ascorbic-acid and titanium-dioxide

ascorbic-acid has been researched along with titanium-dioxide* in 31 studies

Other Studies

31 other study(ies) available for ascorbic-acid and titanium-dioxide

ArticleYear
Photocatalytic degradation of Rhodamine B dye by nanostructured powder systems containing nanoencapsulated curcumin or ascorbic acid and ascorbyl palmitate liposomal.
    Environmental science and pollution research international, 2023, Volume: 30, Issue:28

    Due to inadequate treatment and incorrect management, wastewater with dyes has a great toxic potential as an environmental liability, representing a major concern. In this context, this work aims to investigate the potential application of nanostructured powdery systems (nanocapsules and liposomes) in the photodegradation of Rhodamine B (RhB) dye, under UV and visible irradiation. Curcumin nanocapsules and liposomes containing ascorbic acid and ascorbyl palmitate were prepared, characterized, and dried using the spray drying technique. The drying processes of the nanocapsule and the liposome showed yields of 88% and 62%, respectively, and, after aqueous resuspension of the dry powders, it was possible to recover the nanocapsule size (140 nm) and liposome size (160 nm). The dry powders were characterized by Fourier transform infrared spectroscopy (FTIR), N

    Topics: Ascorbic Acid; Coloring Agents; Curcumin; Liposomes; Nanocapsules; Powders

2023
Titanium dioxide nanoparticles require K
    Environmental pollution (Barking, Essex : 1987), 2023, Oct-01, Volume: 334

    Crop plants face severe yield losses worldwide owing to their exposure to multiple abiotic stresses. The study described here, was conducted to comprehend the response of cucumber seedlings to drought (induced by 15% w/v polyethylene glycol 8000; PEG) and nickel (Ni) stress in presence or absence of titanium dioxide nanoparticle (nTiO

    Topics: Ascorbic Acid; Carbohydrate Metabolism; Cucumis sativus; Droughts; Hydrogen Sulfide; Nanoparticles; Nickel; Nitrogen; Seedlings

2023
Precise and quick detection of ascorbic acid and eugenol in fruits, pharmaceuticals and medicinal herbs using hydroxyapatite-titanium dioxide nanocomposite-based electrode.
    Food chemistry, 2022, Jul-15, Volume: 382

    Topics: Ascorbic Acid; COVID-19; Dopamine; Durapatite; Electrodes; Eugenol; Fruit; Graphite; Nanocomposites; Pharmaceutical Preparations; Plants, Medicinal; Titanium

2022
Characterization of Macrophage Endogenous S-Nitrosoproteome Using a Cysteine-Specific Phosphonate Adaptable Tag in Combination with TiO
    Journal of proteome research, 2018, 03-02, Volume: 17, Issue:3

    Topics: Animals; Ascorbic Acid; Chromatography, Liquid; Gene Ontology; Mice; Molecular Sequence Annotation; Nitric Oxide; Nitroso Compounds; Organophosphonates; Oxidation-Reduction; Protein Processing, Post-Translational; Proteome; Proteomics; RAW 264.7 Cells; Tandem Mass Spectrometry; Titanium

2018
Active packaging from chitosan-titanium dioxide nanocomposite film for prolonging storage life of tomato fruit.
    International journal of biological macromolecules, 2018, Volume: 112

    The feasibility of active packaging from chitosan (CS) and chitosan containing nanosized titanium dioxide (CT) to maintain quality and extend storage life of climacteric fruit was investigated. The CT nanocomposite film and CS film were fabricated using a solution casting method and used as active packaging to delay ripening process of cherry tomatoes. Changes in firmness, weight loss, a*/b* color, lycopene content, total soluble solid, ascorbic acid, and concentration of ethylene and carbon dioxide of the tomatoes packaged in CT film, CS film, and control (without CT or CS films) were monitored during storage at 20°C. Classification of fruit quality as a function of different packaging treatments was visualized using linear discriminant analysis. Tomatoes packaged in the CT film evolved lower quality changes than those in the CS film and control. The results suggested that the CT film exhibited ethylene photodegradation activity when exposed to UV light and consequently delayed the ripening process and changes in the quality of the tomatoes.

