onto the capillary wall. These probes should act as a replacement for the very effective but carcinogenic probe chromate. Two probes were identified and evaluated: p-nitrophenol and 4-hydroxy-3,5-dinitrobenzoic acid. The former showed the most potential with low-mobility anions, while the later had a moderate electrophoretic mobility and was more suitable for a wider mobility range of analytes. However, neither could match the efficiencies and LOD of chromate for the separation of the fast inorganic ions such as chloride, nitrate and sulphate. Nevertheless, application of the 4-hydroxy-3,5-dinitrobenzoic acid system to the determination of oxalate in Bayer liquors showed excellent sensitivity and selectivity.

Topics: Anions; Chromates; Chromogenic Compounds; Electrophoresis, Capillary; Inorganic Chemicals; Light; Molecular Probes; Nitrobenzoates; Nitrophenols; Sensitivity and Specificity; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Ultraviolet Rays

The cytochrome P450 enzymes (P450s) that mediate mammalian xenobiotic metabolism are highly versatile monooxygenases, which show wide and overlapping substrate ranges but generally poor catalytic rates. Re-engineering of these P450s may enable the development of useful biocatalysts for industrial applications. In the current study, restriction enzyme-mediated DNA family shuffling was used to create a library from human CYP1A1 and CYP1A2. Among sequenced clones (four randomly selected and eight functional clones), 5.9 +/- 2.3 crossovers and 1.5 +/- 1.5 spontaneous mutations (mean +/- S.D.) were detected per mutant. A high level of structural integrity as well as diverse functionality were found, with 53% of clones expressed at significant levels (>50 nM P450 hemoprotein) and 23% of clones showing activity on one or more of the following compounds: luciferin 6'-chloroethyl ether (luciferin-CEE), luciferin 6'-methyl ether (luciferin-ME), 6'-deoxyluciferin (luciferin-H), the ethylene glycol ester of luciferin 6'-methyl ether, 7-ethoxyresorufin, and p-nitrophenol (PNP). Different activity profiles were seen with higher specific activity on individual compounds (e.g., clone 22; 9 times the CYP1A1 specific activity toward luciferin-CEE), novel activities (e.g., clone 35; activity toward luciferin-H and PNP), and broadening of substrate range observed in particular clones (e.g., clone 9; activity toward both selective substrates luciferin-ME and luciferin-CEE as well as toward luciferin-H and PNP). In summary, forms were found with distinct and novel activity profiles, despite the relatively small number of mutants examined. In addition, the whole-cell metabolic assays described here provide simple, high-throughput methods useful for screening larger libraries.

Topics: Carbon Monoxide; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP1A2; DNA Mutational Analysis; DNA Restriction Enzymes; DNA Shuffling; Firefly Luciferin; Gene Library; Genotype; Humans; Luminescent Agents; Mutation; Nitrophenols; Oxazines; Phenotype; Spectrophotometry; Substrate Specificity

A novel molecular probe for enzymatic activity with a dual output detection-mode has been developed. The probe effectively detected the presence of the bacterial protease penicillin-G-amidase; a single cleavage by the enzyme initiated the fragmentation of a self immolative dendritic platform to release two reporter units. The signals of the free reporters were detected by two different spectroscopic techniques, fluorescence and UV-vis. This is the first reported molecular probe with two different chromogenic reporter units activated by a specific stimulus.

Topics: Aminoquinolines; Bacterial Proteins; Enzyme Activation; Microscopy, Fluorescence; Molecular Probes; Molecular Structure; Nitrophenols; Penicillin Amidase; Spectrophotometry, Ultraviolet; Structure-Activity Relationship

We previously reported an ontogeny model of hepatic cytochrome P450 (P450) activity that predicts in vivo P450 elimination from in vitro intrinsic clearance. The purpose of this study was to conduct investigations into key assumptions of the P450 ontogeny model using the developing rat model system. We used two developmentally dissimilar enzymes, CYP2E1 and CYP1A2, and male rats (n = 4) at age groups representing critical developmental stages. Total body and liver weights and hepatic microsomal protein contents were measured. Following high-performance liquid chromatography analysis, apparent K(M) and V(max) estimates were calculated using nonlinear regression analysis for CYP2E1- and CYP1A2-mediated chlorzoxazone 6-hydroxylation and methoxyresorufin O-dealkylation, and V(max) estimates for p-nitrophenol and phenacetin hydroxylations, respectively. Hepatic scaling factors and V(max) values provided estimates for infant scaling factors (ISF). The data show microsomal protein contents increased with postnatal age and reached adult values after postnatal day (PD) 7. Apparent K(M) values were similar at all developmental stages except at < or =PD7. Developmental increases in probe substrate V(max) values did not correlate with the biphasic increase in immunoquantifiable P450. The activity of two different probe substrates for each P450 covaried as a function of age. A plot of observed ISF values as a function of age reflected the developmental pattern of rat hepatic P450. In summation, these observations diverge from several of the model's assumptions. Further investigations are required to explain these inconsistencies and to investigate whether the developing rat may provide a predictive paradigm for pediatric risk assessment for P450-mediated elimination processes.

Topics: Age Factors; Aging; Animals; Body Weight; Chlorzoxazone; Cytochrome P-450 CYP1A2; Cytochrome P-450 CYP2E1; Cytochromes; Dealkylation; Hydroxylation; Isoenzymes; Kinetics; Liver; Male; Microsomes, Liver; Models, Biological; Nitrophenols; Organ Size; Oxazines; Phenacetin; Proteins; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Risk Assessment; Substrate Specificity

In order to study the influence of sugar moiety, aglycon structure and microflora concentration on the human ileal hydrolysis of phenol glycosides, various quercetin and p-nitrophenol glycosides were incubated under anaerobic conditions (37 degrees C for 0, 0.5, 1, 2, 4, 6, 8, 10 and 24 h) with ileostomy fluids from three different donors. The glycosides, i.e. beta-D-glucopyranosides, beta-D-galactopyranosides, alpha-L-arabinofuranosides, beta-D-xylopyranosides and alpha-L-rhamnopyranosides as well as the liberated aglycones were identified by HPLC-DAD and HPLC-ESI-MS/MS. Among the quercetin glycosides under study, the 3-O-beta-D-glucopyranoside showed with 0.22 micromol/h the highest hydrolysis rate, followed by the 3-O-beta-D-galactopyranoside, the 3-O-beta-D-xylopyranoside and the 3-O-alpha-L-arabinofuranoside (0.04 and each 0.03 micromol/h, respectively). Quercetin 3-O-alpha-L-rhamnopyranoside was found to be stable for the entire incubation period. Using quercetin 3-O-beta-D-glucopyranoside as a representative example, linear hydrolysis rate was observed from 75 to 2500 microL ileostomy fluid corresponding to its microflora content (log 0.68 up to 21.9 colony forming units). Studies performed in the presence of antibiotics did not reveal any hydrolysis. The p-nitrophenol glycosides were hydrolyzed faster than the corresponding quercetin glycosides. The hydrolysis rate decreased from the beta-D-glucopyranoside (0.41 micromol/h), to the beta-D-galactopyranoside (0.21 micromol/h), the beta-D-xylopyranoside (0.12 micromol/h), the alpha-L-arabinofuranoside (0.09 micromol/h) to the alpha-L-rhamnopyranoside (0.06 micromol/h). These results demonstrate that the human ileal hydrolysis of phenol glycosides depends on the sugar and the aglycon structure as well as the microflora.

Topics: Adult; Body Fluids; Chromatography, High Pressure Liquid; Female; Glycoside Hydrolases; Glycosides; Humans; Hydrolysis; Ileostomy; Intestines; Kinetics; Nitrophenols; Quercetin; Spectrometry, Mass, Electrospray Ionization

Topics: Allosteric Regulation; Catalysis; Crystallography, X-Ray; Models, Chemical; Nitrophenols; Organophosphates; Spectrophotometry, Ultraviolet; Zinc

A bacterium named LZ-1 capable of utilizing high concentrations of p-nitrophenol (PNP) (up to 500 mg L(-1)) as the sole source of carbon, nitrogen and energy was isolated from an activated sludge. Based on the results of phenotypic features and phylogenetic similarity of 16S rRNA gene sequences, strain LZ-1 was identified as a Stenotrophomonas sp. Other p-substituted phenols such as 4-chlorophenol (4-CP) were also degraded by strain LZ-1, and both PNP and 4-CP were degraded via the hydroquinone pathway exclusively. Strain LZ-1 could degrade PNP and 4-CP simultaneously and the degradation of PNP was greatly accelerated due to the increased biomass supported by 4-CP. An indigenous plasmid was found to be responsible for phenols degradation. In soil samples, 100 mg kg(-1) of PNP and 4-CP in mixtures were removed by strain LZ-1 (10(6) cells g(-1)) within 14 and 16 days respectively, and degradation activity was maintained over a wide range of temperatures (4-35 degrees C). Therefore, strain LZ-1 can potentially be used in bioremediation of phenolic compounds either individually or as a mixture in the environment.

Topics: Biomass; Biotransformation; Chlorophenols; DNA, Bacterial; Genes, rRNA; Molecular Sequence Data; Nitrophenols; Phylogeny; Plasmids; RNA, Bacterial; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid; Sewage; Stenotrophomonas

Efficiency of pollution degradation, performance of activated sludge, effect of temperature fluctuation and recalcitrant organic compounds on system stability were investigated in OSA process for minimization of excess sludge. CAS process and OSA process were run with synthetic wastewater for 240 d. The results indicate that the OSA process excels the CAS process as a whole. COD removal efficiency in OSA process was slightly more than that in CAS. Removal efficiency of nitrogen and phosphorus could be enhanced to 42.58% and 53.84% respectively. Biological phosphorus accumulation in aerobic sludge from OSA and CAS were 2.69 g and 1.11 g per 100 g dry sludge, which further approved biological phosphorus removal in OSA process. Because of alternative aerobic and anaerobic environment in OSA process, sludge settleability and activity are improved. SVI in OSA process was 97 averagely. SOUR and dehydrogenase activity of sludge in OSA were higher appreciably than those in CAS. Protein concentration was higher above 1.69 mg x g(-1) and polysaccharide concentration was lower 6.7 mg x g(-1) in OSA sludge than those in CAS, which confirms the effect of anaerobic tank on sludge performance and microorganism diversity. Lower polysaccharide concentration in OSA sludge improves the settleability. Contrasting to CAS process, OSA process is more sensitive to impact of p-nitrophenol(PNP) and more inactive to temperature fluctuation. Temperature fluctuation led to an increase of the concentration of COD, NH4(+) -N, SS in effluent while sludge production Y(MLSS/COD) was reduced to 0.403 mg x mg(-1) and 0.227 mg x mg(-1) in CAS and OSA. When concentration of PNP was increased abruptly to 10 mg x L(-1), biological nutrient removal was ceased in OSA process. Once OSA system is impacted, it is difficult to restore.

Topics: Bacteria, Anaerobic; Biodegradation, Environmental; Carbon; Nitrogen; Nitrophenols; Organic Chemicals; Phosphorus; Sewage; Temperature; Waste Disposal, Fluid

White sturgeon (Acipencer transmontanus) were exposed to 7.2 microM (1.0 ppm) 14C-labeled p-nitrophenol (PNP) in brackish water for 24 h and then allowed to depurate in clean brackish water for another 24h. Absorption, conditional uptake clearance, and conditional elimination rate constants were 0.08+/-0.04 h(-1), 8.1+/-3.6 mL g(-1) h(-1), and 0.46+/-0.21 h(-1), respectively. A whole-organism total concentration factor of 18.7+/-2.6 was determined from equilibrium tissue and water concentrations. Sturgeon depurated 89.4% of absorbed PNP within 24h, of which 53.0+/-8.3% was unmetabolized parent compound, 9.6+/-3.6% was p-nitrophenyl-beta-d-glucuronide, and 39.1+/-8.3% was p-nitrophenylsulfate.

Topics: Animals; Biotransformation; Fishes; Motor Activity; Nitrophenols; Toxicity Tests; Water Pollutants, Chemical

A strain of Pseudomonas putida was found capable of metabolizing p-nitrophenol (PNP) as a sole source of carbon, nitrogen and energy. To explore the applicability of this strain for bioremediation for controlling environmental PNP pollution, its degradation potential at 300 and 500 ppm was examined in a medium devoid of carbon and nitrogen source (minimal medium). At A600, 0.5 OD inoculum, the strain metabolized 300 and 500 ppm within 36 and 72 h, respectively. The degradation was accompanied by release of stoichiometric amount of nitrite. Effect of glucose and nitrogen on PNP degradation under similar conditions revealed that (i) glucose (0.4 g/l) at 20 and 50 ppm PNP did not accelerate the rate of PNP degradation, while glucose (0.4 g/l) at 300 ppm PNP inhibited its degradation, (ii) nitrogen supplement viz. sodium nitrate and ammonium sulphate (0.04 and 0.4 g/l) in minimal medium with PNP (300 ppm) showed no effect on PNP degradation, while glutamate alone (0.04 and 0.4 g/l) showed mere rise in biomass (from 0.5 to 1.6 OD units), and (iii) acidic pH (4.0-6.5) did not support PNP degradation, while alkaline pH (7.5-9.5) significantly enhanced the rate of PNP degradation. The complete degradation of PNP at high concentration (300 ppm) was confirmed by HPTLC analysis. In order to probe root cause of higher PNP degradation, preliminary studies on genetic analysis of P. putida were undertaken, which revealed the prevalence of a degradative plasmid of approximately 15 kb, while cured derivatives of P. putida (PNP-) did not show ability to degrade PNP. Further conjugal transfer of PNP+ phenotype from P. putida to standard strain of E. coli Nova blue (PNP-) confirmed the degradative type of plasmid.

Topics: Ammonium Sulfate; Biodegradation, Environmental; Biomass; Chromatography, High Pressure Liquid; Conjugation, Genetic; Culture Media; Dose-Response Relationship, Drug; Electrophoresis, Agar Gel; Escherichia coli; Glucose; Glutamic Acid; Hydrogen-Ion Concentration; Nitrates; Nitrogen; Nitrophenols; Plasmids; Pseudomonas putida; Time Factors; Water Pollutants, Chemical

The effect of copper on adsorption of p-nitrophenol on two typical Chinese soils was investigated using a batch-equilibration method. Adsorption experiments were carried out when both copper and p-nitrophenol were adsorbed simultaneously, and when copper was previously adsorbed on soils. It was observed that adsorption of p-nitrophenol decreased with increasing copper concentrations thereby indicating a competition between copper and p-nitrophenol for occupying the adsorption sites on soils. Moisture increased the hydrated sphere and the acidity of water surrounding the cation, which further reduced the adsorption of p-nitrophenol. Fourier transform infrared spectroscopy study provided the direct evidence for the coordination of p-nitrophenol sorbed by soils with metal cation in n-hexane system. It was observed that the perturbations included a red shift of the nu(asym) (NO) band, a concomitant blue-shift of the nu(sym) (NO) band and a blue-shift of C-N band when compared with the infrared spectra obtained from water solution.

Topics: Adsorption; Copper; Hexanes; Hydrogen-Ion Concentration; Nitrophenols; Soil; Soil Pollutants; Spectroscopy, Fourier Transform Infrared

Monitoring of micro-organisms released deliberately into the environment is essential to assess their movement during the bio-remediation process. During the last few years, DNA-based genetic methods have emerged as the preferred method for such monitoring; however, their use is restricted in cases where organisms used for bio-remediation are not well characterized or where the public domain databases do not provide sufficient information regarding their sequence. For monitoring of such micro-organisms, alternate approaches have to be undertaken. In this study, we have specifically monitored a p-nitrophenol (PNP)-degrading organism, Arthrobacter protophormiae RKJ100, using molecular methods during PNP degradation in soil microcosm. Cells were tagged with a transposon-based foreign DNA sequence prior to their introduction into PNP-contaminated microcosms. Later, this artificially introduced DNA sequence was PCR-amplified to distinguish the bio-augmented organism from the indigenous microflora during PNP bio-remediation.

Topics: Arthrobacter; Biodegradation, Environmental; DNA Transposable Elements; DNA, Bacterial; Ecosystem; Environmental Monitoring; Nitrophenols; Soil Microbiology; Soil Pollutants

p-nitrophenol (PNP) was investigated as a model pollutant under the improved UV/Fe3+ process by combination with electrocatalysis. In the individual UV/Fe3+ process, PNP degradation rate was dependent on Fe(III) concentration and decreased during degradation due to the depletion of ferric ion and thus it was very difficult to reach the quick mineralization of organics. These drawbacks could be significantly overcome in the modified UV/Fe3+ process, and synergetic effects for PNP and COD removal were observed at two investigated Fe(III) concentrations. The enhancements on the degree of conversion for PNP and COD in presence of 0.5 mM Fe(III) were 184% and 242%, respectively, and PNP of initial concentration of 1.0 mM could be completely removed within 1 h. Thus such a process would be very attractive to the rapid mineralization of the biorefractory compounds for wastewater treatment. The possible reasons for the synergetic effects were the electrochemical regeneration of ferric ion and the role of the oxygen that formed on the anode. Based on degradation intermediates identification and synergetic effect probe, a general reaction pathway for PNP degradation in the improved process was proposed.

Topics: Catalysis; Electrodes; Ferric Compounds; Molecular Structure; Nitrophenols; Oxidation-Reduction; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification

The molecular and kinetic characterization of a microorganism able to aerobically degrade 4-nitrophenol (4NP) is presented. The microorganism was isolated from a mixed culture operating in a laboratory-scale sequencing batch reactor with an aerobic anoxic cycle. It was identified as a member of Ralstonia genus within Betaproteobacteria. It is a gram negative coccobacillum (cell length of 2-3 microm) able to aerobically store lipid inclusions when grown aerobically on nitrophenol as the sole carbon source in the range of tested concentrations (80-320 mg l(-1)). Batch kinetic tests were performed with the pure culture, while the kinetics of the mixed biomass was directly investigated in the reactor. For pure cultures exponential growth was observed, with growth rate values in the range of 2-6 d(-1); in experiments with the mixed cultures 4NP concentrations were correlated with growth using the Haldane equation (k(max) = 0.30 mg 4NP mg(-1) VSSh(-1); K(s) = 55 mg 4NPl(-1) and K(I) = 15 mg 4NPl(-1)). Observed pure culture growth rates were higher than those of mixed cultures. This result can be explained by considering that in mixed culture the biomass is evaluated as volatile suspended solids, including both specialized biomass for 4NP removal and denitrifying bacteria.