    Topics: Ascorbic Acid; Carbon Dioxide; Chitosan; Ethylenes; Food Packaging; Food Preservation; Food Storage; Nanocomposites; Solanum lycopersicum; Titanium

2018
Photo-Electrochemical Sensing of Dopamine by a Novel Porous TiO₂ Array-Modified Screen-Printed Ti Electrode.
    Sensors (Basel, Switzerland), 2018, Oct-21, Volume: 18, Issue:10

    In this paper, the development of a nanoporous TiO₂ array-modified Ti electrode for photo-electrochemical (PEC) sensing of dopamine (DA) is reported. A porous TiO₂ array-modified electrode was fabricated from the controlled anodic oxidation of a Ti working electrode of commercial screen-printed electrodes (SPE). The anodization process and the related morphological and microstructural transformation of the bare Ti electrode into a TiO₂/Ti electrode was followed by scanning electron microscopy (SEM) and UV-visible reflectance spectroscopy (DR-UV-Vis). The modified electrode was irradiated with a low-power (120 mW) UV-Vis LED lamp (λ = 400 nm) and showed good performance for the detection of DA with a large linear response range, a sensitivity of 462 nA mM

    Topics: Ascorbic Acid; Carbon; Dopamine; Electrochemical Techniques; Electrodes; Hydrogen-Ion Concentration; Microscopy, Electron, Scanning; Oxidation-Reduction; Porosity; Titanium; Uric Acid

2018
Surface-modified TiO
    Colloids and surfaces. B, Biointerfaces, 2017, Jul-01, Volume: 155

    Topics: Adult; Antioxidants; Ascorbic Acid; Colloids; Comet Assay; DNA Damage; Female; Humans; Leukocytes, Mononuclear; Male; Metal Nanoparticles; Primary Cell Culture; Quantum Theory; Surface Properties; Titanium

2017
The role of antioxidants in attenuation of Caenorhabditis elegans lethality on exposure to TiO
    Chemosphere, 2017, Volume: 187

    The exponential increase in the usage of engineered nanoparticles (ENPs) has raised global concerns due to their potential toxicity and environmental impacts. Nano-TiO

    Topics: Animals; Antioxidants; Ascorbic Acid; Caenorhabditis elegans; Curcumin; DNA Damage; Nanoparticles; Oxidative Stress; Reactive Oxygen Species; Titanium; Zinc Oxide

2017
Effects of nano-TiO
    Journal of the science of food and agriculture, 2017, Volume: 97, Issue:4

    Nano-TiO. With increased barrier properties, NTLDPE packaging quickly formed a relative lower O. These data indicate that the beneficial effects of NTLDPE packaging on postharvest quality and antioxidant capacity of strawberry are probably associated with the promotion of ROS scavenging and related antioxidant enzyme activities, and NTLDPE packaging together with refrigeration storage is a promising method for strawberry fruit preservation. © 2016 Society of Chemical Industry.

    Topics: Anthocyanins; Antioxidants; Ascorbic Acid; Atmosphere; Biphenyl Compounds; Carbon Dioxide; Cold Temperature; Food Packaging; Food Preservation; Food Storage; Fragaria; Fruit; Humans; Hydrogen Peroxide; Nanostructures; Oxygen; Phenols; Picrates; Polyethylene; Refrigeration; Superoxides; Titanium

2017
Facile fabrication of an aptasensor for thrombin based on graphitic carbon nitride/TiO2 with high visible-light photoelectrochemical activity.
    Biosensors & bioelectronics, 2016, Jan-15, Volume: 75

    A novel aptasensor for thrombin with high visible-light activity was facilely fabricated based on graphitic carbon nitride/TiO2 (g-C3N4/TiO2) photoelectrochemical (PEC) composite. Crystallization of TiO2 nanoparticles (NPs) and their strong interaction with g-C3N4 sheet were confirmed by high-resolution transmission electron microscope (HR-TEM), both of which contributed to the high photocurrent intensity under visible-light irradiation. Carboxyl functionalized thrombin aptamers were first successfully bound to the g-C3N4/TiO2 modified electrode as proven by photoelectrochemical test and electrochemical impedance spectroscopy (EIS) analysis. Ascorbic acid was utilized as the electron donor for scavenging photo-generated holes and inhibiting light driven electron-hole pair recombination. The specific recognition between thrombin aptamer and thrombin led to the linear decrease of photocurrent with the increase of logarithm of thrombin concentration in the range of 5.0×10(-13)molL(-1) to 5.0×10(-9)molL(-1) with a detection limit of 1.2×10(-13)molL(-1). This proposed low-cost, convenient and sensitive aptasensor showed promising applications in biosensor and photoelectrochemical analysis.

    Topics: Aptamers, Nucleotide; Ascorbic Acid; Biosensing Techniques; Electrochemical Techniques; Graphite; Humans; Light; Limit of Detection; Nanoparticles; Nitriles; Photochemical Processes; Thrombin; Titanium

2016
Real-time direct electrochemical sensing of ascorbic acid over rat liver tissues using RuO2 nanowires on electrospun TiO2 nanofibers.
    Biosensors & bioelectronics, 2016, Mar-15, Volume: 77

    This paper reports that the high electrocatalytic activity of RuO2 nanowires grown on electrospun TiO2 nanofibers for the oxidation of l-ascorbic acid (AA); and the application of these materials for direct selective sensing of AA in complex samples. Compared to bare glassy carbon (GC) electrode, RuO2 nanowires on TiO2 nanofibers-loaded GC electrode facilitates the oxidation of AA most drastically among the tested species: AA, 4-acetamidophenol (AP), dopamine (DA), uric acid (UA), and glucose. The amperometric response of RuO2 nanowires on TiO2 nanofibers at the applied potential of 0.018 V (vs. SCE) exhibits high sensitivity (268.2 ± 3.7 μAmM(-1)cm(-2), n=5), low detection limit (<1.8 μM), great linearity, reasonable stability, and exclusive selectivity over AP, DA, glucose and UA at their physiological levels. In differential pulse voltammetry, it is verified that the potential resolution of RuO2 nanowires on TiO2 nanofibers is able to differentiate AA, DA, UA, and AP one from the others. In addition, as prepared RuO2 nanowires on TiO2 nanofibers are successfully applied for direct and selective AA measurements in commercial vitamin samples and for the real-time direct analysis of AA generated from living rat liver tissue in vitro.

    Topics: Adsorption; Animals; Ascorbic Acid; Computer Systems; Conductometry; Electroplating; Equipment Design; Equipment Failure Analysis; Liver; Male; Nanofibers; Nanowires; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Rotation; Ruthenium Compounds; Sensitivity and Specificity; Tissue Distribution; Titanium

2016
Simultaneous Photoelectrochemical Immunoassay of Dual Cardiac Markers Using Specific Enzyme Tags: A Proof of Principle for Multiplexed Bioanalysis.
    Analytical chemistry, 2016, Feb-16, Volume: 88, Issue:4

    In this Letter, on the basis of the CdS quantum dots functionalized TiO2 nanotubes electrode, we proposed a simultaneous photoelectrochemical (PEC) immunoassay of dual cardiac markers using specific enzyme tags of alkaline phosphatase (ALP) and acetylcholine esterase (AChE). ALP and AChE were integrated into the PEC system through the sandwich immunobinding and could specifically catalyze the hydrolysis of ascorbic acid 2-phosphate (AAP) or the acetylthiocholine (ATC) to in situ generate ascorbic acid (AA) or thiocholine (TC) for sacrificial electron donating. These two enzymes were thus used to differentiate the signals of two cardiac targets in connection with the sandwich immunorecognition and PEC responses to the corresponding electron donors. This strategy demonstrates a proof of principle for the successful integration of dual enzyme tags with PEC immunoassay that can potentially provide a general format for multiplexed PEC bioanalysis.

    Topics: Acetylcholinesterase; Acetylthiocholine; Alkaline Phosphatase; Antibodies, Immobilized; Ascorbic Acid; C-Reactive Protein; Chemistry Techniques, Analytical; Electrochemical Techniques; Electrodes; Humans; Immunoassay; Nanotubes; Quantum Dots; Titanium; Troponin I

2016
TiO2 decorated Co3O4 acicular nanotube arrays and its application as a non-enzymatic glucose sensor.
    Biosensors & bioelectronics, 2016, Jun-15, Volume: 80