Topics: Aerobiosis; Biodegradation, Environmental; Bioreactors; DNA, Bacterial; Kinetics; Nitrophenols; Ralstonia; RNA, Ribosomal, 16S; Sewage; Water Pollutants, Chemical

The role of pharyngeal lymphoid tissue in etiopathogenesis of secretory otitis is not yet defined. The influence of tonsillar and adenoid mass, weight, obstruction of naspharyngeal orrifitium, bacterial reservoire or some immunological events are of scientific interest. Tissue nonspecific alkaline phosphatase (TNAP) and acid phosphatase (ACP) are enzymes detected in lymphoid tissue, TNAP as characteristic of B cells, ACP as a characteristic of macrophages and folucullardentritic cells. These enzymes interfere in cell metabolism by removing 5' phosphate group from nucleotides and proteins. Specific activity and kinetic properties were studied in palatinal tonsils and adenoids of children with secretory otitis (OME) and compared with children with recurrent tonsillitis without ear involvement.. Adenoid and tonsillar tissue of l7 children with OME and 30 children with recurrent tonsillitis were subjected to biochemical investigation using method of releasing of p-nitrophenol from p-nitrophenylphosphate (pNPP). Kinetic parameters as Michaelis-Menten constant were calculated by non-linear regression estimation method.. Specific activity of adenoid alkaline phosphatase was lower in children with OME in relation to children with recurrent tonsillitis (t=5.733507, p<0.01). Specific activity of adenoid acid phosphatase was also lower in children with OME (t=3.655456, p<0.01). pH optimum for both enzymes was the same in these two groups of children. Michaelis-Menten constant for both enzymes was significantly higher in adenoid of children with OME than in children with recurrent tonsillitis suggesting lower enzyme affinity for the substrate.. Differences in specific activities and kinetic properties of adenoid alkaline and acid phosphatases between children with OME and children with recurrent tonsillitis without OME were verified in this study. The results of the study are not able to explain the alteration of alkaline and acid phosphatase characteristics but could point to some possible and specific role of nasopharyngeal lymphoid tissue in pathogenesis of secretary otitis.

Topics: Acid Phosphatase; Adenoidectomy; Adenoids; Alkaline Phosphatase; B-Lymphocytes; Child; Child, Preschool; Dendritic Cells, Follicular; Female; Humans; Hydrogen-Ion Concentration; Indicators and Reagents; Macrophages; Male; Nasal Obstruction; Nitrophenols; Organophosphorus Compounds; Otitis Media with Effusion; Palatine Tonsil; Recurrence; Tonsillectomy; Tonsillitis

Polychlorobiphenylols (OH-PCBs) were reported as potent inhibitors of estrogen sulfotransferase, thyroid hormone and 3-hydroxybenzo(a)pyrene sulfotransferases. The aim of this study was to examine the effects of selected OH-PCBs on SULT1A1 activity in human liver cytosol, measured with 4microM 4-nitrophenol, a concentration considered to be diagnostic for selectively detecting SULT1A1. All the OH-PCBs studied inhibited the sulfonation of 4-nitrophenol in human liver cytosol. Among the eighteen OH-PCBs studied, 3'-OH-CB3 (4-chlorobiphenyl-3'-ol) was the most potent inhibitor (IC(50): 0.73+/-0.15microM, mean+/-S.D., n=3). The least potent inhibitor studied was 6'-OH-CB35 (3,3',4-trichlorobiphenyl-6'-ol) with IC(50): 49.1+/-10.8microM. The IC(50) values of the other OH-PCBs studied ranged from 0.78 to 3.76microM. Some OH-PCBs with various inhibitory potencies with human liver cytosol were selected for study with recombinant human SULT1A1 and SULT1B1. These OH-PCBs showed more potent inhibition of 4-nitrophenol sulfonation with SULT1A1 than with human liver cytosol. The IC(50) values with human liver cytosol showed a perfect linear correlation with those found with SULT1A1 (r(2)=1), but not with SULT1B1 (r(2)=0.21). The results suggested that in these human samples SULT1A1 was predominantly responsible for the sulfonation of 4-nitrophenol, with very little or no contribution from SULT1B1. The kinetics of inhibition were studied with 4'-OH-CB165, which is similar in structure to OH-PCBs found in human blood. The 4'-OH-CB165 was a mixed noncompetitive-uncompetitive inhibitor (K(i)=1.80+/-0.2microM, K(ies)=0.16+/-0.02microM). Finally, it was demonstrated that the tested OH-PCBs were themselves only slowly sulfonated by human sulfotransferases in the presence of (35)S-PAPS, as measured by the production of (35)S-labeled metabolites. Although this series of 18 OH-PCBs was too small to draw conclusions about structure-potency relationships, this work demonstrated that several OH-PCBs were potent inhibitors of 4-nitrophenol sulfonation but poor substrates in human liver cytosol, and suggested that OH-PCBs may inhibit the sulfation rate of those xenobiotics sulfated by SULT1A1.

Topics: Alleles; Arylsulfotransferase; Chlorophenols; Enzyme Inhibitors; Genotype; Humans; Hydroxylation; Inhibitory Concentration 50; Kinetics; Liver; Molecular Structure; Nitrophenols; Sensitivity and Specificity; Substrate Specificity

Interference of antiviral agent adefovir, i.e. 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA) with microsomal drug metabolizing system was investigated in rats. The content of total liver cytochrome P450 (CYP) was lowered while that of its denaturated form, P420, was elevated in animals intraperitoneally treated with PMEA (25 mg/kg). Similar effect was observed after treatment with a prodrug of adevofir, adefovir dipivoxil (bisPOM-PMEA). The CYP2E1-dependent formation of 4-nitrocatechol from p-nitrophenol was diminished, though the specific activity of p-nitrophenol hydroxylase remained unchanged. PMEA had no influence on expression of CYP2E1 protein and mRNA and mRNAs of other P450 isoenzymes (1A1, 1A2, 2C11, 3A1, 3A2, and 4A1). It may be concluded that repeated systemic administration of higher doses of PMEA results in a partial degradation of rat CYP protein to inactive P420.

Topics: Adenine; Animals; Antiviral Agents; Catechols; Cytochrome P-450 Enzyme System; Female; Microsomes, Liver; Nitrophenols; Organophosphonates; Rats; Rats, Inbred Lew; RNA, Messenger

The efficiency of photocatalytic reactions was limited by the wide band-gap of TiO(2) and the high degree of electron-hole recombination inherent in photocatalytic process, as well as by the limited adsorption capability of photocatalysts. In order to increase the overall efficiency, the surface of nanometer size TiO(2) was simply and fast modified by chemical adsorption in saturated solution of salicylic acid. A stable, light yellow surface complex was formed quickly, which has obvious absorption in the region from 320 to 420 nm. Through surface modification, the adsorption efficiency of 4-nitrophenol by TiO(2) was enhanced from 42 to 84%. The photocatalytic efficiency was tested on the degradation of 4-nitrophenol. The influences of catalyst and its dosage, pH value, and 4-nitrophenol concentration on the degradation were investigated. Under such photodegradation conditions as initial pH 4.0, 4-nitrophenol 5 mg l(-1), catalyst 100 mg, and irradiation time 160 min with 160 W high-pressure mercury lamp, the degradation efficiency of 4-nitrophenol by TiO(2) was increased from 39.5 to 79.3% after surface modification, and furthermore, the degradation efficiency could be enhanced to 91.1% if the concentration of 4-nitrophenol was not more than 1 mg l(-1). Compared with the pure TiO(2), surface modification led not only to improve the surface coverage of 4-nitrophenol, but also to increase the light utilization. Both of these factors were crucial for the photocatalytic activity of heterogeneous photocatalysis, especially for photodegradation of aromatic pollutants.

Topics: Adsorption; Catalysis; Hydrogen-Ion Concentration; Molecular Structure; Molecular Weight; Nanostructures; Nitrophenols; Oxidation-Reduction; Photochemistry; Salicylic Acid; Spectrum Analysis; Titanium

The effect of nitrophenolic shock loads on the performance of three bench-scale upflow anaerobic sludge blanket (UASB) reactors was studied using synthetic wastewater. Reactors R1, R2 and R3 were fed with 30 mg/L concentration of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP), respectively, along with methanol (COD = 2000 mg/ L), sodium nitrate (NO3(-)-N=200mg/L), and other nutrients. The reactors were in continuous operation for more than 2 years before the shock loading study was performed. Five nitrophenolic shock loadings of 45, 60, 75, 90 and 120mg/L d were administrated by increasing the influent nitrophenolic concentration to 45, 60, 75, 90 and 120mg/L, respectively, while keeping hydraulic retention time as 24h. The shocks were given continuously for a period of 4 days before switching back to normal nitrophenolic loading (30mg/Ld). The reactors were allowed to recover to normal performance level before administrating the next nitrophenolic shock load. The study showed that the nitrophenolic shock load of as high as 120 mg/L d did not affect the reactors performance irreversibly. After resuming the normal nitrophenolic loading, it took almost 3-18 days for the reactors to recover from the shock effect. The study was further extended to assess the maximum possible mixed nitrophenolic loading (2NP:4NP:2,4:DNP = 1:1:1) to which 2,4-DNP acclimated granular sludge containing reactor (R3) can be exposed without hampering the reactor (R3) performance irreversibly. The reactor was able to achieve pseudo-steady-state at a mixed nitrophenolic loading of 180 mg/L d with more than 90% removal of all the three nitrophenols, but failed at a mixed nitrophenolic loading of 225 mg/Ld.

Topics: 2,4-Dinitrophenol; Anaerobiosis; Bioreactors; Nitrophenols; Sewage; Time Factors; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

Comparison of the ability of the enantiomeric forms of trehalose to stabilise alkaline phosphatase towards dehydration and heat showed that natural D-trehalose is superior to L-trehalose, although both disaccharides provide some protection for the enzyme. The result of this novel experiment suggests a chiral differentiation between carbohydrate and protein and thus lends support for the water replacement hypothesis of solute-based stabilisation of biomolecules, but the non-crystallinity and the physical form of the L-isomer may also be a key factor.

Topics: Alkaline Phosphatase; Enzyme Stability; Freeze Drying; Hot Temperature; Nitrophenols; Stereoisomerism; Trehalose

4-Azido-2-hydroxybenzoic acid (4-AzHBA), a novel photoactive benzoic acid derivative, has been synthesized and used as a photoprobe to identify the phenol binding site of UDP-glucuronosyltransferases (UGTs). Analysis of recombinant His-tag UGTs from the 1A family for their ability to glucuronidate p-nitrophenol (pNP) and 4-methylumbelliferone (4-MU) revealed that UGT1A10 shows high activity toward phenols and phenol derivatives. Purified UGT1A10 was photolabeled with 4-AzHBA, digested with trypsin, and analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF)-mass spectrometry. A single modified peak corresponding to amino acid residues 89-98 (EFMVFHAQWK) of UGT1A10 was identified. The attachment site of the 4-AzHBA probe was localized to the quadruplet Phe(90)-Met(91)-Val(92)-Phe(93) using ESI LC-MS/MS. Sequence alignment revealed that the Phe(90) and Phe(93) are conserved in UGT1A7-10. Site-directed mutagenesis of these two amino acids was then followed by kinetic analysis of the mutants with two phenolic substrates, pNP and 4-MU, containing one and two planar rings, respectively. Using the combination of photoaffinity labeling, enzymatic digestion, MALDI-TOF and LC-MS mass spectrometry, and site-directed mutagenesis, we have determined for the first time that Phe(90) and Phe(93) are directly involved in the catalytic activity of UGT1A10 toward 4-MU and pNP.

Topics: Amino Acid Sequence; Azides; Binding Sites; Chromatography, Liquid; Glucuronosyltransferase; Humans; Hymecromone; Kinetics; Mass Spectrometry; Molecular Sequence Data; Mutagenesis, Site-Directed; Nitrophenols; Phenol; Phenylalanine; Photoaffinity Labels; Recombinant Proteins; Salicylates; Sequence Alignment; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Influence of different doses of 4-nitrophenol on some biochemical and morphological indices of rat blood was studied. Glucose and beta-lipoprotein concentration increased, but total protein concentration decreased in response to intraperitoneal injection of xenobiotic. As a result of xenobiotic action, the total amount of leukocytes and thrombocytes increased, while the amount of erythrocytes decreased. The morphological study of structural indices of blood formed elements has demonstrated, that intensity of the defensive response of blood formed elements was 4-nitrophenol dose-dependent.

Topics: Animals; Blood Glucose; Blood Platelets; Disease Models, Animal; Dose-Response Relationship, Drug; Environmental Illness; Erythrocytes; Injections, Intraperitoneal; Leukocytes; Lipoproteins, LDL; Male; Nitrophenols; Rats

The superfamily of sulfotransferase (SULT) enzymes catalyzes the sulfate conjugation of several pharmacologically important endo- and xenobiotics. SULT1A1 catalyzes the sulfation of small planar phenols such as neurotransmitters, steroid hormones, acetaminophen, and p-nitrophenol (PNP). Genetic polymorphisms in the human SULT1A1 gene define three alleles, SULT1A1*1, *2, and *3. The enzyme activities of the SULT1A1 allozymes were studied with a variety of substrates, including PNP, 17beta-estradiol, 2-methoxyestradiol, catecholestrogens, the antiestrogen 4-hydroxytamoxifen (OHT), and dietary flavonoids. Using purified recombinant SULT1A1 protein, marked differences in *1, *2, and *3 activity toward every substrate studied were noted. Substrate inhibition was observed for most substrates. In general, the trend in V(max) estimates was *1 > *3 > *2; however, V(max)/K(m) estimate trends varied with substrate. In MCF-7 cells stably expressing either SULT1A1*1 or *2, the antiestrogenic response to OHT was found to be allele-specific: the cells expressing *2 exhibited a better antiproliferative response. The intracellular stability of the *1 and *2 allozymes was examined in insect as well as mammalian cells. The SULT1A1*2 protein had a shorter half-life than the *1 protein. In addition, the *2 protein was ubiquitinated to a greater extent than *1, suggesting increased degradation via a proteasome pathway. The results of this study suggest marked differences in activity of polymorphic SULT1A1 variants, including SULT1A1*3, toward a variety of substrates. These differences are potentially critical for understanding interindividual variability in drug response and toxicity, as well as cancer risk and incidence.

Topics: 2-Methoxyestradiol; Animals; Arylsulfotransferase; Cells, Cultured; Estradiol; Estrogens, Catechol; Humans; Nitrophenols; Phenotype; Polymorphism, Genetic; Recombinant Proteins; Substrate Specificity

p-Nitrophenyl phosphate is one of the most widely used substrates for alkaline phosphatase in ELISAs because its yellow, water-soluble product, p-nitrophenol, absorbs strongly at 405 nm. p-Nitrophenol is also electroactive; an oxidative peak at 0.97 V (vs. an Ag pseudoreference electrode) is obtained when a bare screen-printed carbon electrode is used. When an amperometric detector was coupled to a flow-injection analysis system the detection limit achieved for p-nitrophenol was 2x10(-8) mol L(-1), almost two orders of magnitude lower than that obtained by measuring the absorbance of the compound. By use of this electrochemical detection method, measurement of 7x10(-14) mol L(-1) alkaline phosphatase was achieved after incubation for 20 min. The feasibility of coupling immunoassay to screen-printed carbon electrode amperometric detection has been demonstrated by performing an ELISA for detection of pneumolysin, a toxin produced by Streptococcus pneumoniae, which causes respiratory infections. The method is simple, reproducible, and much more sensitive than traditional spectrophotometry.

Topics: Alkaline Phosphatase; Bacterial Proteins; Electrochemistry; Electrodes; Enzyme-Linked Immunosorbent Assay; Feasibility Studies; Methods; Nitrophenols; Streptolysins

In this study, aerobic granules to treat wastewater containing p-nitrophenol (PNP) were successfully developed in a sequencing batch reactor (SBR) using activated sludge as inoculum. A key step was the conditioning of the activated sludge seed to enrich for biomass with improved settleability and higher PNP degradation activity by implementing progressive decreases in settling time and stepwise increases in PNP concentration. The aerobic granules were cultivated at a PNP loading rate of 0.6 kg/ m3 x day, with glucose to boost the growth of PNP-degrading biomass. The granules had a clearly defined shape and appearance, settled significantly faster than activated sludge, and were capable of nearly complete PNP removal. The granules had specific PNP degradation rates that increased with PNP concentration from 0 to 40.1 mg of PNP/L, peaked at 19.3 mg of PNP/(g of VSS) x h (VSS = volatile suspended solids), and declined with further increases in PNP concentration as substrate inhibition effects became significant. Batch incubation experiments show that the PNP-degrading granules could also degrade other phenolic compounds, such as hydroquinone, p-nitrocatechol, phenol, 2,4-dichlorophenol, and 2,6-dichlorophenol. The PNP-degrading granules contained diverse microbial morphotypes, and PNP-degrading bacteria accounted for 49% of the total culturable heterotrophic bacteria. Denaturing gradient gel electrophoresis analysis of 16S rRNA gene fragments showed a gradual temporal shift in microbial community succession as the granules developed from the activated sludge seed. Specific oxygen utilization rates at 100 mg/L PNP were found to increase with the evolution of smaller granules to large granules, suggesting that the granulation process can enhance metabolic efficiency toward biodegradation of PNP. The results in this study demonstrate that it is possible to use aerobic granules for PNP biodegradation and broadens the benefits of using the SBR to target treatment of toxic and recalcitrant organic compounds.

Topics: Aerobiosis; Biodegradation, Environmental; Electrophoresis, Polyacrylamide Gel; Nitrophenols; RNA, Ribosomal, 16S

Three-phase electrochemical reactor is still far from concerned in wastewater treatment in order to improve electrochemical treatment efficiency especially when the concentrations of organic pollutants are relatively low. This paper presents a novel process integrated electrocatalysis and activated carbon (AC) adsorption in a fluidization mode for p-nitrophenol (PNP) abatement, with special attention on probing the role of AC. Sparged by external gas (e.g., O(2)), the electrochemical reactor is actually a three-phase (gas, liquid, solid) reactor. By this one-step integrated process, the treatment efficiency was significantly promoted where PNP of initial concentration 150 mg l(-1) could be completely removed in no more than 30 min and it kept good performance for five consecutive runs, showing potential application for environmental remediation. In the integrated process, AC is in a dynamic state of adsorption and in situ electrochemical regeneration by the attack of electrogenerated hydroxyl radical on organic pollutants. When oxygen is sparged into the process, hydrogen peroxide can be formed by cathodic reduction and then decomposed by catalytic reaction on AC, which further promotes organic pollutants degradation.

Topics: Adsorption; Carbon; Catalysis; Electrochemistry; Environmental Restoration and Remediation; Nitrogen; Nitrophenols; Oxygen; Water Pollutants, Chemical; Water Purification

The aim of this study was to evaluate diazepam and oxazepam as cytochrome P450 inducers at doses previously shown to cause liver tumors in mice but not rats. In rats, diazepam and oxazepam induced CYP2B, and were as effective as phenobarbital despite lacking phenobarbital's tumor-promoting effect in rats. In mice, diazepam and oxazepam induced both CYP2B and CYP4A at dietary doses associated with liver tumor formation. It remains to be determined why diazepam and oxazepam induce CYP4A in mice but not rats and whether this difference accounts for the apparent species difference in the tumor-promoting activity of diazepam and oxazepam.

Topics: Animals; Benzodiazepines; Blotting, Western; Body Weight; Carcinogens; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP2B1; Cytochrome P-450 CYP4A; Cytochrome P-450 Enzyme System; Diazepam; Hypnotics and Sedatives; Immunohistochemistry; Isoenzymes; Lauric Acids; Liver Neoplasms; Male; Mice; Microsomes, Liver; Nitrophenols; Organ Size; Oxazepam; Phenobarbital; Rats; Rats, Sprague-Dawley

A chloromethylated styrene-divinylbenzene copolymer was post-cross-linked through Friedel-Crafts reaction to get a macroreticular resin adsorbent NA-01, and then chemically modified by dimethylamine to obtain an aminated adsorbent NA-01A. Batch adsorption runs of p-nitrophenol from aqueous solution onto adsorbent NA-01A were conducted to evaluate the effect of amino group on adsorption. The adsorption capacity of p-nitrophenol on NA-01A increased noticeably by comparison with the mother adsorbent. A linear relationship was observed between the adsorption capacity of NA-01A caused by amination and the equilibrium concentration of p-nitrophenol in aqueous solution, which can be reasonably elucidated by a modified isotherm equation based on the Freundlich model. The breakthrough curves on both adsorbents were experimentally determined and also predicted by the mathematic model based on the non-linear wave propagation theory and the corresponding isotherm model. The model based on the Freundlich model gave a good prediction of the breakthrough curve on NA-01, but a deviation occurred for NA-01A when C/C0 less than 0.3. However, another model based on the modified isotherm equation provided a better prediction for the breakthrough curves on NA-01A.

Topics: Adsorption; Amines; Nitrophenols; Resins, Synthetic; Water; Water Purification

The cytochrome P450 enzyme CYP2E1 catalyzes the oxidative metabolism of many solvents and other small organic molecules. A spectrophotometric method is described for determination of CYP2E1 activity by monitoring the formation of p-nitrocatechol from p-nitrophenol by cDNA-expressed CYP2E1 or isolated liver microsomes. The enzymatic product, p-nitrocatechol, is assayed at 535 nm after acidification of the reaction mixture with trichloroacetic acid followed by neutralization using 2 M NaOH. This method is applicable to enzymatic studies for determination of P450-catalyzed p-nitrophenol hydroxylation activity.

Topics: Catalysis; Cytochrome P-450 CYP2E1; Humans; Hydroxylation; Microsomes, Liver; Nitrophenols

A procedure for the on-line measurement of concentrations of toxins in wastewater using spectrophotometric data is proposed. The complete absorbance spectrum of a wastewater sample is used to predict the concentrations of all possible substances within. Two techniques are examined. In nonlinear spectral deconvolution, the spectrum is decomposed as a linear combination of base spectra and the coefficients of this deconvolution are used to nonlinearly estimate the concentrations. Under partial least squares analysis, the concentrations are directly estimated as a linear combination of the measured spectrum data. Both techniques show good results for estimating the kinetics of samples taken during the reaction phase in a laboratory anaerobic/aerobic SBR used for p-nitrophenol biodegradation.

Topics: Aerobiosis; Anaerobiosis; Biodegradation, Environmental; Bioreactors; Least-Squares Analysis; Nitrophenols; Online Systems; Sewage; Spectrophotometry, Ultraviolet; Waste Disposal, Fluid

1,4-beta-D-glucan cellobiohydrolase I (CBH I), p-nitrophenyl beta-D-cellobioside, p-nitrophenol and cellobiose show distinct ultraviolet spectra, allowing the design of an assay to track the dynamic process of p-nitrophenyl beta-D-cellobioside hydrolysis by CBH I. Based on the linear relationship between p-nitrophenol formation in the hydrolysate and its first derivative absorption curve of AUC340-400 nm (area under the curve), a new sensitive assay for the determination of CBH I activity was developed. The dynamic parameters of catalysis reaction, such as Vm and kcat, can all be derived from this result. The influence of beta-glucosidase and endoglucanase in crude enzyme sample on the assay was discussed in detail. This approach is useful for accurate determination of the activity of CBHs.

Topics: Algorithms; Area Under Curve; beta-Glucosidase; Catalytic Domain; Cellobiose; Cellulose 1,4-beta-Cellobiosidase; Dose-Response Relationship, Drug; Hydrolysis; Kinetics; Models, Chemical; Models, Theoretical; Nitrophenols; Spectrophotometry, Ultraviolet; Trichoderma

To elucidate the mechanism underlying suppression by curcumin of esophageal carcinogenesis induced by NMBA, we evaluated the CYP level and mutagenic activation of environmental carcinogens, by immunoblot analyses and Ames preincubation test, respectively, and bilirubin, 4-nitrophenol and testosterone UDPGT activities in F344 rats treated with curcumin and/or NMBA. No significant alterations in the hepatic levels of constitutive CYP proteins, mutagenic activation by liver S9 or hepatic UDPGT activities were produced by subcutaneous treatment with 0.5 mg/kg NMBA for 5 weeks and/or feeding of 0.05% and 0.2% curcumin for 6 weeks. In contrast, gavage of 0.2% curcumin decreased esophageal CYP2B1 and 2E1 by up to 60%, compared with vehicle control. Similarly, intragastric treatment with 270 mg/kg curcumin decreased esophageal and gastric CYP2B1 and CYP2E1, but not in lung, kidney or intestine. Conversely, large intestinal CYP2B1 was 2.8-fold higher in the treated rats than in control rats. Mutagenic activities of NOC, including NMBA, in the presence of esophagus and stomach S9 were markedly decreased in the treated rats, whereas those in the presence of large intestine S9 were 2.2-3.0-fold above control. These results show that modifying effects of curcumin on esophageal carcinogenesis can be attributed to a decrease in metabolic activation of NMBA by esophageal CYP2B1 during the initiation phase, without the contribution of metabolic activation and inactivation by liver. Further, the present findings suggest the potential of curcumin for modification of gastric and intestinal carcinogenesis initiated with NOC.

Topics: Animals; Antineoplastic Agents; Bilirubin; Blotting, Western; Carcinogens; Curcumin; Cytochrome P-450 CYP2B1; Cytochrome P-450 CYP2E1; Dimethylnitrosamine; Esophagus; Glucuronosyltransferase; Intestines; Liver; Male; Mutagenicity Tests; Nitrophenols; Nitrosamines; Rats; Rats, Inbred F344; Stomach; Testosterone; UDP-Glucuronosyltransferase 1A9

We have characterized hepatic phenol sulfotransferase (SULT) activities in two benthic fish species, Mullus barbatus and Lepidorhombus boscii, using p-nitrophenol, dopamine, 17beta-estradiol, 4-nonylphenol, and 1-naphthol as substrates. High affinity sulfation of 17beta-estradiol was observed in both species (Km=28-75 nM), suggesting the presence of a specific estrogen sulfotransferase that catalyzes the formation of estradiol-3 sulfate. Among the tested compounds, 1-naphthol was the most effective substrate for sulfation, with Vmax/Km ratios several hundred-fold higher than the other substrates examined. Both species sulfated the tested compounds, but only M. barbatus was able to sulfate dopamine. We also tested the inhibitory effects of common marine pollutants with estrogenic (4-nonylphenol) and androgenic (tributyltin, triphenyltin) properties on p-nitrophenol and 17beta-estradiol SULT activities. 4-Nonylphenol and triphenyltin inhibited sulfation of both substrates at micromolar concentrations in both species. However, tributyltin was only effective against SULTs from L. boscii, again at micromolar concentrations. The data indicate that M. barbatus and L. boscii are able to sulfate a range of xenobiotics and endogenous compounds, and inhibition of these activities by environmental pollutants may contribute to the known toxic effects of these compounds.

Topics: Animals; Arylsulfotransferase; Dopamine; Endocrine Disruptors; Estradiol; Female; Flatfishes; Inhibitory Concentration 50; Liver; Male; Nitrophenols; Organotin Compounds; Perciformes; Phenols; Trialkyltin Compounds; Water Pollutants, Chemical

The introduction of culture-independent molecular screening techniques, especially based on 16S rRNA gene sequences, has allowed microbiologists to examine a facet of microbial diversity not necessarily reflected by the results of culturing studies. The bacterial community structure was studied for a pesticide-contaminated site that was subsequently remediated using an efficient degradative strain Arthrobacter protophormiae RKJ100. The efficiency of the bioremediation process was assessed by monitoring the depletion of the pollutant, and the effect of addition of an exogenous strain on the existing soil community structure was determined using molecular techniques. The 16S rRNA gene pool amplified from the soil metagenome was cloned and restriction fragment length polymorphism studies revealed 46 different phylotypes on the basis of similar banding patterns. Sequencing of representative clones of each phylotype showed that the community structure of the pesticide-contaminated soil was mainly constituted by Proteobacteria and Actinomycetes. Terminal restriction fragment length polymorphism analysis showed only nonsignificant changes in community structure during the process of bioremediation. Immobilized cells of strain RKJ100 enhanced pollutant degradation but seemed to have no detectable effects on the existing bacterial community structure.

Topics: Arthrobacter; Biodegradation, Environmental; Ecosystem; Gene Library; India; Methyl Parathion; Molecular Sequence Data; Nitrophenols; Parathion; Polymorphism, Restriction Fragment Length; Population Dynamics; Principal Component Analysis; RNA, Ribosomal, 16S; Soil Microbiology

Irinotecan (CPT-11) is a prodrug that is used to treat metastatic colorectal cancer. It is activated to the topoisomerase poison SN-38 by carboxylesterases. SN-38 is metabolized to its inactive glucuronide, SN-38 glucuronide. The aim of this study was to determine, the reactivation of SN-38 from SN-38 glucuronide by beta-glucuronidase may represent a significant pathway of SN-38 formation.. The production of SN-38 from irinotecan and SN-38 glucuronide (2.4, 9.6 and 19.2 microm) was measured in homogenates of human colorectal tumour, and matched normal colon mucosa from 21 patients).. The rate of conversion of irinotecan (9.6 microm) was lower in tumour tissue than matched normal colon mucosa samples (0.30+/-0.14 pmol min-1 mg-1 protein and 0.77+/-0.59 pmol min-1 mg-1 protein, respectively; P<0.005). In contrast, no significant difference was observed in beta-glucuronidase activity between tumour and matched normal colon samples (4.56+/-6.9 pmol min-1 mg-1 protein and 3.62+/-2.95 pmol min-1 mg-1 protein, respectively, using 9.6 microm SN-38 glucuronide; P>0.05). beta-Glucuronidase activity in tumour correlated to that observed in matched normal tissue (r2>0.23, P<0.05), whereas this was not the case for carboxylesterase activity. At equal concentrations of irinotecan and SN-38 glucuronide, the rate of beta-glucuronidase-mediated SN-38 production was higher than that formed from irinotecan in both tumour and normal tissue (P<0.05). However, at concentrations that reflect the relative plasma concentrations observed in patients, the rate of SN-38 production via these two pathways was comparable.. Tumour beta-glucuronidase may play a significant role in the exposure of tumours to SN-38 in vivo.

Topics: Antineoplastic Agents, Phytogenic; Camptothecin; Carboxylesterase; Colorectal Neoplasms; Glucuronidase; Humans; Hydroxyquinolines; Irinotecan; Nitrophenols; Tumor Cells, Cultured

Because of its simple and well characterized metabolic profile, 4-nitrophenol is widely used as a model substrate to investigate the influence of drug therapy, disease, nutrient deficiencies and other physiologically altered conditions on conjugative drug metabolism in animal studies. For simultaneous determination of 4-nitrophenol (PNP), 4-nitrophenyl-beta-D-glucuronide (PNP-G) and 4-nitrophenyl-sulfate (PNP-S) in samples generated in rat small intestine luminal perfusion experiments, an ion-pair HPLC assay coupled with UV detection was set up. The RP-HPLC separation was achieved with a methanol-water mixture (50:50, v/v) containing 0.01 M tetrabutyl-ammonium-bromide with UV detection of the analytes at 290 nm. The isocratic system was operated at ambient temperature and required less than 7 min of chromatographic time. The method provided good enough within-day precision, between-day precision and linearity in the target concentration ranges of 6-1200 microM (PNP) and 2.5-100 microM (PNP-G and PNP-S). The instrumental limit of quantification for PNP-G and PNP-S was found to be 2.7 microM and 2.1 microM, respectively. The assay was applied for determination of PNP, PNP-G and PNP-S in rat small intestine perfusates.

Topics: Animals; Chromatography, High Pressure Liquid; Glucuronides; Jejunum; Nitrophenols; Perfusion; Rats; Reproducibility of Results; Sulfates

Sorption behavior of p-nitrophenol by sediment in the presence of both cetylpyridinium chloride (CPC) and Pb(NO3)2 were investigated. The concurrence of Pb(NO3)2 inhibited the enhancement of sorption induced by CPC. The removal effect of pnitrophenol from sediment by compounding of CPC and Pb(NO3)2 presented antagonistic effect. At a given concentration of CPC, the antagonistic effect increased with increasing of the initial concentration of Pb(NO3)2. The antagonistic effect was also dependent on CPC concentrations. At the initial concentration below 3000 mg/L(the equilibrium concentration was below CMC), the antagonistic effect was especially significant. With the increase of the concentration of CPC, the antagonistic effect decreased gradually. Especially at the higher concentration above CMC, the effect went to be an independent effect just induced by CPC. In addition, the study also indicate that Pb2+ and CPC may not compete for the same adsorption sites.

Topics: Adsorption; Cetylpyridinium; Geologic Sediments; Lead; Nitrates; Nitrophenols; Surface-Active Agents; Water Pollutants, Chemical

A 4-nitrophenol (PNP) isolated from diesel exhaust particles (DEP) has been identified as a vasodilator. PNP is also a known degradation product of the insecticide parathion. We used uterotrophic and Hershberger assays to study the estrogenic and anti-androgenic activities of PNP in-vivo. In ovariectomized immature female rats injected subcutaneously with 1, 10, or 100 mg/kg PNP daily for 7 days, significant (P<0.05) increases in uterine weight were seen in only those receiving 10 or 100 mg/kg PNP. Furthermore, in castrated immature male rats implanted with a silastic tube (length, 5 mm) containing crystalline testosterone and injected subcutaneously with 0.01, 0.1, or 1 mg/kg PNP daily for 5 days, those receiving the doses of 0.1 mg/kg showed significant (P<0.05) weight decreases in seminal vesicles, ventral prostate, levator ani plus bulbocavernosus muscles, and glans penis. Plasma FSH and LH levels did not change in female rats but were significantly (P<0.05) increased in male rats treated with 0.1 mg/kg PNP. These results clearly demonstrated that PNP has estrogenic and anti-androgenic activities in-vivo. Our results therefore suggest that diesel exhaust emissions and the degradation of parathion can lead to accumulation of PNP in air, water, and soil and thus could have serious deleterious effects on wildlife and human health.

Topics: Androgen Antagonists; Animals; Biological Assay; Dose-Response Relationship, Drug; Endocrine Disruptors; Estrogens; Female; Follicle Stimulating Hormone; Genitalia, Male; Luteinizing Hormone; Male; Nitrophenols; Orchiectomy; Organ Size; Ovariectomy; Rats; Rats, Wistar; Uterus; Vehicle Emissions

A microwave (MW) assisted oxidation process was investigated for degradation of p-nitrophenol (PNP) from aqueous solution. The process consisted of a granular activated carbon (GAC) fixed bed reactor, a MW source, solution and air supply system, and a heat exchanger. The process was operated in continuous flow mode. Air was applied for oxygen supply. GAC acted as a MW energy absorption material as well as the catalyst for PNP degradation. MW power, air flow, GAC dose, and influent flow proved to be major factors which influenced PNP degradation. The results showed that PNP was degraded effectively by this new process. Under a given condition (PNP concentration 1330mg/L, MW power 500 W, influent flow 6.4 mL/min, air flow 100 mL/min), PNP removed 90%, corresponding to 80% of TOC removal. The pathway of PNP degradation was deduced based on GC-MS identification of course products. PNP experienced sequential oxidation steps and mineralized ultimately. Nitro-group of PNP converted to nitrite and nitrate. Biodegradability of the solution was improved apparently after treatment by MW assisted oxidation process, which benefit to further treatment of the solution using biochemical method.

Topics: Adsorption; Air; Biodegradation, Environmental; Carbon; Microwaves; Nitrophenols; Oxidation-Reduction; Solutions; Temperature; Water Purification

Carbon fixed-beds are usually used to remove organic contaminants. Adsorption in a carbon filter is a dynamic, non-steady process which is not yet completely understood. The objective of this paper is to establish a methodology to simplify the study of this process based on the wave theory, rapid small-scale column test and experimental design/surface response analysis. The constant pattern wave hypothesis was confirmed by the experimental data. The influence of the inlet concentration of p-nitrophenol and the flow rate on dynamic adsorption was studied at 20 degrees C following a central composite design using a second-order model. Both parameters have an important influence on the response variables studied. The methodology used is a useful tool for studying the dynamic process and shows interactions that are difficult to verify by the classical step-by-step method.

Topics: Adsorption; Carbon; Filtration; Nitrophenols; Surface Properties; Water Purification

Nanometer size titanium dioxide modified with 3,5-dinitrosalicylic acid (3,5-DA) was prepared using chemical adsorption method. The influences of surface modification on the adsorption of p-nitrophenol (PNP) and the dispersion in solvent such as water, benzene and ethanol were studied. The 3,5-dinitrosalicylic acid is bonded to the surface hydroxyl from TiO2 nanoparticles, results in the formation of a stable, six-ring complex which color is buff. The 3, 5-DA-modified TiO2 nanoparticles have good dispersive capacity in water, benzene and ethanol. Under the optimum conditions such as pH value 3, adsorption time 10 min, the adsorption ratio of PNP by TiO2 is improved from 43% to 99.9% through surface modification. A new method could be used to remove directly 3 approximately 10mg/L PNP, and the residual concentrations is below the integrated wastewater discharge standard (GB 8978-1996).

Topics: Adsorption; Metal Nanoparticles; Nitrophenols; Salicylates; Titanium; Waste Disposal, Fluid

Polymer-microsphere-stabilized gold metallic colloids have been prepared by a novel strategy of simple and convenient reduction of the metallic salt through the stabilization of the active carboxylic acid group on the gel and surface layer of the microsphere. The nature of the interaction between the carboxylic acid and Au nanoparticles was studied in detail by XPS. Preliminary results indicate that polymer-microsphere-stabilized gold colloids are active catalysts for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride as reductant. The catalytic properties of the stabilized catalyst for recycling were also investigated.