    TiO2 modified Co3O4 acicular nanotube arrays (ANTAs) have been fabricated in this study, showing a good performance in glucose detection. In the experiment, the precursor Co(CO3)0.5(OH)·0.11H2O acicular nanowire arrays (ANWAs) was first grown on the fluorine doped tin oxide (FTO) substrate by a hydrothermal method. Thereafter, the uniform pink precursor Co(CO3)0.5(OH)·0.11H2O ANWAs was completely converted to the black Co3O4 ANTAs thin film by alkaline treatment. After the decoration of TiO2, the TiO2/Co3O4 ANTAs electrode exhibits a much higher current response to glucose compared with the Co3O4 ANTAs. Importantly, this neotype composite structure of Co3O4 enhances the glucose sensing performance by increasing specific surface area, additional reactive sites and synergistic effect, which make the TiO2/Co3O4 glucose sensor show a high sensitivity of 2008.82 μA mM(-1) cm(-2), a fast response time (less than 5s) and a detection limit as low as 0.3396 μM (S/N=3). The TiO2/Co3O4 ANTAs modified electrode exhibits a high selectivity for glucose in human serum, against ascorbic acid and uric acid.

    Topics: Ascorbic Acid; Biosensing Techniques; Blood Glucose; Cobalt; Humans; Limit of Detection; Nanotubes; Oxides; Titanium; Uric Acid

2016
Zinc oxide as a new antimicrobial preservative of topical products: interactions with common formulation ingredients.
    International journal of pharmaceutics, 2015, Feb-01, Volume: 479, Issue:1

    Zinc oxide (ZnO) appears as a promising preservative for pharmaceutical or cosmetic formulations. The other ingredients of the formulations may have specific interactions with ZnO that alter its antimicrobial properties. The influence of common formulation excipients on the antimicrobial efficacy of ZnO has been investigated in simple model systems and in typical topical products containing a complex formulation. A wide variety of formulation excipients have been investigated for their interactions with ZnO: antioxidants, chelating agents, electrolytes, titanium dioxide pigment. The antimicrobial activity of ZnO against Escherichia coli was partially inhibited by NaCl and MgSO4 salts. A synergistic influence of uncoated titanium dioxide has been observed. The interference effects of antioxidants and chelating agents were quite specific. The interactions of these substances with ZnO particles and with the soluble species released by ZnO were discussed so as to reach scientific guidelines for the choice of the ingredients. The preservative efficacy of ZnO was assessed by challenge testing in three different formulations: an oil-in-water emulsion; a water-in-oil emulsion and a dry powder. The addition of ZnO in complex formulations significantly improved the microbiological quality of the products, in spite of the presence of other ingredients that modulate the antimicrobial activity.

    Topics: Administration, Topical; Anti-Infective Agents; Antioxidants; Ascorbic Acid; Aspergillus; Butylated Hydroxytoluene; Candida albicans; Chelating Agents; Edetic Acid; Escherichia coli; Excipients; Magnesium Sulfate; Preservatives, Pharmaceutical; Pseudomonas aeruginosa; Sodium Chloride; Staphylococcus aureus; Titanium; Zinc Oxide

2015
Characteristics of titanium dioxide microdispersions with different photo-activity suitable for sunscreen formulations.
    International journal of pharmaceutics, 2015, Mar-15, Volume: 481, Issue:1-2

    The aim of the study was the comparison of photo-activity of three types of titanium dioxide (TiO2) micro-dispersions intended for use as UV filters for cosmetic sunscreen products. The dispersions were also investigated with regard to their influence on the stability of photo-protective systems in cosmetic emulsions, their skin penetration/absorption and their photo-toxicity for humans and skin bacterial flora. All the tested micro-dispersions of rutile TiO2 type (agglomerates with diameter 120-150 nm), with primary particle size lower than 100 nm, demonstrated no phototoxic effect and insignificant antimicrobial behaviour. On the other hand, TiO2 with insufficient deactivation of photo-activity had significant negative impact on the stability of other organic UV filters and therefore on the stability of declared UV protective factors (SPF, UVA-PF). The study demonstrated that the level of deactivation of TiO2 is one of the highly important factors for evaluation of UV filters used as sunscreens.