Topics: Adsorption; Aminophenols; Carboxylic Acids; Catalysis; Colloids; Gold; Microspheres; Nitrophenols; Oxidation-Reduction; Particle Size; Polymers; Spectrophotometry; Surface Properties; Water; X-Rays

Heavy metals and organic contaminants often coexist in soils. However, very little information is available regarding the effect of metals on the sorption of organic contaminants onto soils and/or of organic contaminants on metal sorption. In the present study, the effect of Cu on the sorption of p-nitrophenol on two Chinese soils was investigated using a batch-equilibration method for three conditions: Copper and p-nitrophenol were sorbed simultaneously, either Cu orp-nitrophenol was sorbed previously, or the soil colloidal phase was removed in part previously. The results suggested that Cu suppressed the sorption ofp-nitrophenol on soils, whereas p-nitrophenol had little effect on Cu sorption because of the higher affinity of Cu for soils. Mechanisms of the Cu suppression effect were suggested by the results. First, large hydrated Cu occupy the siloxane surface of soils and prevent nonspecific interaction between p-nitrophenol and soils. Second, the soil colloidal phase is an effective adsorbent of p-nitrophenol; thus, more p-nitrophenol is retained in the aqueous phase. In addition, the aggregation of the colloidal particles may occur, which blocks soil pores, thereby decreasing the sorption of p-nitrophenol on the solid soil phase. Third, x-ray absorption spectroscopy revealed that Cu forms inner-sphere complexes with the carboxyl and hydroxyl functional moieties of the soil particles (clay minerals and organic matter). Fourier-transform infrared spectroscopy study indicated that these groups also react with p-nitrophenol through H-bond formation. These results suggested that Cu and p-nitrophenol have common sorption sites, at least in the soil organic matter domain, which is partially responsible for the observed overall Cu suppression effect.

Topics: Adsorption; China; Copper; Nitrophenols; Soil Pollutants; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis

A three-stage system was developed to automate a batchwise toxicity testing protocol designed for assessing wastewater toxicity to activated sludge. The three-stage system used the luminescent bacterium Shkl. The three stages were cell storage, cell activation, and continuous toxicity testing. Shkl cells were stored in a bioreactor at 4 degrees C when the system was not in use and activated in another bioreactor for use in toxicity tests conducted in a continuous manner. The system could quickly be switched between the "off" and "on" modes, and operation of the system was easy. The stability of the system, in terms of cell density and bioluminescence in the storage and activation bioreactors, and the response of the activated cells to a metal and an organic toxicant were studied. The feasibility of the system design was demonstrated by simulating zinc toxicity episodes in synthetic wastewater. The needs for further modifications and improvements of the system were discussed.

Topics: Bioreactors; Chlorides; Environmental Monitoring; Feasibility Studies; Nitrophenols; Pseudomonas fluorescens; Time Factors; Waste Disposal, Fluid; Water Pollutants, Chemical; Zinc Compounds

This work presents a comparison of two inocula used for the acclimation of two anaerobic-aerobic sequencing batch bioreactors used for toxic wastewater treatment. The bioreactors were acclimated with different types of sludge: one coming from an anaerobic wastewater treatment plant and the other one from a conventional aerobic activated sludge plant. The model toxic compound was p-nitrophenol, which is reduced to p-aminophenol during the initial anaerobic phase of the reaction, and later mineralized during a posterior aerated reaction phase. Biodegradation of the compounds was monitored using UV/Vis spectrophotometry. After acclimation stabilization of the sludge and of the process was also monitored. Results show that there is no significant difference in acclimation times and stability of the process between the two employed inocula, and thus an originally anaerobic inoculum presents no apparent advantage over a more easily accessible aerobic one.

Topics: Aerobiosis; Anaerobiosis; Biodegradation, Environmental; Bioreactors; Nitrophenols; Sewage; Sulfur-Reducing Bacteria; Time Factors; Waste Disposal, Fluid

This communication reports a nanocatalyst-based electrochemical assay for proteins. Ultrasensitive detection has been achieved by signal amplification combined with noise reduction: the signal is amplified both by the catalytic reduction of p-nitrophenol to p-aminophenol by gold-nanocatalyst labels and by the chemical reduction of p-quinone imine to p-aminophenol by NaBH4; the noise is reduced by employing an indium tin oxide electrode modified with a ferrocenyl-tethered dendrimer and a hydrophilic immunosensing layer.

Topics: DNA; Electrochemistry; Gold; Molecular Structure; Nanoparticles; Nitrophenols; Oxidation-Reduction; Proteins

Photodegradation of pentachlorophenol (PCP) and p-nitrophenol (PNP) in soil was carried out in a designed rotary reactor, which can provide the soil particles with continually uniform irradiation, and on a series of thin soil layers. TiO2, as a kind of environmental friendly photocatalyst, was introduced to the soil to enhance the processes. Compared with that on the soil layers, photodegradation of PCP at initial concentration of 60 mg/kg was improved dramatically in the rotary reactor no matter whether TiO2 was added, with an increase of 3.0 times in the apparent first-order rate constants. The addition of 1 wt% TiO2 furthered the improvement by 1.4 times. Without addition of TiO2, PNP (initial concentration of 60 mg/kg) photodegradation rate in the rotary reactor was similar to that on the soil layers. When 1 wt% additional TiO2 was added, PNP photodegradation was enhanced obviously, and the enhancement in the rotary reactor was 2 times of that on the soil layers, which may be attributed to the higher frequency of the contact between PNP on soil particles and the photocatalyst. The effect of soil pH and initial concentrations of the target compounds on the photodegradation in the rotary reactor was investigated. The order of the degradation rate at different soil pH was relative to the aggregation of soil particles during mixing in the rotary reactor. Photodegradation of PCP and PNP at different initial concentrations showed that addition of TiO2 to enhance the photodegradation was more suitable for contaminated soil with higher concentration of PCP, while was effective for contaminated soil at each PNP concentration tested in our study.

Topics: Catalysis; Chromatography, High Pressure Liquid; Environmental Pollution; Hydrogen-Ion Concentration; Nitrophenols; Pentachlorophenol; Photolysis; Soil; Soil Pollutants; Titanium

The strain X4 was isolated from polluted wastes of Shandong Huayang Pesticide Chemical Industry Group Co., Ltd. It was cultured with methylparathion and p-nitrophenol, a kind of intermediate during methylparathion degrading process, and used them as the sole carbon source and decomposed them into carbon dioxide and wastes. It is identified as Arthrobacter sp. by means of a series of tests, and it has visible sphere-pole variable cycle. It is bacilliform when it is cultured in nutrient broth medium within 36h, then it become short gradually, and ultimately become uniform sphericity. Bacilliform strains array in "V" or "Y" shape. It has flagellum, moveable, no sporangium, oxidates glucose: The degradative ability to pesticides of X4 was determined by gas chromatography (GC) and spectrophotometer, and the degradative rate for methylparathion at 50mg/L and rho - nitrophenol at 50mg/L is above 99% within 7h. Moreover, X4 also can degrade other organophosphate pesticides quickly. The degradative rate for methamidophos, chlorpyrifos and carbofuran is 64%, 54% and 68%, respectively. The maximal tolerant concentration of X4 to MP, PNP, methamidophos, chlorpyrifos and carbofuran is 1700mg/L, 500mg/L, 500mg/L, 300mg/L and 300mg/L, respectively. All of the above tests were determined at 30 degrees C , pH7, with an inoculum of 30% . At the same time, 16S rRNA sequence of X4 is obtained, and the similar sequences to X4 were selected from GenBank by BLAST program and the phylogenetic tree with these sequences was constructed, the relationship between X4 and referenced strains was worked out. At present, methylparathion and p-nitrophenol degradative strains reported are mostly Pseudomonas sp., Flavobacterium, Alcaligenes sp. and so on. Furthermore, those strains can only degrade MP and PNP partially. It is reported firstly here that Arthrobacter sp. can degrade both MP and PNP to small molecule synchronously and effectively. Finally, the strain X4 shows a huge potential to be used in a bioremediation application for the treatment of methlparation residues, and further research may lead to an alternative route of disposal for use in agriculture or industry.

Topics: Arthrobacter; Biodegradation, Environmental; Industrial Waste; Insecticides; Methyl Parathion; Nitrophenols; Phylogeny; Water Microbiology

The present contribution reports experimental and computational investigations of the interaction between [Cp*Fe(dppe)H] and different proton donors (HA). The focus is on the structure of the proton transfer intermediates and on the potential energy surface of the proton transfer leading to the dihydrogen complex [Cp*Fe(dppe)(H2)]+. With p-nitrophenol (PNP) a UV/Visible study provides evidence of the formation of the ion-pair stabilized by a hydrogen bond between the nonclassical cation [Cp*Fe(dppe)(H2)]+ and the homoconjugated anion ([AHA]-). With trifluoroacetic acid (TFA), the hydrogen-bonded ion pair containing the simple conjugate base (A-) in equilibrium with the free ions is observed by IR spectroscopy when using a deficit of the proton donor. An excess leads to the formation of the homoconjugated anion. The interaction with hexafluoroisopropanol (HFIP) was investigated quantitatively by IR spectroscopy and by 1H and 31P NMR spectroscopy at low temperatures (200-260 K) and by stopped-flow kinetics at about room temperature (288-308 K). The hydrogen bond formation to give [Cp*Fe(dppe)H]HA is characterized by DeltaH degrees =-6.5+/-0.4 kcal mol(-1) and DeltaS degrees = -18.6+/-1.7 cal mol(-1) K(-1). The activation barrier for the proton transfer step, which occurs only upon intervention of a second HFIP molecule, is DeltaH(not equal) = 2.6+/-0.3 kcal mol(-1) and DeltaS(not equal) = -44.5+/-1.1 cal mol(-1) K(-1). The computational investigation (at the DFT/B3 LYP level with inclusion of solvent effects by the polarizable continuum model) reproduces all the qualitative findings, provided the correct number of proton donor molecules are used in the model. The proton transfer process is, however, computed to be less exothermic than observed in the experiment.

Topics: Computer Simulation; Hydrogen Bonding; Iron; Ligands; Models, Molecular; Molecular Structure; Nitrophenols; Organometallic Compounds; Propanols; Protons; Quantum Theory; Sensitivity and Specificity; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet; Thermodynamics

The interaction of the monooxygenating type-3 copper enzyme Tyrosinase (Ty) from Streptomyces antibioticus with its inhibitor p-nitrophenol (pnp) was studied by paramagnetic NMR methods. The pnp binds to oxidized Ty (Ty(met)) and its halide (F(-), Cl(-)) bound derivatives with a dissociation constant in the mM range. The Cu(2) bridging halide ion is not displaced upon the binding of pnp showing that the pnp does not occupy the Cu(2) bridging position. The binding of pnp to Ty(met) or Ty(met)Cl leads to localized changes in the type-3 (Cu-His(3))(2) coordination geometry reflecting a change in the coordination of a single His residue that, still, remains coordinated to Cu. The binding of pnp to Ty(met)Cl causes a decrease in the Cu(2) magnetic exchange parameter -2J from 200 cm(-)(1) in the absence to 150 +/- 10 cm(-)(1) in the presence of pnp. From the (1)H and (2)D NMR relaxation parameters of pnp bound to Ty(met), a structural model of pnp coordination to the Ty type-3 center could be derived. The model explains the absence of hydroxylase activity in the closely related type-3 copper protein catechol oxidase. The relevance of the experimental findings toward the Ty catalytic mechanism is discussed.

Topics: Copper; Deuterium; Metalloproteins; Models, Molecular; Monophenol Monooxygenase; Nitrophenols; Nuclear Magnetic Resonance, Biomolecular; Streptomyces antibioticus; Titrimetry

In this study, the effect of temperature on the adsorption of some dyestuffs [orange II (O-II), crystal violet (CV) and reactive blue 5 (RB5)] and p-nitrophenol (PNP) by chitosan and of O-II and CV by modified chitosan [monocarboxymethylated(mcm)-chitosan] from aqueous solution was investigated. Kinetical data related to the adsorptions of each dyestuff and PNP by chitosan and of O-II and CV by mcm-chitosan were applied to Lagergren and Weber-Morris equations, and adsorption rate constants (kads) and pore diffusion rate constants (kp) were determined, respectively. In addition, Langmuir isotherm constants with experimental data related to the adsorptions of O-II and CV by chitosan and of CV by mcm-chitosan were applied to McKay et al. equation, and external mass transfer coefficients (kf) were also determined. Lastly, chitosan and mcm-chitosan were compared according to their dyestuffs and PNP uptake capabilities. It was seen that mcm-chitosan removed more O-II (99.2%) and RB5 (34.9%) but less CV (3.1%) and PNP (0.9%).

Topics: Adsorption; Chitosan; Diffusion; Kinetics; Nitrophenols; Temperature; Water Pollutants, Chemical; Water Purification

The oxidation of phenol and two substituted species (4-nitrophenol and 4-chlorophenol) has been carried out by means of the O3, UV-vis, O3+UV-vis, TiO2+UV-vis, O(3)+UV-vis+TiO2 and O3+TiO2 systems. From UV-vis experiments, the quantum yield of these organics has been calculated (0.018, 0.005 and 0.017 mol per Einstein for phenol, 4-nitrophenol and 4-chlorophenol, respectively). Broadly speaking, the addition of titania powder results in a slight inhibition of the parent compound degradation rate, although a positive effect is experienced when measuring the chemical oxygen demand (COD) and total organic carbon (TOC) removals. Amongst the technologies investigated, those combining ozone and radiation show the best efficiency in terms of phenols elimination and also COD and TOC decay rates. A simple economy analysis of the processes illustrates how the combinations O3+UV-vis and O3+UV-vis+TiO2 are the most attractive technologies, although some additional considerations have to be taken into account.

Topics: Chlorophenols; Environmental Pollution; Nitrophenols; Oxidants, Photochemical; Oxidation-Reduction; Ozone; Photochemistry; Ultraviolet Rays

LC coupled to an electrochemical detector (LC-EC) operating in cathodic mode with a column-switching system realizes a high-throughput detection of p-nitrophenol (NP). The measurement-time for each NP sample was shortened to 20 s, and the successive analyses of 39 samples was completed within 13 min. In the present system, the limits of detection and quantification were 0.15 and 0.20 microM, respectively, and further, up to 25 microM, a linear calibration curve was afforded. Relative standard deviations for standard solutions of 0.20, 1.0, and 25 microM NP were 4.3, 2.0, and 1.1% (n = 5), respectively. Between-run precisions of the analysis of 5.0 and 25 microM NP over 6 days were 4.8 and 1.3%, respectively. A comparison with the commonly used Bessey-Lowry-Brock method indicates that the present LC-EC is useful for the high-throughput assay of acid and alkaline phosphatases in urine and blood samples with a p-nitrophenyl phosphate substrate.

Topics: Acid Phosphatase; Alkaline Phosphatase; Chromatography, High Pressure Liquid; Nitrophenols; Organophosphorus Compounds; Oxygen; Quality Control; Reproducibility of Results; Sensitivity and Specificity

p-Nitrophenol (PNP), a toxic nitroaromatic compound, can build up in soils due to extensive usage of nitrophenolic pesticides and hence needs to be removed. Arthrobacter protophormiae RKJ100, a PNP-degrading organism, was used in this work to study factors affecting its growth, and then evaluated for its capacity to degrade PNP in soil microcosms. Molasses (10%) treated with 0.1% potassium hexacyanoferrate was found to be a suitable and cheap carbon source for inoculum preparation. Induction studies showed that PNP depletion was quicker when cells were induced by pre-exposure to PNP. The efficiency of PNP degradation in soil by strain RKJ100 was seen to be dependent on pH, temperature, initial PNP concentration and inoculum size. Microcosm studies performed with varying concentrations (1.4-210 ppm) of PNP-spiked soils showed that strain RKJ100 could effectively degrade PNP over the range 1.4-140 ppm. A cell density of 2x10(8) colony forming units/g soil was found to be suitable for PNP degradation over a temperature range of 20-40 degrees C and at a slightly alkaline pH (7.5). Our results indicate that strain RKJ100 has potential for use in in situ bioremediation of PNP-contaminated sites. This is a model study that could be used for decontamination of sites contaminated also with other compounds.

Topics: Arthrobacter; Biodegradation, Environmental; Culture Media; Hydrogen-Ion Concentration; Nitrophenols; Soil Pollutants; Temperature; Time Factors

With more accurate simulation models and more efficient algorithms becoming available, the binding constants of an affinity interaction can be obtained from much simpler experiments using capillary electrophoresis. With the enumeration algorithm, all possible combinations of the binding constant and the complex mobility in certain ranges that could result in the experimental migration time of an injected analyte are extracted from a 3-D surface, which depicts the migration times resulting from different values of the binding constant and the mobility of the complex formed between the interacting pair, to form a 2-D curve. When the experimental conditions are changed, the analyte migration time will also change. A new 2-D curve can be constructed from another 3-D surface on the basis of the pairs of binding constants and complex mobility values that could result in the new migration time. Because the true binding constant and complex mobility values have to be the same for both experimental conditions under the same temperature, there has to be a point where both 2-D curves will converge. The coordinates of the converging point give the values for a binding constant and a complex mobility that will fit all 2-D curves generated under certain experimental conditions. p-Nitrophenol is used as the analyte, beta-cyclodextrin is used as the additive, and a one-cell model is used to simulate affinity CE. The experimental conditions that can improve the accuracy of the binding constants are discussed.

Topics: Algorithms; beta-Cyclodextrins; Electrophoresis, Capillary; Nitrophenols; Regression Analysis

Here we report the crystal structure of YqjM, a homolog of Old Yellow Enzyme (OYE) that is involved in the oxidative stress response of Bacillus subtilis. In addition to the oxidized and reduced enzyme form, the structures of complexes with p-hydroxybenzaldehyde and p-nitrophenol, respectively, were solved. As for other OYE family members, YqjM folds into a (alpha/beta)8-barrel and has one molecule of flavin mononucleotide bound non-covalently at the COOH termini of the beta-sheet. Most of the interactions that control the electronic properties of the flavin mononucleotide cofactor are conserved within the OYE family. However, in contrast to all members of the OYE family characterized to date, YqjM exhibits several unique structural features. For example, the enzyme exists as a homotetramer that is assembled as a dimer of catalytically dependent dimers. Moreover, the protein displays a shared active site architecture where an arginine finger (Arg336) at the COOH terminus of one monomer extends into the active site of the adjacent monomer and is directly involved in substrate recognition. Another remarkable difference in the binding of the ligand in YqjM is represented by the contribution of the NH2-terminal Tyr28 instead of a COOH-terminal tyrosine in OYE and its homologs. The structural information led to a specific data base search from which a new class of OYE oxidoreductases was identified that exhibits a strict conservation of active site residues, which are critical for this subfamily, most notably Cys26, Tyr28, Lys109, and Arg336. Therefore, YqjM is the first representative of a new bacterial subfamily of OYE homologs.