    Topics: 3T3 Cells; Animals; Anti-Bacterial Agents; Ascorbic Acid; Azo Compounds; Benzenesulfonates; Chemistry, Pharmaceutical; Coloring Agents; Escherichia coli; Female; In Vitro Techniques; Mice; Myristates; Nanoparticles; Particle Size; Skin; Skin Absorption; Staphylococcus epidermidis; Sunscreening Agents; Swine; Titanium; Ultraviolet Rays; Water

2015
Electrochemical Sensing of Dopamine, Uric Acid and Ascorbic Acid Using tRGO-TiO2 Nanocomposites.
    Journal of nanoscience and nanotechnology, 2015, Volume: 15, Issue:7

    This work reports a graphene-based nonenzymatic electrochemical sensing platform for the detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA). Graphene oxide, synthesized by modified Hummers method, was thermally reduced in an induction furnace at 200 °C in an Ar-H2 atmosphere to obtain thermally reduced graphene oxide (tRGO). Nanocomposites of tRGO-TiO2 were obtained by a hydrothermal method, and were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). FTIR spectra showed Ti-O-C peaks, indicating covalent linkage between the TiO2 nanoparticles and the reduced graphene oxide sheets. Glassy carbon electrode (GCE) was modified with the nanocomposite (tRGO-TiO2-GCE), and the modified electrode could detect dopamine (DA: 1 to 1000 µM), uric acid (UA: 1 to 900 µM), and ascorbic acid (AA: 10 to 1000 µM) in each other's presence over wide ranges, with adequate separation in peak potentials. Differential pulse voltammetry experiments yielded linear responses with sensitivities of 133.18, 33.96, and 155.59 µA mM(-1) cm(-2) for DA, UA, and AA, respectively.

    Topics: Ascorbic Acid; Dopamine; Electrochemical Techniques; Graphite; Nanocomposites; Titanium; Uric Acid

2015
Phoxim-induced damages of Bombyx mori larval midgut and titanium dioxide nanoparticles protective role under phoxim-induced toxicity.
    Environmental toxicology, 2014, Volume: 29, Issue:12

    Phoxim (O,O-diethyl O-(alpha-cyanobenzylideneamino) phosphorothioate) is a powerful organophosphorus pesticide with high potential for Bombyx mori larvae of silkworm exposure. However, it is possible that during the phoxim metabolism, there is generation of reactive oxygen species (ROS) and phoxim may produce oxidative stress and neurotoxicity in an intoxicated silkworm. Titanium dioxide nanoparticles (TiO2 NPs) pretreatment has been demonstrated to increase antioxidant capacity and acetylcholinesterase (AChE) activity in organisms. This study was, therefore, undertaken to determine phoxim-induced oxidative stress and neurotoxicity to determine whether phoxim intoxication alters the antioxidant system and AChE activity in the B. mori larval midgut, and to determine whether TiO2 NPs pretreatment attenuates phoxim-induced toxicity. The findings suggested that phoxim exposure decreased survival of B. mori larvae, increased malondialdehyde (MDA), carbonyl and 8-OHdG levels, and ROS accumulation in the midgut. Furthermore, phoxim significantly decreased the activities of AChE, superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione-S-transferase (GST), and levels of ascorbic acid (AsA), reduced glutathione (GSH), and thiol in the midgut. TiO2 pretreatment, however, could increase AChE activity, and remove ROS via activating SOD, CAT, APX, GR, and GST, and accelerating AsA-GSH cycle, thus attenuated lipid, protein, and DNA peroxidation and improve B. mori larval survival under phoxim-induced toxicity. Moreover, this experimental system would help nanomaterials to be applied in the sericulture.

    Topics: Animals; Antioxidants; Ascorbic Acid; Bombyx; Gastrointestinal Tract; Glutathione Transferase; Insecticides; Larva; Nanoparticles; Organothiophosphorus Compounds; Oxidative Stress; Protective Agents; Reactive Oxygen Species; Titanium

2014
Impact of TiO₂ nanoparticles on Vicia narbonensis L.: potential toxicity effects.
    Protoplasma, 2014, Volume: 251, Issue:6