Topics: Amino Acid Sequence; Arginine; Bacillus subtilis; Benzaldehydes; Binding Sites; Catalysis; Crystallography, X-Ray; Dimerization; Electrons; Escherichia coli; Flavoproteins; Kinetics; Ligands; Models, Molecular; Molecular Sequence Data; Nitrophenols; Open Reading Frames; Oxidative Stress; Oxidoreductases; Phylogeny; Protein Binding; Protein Conformation; Protein Folding; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Substrate Specificity; Tyrosine; X-Ray Diffraction

Tubular structure of nanoparticles is highly attractive due to their structural attributes, such as the distinctive inner and outer surfaces, over conventional spherical nanoparticles. Inner voids can be used for capturing, concentrating, and releasing species ranging in size from large proteins to small molecules. Distinctive outer surfaces can be differentially functionalized with environment-friendly and/or probe molecules to a specific target. Magnetic particles have been extensively studied in the field of biomedical and biotechnological applications, including drug delivery, biosensors, chemical and biochemical separation and concentration of trace amounts of specific targets, and contrast enhancement in magnetic resonance imaging (MRI). Therefore, by combining the attractive tubular structure with magnetic property, the magnetic nanotube (MNT) can be an ideal candidate for the multifunctional nanomaterial toward biomedical applications, such as targeting drug delivery with MRI capability. Here, we successfully synthesized magnetic silica-iron oxide composite nanotubes and demonstrated the magnetic-field-assisted chemical and biochemical separations, immunobinding, and drug delivery.

Topics: Animals; Antigen-Antibody Reactions; Drug Delivery Systems; Ferrosoferric Oxide; Fluorescein; Fluorouracil; Humans; Ibuprofen; Immunoglobulin G; Iron; Magnetics; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Nanotubes; Nitrophenols; Oxides; Serum Albumin, Bovine; Silicon Dioxide

Biodegradation of p-nitrophenol (PNP), a priority pollutant, was studied as a model system for bioremediation of sites contaminated with nitroaromatic/organic compounds. Bioremediation of PNP-containing soil was first carried out in pots using immobilized and free cells of Arthrobacter protophormiae RKJ100 in order to ascertain the role of a suitable carrier material. Results showed that stability of the introduced strain was enhanced upon immobilization and that the rate of PNP depletion decreased with increasing depth of soil. Small-scale field studies (in one square meter plots) were then conducted in which PNP-contaminated soil from an agricultural field was bioaugmented with strain RKJ100 under natural environmental conditions. PNP was totally depleted in 5 days by immobilized cells, whereas free cells were able to deplete 75% of PNP in the same time period. The fate of the released strain as monitored by plate counts, hybridization studies, and real-time polymerase chain reaction revealed fairly stable population of the cells upon immobilization on corncob powder throughout the period of study.

Topics: Arthrobacter; Biodegradation, Environmental; DNA, Bacterial; Nitrophenols; Polymerase Chain Reaction; Population Dynamics; Soil Pollutants

Two lipophilic ligands containing triazole and hydroxyl groups, N-alkyl(C(n)H(2n+1))-3,5-bis(hydroxymethyl)-1,2,4-triazole (n=10 and 12), were synthesized. Effects of their Cu(II) and Ni(II) complexes on the hydrolysis of p-nitrophenyl picolinate (PNPP) in cetyltrimethylammonium bromide (CTAB) micelles have been investigated kinetically, and some kinetic parameters of the reactions were obtained by employing the ternary complex kinetic model for metallomicellar catalysis. It was found that Cu(II) complexes of these triazole-based ligands showed more effective catalytic activity on the hydrolysis of PNPP than Ni(II) complexes. Also, the apparent first-order rate constants for product formation in the metallomicellar phase (k(N)(')), the association constants between the substrate and the binary complex (K(T)), and the association constants between the metal ion and the ligand (K(M)) increased with an increase in pH value, which may be attributed to an increase in the nucleophilicity of the hydroxyl groups in the ligand or the electrophilicity of the substrate at higher pH. In addition, at constant pH, k(N)(') and K(T) increased with an increase in the hydrocarbon chain length of the ligand, while K(M) decreased.

Topics: Catalysis; Cetrimonium; Cetrimonium Compounds; Copper; Hydrogen-Ion Concentration; Hydrolysis; Ligands; Micelles; Nickel; Nitrophenols; Organometallic Compounds; Picolinic Acids; Surface Properties; Triazoles

Adsorption of phenol, hydroquinone, m-cresol, p-cresol and p-nitrophenol from aqueous solutions onto high specific area activated carbon cloth has been studied. The effect of ionization on adsorption of these ionizable phenolic compounds was examined by studying the adsorption from acidic, basic and natural pH solutions. Kinetics of adsorption was followed by in situ UV spectroscopy over a period of 90 min. First-order rate law was found to be valid for the kinetics of adsorption processes and the rate constants were determined. The highest rate constants were obtained for the adsorption from solutions at the natural pH. The lowest rate constants were observed in basic solutions. The rate constants decreased in the order p-nitrophenol approximately m-cresol>p-cresol>hydroquinone approximately phenol. Adsorption isotherms were derived at 30 degrees C and the isotherm data were treated according to Langmuir, Freundlich and Tempkin isotherm equations. The goodness of fit of experimental data to these isotherm equations was tested and the parameters of equations were determined. The possible interactions of compounds with the carbon surface were discussed considering the charge of the surface and the possible ionization of compounds at acidic, basic and natural pH conditions.

Topics: Adsorption; Charcoal; Cresols; Hydrogen-Ion Concentration; Hydroquinones; Nitrophenols; Osmolar Concentration; Phenols; Temperature; Water; Water Pollutants, Chemical; Water Pollution, Chemical

CYP2E1 is known to be induced in streptozotocin (STZ)-treated diabetic rats (STZ rats), and its induction is improved by insulin. We have examined the age-dependent changes of CYP2E1 in the liver microsomes of type 1 diabetic STZ rats, the effects of VOSO4 on the contents of total P450 and CYP2E1, and the activities of CYP2E1 in terms of p-nitrophenol hydroxylation. The contents of P450 and CYP2E1 and CYP2E1 activity were enhanced with the development of diabetes. When the hyperglycemia of STZ rats was improved by daily intraperitoneal injections of VOSO4 for 10 days at the doses of 7 mg/kg body weight for 5 days, 5 mg/kg for the following 3 days, and then 2.5 mg/kg for 2 days, the P450 and CYP2E1 levels and CYP2E1 activity were lowered than those in the untreated STZ rats. To understand the mechanism underlying CYP2E1-dependent hydroxylation activity, the production of reactive oxygen species was examined in the NADPH-liver microsomal systems by ESR spin-trapping. Singlet oxygen (1O2) was detected in all microsomal systems, while superoxide anion radical(*O2-) and hydroxyl radical (*OH) were not. On the basis of these results, we conclude that (1) CYP2E1 level and activity are enhanced in the diabetic state, however, they are improved by VOSO4 treatment, and (2) 1O2 is generated during CYP2E1-dependent substrate oxygenation.

Topics: Age Factors; Analysis of Variance; Animals; Cytochrome P-450 CYP2E1; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Electron Spin Resonance Spectroscopy; Hydroxylation; Hypoglycemic Agents; Immunoblotting; Microsomes, Liver; Nitrophenols; Rats; Rats, Wistar; Spin Trapping; Streptozocin; Vanadium Compounds

Removal of many organic pollutants including phenolic compounds from industrial wastewater can always be achieved by fixed-bed adsorption onto the polymeric resin adsorbent, and the relevant breakthrough curves would provide much valuable information to help to design a fixed-bed adsorption process in field application. In the present study, a model developed based on the constant-pattern wave approach theory and the Freundlich model was adopted to describe the breakthrough curves of phenol and p-nitrophenol adsorption onto a macroreticular resin adsorbent NDA-100 from aqueous solution. Column experiments were performed at different conditions to verify the model and the results proved that the model would describe the breakthrough curves well. Effect of the operation parameters on breakthrough curves was also discussed to get helpful information in choosing the adsorption process.

Topics: Adsorption; Hydrogen-Ion Concentration; Industrial Waste; Models, Chemical; Nitrophenols; Osmolar Concentration; Phenol; Reproducibility of Results; Resins, Synthetic; Temperature; Water; Water Pollutants, Chemical; Water Pollution, Chemical

The study regards 4-nitrophenol removal performed in a lab-scale sequential batch reactor with an integrated aerobic-anoxic cycle. The purpose of the study was to examine the kinetics of 4-nitrophenol biological oxidation and denitrification in order to test the feasibility of the proposed technological solution for xenobiotic removal. The results obtained show that high removal efficiency of 4-nitrophenol is easily achieved when the compound is fed into the reactor as the sole carbon source. Residual concentrations of 4-nitrophenol and nitrous/nitric nitrogen in the effluent lower than 1 mg L(-1) were observed in the range of applied feed concentration (200-320 mg L(-1)). Low concentrations of dissolved oxygen (< or =2 mg L(-1)) in the feed and aerobic phases lead to appreciable simultaneous denitrification. As regards the denitrification process, while no carbon-limiting effects were observed at COD/N ratios > or = 3, a significant decrease in the rate of denitrification is detected for COD/N ratios < or = 2. The denitrification rate obtained in tests with no external carbon addition proved very low and unsuitable for practical application. A model of the denitrification process taking into account both the limiting effect of nitrogen and carbonaceous substrate has been proposed and applied for experimental data correlation.

Topics: Bacteria, Aerobic; Biodegradation, Environmental; Bioreactors; Kinetics; Nitrophenols; Oxidation-Reduction; Water Purification; Xenobiotics

An amperometric microbial biosensor for highly specific, sensitive and rapid quantitative determination of p-nitrophenol was developed. The biosensor takes advantage of the ability of Moraxella sp. to specifically degrade p-nitrophenol to hydroquinone, a more electroactive compound than p-nitrophenol. The electrochemical oxidation current of hydroquinone formed in biodegradation of p-nitrophenol was measured at Moraxella sp.-modified carbon paste electrode and correlated to p-phenol concentrations. The optimum response was realized by electrode constructed using 15 mg of dry cell weight per 1 g of carbon paste and operating at 0.3 V (versus Ag/AgCl reference) in pH 7.5, 20 mM sodium phosphate buffer. Operating at these optimum conditions the biosensor had excellent selectivity against phenol derivatives and was able to measure as low as 20 nM (2.78 ppb) p-nitrophenol with very good accuracy and reproducibility. The biosensor was stable for approximately 3 weeks when stored at 4 degrees C. The applicability of the biosensor to measure p-nitrophenol in lake water was demonstrated.

Topics: Biological Assay; Biosensing Techniques; Carbon; Electrochemistry; Environmental Monitoring; Equipment Design; Equipment Failure Analysis; Microelectrodes; Moraxella; Nitrophenols; Ointments; Water Pollutants, Chemical

Thermal parametric pumping is a cyclic adsorptive process based on periodic changes in the bed temperature simultaneously with flow reversal. This is an innovative technology which may allow removing phenolic compounds from waste solutions to be recovered and recycled. The recovery and/or purification of liquid streams containing phenol and 4-nitrophenol by adsorptive parametric pumping was studied in this work. An automated parametric pumping pilot unit was operated in semi-continuous recuperative mode. The adsorbent used was the polymeric resin Sephabeads SP206 (Mitsubishi Kasei Corporation, Japan) and temperatures of the hot and the cold half-cycles were 333 and 293 K, respectively. Basic data were obtained from batch equilibrium experiments and fixed-bed adsorption. Different experimental conditions were run and two simplified models were used to simulate the results: an equilibrium model and a linear driving force (LDF) model. Experimental and simulated results using the LDF model were in quite good agreement. Purification levels below three orders of magnitude lower than the concentration of the feed solution were obtained for phenol and 4-nitrophenol.

Topics: Adsorption; Models, Theoretical; Nitrophenols; Phenol; Polymers; Temperature; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

The effect of the p-nitrophenol to propionic acid ratio, the biomass concentration, and the presence of sulfates on the performance of a control strategy of an anaerobic/aerobic SBR degrading p-nitrophenol was studied. The duration of the anaerobic stage was controlled by an algorithm based on the on-line measurement of the oxidation-reduction potential, which indicates the end of the reduction of p-nitrophenol to p-aminophenol. It was observed that no significant influence on the performance of the algorithm was found when the co-substrate, the biomass concentration and the presence of sulfates were varied, indicating the robustness of the control strategy. Only for the case when a low concentration of cosubstrate was used, was there no transformation of p-nitrophenol.

Topics: Aerobiosis; Algorithms; Anaerobiosis; Bacteria, Aerobic; Bacteria, Anaerobic; Biodegradation, Environmental; Biomass; Bioreactors; Nitrophenols; Oxidation-Reduction; Propionates; Sewage; Sulfates

The surface of nanometer size TiO(2) was simply and fast modified by chemical adsorption in saturated solution of 5-sulfosalicylic acid. After surface modification, a stable, yellow surface complex was formed quickly, the wavelength response range of TiO(2) was expanded, it has obvious absorption in the region from 320 to 450 nm; the adsorption efficiency of p-nitrophenol (PNP) by TiO(2) was enhanced from 42% to 84%. The photocatalytic activity was tested on the degradation of PNP. The influences of catalyst and its dosage, pH value, and PNP concentration on the degradation were investigated. On optimal photodegradation conditions, including initial pH 4.0, PNP 5 mg l(-1), catalyst 100 mg, irradiation time 120 min with 160 W high-pressure mercury lamp, the degradation efficiency of PNP was increased from 40% to 88% after surface modification. Surface modification led not only to an increase in the light utilization, but also improved the surface coverage of PNP in comparison with the pure TiO(2). Both of these factors are crucial for the photocatalytic activity of heterogeneous photocatalysis, especially for photodegradation of benzenoid pollutants.

Topics: Adsorption; Benzenesulfonates; Benzoic Acid; Catalysis; Nitrophenols; Particle Size; Photochemistry; Salicylates; Surface Properties; Titanium; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification

The human cytochrome P450s constitute an important family of monooxygenase enzymes that carry out essential roles in the metabolism of endogenous compounds and foreign chemicals. We present here results of a fusion between a human P450 enzyme and a bacterial reductase that for the first time is shown does not require the addition of lipids or detergents to achieve wild-type-like activities. The fusion enzyme, P450 2E1-BMR, contains the N-terminally modified residues 22-493 of the human P450 2E1 fused at the C-terminus to residues 473-1049 of the P450 BM3 reductase (BMR). The P450 2E1-BMR enzyme is active, self-sufficient and presents the typical marker activities of the native human P450 2E1: the hydroxylation of p-nitrophenol (KM=1.84+/-0.09 mM and kcat of 2.98+/-0.04 nmol of p-nitrocatechol formed per minute per nanomole of P450) and chlorzoxazone (KM=0.65+/-0.08 mM and kcat of 0.95+/-0.10 nmol of 6-hydroxychlorzoxazone formed per minute per nanomole of P450). A 3D model of human P450 2E1 was generated to rationalise the functional data and to allow an analysis of the surface potentials. The distribution of charges on the model of P450 2E1 compared with that of the FMN domain of BMR provides the ground for the understanding of the interaction between the fused domains. The results point the way to successfully engineer a variety of catalytically self-sufficient human P450 enzymes for drug metabolism studies in solution.

Topics: Biotransformation; Chlorzoxazone; Cytochrome P-450 CYP2E1; Cytochromes b5; Humans; Hydroxylation; Mixed Function Oxygenases; NADP; Nitrophenols; Oxygen; Protein Conformation; Protein Structure, Tertiary; Recombinant Fusion Proteins

[reaction: see text] Beta-nitroenamine having a formyl group behaves as the synthetic equivalent of unstable nitromalonaldehyde upon treatment with ketones under basic conditions and leads to 2,6-disubstituted 4-nitrophenols. The present method is safer than the conventional one using sodium nitromalonaldehyde and enables the preparation of hitherto unknown nitrophenols.

Topics: Molecular Structure; Nitrophenols; Stereoisomerism

Field studies have shown that the powerful phytotoxic agent 2,4-dinitrophenol is very likely to form in the atmospheric aqueous phase upon nitration of 2-nitrophenol or 4-nitrophenol. However, until now, the nitration pathway and the relative importance of the two mononitrophenols as sources of 2,4-dinitrophenol were not known. The present study shows that 2,4-dinitrophenol formation from mononitrophenols can take place upon photolysis and photooxidation of nitrite/nitrous acid (NO2-/HONO) and that nitrogen dioxide plays a key role in the process. A possible pathway might be the reaction between light-excited mononitrophenols (both 2- and 4-isomers) and nitrogen dioxide, in the presence of oxygen. As an alternative, nitration might involve *NO3 + *NO2. Possible sources of nitrogen dioxide in the atmospheric aqueous phase are dissolution from the gas phase and oxidation of NO2-. In the latter case, however, it is necessary that NO2- oxidation is faster than the oxidation of mononitrophenols. This would happen, for instance, in the presence of hematite under irradiation. Radiation absorption and scattering by hematite would also inhibit the direct photolysis of nitrophenols. The formation rate and the yield of 2,4-dinitrophenol are slightly higher when starting from 2-nitrophenol than those from 4-nitrophenol, but they are compensated by the higher concentration of 4-nitrophenol in the atmospheric aqueous phase.

Topics: 2,4-Dinitrophenol; Atmosphere; Gas Chromatography-Mass Spectrometry; Nitrogen Dioxide; Nitrophenols; Photolysis; Rain; Ultraviolet Rays

We report herein a whole cell-based amperometric biosensor for highly selective, highly sensitive, direct, single-step, rapid, and cost-effective determination of organophosphate pesticides with a p-nitrophenyl substituent. The biosensor was comprised of a p-nitrophenol degrader, Pseudomonas putida JS444, genetically engineered to express organophosphorus hydrolase (OPH) on the cell surface immobilized on the carbon paste electrode. Surface-expressed OPH catalyzed hydrolysis of the p-nitrophenyl substituent organophosphorus pesticides such as paraoxon, parathion, and methyl parathion to release p-nitrophenol, which was subsequently degraded by the enzymatic machinery of P. putida JS444. The electrooxidization current of the intermediates was measured and correlated to the concentration of organophosphates. The best sensitivity and response time were obtained using a sensor constructed with 0.086 mg dry weight of cells operating at 600 mV applied potential (vs Ag/AgCl reference) in 50 mM citrate--phosphate pH 7.5 buffer with 50 microM CoCl2 at room temperature. Under optimum operating conditions the biosensor measured as low as 0.28 ppb of paraoxon, 0.26 ppb of methyl parathion, and 0.29 ppb parathion. These detection limits are comparable to cholinesterase inhibition-based biosensors. Unlike the inhibition-based format, this biosensor manifests a selective response to organophosphate pesticides with a p-nitrophenyl substituent only, has a simplified single-step protocol with short response time, and can be used for repetitive/multiple and on-line analysis. The service life of the microbial amperometric biosensor was 5 days when stored in the operating buffer at 4 degrees C. The new biosensor offers great promise for rapid environmental monitoring of OP pesticides with nitrophenyl substituent.

Topics: Aryldialkylphosphatase; Biosensing Techniques; Carbon; Chemical Warfare Agents; Electrodes; Hydrolysis; Neuromuscular Diseases; Nitrophenols; Organophosphorus Compounds; Pesticides; Pseudomonas putida; Sensitivity and Specificity

The objective of this study was to investigate whether metabolic activation of parathion by cytochrome P-450s (CYPs) was responsible for pesticide-induced hepatotoxicity and immunotoxicity. Initially, to investigate parathion metabolism in vitro, the production of paraoxon and p-nitrophenol, major metabolites of parathion, was determined by high-performance liquid chromatography (HPLC). Subsequently, metabolic fate and CYP enzymes involved in the metabolism of parathion were partially monitored in rat liver microsomes in the presence of the NADPH-generating system. Among others, phenobarbital (PB)-induced microsomes produced the metabolites paraoxon and p-nitrophenol to the greatest extent, indicating the involvement of CYP 2B in parathion metabolism. When female BALB/c mice were treated orally with 1, 4, or 16 mg/kg of parathion in corn oil once, parathion suppressed the antibody response to sheep red blood cells. To further investigate a possible role of metabolic activation by CYP enzymes in parathion-induced toxicity, female BALB/c mice were pretreated intraperitoneally with 40 mg/kg PB for 3 d, followed by a single oral treatment with 16 mg/kg parathion. PB pretreatment produced a decrease in hepatic glutathione content and increases in hepatotoxic paramenters in parathion-treated mice with no changes in the antibody response. In addition, greater p-nitrophenol amounts were produced when mice were pretreated with PB, compared to treatment with parathion alone. These results indicate that parathion-induced hepatotoxicity might be differentiated from immunotoxicity in mice.

Topics: Alanine Transaminase; Animals; Antibody-Producing Cells; Aspartate Aminotransferases; Biotransformation; Cytochrome P-450 CYP2B1; Female; Glutathione; Insecticides; Liver; Mice; Mice, Inbred BALB C; Microsomes, Liver; Nitrophenols; Paraoxon; Parathion; Phenobarbital; Rats; Rats, Sprague-Dawley; Sheep; Spleen

This study examines the effect of carbon starvation on the ability of a Moraxella sp. strain to degrade p-nitrophenol (PNP). Carbon starvation for 24 h decreased the induction time for p-nitrophenol degradation by the bacterium in a minimal salt medium from 6 to 1 h but it did not completely eliminate the induction time. Moraxella cells with 2-day carbon starvation had an induction time of 3 h and the induction time of the 3-day starved cells was 6 h. A 100% increase in density of the non-starved cells did not affect the induction time for p-nitrophenol degradation by the bacterium, indicating that the initial increase in cell density of the carbon-starved culture did not cause the faster onset of p-nitrophenol degradation. However, the initial uptake of p-nitrophenol of the 1-day carbon-starved Moraxella cells was 3-fold higher than the non-starved cells. A green fluorescent protein gene (gfp)-labelled Moraxella (M6 strain) was constructed to examine the survival of and p-nitrophenol degradation by the bacterium in non-sterile river water samples. Similar p-nitrophenol degradation behaviour was observed in the river water samples inoculated with the M6 cells. The time needed for complete degradation of p-nitrophenol by the non-starved M6 was 19-27 and 33 h in samples spiked with 80, 200 and 360 microM p-nitrophenol, respectively. However, the 1-day carbon-starved inocula required about 16 h to degrade the p-nitrophenol completely regardless of its concentration in the water samples. Survival of the carbon-starved and non-starved M6 was not significantly different from each other in the river water regardless of the p-nitrophenol concentration. In the absence of p-nitrophenol, the inoculum density decreased continuously. At 200 and 360 microM p-nitrophenol, the cell densities of M6 increased in the first two days of incubation and declined steadily afterward.

Topics: Buffers; Carbon; Fresh Water; Moraxella; Nitrophenols; Time Factors

Catalytic activity of Au-Pt, Au-Pd, and Pt-Pd dendrimer nanocomposites for reduction of p-nitrophenol was investigated in water. The bimetallic dendrimer nanocomposites were prepared by simultaneous reduction with sodium borohydride in the presence of poly(amidoamine) (PAMAM) dendrimers with amine and carboxyl terminal groups. Average diameters of the obtained particles were 2-4 nm by transmission electron microscopy. From UV-vis spectroscopy, it was found that the particles were not mixtures of monometallic particles but binary ones. X-ray photoelectron spectroscopy showed that formation of binary composite particles prevents palladium atoms from oxidation. The Au-Pd and Pt-Pd binary particles exhibited higher catalytic activity than monometallic ones. On the other hand, catalytic activity of Au-Pt binary particle was comparable to that of platinum nanoparticles.

Topics: Borohydrides; Catalysis; Dendrimers; Gold; Materials Testing; Metals; Microscopy, Electron, Transmission; Nanostructures; Nanotechnology; Nitrophenols; Oxygen; Palladium; Platinum; Polyamines; Surface Properties; Time Factors; Ultraviolet Rays

Characterization of polycrystalline TiO(2) bare or porphyrin impregnated powders, used as photocatalysts for the degradation of 4-nitrophenol (4-NP) in aqueous suspension, was performed by time-resolved microwave conductivity (TRMC) measurements and electronic paramagnetic resonance (EPR) and X-ray photoelectron (XPS) spectroscopies. The presence of porphyrin sensitizers, as the metal-free or Cu [5,10,15,20-tetra (4-tert-butylphenyl)] porphyrin, impregnated onto the TiO(2) surface improved the photocatalytic activity of the bare TiO(2). TRMC measurements indicate that the number and lifetime of the photoinduced excess charge carriers increase in the presence of the macrocycles, and EPR and XPS spectroscopies support the mechanistic hypotheses based on the photoreactivity experiments.

Topics: Catalysis; Crystallization; Electric Conductivity; Microwaves; Molecular Structure; Nitrophenols; Photochemistry; Porphyrins; Spectrum Analysis; Time Factors; Titanium

The SULT (sulphotransferase) family plays a critical role in the detoxification and activation of endogenous and exogenous compounds as well as in the regulation of steroid hormone actions and neurotransmitter functions. The structure-activity relationships of the human SULTs have been investigated with focus on the amino acid 146 in hSULT1A3 and its impact on dopamine/PNP (p-nitrophenol) specificity. In the present study, we have generated canine SULT1D1 (cSULT1D1) variants with mutations at amino acid residues in the substrate-binding pocket [A146E (Ala-146-->Glu), A146D, A146Q, I86D or D247L]. These mutation sites were chosen with regard to their possible contribution to the marked dopamine/PNP preference of cSULT1D1. After characterization, we found that the overall sulphation efficiencies for the cSULT1D1 A146 and the I86 mutants were strongly decreased for both substrates compared with wild-type cSULT1D1 but the substrate preference was unchanged. In contrast, the D247L mutant was found to be more than 21-fold better at sulphating PNP (120-fold decrease in K(m) value) but 54-fold less efficient in sulphating dopamine (8-fold increase in K(m) value) and the preference was switched from dopamine to PNP, indicating the importance of this amino acid in the dopamine/PNP preference in cSULT1D1. Our results show that Asp-247 has a pronounced effect on the substrate specificity of cSULT1D1 and thus we have identified a previously unrecognized contributor to active-site selectivity.

Topics: Amino Acids; Animals; Aspartic Acid; Binding Sites; Dogs; Dopamine; Models, Molecular; Mutation; Nitrophenols; Recombinant Proteins; Structure-Activity Relationship; Substrate Specificity; Sulfotransferases

Biodegradation kinetics of 4-nitrophenol (4NP) was investigated in a lab-scale sequencing batch reactor fed with the compound as the sole carbon source. The experimental results showed that complete 4NP removal can be easily achieved with acclimatized biomass, even if an inhibition kinetics is observed; furthermore, an improvement in the removal kinetics is obtained if the substrate concentration peak, reached in the reactor at the end of the filling time, is maintained to quite a low value. Both long feed phase and high biomass concentration are effective in reducing the substrate concentration peak and then improving the process efficiency. Kinetic test data are well correlated by the Haldane equation, with a saturation constant Ks and an inhibition constant KI, of 17.6 and 30.7 (mg l(-1) 4NP), respectively, whereas the maximum removal rate was in the range of 3.3-8.4 (mg 4NP mg VSS(-1) d(-1)) depending on the substrate concentration peak reached in the reaction phase.

Topics: Biodegradation, Environmental; Biomass; Bioreactors; Industrial Waste; Kinetics; Nitrophenols; Waste Disposal, Fluid

Human SULT1A1 is primarily responsible for sulfonation of xenobiotics, including the activation of promutagens, and it has been implicated in several forms of cancer. Human SULT1A3 has been shown to be the major sulfotransferase that sulfonates dopamine. These two enzymes shares 93% amino acid sequence identity and have distinct but overlapping substrate preferences. The resolution of the crystal structures of these two enzymes has enabled us to elucidate the mechanisms controlling their substrate preferences and inhibition. The presence of two p-nitrophenol (pNP) molecules in the crystal structure of SULT1A1 was postulated to explain cooperativity at low and inhibition at high substrate concentrations, respectively. In SULT1A1, substrate inhibition occurs with pNP as the substrate but not with dopamine. For SULT1A3, substrate inhibition is found for dopamine but not with pNP. We investigated how substrate inhibition occurs in these two enzymes using molecular modeling, site-directed mutagenesis, and kinetic analysis. The results show that residue Phe-247 of SULT1A1, which interacts with both p-nitrophenol molecules in the active site, is important for substrate inhibition. Mutation of phenylalanine to leucine at this position in SULT1A1 results in substrate inhibition by dopamine. We also propose, based on modeling and kinetic studies, that substrate inhibition by dopamine in SULT1A3 is caused by binding of two dopamine molecules in the active site.

Topics: Arylsulfotransferase; Binding Sites; Dopamine; Enzyme Inhibitors; Humans; Kinetics; Mutagenesis, Site-Directed; Mutation, Missense; Nitrophenols; Protein Binding; Sulfotransferases

The effects of chloride, nitrate, perchlorate and sulfate ions on the rates of the decomposition of hydrogen peroxide and the oxidation of organic compounds by the Fenton's process have been investigated. Experiments were conducted in a batch reactor, in the dark at pH < or = 3.0 and at 25 degrees C. Data obtained from Fe(II)/H2O2 experiments with [Fe(II)]0/[H2O2]0 > or = 2 mol mol(-1), showed that the rates of reaction between Fe(II) and H2O2 followed the order SO4(2-) > ClO4(-) = NO3- = Cl-. For the Fe(III)/H2O2 process, identical rates were obtained in the presence of nitrate and perchlorate, whereas the presence of sulfate or chloride markedly decreased the rates of decomposition of H2O2 by Fe(III) and the rates of oxidation of atrazine ([atrazine]0 = 0.83 microM), 4-nitrophenol ([4-NP]0 = 1 mM) and acetic acid ([acetic acid]0 = 2 mM). These inhibitory effects have been attributed to a decrease of the rate of generation of hydroxyl radicals resulting from the formation of Fe(III) complexes and the formation of less reactive (SO4(*-)) or much less reactive (Cl2(*-)) inorganic radicals.

Topics: Acetic Acid; Atrazine; Chlorides; Ferric Compounds; Ferrous Compounds; Hydrogen Peroxide; Hydrogen-Ion Concentration; Kinetics; Nitrates; Nitrophenols; Sulfates

The photocatalytic degradation of various organics such as phenol, p-nitrophenol, and salicylic acid was carried out with combustion-synthesized nano-TiO2 under UV and solar exposure. Under identical conditions of UV exposure, the initial degradation rate of phenol with combustion-synthesized TiO2 is 2 times higher than the initial degradation rate of phenol with commercial Degussa P-25 TiO2. The intermediates such as catechol (CC) and hydroquinone (HQ) were not detected during the degradation of phenol with combustion-synthesized TiO2, while both the intermediates were detected when phenol was degraded over Degussa P-25. This indicates that the rates of secondary photolysis of CC and HQ occur extremely faster than the rates at which they are formed from phenol and further implies that the primary hydroxylation step is rate limiting for the combustion-synthesized TiO2 aided photodegradation of phenol. The degradation rates of salicylic acid and p-nitrophenol were also investigated, and the rates were higher for combustion-synthesized titania compared to Degussa P-25 TiO2. Superior activity of combustion-synthesized TiO2 toward photodegradation of organic compounds can be attributed to crystallinity, higher surface area, more surface hydroxyl groups, and optical absorption at higher wavelength.

Topics: Anti-Infective Agents; Catalysis; Coloring Agents; Environmental Pollution; Incineration; Nanotechnology; Nitrophenols; Phenol; Photochemistry; Salicylic Acid; Semiconductors; Titanium

The toxicity of four xenobiotic compounds 3,5-dichlorophenol, formaldehyde, 4-nitrophenol and dichloromethane, representative of industrial wastewater contaminants was evaluated by a simple respirometric procedure set up on the basis of OECD Method 209 and by the Microtox bioassay. Very good reproducibility was observed for both methods, the variation coefficients being in the range of 2-10% for the respirometric procedure and 6-15% for Microtox, values that can be considered very good for a biological method. Comparison of EC(50) data obtained with the two methods shows that in both cases 3,5-dichlorophenol is more toxic than other compounds investigated and dichloromethane has a very low toxicity value. Intermediate EC(50) values were found for the two other chemicals, formaldehyde and 4-nitrophenol. Moreover, the Microtox EC(50) values are generally lower (except for dichloromethane) than the respirometric ones: these differences could be explained by the fact that the Microtox method uses a pure culture of marine species and, therefore, should not necessarily be expected to behave like a community of activated sludge bacteria. In conclusion, both methods can be usefully applied for toxicity detection in wastewater treatment plants but it is advisable to take into account that Microtox is more sensitive than respirometry in estimating the acute toxicity effect on the biomass operating in the plant.

Topics: Bacteria; Biological Assay; Biomass; Chlorophenols; Cities; Environmental Monitoring; Formaldehyde; Methylene Chloride; Nitrophenols; Oxygen; Reproducibility of Results; Sewage; Toxicity Tests; Waste Disposal, Fluid; Water Pollutants, Chemical; Xenobiotics

This communication reports the first electrochemical study of the human P450 2E1 either absorbed or covalently linked to different electrode surfaces. Glassy-carbon and gold electrodes gave reversible electrochemical signals of an active P450 2E1. Molecular modeling of the enzyme helped to rationalize the results. A monolayer coverage was obtained on gold modified with cystamine/maleimide that covalently linked surface accessible cysteines of P450 2E1. The midpoint potential measured for the oriented P450 2E1 was -177 +/- 5 mV comparable to that of the FeIII/FeII of other P450 enzymes. The observed electron-transfer rate for this electrode was 10 s-1. The turnover of the active enzyme was measured with the P450 2E1 specific substrate p-nitrophenol, resulting in a KM of 130 +/- 3 muM and the formation of 2.2 muM of the p-nitrocatechol product upon application of a -300 mV bias.

Topics: Carbon; Catalysis; Cytochrome P-450 CYP2E1; Electrochemistry; Electrodes; Enzymes, Immobilized; Escherichia coli; Gold; Humans; Liver; Nitrophenols; Oxidation-Reduction

1,1-Dichloroethylene (DCE) exposure evokes lung toxicity with selective damage to bronchiolar Clara cells. Recent in vitro studies have implicated CYP2E1 and CYP2F2 in the bioactivation of DCE to 2-S-glutathionyl acetate [C], a putative conjugate of DCE epoxide with glutathione. An objective of this study was to test the hypothesis that bioactivation of DCE is catalyzed by both CYP2E1 and CYP2F2 in murine lung. Western blot analysis of lung microsomal proteins from DCE-treated CD-1 mice showed time-dependent loss of immunodetectable CYP2F2 and CYP2E1 protein. Dose-dependent formation of conjugate [C] was observed in the lungs of CD-1 mice treated with DCE (75-225 mg/kg), but it was not detected after pretreatment with 5-phenyl-1-pentyne (5-PIP). Treatment of mice with 5-PIP and also with diallyl sulfone (DASO2) significantly inhibited hydroxylation of p-nitrophenol (PNP) and chlorzoxazone (CHZX). Incubation of recombinant CYP2F3 (a surrogate for CYP2F2) and recombinant CYP2E1 with PNP and CHZX confirmed that they are substrates for both of the recombinant enzymes. Incubation of the recombinant enzymes with DASO2 or 5-PIP significantly inhibited hydroxylation of both PNP and CHZX. Bronchiolar injury was elicited in CD-1 mice treated with DCE (75 mg/kg), but it was abrogated with 5-PIP pretreatment. Bronchiolar toxicity also was manifested in the lungs of CYP2E1-null and wild-type mice treated with DCE (75 mg/kg), but protection ensued after pretreatment with 5-PIP or DASO2. These results showed that bioactivation of DCE in murine lung occurred via the catalytic activities of both CYP2E1 and CYP2F2 and that bioactivation by these enzymes mediated the lung toxicity.

Topics: Animals; Blotting, Western; Chlorzoxazone; Cytochrome P-450 CYP2E1; Cytochrome P-450 Enzyme System; Cytosol; Dichloroethylenes; Female; Hydroxylation; Lung; Mice; Nitrophenols

Insects express arthro-series glycosphingolipids, which contain an alpha1,4-linked GalNAc residue. To determine the genetic basis for this linkage, we cloned a cDNA (CG17223) from Drosophila melanogaster encoding a protein with homology to mammalian alpha1,4-glycosyltransferases and expressed it in the yeast Pichia pastoris. Culture supernatants from the transformed yeast were found to display a novel UDP-GalNAc:GalNAcbeta1,4GlcNAcbeta1-R alpha-N-acetylgalactosaminyltransferase activity when using either a glycolipid, p-nitrophenylglycoside or an N-glycan carrying one or two terminal beta-N-acetylgalactosamine residues. NMR and MS in combination with glycosidase digestion and methylation analysis indicate that the cloned cDNA encodes an alpha1,4-N-acetylgalactosaminyltransferase. We hypothesize that this enzyme and its orthologues in other insects are required for the biosynthesis of the N5a and subsequent members of the arthro-series of glycolipids as well as of N-glycan receptors for Bacillus thuringiensis crystal toxin Cry1Ac.

Topics: Amino Acid Sequence; Animals; Carbohydrate Sequence; Cloning, Molecular; Drosophila melanogaster; Drosophila Proteins; Gene Expression Regulation, Enzymologic; Glycolipids; Humans; Life Cycle Stages; Molecular Sequence Data; N-Acetylgalactosaminyltransferases; Nitrophenols; P Blood-Group System; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity

Utilizing a commercially available helium-purging device and PEEK tubes for all tubing, especially for connection between the mobile phase and pump, high performance liquid chromatography with an electrochemical detector (ECD/HPLC) at the cathodic mode is a simple and precise method for the determination of p-nitrophenol (NP). Studies with cyclic and hydrodynamic voltammetry indicated that 25% aqueous MeOH containing 0.1% (v/v) CF(3)CO(2)H and -0.8 V vs. Ag/AgCl are the best mobile phase and detection potential for cathodic ECD/HPLC. With the present system, the limits of detection and determination were 0.2 and 0.25 microM, respectively, and up to 50 microM, a linear calibration curve was afforded. Within-day precisions for the analysis of 5 and 50 microM NP were 0.8 and 0.7% (n=6), respectively, and between-day precisions (n=6) for these samples were 3.5 and 2.2%, respectively. Compared with the commonly used Bessey-Lowry-Brock method, cathodic ECD/HPLC was useful for the assay of acid phosphatase in urine samples with p-nitrophenyl phosphate disodium salt as a substrate.