    This work was aimed to provide further information about toxicology of TiO2 nanoparticles (NPs) on Vicia narbonensis L., considering different endpoints. After exposure to TiO2 nanoparticle suspension (mixture of rutile and anatase, size <100 nm) at four different concentrations (0.2, 1.0, 2.0 and 4.0 ‰), the seeds of V. narbonensis were let to germinate in controlled environmental conditions. After 72 h, the extent of the success of the whole process (seed germination plus root elongation) was recorded as the vigour index, an indicator of possible phytotoxicity. After the characterisation of the hydric state of different materials, oxidative stress and enzymatic and nonenzymatic antioxidant responses were considered as indicators of possible cytotoxicity and to assess if damage induced by TiO2 NPs was oxidative stress-dependent. Cytohistochemical detection of in situ DNA fragmentation as genotoxicity endpoint was monitored by TUNEL reaction. The treatments with TiO2 NPs in our system induced phytotoxic effects, ROS production and DNA fragmentation. The nonenzymatic and enzymatic antioxidant responses were gradually and differentially activated and were able to maintain the oxidative damage to levels not significantly different from the control. On the other hand, the results of DNA fragmentation suggested that the mechanisms of DNA repair were not effective enough to eliminate early genotoxicity effects.

    Topics: Antioxidants; Ascorbic Acid; Germination; Glutathione; Hybrid Vigor; Hydrogen Peroxide; In Situ Nick-End Labeling; Meristem; Nanoparticles; Proline; Seedlings; Titanium; Toxicity Tests; Vicia; Water

2014
Confirmation of hydroxyl radicals (•OH) generated in the presence of TiO2 supported on AC under microwave irradiation.
    Journal of hazardous materials, 2014, Aug-15, Volume: 278

    In order to study the degradation mechanism of technology of microwave (MW) combined with TiO2 supported on activated carbon (TiO2/AC), the reactive oxygen species (ROS) was explored through oxidation of 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Furthermore, 2,6-di-tert-butyl-4-methylphenol (BHT), Mannitol (MT) and Vitamin C (VC) were used as radical scavengers to confirm the generation of the hydroxyl radicals ((•)OH). In addition, the influence of some parameters such as TiO2 mass ratio content, irradiation time, material dose, DPCI concentration and MW power on the determination of (•)OH were examined. The results showed that the (•)OH could be generated under MW combined with loaded TiO2/AC. Also, anatase TiO2/AC can generate more (•)OH radicals than rutile TiO2/AC under MW irradiation. This work would provide new mechanistic insights on the enhanced degradation effect of organic pollutants in water using the supported TiO2/AC coupled with MW technology.

    Topics: Antioxidants; Ascorbic Acid; Butylated Hydroxytoluene; Carbon; Diphenylcarbazide; Hydroxyl Radical; Mannitol; Microwaves; Oxidation-Reduction; Semicarbazones; Titanium

2014
Ascorbic acid surface modified TiO₂-thin layers as a fully integrated analysis system for visual simultaneous detection of organophosphorus pesticides.
    Nanoscale, 2014, Nov-06, Volume: 6, Issue:23

    TiO₂ photocatalysis and colorimetric detection are coupled with thin layer chromatography (TLC) for the first time to develop a fully integrated analysis system. Titania@polystyrene hybrid microspheres were surface modified with ascorbic acid, denoted AA-TiO₂@PS, and used as the stationary phase for TLC. Because the affinity between AA-TiO₂@PS and organophosphorus pesticides (OPs) was different for different species of OPs (including chlopyrifos, malathion, parathion, parathion-methyl, and methamidophos), OPs could be separated simultaneously by the mobile phase in 12.0 min with different Rf values. After surface modification, the UV-vis wavelength response range of AA-TiO₂@PS was expanded to 650 nm. Under visible-light irradiation, all of the OPs could be photodegraded to PO₄(3-) in 25.0 min. Based on the chromogenic reaction between PO₄(3-) and chromogenic agents (ammonium molybdate and ascorbic acid), OPs were quantified from color intensity images using a scanner in conjunction with image processing software. So, AA-TiO₂@PS was respectively used as the stationary phase of TLC for efficient separation of OPs, as a photocatalyst for species transformation of phosphorus, and as a colorimetric probe for on-field simultaneous visual detection of OPs in natural water. Linear calibration curves for each OP ranged from 19.3 nmol P L(-1) to 2.30 μmol P L(-1). This integrated analysis system was simple, inexpensive, easy to operate, and sensitive.