Topics: Acid Phosphatase; Chromatography, High Pressure Liquid; Electrochemistry; Electrodes; Humans; Nitrophenols

p-Nitrophenol hydroxylation is widely used as a probe for microsomal CYP2E1. Several drugs are known as CYP2E1 inhibitors because of their capability to inhibit p-nitrophenol hydroxylation. Our results suggest further participation of CYP2A6 and CYP2C19 enzymes in p-nitrophenol hydroxylation. Moreover, CYP2A6 and CYP2C19 may be considered as the primary catalysts, whereas CYP2E1 can also contribute to the hydroxylation of p-nitrophenol. Further aim of our study was to evaluate the selectivity of p-nitrophenol hydroxylase inhibitors towards cytochrome P450 enzymes. The effects of antifungals: bifonazole, econazole, clotrimazole, ketoconazole, miconazole; CNS-active drugs: chlorpromazine, desipramine, fluphenazine, thioridazine; and the non-steroidal anti-inflammatory drug: diclofenac were investigated on the enzyme activities selective for CYP2A6, CYP2C9, CYP2C19, CYP2E1 and CYP3A4. None of the drugs could be considered as a potent inhibitor of CYP2E1. Strong inhibition was observed for CYP3A4 by antifungals with IC(50) values in submicromolar range. However, ketoconazole was the only imidazole derivative that could be considered as a selective inhibitor of CYP3A4. The CNS-active drugs investigated were found to be weak inhibitors of CYP2A6, CYP2C9, CYP2C19, CYP2E1 and CYP3A4. Diclofenac efficiently inhibited CYP2C9 and to a less extent CYP3A4 enzyme.

Topics: Adult; Antifungal Agents; Antipsychotic Agents; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Diclofenac; Enzyme Inhibitors; Humans; Hydroxylation; Male; Microsomes, Liver; Middle Aged; Nitrophenols; Substrate Specificity

Amination of 4-nitrophenol, umbelliferone and 4-methylumbelliferone gave the corresponding oxyamines 1-3. These oxyamines react with aldehydes and ketones to form oximes. In the case of aliphatic aldehydes and electron-poor aromatic aldehydes, the oximes undergo base-catalyzed fragmentation in aqueous buffer in the presence of bovine serum albumin to give the parent phenols, which is the acyclic analog of Kemp's elimination reaction of 5-nitrobenzisoxazole 28. The process can be used as a spectrophotometric assay for formaldehyde under aqueous neutral conditions.

Topics: Aldehydes; Amination; Chromatography, Thin Layer; Chromogenic Compounds; Ethers; Fluorescent Dyes; Formaldehyde; Hymecromone; Ketones; Kinetics; Lipoprotein Lipase; Magnetic Resonance Spectroscopy; Molecular Structure; Nitrophenols; Oximes; Pseudomonas; Serum Albumin, Bovine; Spectrophotometry; Umbelliferones

The effect of initial concentration, temperature, and shaking rate on the adsorption of three dyestuffs [orange II (O-II), crystal violet (CV), and reactive blue 5 (RB5)] and an ideal adsorbate, p-nitrophenol (PNP), by chitosan (Sigma C-3646) and the effect of temperature on the adsorption of O-II and CV by monocarboxymethylated chitosan (MCM-chitosan) were investigated. Kinetic data obtained for the adsorption of each dyestuff and PNP by chitosan and of O-II and CV by MCM-chitosan at different temperatures were applied to the Lagergren equation, and adsorption rate constants (k(ads)) at these temperatures were determined. These rate constants related to the adsorption of O-II and RB5 by chitosan and of O-II by MCM-chitosan were applied to the Arrhenius equation, and activation energies (E(a)) were determined. In addition, the isotherms for adsorption, at different temperatures, of each dyestuff and PNP by chitosan and of O-II and CV by MCM-chitosan were also determined. These isothermal data were applied to linear forms of isotherm equations that they fit, and isotherm constants were calculated. Because the isotherm curves obtained for the adsorption of O-II and CV by chitosan and of CV by MCM-chitosan fit the Langmuir adsorption isotherm, b constants were applied to thermodynamic equations, and thermodynamic parameters (delta G, delta H, and delta S) were calculated. Lastly, chitosan and MCM-chitosan were compared with respect to the ability to take up the dyestuffs and PNP.

Topics: Adsorption; Chitosan; Coloring Agents; Kinetics; Microscopy, Electron, Scanning; Models, Chemical; Nitrophenols; Temperature; Thermodynamics; Time Factors

1: The metabolism by HepG2 cell from two sources (M1, M2) of 12 substrates is reported: ethoxyresorufin, ethoxycoumarin, testosterone, tolbutamide, chlorzoxazone, dextromethorphan, phenacetin, midazolam, acetaminophen, hydroxycoumarin, p-nitrophenol and 1-chloro-2,4-dinitrobenzene (CDNB), and a pharmaceutical compound, EMD68843. 2: Activities varied markedly. Some were present in M1 (CYP1A, CYP2C9, CYP2E1) but absent in M2. M1 had a more complete set of Phase I enzymes than M2. CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A activities were present at levels similar to human hepatocytes. Phase II metabolism differed between M1 and M2. M1 conjugated hydroxycoumarin and p-nitrophenol to glucuronides only, whereas M2 produced sulfates. Glutathione conjugation of CDNB metabolism was 10-fold higher in M1 than in M2, but was still much lower than in human hepatocytes. CYP2E, CYP2C, CYP2B6 and CYP3A (but not CYP1A, glucuronyl S-transferase or S-transferase) were inducible in M1. Metabolites of EMD68843, produced by induced (but not uninduced) M1 were the same as those produced in human hepatocytes. 3: In conclusion, HepG2 cells have both Phase I and II enzymes, which activities and at what levels depend on the source and culture conditions. Therefore, HepG2 cells routinely used in in vitro assays should be characterized for their drug-metabolizing capabilities before any results can be fully interpreted.

Topics: Aryl Hydrocarbon Hydroxylases; Benzofurans; Carcinoma, Hepatocellular; Cell Culture Techniques; Cell Line, Tumor; Coumarins; Dinitrochlorobenzene; Enzyme Activation; Humans; Indoles; Kinetics; Liver Neoplasms; Nitrophenols; Oxazines; Piperazines; Substrate Specificity; Umbelliferones; Vilazodone Hydrochloride

Enzymatic activities are routinely used to identify the contribution of individual forms of cytochrome P450 in a particular biotransformation. p-Nitrophenol O-hydroxylation (PNPH) has been widely used as a measure of CYP2E1 catalytic activity. However, rat and human forms of CYP3A have also been shown to catalyze this activity. In mice, the contributions of CYP3A and CYP2E1 to PNPH activity are not known. Here we used hepatic microsomes from Cyp2e1(-/-) and wild-type mice to investigate the contributions of constitutively expressed and alcohol-induced murine CYP2E1 and CYP3A to PNPH activity. In liver microsomes from untreated mice, PNPH activity was much greater in wild-type mice compared with Cyp2e1(-/-) mice, suggesting a major role for CYP2E1 in catalyzing PNPH activity. Hepatic PNPH activities were not significantly different in microsomes from male and female mice, although the microsomes from females have dramatically higher levels of CYP3A. Treatment with a combination of ethanol and isopentanol resulted in induction of CYP3A proteins in wild-type and Cyp2e1(-/-) mice, as well as CYP2E1 protein in wild-type mice. The alcohol treatment increased PNPH activities in hepatic microsomes from wild-type mice but not from Cyp2e1(-/-) mice. Our findings suggest that in untreated and alcohol-treated mice, PNPH activity may be used as a specific probe for CYP2E1 and that constitutively expressed and alcohol-induced forms of mouse CYP3A have little to no role in catalyzing PNPH activity.

Topics: Animals; Aryl Hydrocarbon Hydroxylases; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP3A; Enzyme Induction; Ethanol; Female; Hydroxylation; In Vitro Techniques; Male; Mice; Mice, Knockout; Microsomes, Liver; Nitrophenols; Oxidoreductases, N-Demethylating; Pentanols; Sex Factors

UDP-glucuronosyltransferase (UGT) enzymes catalyze the glucuronidation and typically inactivation of endogenous and exogenous molecules including steroid hormones, bilirubin and many drugs. The UGT1A6 protein is expressed predominantly in liver and metabolizes small phenolic drugs including acetaminophen, salicylates and many beta-blockers. Interindividual variation in the capacity of humans to glucuronidate drugs has been observed.. We have identified a novel common single nucleotide polymorphism (SNP) in the human UGT1A6 gene resulting in a Ser7Ala change in encoded amino acid. We have further functionally characterized that polymorphism in the context of two previously reported polymorphisms, Thr181Ala and Arg184Ser. These non-synonymous cSNPs define four common haplotypes. Alleles appear with similar frequencies in Caucasian and African-American populations with distributions adhering to Hardy-Weinberg equilibrium. UGT1A6 genotype, rate of substrate glucuronidation and level of immunoreactive UGT1A6 protein was determined. A 25-fold variation in the rate of substrate glucuronidation and an 85-fold variation in level of immunoreactive protein were measured. Liver tissue samples that were homozygous for UGT1A6*2 exhibited a high rate of glucuronidation relative to tissues with other genotypes. Biochemical kinetic studies of recombinant UGT1A6 expressed in HEK293 cells indicated that the UGT1A6*2 allozyme, expressed homozygously, had almost two-fold greater activity toward p-nitrophenol than UGT1A6*1 and when expressed heterozygously (UGT1A6*1/*2) it was associated with low enzyme activity.. These data suggest that common genetic variation in human UGT1A6 confers functionally significant differences in biochemical phenotype as assessed in human tissue and cultured cells expressing recombinant allozymes. This genetic variation might impact clinical efficacy or toxicity of drugs metabolized by UGT1A6.

Topics: Black or African American; Carcinoma, Hepatocellular; Cells, Cultured; Colonic Neoplasms; Gene Frequency; Genetic Variation; Genotype; Glucuronates; Glucuronosyltransferase; Heterozygote; Homozygote; Humans; Isoenzymes; Liver Neoplasms; Microsomes, Liver; Nitrophenols; Pharmacogenetics; Polymorphism, Single Nucleotide; Recombinant Proteins; White People

Three different monoacetates of 4-nitrophenyl beta-D-xylopyranoside were tested as substrates for beta-xylosidase and for microbial carbohydrate esterases and a series of non-hemicellulolytic esterases. The acetyl group in 2-O-acetyl, 3-O-acetyl, and 4-O-acetyl 4-nitrophenyl beta-D-xylopyranoside makes the glycoside resistant to the action of beta-xylosidase (EC 3.2.1.37). This fact was explored to introduce a new enzyme-coupled assay of acetylxylan esterases (EC 3.1.1.72) and other carbohydrate-deacetylating enzymes. The deacetylation converts the monoacetates into the substrate of beta-xylosidase, the auxiliary enzyme. The effect of the acetyl group migration along the xylopyranoid ring in aqueous media can be avoided by shortening the assay duration. The assay enables an easy examination of the positional specificity of the enzymes, which is important for classification of acetylxylan esterases and for elucidation of the structure-function relationship among carbohydrate esterases in general. Non-hemicellulolytic esterases showed different positional specificity of deacetylation than did acetylxylan esterases.

Topics: Acetates; Acetylesterase; Fungi; Glycosides; Kinetics; Nitrophenols; Streptomyces lividans; Xylosidases

This article describes a method for treating aqueous 4-nitrophenol by mixing with TiO2-SnO2 coupled particles. The reactivity of single photocatalysis (TiO2 and SnO2 all as 1.2 g/L) is compared with that of mixing TiO2-SnO2 (0.6 g/L + 0.6 g/L) coupled particles. Aqueous 4-nitrophenol was treated by single photocatalysis or coupled semiconducting particles in a double-layer glass batch reactor using a 15W UV fluorescent tube at 25 degrees C and 300 rpm for mixing. The results demonstrated that pH and the concentration of TiO2 were the factors that most influenced the degradation characteristics, and that the system of TiO2-SnO2 coupled particles improved the efficiency of removal of refractory organic pollutants by 15%, by the inter-particle electron transfer (IPET) effect. The results showed that the degradation of aqueous 4-nitrophenol was 75% when coupled particles were used--better than the 60% obtained using single photocatalysis--with a reaction time of 120min.

Topics: Catalysis; Coloring Agents; Nitrophenols; Photochemistry; Semiconductors; Titanium; Water Purification

The adsorption of p-chlorophenol (p-CP) and p-nitrophenol (p-NP) on organophilic bentonite (dodecylammonium bentonite, DDAB) was studied as a function of solution concentration and temperature. The observed adsorption rates were found to be equal to the first-order kinetics. The rate constants were calculated for temperatures ranging between 25.0-35.0 degrees C at constant concentration. The adsorption energies, E and adsorption capacity, (qm), for phenolic compounds adsorbed to organophilic bentonite were estimated by using the Dubinin-Radushkevic equation. Thermodynamic parameters from the adsorption isotherms of p-CP and p-NP on organophilic bentonite were determined. These isotherms were modeled according to Freundlich and Dubinin-Radushkevic adsorption isotherms and followed the V-shaped isotherm category with two steps. The amount of adsorption was found to be dependent on the relative energies of adsorbent-adsorbate, adsorbate-solvent and adsorbate-adsorbate interaction.

Topics: Adsorption; Bentonite; Chlorophenols; Kinetics; Nitrophenols; Solutions; Water

The fungal metabolism of 4-nitrophenol (4-NP) was investigated using the lignin-degrading basidiomycete, Phanerochaete chrysosporium. Despite its phenolic feature, 4-NP was not oxidized by extracellular ligninolytic peroxidases. However, 4-NP was converted to 1,2-dimethoxy-4-nitrobenzene via intermediate formation of 4-nitroanisole by the fungus only under ligninolytic conditions. The metabolism proceeded via hydroxylation of the aromatic ring and methylation of phenolic hydroxyl groups. Although the involvement of nitroreductase in the metabolism of 2,4-dinitrotoluene by many aerobic and anaerobic microorganisms including P. chrysosporium has been reported, no formation of 4-aminophenol was observed during 4-NP metabolism. The formation of 1,2-dimethoxy-4-nitrobenzene was effectively inhibited by exogenously added piperonyl butoxide, a cytochrome P450 inhibitor, suggesting that cytochrome P450 is involved in the hydroxylation reaction. Thus, P. chrysosporium seems to utilize hydroxylation and methylation reactions to produce a more susceptible structure for an oxidative metabolic system.

Topics: Biodegradation, Environmental; Cytochrome P-450 Enzyme System; Lignin; Nitrophenols; Nitroreductases; Oxidation-Reduction; Phanerochaete

We have expanded previous observations on olfactory metabolic enzymes by examining the content of various metabolic enzymes in the olfactory mucosa of the male Long-Evans rat at different ages. Age-related changes in metabolic enzyme content may be related to changes in susceptibility to toxicants with age and may also contribute to altered odorant perception in the elderly. While some enzymes did not vary over the age range examined, decreases in the microsomal content of other enzymes were observed. While mRNA for acetyltransferase enzymes has previously been described in olfactory mucosa, the markedly higher activity of olfactory acetyltransferases compared to liver had not previously been described. Acetyltransferases are important in the metabolism of drugs and toxicants that are aromatic amine derivatives and may contribute to the bioactivation of rodent olfactory mucosal carcinogens such as 2,6-dimethylaniline and alachlor. These studies show that the olfactory mucosa varies in its metabolic capacity with age, and characterize another class of metabolic enzymes in the olfactory mucosa, both of which may impact significantly on responses to toxicants and therapeutic agents in the nasal cavity.

Topics: Acetyltransferases; Aging; Animals; Aryl Hydrocarbon Hydroxylases; Cytochrome P-450 Enzyme System; Epoxide Hydrolases; Male; Microsomes; Microsomes, Liver; Nitrophenols; Olfactory Mucosa; Oxidoreductases; Rats; Rats, Long-Evans

Human sulfotransferases catalyze sulfate conjugation and 2 polymorphic genes, SULT1A1 and SULT1A2 in this family of transferases have been identified, encoding for 2 isoenzymes with very similar properties and substrate specificities. In order to test the hypothesis that variability in sulfation is due to genetic polymorphism in SULT1A1, the sulfation rate of 4-nitrophenol, a diagnostic substrate, was measured in 50 human liver samples and the genotype at the SULT1A1 locus was analyzed. The rate of 4-nitrophenol sulfation varied from 473 - 1,405 pmol/min/mg between the 5th and 95th percentiles, with a median and a mean +/- SD of 757 and 807 +/- 292 pmol/min/mg, respectively. The activities detected among the SULT1A1*2/*2 homozygotes (5 cases) were significantly lower than those of the other 2 genotypes, SULTA1*11/*1 and SULT1A1*1/*2 (5 and 40 cases, respectively), whereas there was no significant difference found between the SULT1A1*1/*1 and SULT1A1*1/*2 genotypes. To evaluate the possible influence of SULT1A2 polymorphism, genotype assays were also performed for this locus. No SULT1A2*2/*2 carrier, 26 SULT1A2*1/*1 and 24 SULT1A2*1/*2 were detected in the population sample under study. However, no correlation between the rate of 4-nitrophenol sulfation and the SULT1A2 genotype was detected. These results confirm that the variation in the rate of 4-nitrophenol sulfation in human liver is mainly due to SULT1A. Since SULT1A1*1/*2 polymorphism accounts for no more than 10% of the phenotypic variation seen in this cohort, other factors must also contribute to the variability in the rate of 4-nitrophenol sulfation in human liver. However, on the basis of the data obtained, variations in age, gender and liver function as possible causative factors can be excluded. The IC50 of quercetin, a potent inhibitor of 4-nitrophenol sulfation, was measured in the liver samples and ranged from 4.6 to 17.3 nM between the 5th and 95th percentiles. The median and the mean +/- SD were 7.7 nM and 8.3 +/- 2.5 nM, respectively. There was a weak but significant correlation between the IC50 value and age of the liver donors (r = 0.283, p = 0.046). The observed variation did not correlate with the genotypes at the SULT1A1 and SULT1A2 loci.

Topics: Adult; Aged; Aged, 80 and over; Arylsulfotransferase; Enzyme Inhibitors; Female; Genotype; Humans; In Vitro Techniques; Inhibitory Concentration 50; Liver; Male; Middle Aged; Nitrophenols; Phenotype; Phosphoadenosine Phosphosulfate; Polymorphism, Genetic; Quercetin

The TNF family cytokine B cell-activating factor belonging to the TNF family (BAFF) (BLyS) plays a fundamental role in regulating peripheral B cell survival and homeostasis. A BAFF-specific receptor (BAFF-R; BR3) appears to mediate these functions via activation of the NF-kappaB2 pathway. Signaling by the BAFF-R is also required to sustain the germinal center (GC) reaction. Engagement of this receptor results in the induction of Bcl-2, suggesting that this antiapoptotic factor acts downstream of the BAFF-R and NF-kappaB2 pathway to promote peripheral B cell survival during primary and Ag-driven development. To test this idea, we created lines of mice coexpressing a Bcl-2 transgene and a signaling-deficient form of the BAFF-R derived from the B lymphopenic A/WySnJ strain. Surprisingly, although dramatically elevated numbers of B cells accumulate in the periphery of these mice, these B cells exhibit extremely perturbed primary development, formation of lymphoid microenvironments, and GC and IgG responses. Moreover, mice expressing the bcl-2 transgene alone display a loss of marginal zone B cells, an expansion of follicular B cells that appear immature, and alterations of the GC reaction. These results suggest that the BAFF-R and Bcl-2 regulate key and nonoverlapping aspects of peripheral B cell survival and development.

Topics: Animals; Apoptosis; B-Cell Activating Factor; B-Cell Activation Factor Receptor; B-Lymphocyte Subsets; Cell Aggregation; Cell Death; Cell Differentiation; Cell Lineage; Chickens; gamma-Globulins; Germinal Center; Immune Sera; Lymphoid Tissue; Lymphopenia; Membrane Proteins; Mice; Mice, Inbred A; Mice, Transgenic; Nitrophenols; Protein Isoforms; Proto-Oncogene Proteins c-bcl-2; Receptors, Tumor Necrosis Factor; Signal Transduction; Spleen; T-Lymphocytes; Tumor Necrosis Factor-alpha

A novel fluidized electrochemical reactor that integrated advanced electrochemical oxidation with activated carbon (AC) fluidization in a single cell was developed to model pollutant p-nitrophenol (PNP) abatement. AC fluidization could enhance COD removal by 22%-30%. In such a combined process, synergetic effects on PNP and COD removal was found, with their removal rate being enhanced by 137.8% and 97.8%, respectively. AC could be electrochemically regenerated and reused, indicating the combined process would be promising for treatment of biorefractory organic pollutants.

Topics: Charcoal; Electrochemistry; Equipment Design; Equipment Failure Analysis; Nitrophenols; Ultrafiltration; Water Pollutants, Chemical; Water Purification

This paper describes a new approach to achieve selectivity in an immunoassay by separating the signals given by two cross-reactive compounds present simultaneously in a complex sample matrix. The method is based on the sequential dilution of the sample containing a mixture of the two analytes, spiking each diluted sample with a reference compound, and the detection by enzyme-linked immunosorbent assay (ELISA). The obtained multivariate response was used for the individual calibrations of the assay for each of the two cross-reactants simultaneously by using principal component analysis (PCA) and partial least squares regression (PLSR) data modeling. The calibration models showed that the signal separation due the analytes 2,4-dinitrophenol (2,4-DNP) and 4-nitrophenol (4-NP) was possible with a prediction concentration error of 1.4 microM and 72 microM, respectively.

Topics: 2,4-Dinitrophenol; Animals; Calibration; Cross Reactions; Enzyme-Linked Immunosorbent Assay; Least-Squares Analysis; Milk; Multivariate Analysis; Nitrophenols; Principal Component Analysis; Reproducibility of Results; Sensitivity and Specificity

The aim was to characterize mouse gender and strain differences in the metabolism of commonly used human cytochrome (CYP) P450 probe substrates. Thirteen human CYP probe substrates (phenacetin, coumarin, 7-ethoxy-4-trifluoromethyl coumarin, amiodarone, paclitaxel, diclofenac, S-mephenytoin, bufuralol, dextromethorphan, chlorzoxazone, p-nitrophenol, testosterone and lauric acid) were used in activity measurements. The metabolism of the probe substrates was compared in liver microsomes from male and female NMRI, CBA, C57bl/6, 129/SvJ and CD1 strains. The expression of proteins identified on Western blots with commonly available antibodies selective for specific human and rat CYP enzymes were compared in the different mouse strains. Males had higher metabolism than corresponding females for phenacetin O-deethylation (human marker for CYP1A2 activity), and a high correlation was found between phenacetin activity and immunoreactivity in Western blots produced with rat CYP1A2 antibodies. Protein detected by antibodies cross-reacting with human CYP2B6 and rat CYP2B1/2 antibodies was female specific except for the 129/SvJ strain, where it was absent in both genders. Females generally had a higher metabolism of bufuralol 1'-hydroxylation and dextromethorphan O-demethylation (human markers for CYP2D activity). Bufuralol 1'-hydroxylation correlated with a female-dominant mouse CYP, which was detected with antibodies against rat CYP2D4. p-Nitrophenol 2-hydroxylation correlated better than chlorzoxazone 6-hydroxylation with the protein detected with antibodies against rat CYP2E1, indicating that p-nitrophenol is a more specific substrate for mouse CYP2E1.

Topics: Amiodarone; Animals; Aryl Hydrocarbon Hydroxylases; Blotting, Western; Chlorzoxazone; Coumarins; Cytochrome P-450 CYP1A2; Cytochrome P-450 CYP2B6; Cytochrome P-450 Enzyme System; Dextromethorphan; Diclofenac; DNA, Complementary; Ethanolamines; Female; Humans; Kinetics; Lauric Acids; Male; Mephenytoin; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Microsomes, Liver; Mixed Function Oxygenases; NADP; Nitrophenols; Oxidoreductases, N-Demethylating; Oxygen; Paclitaxel; Phenacetin; Rats; Sex Factors; Species Specificity; Substrate Specificity; Testosterone

Dendrimer-metal (silver, platinum, and palladium) nanocomposites are prepared in aqueous solutions containing poly(amidoamine) (PAMAM) dendrimers with surface amino groups (generations 3, 4, and 5) or poly(propyleneimine) (PPI) dendrimers with surface amino groups (generations 2, 3, and 4). The particle sizes of the metal nanoparticles obtained are almost independent of the generation as well as the concentration of the dendrimer for both the PAMAM and the PPI dendrimers; the average sizes of silver, platinum, and palladium nanoparticles are 5.6-7.5, 1.2-1.6, and 1.6-2.0 nm, respectively. It is suggested that the dendrimer-metal nanocomposites are formed by adsorbing the dendrimers on the metal nanoparticles. Studies of the reduction reaction of 4-nitrophenol by these nanocomposites show that the rate constants are very similar between PAMAM and PPI dendrimer-silver nanocomposites, whereas the rate constants for the PPI dendrimer-platinum and -palladium nanocomposites are greater than those for the corresponding PAMAM dendrimer nanocomposites. In addition, it is found that the rate constants for the reduction of 4-nitrophenol involving all the dendrimer-metal nanocomposites decrease with an increase in the dendrimer concentrations, and the catalytic activity of dendrimer-palladium nanocomposites is highest.

Topics: Catalysis; Metals, Heavy; Nanostructures; Nitrophenols; Organometallic Compounds; Oxidation-Reduction; Palladium; Particle Size; Platinum; Polyamines; Polypropylenes; Silver; Surface Properties

A new route to obtain chitosan derivatives containing cyclodextrin moieties as pendant groups was developed. The chitosan microspheres, obtained through crosslinking with glutaraldehyde of an acetic acid solution of chitosan, in an organic suspension medium, were reacted with chloroacyl cyclodextrins in organic basic solvents. The acyl cyclodextrin moieties are linked to the chitosan microspheres through C-N bonds, with the elimination of HCl; higher amounts of acyl cyclodextrin are linked to the microspheres with a smaller crosslinking degree. The chitosan-cyclodextrin conjugates retain higher amounts of bioactive substances (nalidixic acid, piroxicam) or of p-nitrophenol (model substance) than their parent chitosan supports, both by ionic forces and by the formation of inclusion complexes in the cyclodextrin inner cavities. After these preliminary studies, one can appreciate that the cyclodextrin-chitosan conjugates could be used as supports for chromatographic separations or controlled release drug systems.

Topics: Chitosan; Combinatorial Chemistry Techniques; Cyclodextrins; Drug Interactions; Microspheres; Molecular Weight; Nalidixic Acid; Nitrophenols; Piroxicam

The dinuclear copper enzyme tyrosinase (Ty) from genetically engineered Streptomyces antibioticus has been investigated in its paramagnetic half-met form [Cu(I)-Cu(II)]. The cw EPR, pulsed EPR, and hyperfine sublevel correlation spectroscopy (HYSCORE) experiments on the half-met-Ty and on its complexes with three different types of competitive inhibitor are reported. The first type includes p-nitrophenol, a very poor substrate for the monooxygenase activity of Ty. The second type comprises hydroxyquinones, such as kojic acid and l-mimosine, and the third type of inhibitor is represented by toluic acid. The electronic and structural differences of the half-met-Ty form induced at the cupric site by the different inhibitors have been determined. Probes of structural effects are the hyperfine coupling constants of the non coordinating Ndelta histidyl nitrogens. By using the available crystal structures of hemocyanin as a template in combination with the spectroscopic results, a structural model for the active site of half-met-Ty is obtained and a model for the binding modes of both mono- and diphenols could be proposed.

Topics: Binding Sites; Copper; Electron Spin Resonance Spectroscopy; Hemocyanins; Ligands; Models, Molecular; Monophenol Monooxygenase; Nitrophenols; Protein Binding; Spectrophotometry; Streptomyces antibioticus

UDP-glucuronosyltransferases (UGTs) are important enzymes involved in glucuronidation of various exogenous and endogenous compounds. Studies were undertaken on the variability of three UGT enzyme activities in human livers. Enzyme activities were associated with genetic polymorphisms in UGT1A1 (UGT1A1*28) and UGT1A6 (UGT1A6*2). UGT1A1*28 is associated with Gilbert's syndrome, a deficiency in glucuronidation of bilirubin leading to mild hyperbilirubinemia, whereas UGT1A6*2 may result in low glucuronidation rates of several drugs.. Enzyme activities and genetic polymorphisms were assessed in 39 human liver samples, and polymorphisms were also assessed in blood of 253 healthy controls.. Associations were found between UGT enzyme activities of bilirubin (B) and 4-nitrophenol (NP; r=0.47, P=0.0024), B and 4-methylumbelliferone (MUB; r=0.54, P=0.0003), and NP and MUB (r=0.89, P<0.0001). In addition to the association between B-UGT enzyme activity and UGT1A1*28 (r=0.45, P=0.0034) as reported earlier, an association between B-UGT and UGT1A6*2 (r=0.43, P=0.007) was found. In 253 Dutch Caucasian controls, co-occurrence of UGT1A1*28 and UGT1A6*2 was found (r=0.9, P<0.0001).. Most patients with Gilbert's syndrome, in addition to their reduced B-UGT enzyme activity, may have abnormalities in the glucuronidation of aspirin or coumarin- and dopamine-derivatives, due to this combination of UGT1A1*28 and UGT1A6*2 genotypes.

Topics: Adult; Bilirubin; Case-Control Studies; Female; Genotype; Gilbert Disease; Glucuronosyltransferase; Humans; Hymecromone; Male; Nitrophenols; Polymorphism, Genetic

1. The use of everted sacs of the small intestine as an enzyme source for studying the metabolism of xenobiotics by cytochrome P450 (P450, CYP) enzymes and UDP-glucuronosyltransferases has been investigated. 2. Most of the drug oxidation activities for testosterone, bufuralol, ethoxyresorufin and 7-ethoxycoumarin resided in the upper part of the everted sacs and in intestinal microsomes. Testosterone 6 beta-hydroxylase activities in the everted sacs were about two times higher than those in the intestinal microsomes. By freezing and thawing treatment, the testosterone 6 beta- and 16 alpha-hydroxylase activities of the everted sacs were considerably decreased, and those of the intestinal microsomes were abolished. 3. Microsomal testosterone 6 beta-hydroxylation, bufuralol 1'-hydroxylation, and pentoxyresorufin and ethoxyresorufin O-dealkylation were inhibited by ketoconazole, quinine, metyrapone and alpha-naphthoflavone respectively. Immunoreactive proteins using anti-CYP2B1 and anti-CYP3A2 antibodies were detected in the upper and middle parts of the rat small intestine. 4. Except for morphine 3-glucuronidation, glucuronidation activities in intestinal microsomes or everted sacs were not dependent on the intestinal region. The lower part of the everted sacs exhibited about 10 times higher morphine-3-glucuronidation activities compared with those of the upper part. The glucuronidation activities of 4-nitrophenol in the everted sacs were 10 times higher than those in microsomes. 5. These results demonstrated that the upper part of rat small intestine serves as the major site for intestinal P450-mediated first-pass metabolism. CYP3A enzymes in rat intestinal microsomes may not be stable but probably play an important role in drug oxidations. The high activity of glucuronidation in the rat small intestine should also be considered in terms of drug metabolism.

Topics: Adrenergic beta-Antagonists; Animals; Catalysis; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Enzyme Inhibitors; Ethanolamines; Freezing; Glucuronides; Glucuronosyltransferase; Immunoblotting; Intestines; Male; Microsomes; Microsomes, Liver; Morphine; Naphthols; Nitrophenols; Oxidation-Reduction; Pharmaceutical Preparations; Rats; Rats, Wistar; Testosterone; Xenobiotics

Adsorption characteristics of a reverse stratified tapered adsorber (RSTA) system and competitive adsorption for phenol and 4-nitrophenol were investigated. In this study, a novel technology, RSTA, was introduced and compared with a conventional cylindrical adsorber (CA). The optimum study of RSTA in a single-solute system with phenol for size distribution, mean velocity and optimum angle was conducted to satisfy environmental criteria and reduce granular activated carbon (GAC) treatment costs. The competitive adsorption efficiency of RSTA and CA was also compared in a binary solute system with phenol and 4-nitrophenol. In the results of single-solute experiment, breakthrough time of RSTA was increased by 30-50% over conventional CA. The mean bed velocity was 19.10 cm/min and the optimum angle of RSTA was decided to 3 degrees. Adsorption efficiency was increased with increasing GAC dose and the number of GAC layers. The affinity of competitive adsorption was significantly increased with decreasing GAC dose and increasing adsorbate concentration. The RSTA can be considered to provide an increase in breakthrough time with decreasing flow rate and increasing the number of layers. Water and wastewater plants processing large volumes of water can realize significant savings in capital and operation costs by utilizing this type of operation.

Topics: Adsorption; Carbon; Disinfectants; Nitrophenols; Phenol; Water Pollutants; Water Pollutants, Chemical; Water Purification

Infection of rat liver by Taenia taeniformis metacestodes produced an increase in total CYP450 content and induced activity of the CYP1A1, CYP2B1 and COH isoforms. Variations in activity and p450 total content were found with increasing time of infection. During increased activity of p450 isoforms, rats were challenged with carcinogens metabolized by the mentioned isozymes and an increased amount of genotoxic damage was found when benzo[a] pyrene, cyclophosphamide and aflatoxin B(1) were used. No change was seen in CYP2E1 activity. These results support previous findings regarding an increased susceptibility to genotoxic damage of infected organisms.

Topics: Aflatoxin B1; Animals; Aryl Hydrocarbon Hydroxylases; Benzo(a)pyrene; Carcinogens; Cats; Cyclophosphamide; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP2A6; Cytochrome P-450 CYP2B1; Female; Immunoblotting; Liver; Microsomes, Liver; Mixed Function Oxygenases; Mutagens; Nitrophenols; Protein Isoforms; Rats; Rats, Sprague-Dawley; Reticulocytes; Taenia; Time Factors

When chlorine is introduced into public drinking water for disinfection, it can react with organic compounds in surface waters to form toxic by-products such as 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX). We investigated the effect of exposure to MX on cytochrome P450 2E1 (CYP2E1)-like activity and total glutathione (GSH) in the liver of the small fish model, medaka (Oryzias latipes). The multi-site carcinogen methylazoxymethanol acetate (MAMAc) was the positive control compound. Both medaka liver microsome preparations and S-9 fractions catalyzed the hydroxylation of p-nitrophenol (PNP), suggesting CYP2E1-like activity in the medaka. Male medaka exposed for 96 h to the CYP2E1 inducers ethanol and acetone under fasted conditions showed significant increases in PNP-hydroxylation activity. Furthermore, total reduced hepatic GSH was reduced in fish fasted for 96 h, indicating that normal feeding is a factor in maintaining xenobiotic defenses. Exposure to MX and MAMAc induced significant increases in hepatic CYP2E1-like activity, however MX exposure did not alter hepatic GSH levels. These data strengthen the role of the medaka as a suitable species for examining cytochrome P450 and GSH detoxification processes and the role these systems play in chemical carcinogenesis.

Topics: Acetone; Animals; Carcinogens; Cytochrome P-450 CYP2E1; Ethanol; Fasting; Female; Furans; Glutathione; Hydroxylation; Liver; Male; Microsomes, Liver; Nitrophenols; Oryzias; Water Pollutants, Chemical; Water Supply

Estragole (4-allyl-1-methoxybenzene) is a naturally occurring food flavoring agent found in basil, fennel, bay leaves, and other spices. Estragole and its metabolite, 1'-hydroxyestragole (1'-HE), are hepatocarcinogens in rodent models. Recent studies from our laboratory have shown that glucuronidation of 1'-HE is a major detoxification pathway for estragole and 1'-HE, accounting for as much as 30% of urinary metabolites of estragole in rodents. Therefore, this study was designed to investigate the glucuronidation of 1'-HE in human liver microsomes in vitro and identify the specific uridine diphosphate glucuronosyltransferase (UGT) isoforms responsible for 1'-HE glucuronidation. The formation of the glucuronide of 1'-HE (1'-HEG) followed atypical kinetics, and the data best fit to a Hill equation, resulting in apparent kinetic parameters of Km = 1.45 mM, Vmax = 164.5 pmoles/min/mg protein, and n = 1.4. There was a significant intersubject variation in 1'-HE glucuronidation in 27 human liver samples, with a CV of 42%. A screen of cDNA expressed UGT isoforms indicated that UGT2B7 (83.94 +/- 0.188 pmols/min/mg), UGT1A9 (51.36 +/- 0.72 pmoles/min/mg), and UGT2B15 (8.18 +/- 0.037 pmoles/min/mg) were responsible for 1'-HEG formation. Glucuronidation of 1'-HE was not detected in cells expressing UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A7, UGT1A8, and UGT1A10. 1'-HE glucuronidation in 27 individual human liver samples significantly (p < 0.05) correlated with the glucuronidation of other UGT2B7 substrates (morphine and ibuprofen). These results imply that concomitant chronic intake of therapeutic drugs and dietary components that are UGT2B7 and/or UGT1A9 substrates may interfere with estragole metabolism. Our results also have toxicogenetic significance, as UGT2B7 is polymorphic and could potentially result in genetic differences in glucuronidation of 1'-HE and, hence, toxicity of estragole.

Topics: Analgesics, Opioid; Anisoles; Anti-Inflammatory Agents, Non-Steroidal; Carcinogens; Glucuronides; Glucuronosyltransferase; Humans; Ibuprofen; In Vitro Techniques; Isoenzymes; Kinetics; Microsomes, Liver; Morphine; Nitrophenols