    Topics: Ascorbic Acid; Catalysis; Chromatography, Thin Layer; Colorimetry; Organophosphorus Compounds; Pesticides; Photochemical Processes; Titanium

2014
Flash photo stimulation of human neural stem cells on graphene/TiO2 heterojunction for differentiation into neurons.
    Nanoscale, 2013, Nov-07, Volume: 5, Issue:21

    For the application of human neural stem cells (hNSCs) in neural regeneration and brain repair, it is necessary to stimulate hNSC differentiation towards neurons rather than glia. Due to the unique properties of graphene in stem cell differentiation, here we introduce reduced graphene oxide (rGO)/TiO2 heterojunction film as a biocompatible flash photo stimulator for effective differentiation of hNSCs into neurons. Using the stimulation, the number of cell nuclei on rGO/TiO2 increased by a factor of ~1.5, while on GO/TiO2 and TiO2 it increased only ~48 and 24%, respectively. Moreover, under optimum conditions of flash photo stimulation (10 mW cm(-2) flash intensity and 15.0 mM ascorbic acid in cell culture medium) not only did the number of cell nuclei and neurons differentiated on rGO/TiO2 significantly increase (by factors of ~2.5 and 3.6), but also the number of glial cells decreased (by a factor of ~0.28). This resulted in a ~23-fold increase in the neural to glial cell ratio. Such highly accelerated differentiation was assigned to electron injection from the photoexcited TiO2 into the cells on the rGO through Ti-C and Ti-O-C bonds. The role of ascorbic acid, as a scavenger of the photoexcited holes, in flash photo stimulation was studied at various concentrations and flash intensities.

    Topics: Ascorbic Acid; Biocompatible Materials; Catalysis; Cell Differentiation; Cells, Cultured; Culture Media; Graphite; Humans; Light; Neural Stem Cells; Neurons; Titanium

2013
Small sizes of TiO2-NPs exhibit adverse effects at predicted environmental relevant concentrations on nematodes in a modified chronic toxicity assay system.
    Journal of hazardous materials, 2012, Volume: 243

    In Caenorhabditis elegans, although acute toxicity of TiO(2) nanoparticles (TiO(2)-NPs) at high concentrations has been investigated, we still know little about chronic toxicity of TiO(2)-NPs. Our data here showed that acute TiO(2)-NPs exposure in the range of μg/L had no obviously adverse effects on nematodes, but the chronic toxicities of large sizes (60 nm and 90 nm) of TiO(2)-NPs in the range of μg/L were detected in nematodes in a modified chronic toxicity assay system. Moreover, chronic toxicities of small sizes (4 nm and 10nm) of TiO(2)-NPs in the range of ng/L were observed in nematodes with locomotion behavior and ROS production as endpoints. In nematodes chronically exposed to small sizes of TiO(2)-NPs at predicted environmental relevant concentrations, locomotion behavior was significantly (P<0.01) correlated with ROS production. Furthermore, treatment with antioxidants (ascorbate and N-acetyl-l-cysteine) inhibited both the induction of ROS production and the decrease of locomotion behaviors observed in nematodes chronically exposed to small sizes of TiO(2)-NPs at predicted environmental relevant concentrations. Therefore, chronic exposure to small sizes of TiO(2)-NPs at predicted environmental relevant concentrations can cause adverse effects on nematodes, and formation of such adverse effects may be largely due to the induction of oxidative stress.

    Topics: Acetylcysteine; Animals; Antioxidants; Ascorbic Acid; Caenorhabditis elegans; Growth; Indicators and Reagents; Intestines; Motor Activity; Nanoparticles; Oxidative Stress; Particle Size; Reactive Oxygen Species; Suspensions; Titanium

2012
In situ enzymatic ascorbic acid production as electron donor for CdS quantum dots equipped TiO2 nanotubes: a general and efficient approach for new photoelectrochemical immunoassay.
    Analytical chemistry, 2012, Dec-18, Volume: 84, Issue:24

    In this work, a novel photoelectrochemical (PEC) immunoanalysis format was developed for sensitive and specific detection of prostate-specific antigen (PSA) based on an in situ electron donor producing approach. Thioglycolic acid-capped CdS quantum dots (QDs) equipped TiO(2) nanotubes (NTs) were fabricated via a facile electrostatic adsorption method. The coupling of CdS QDs and TiO(2) NTs results in an enhanced excitation and photo-to-electric conversion efficiency. Using alkaline phosphatase catalytic chemistry to in situ generate ascorbic acid for electron donating, an exquisite immunosandwich protocol was successfully constructed for the PSA assay due to the dependence of the photocurrent signal on the concentration of electron donor. This work opens a different perspective for transducer design in PEC detection and provides a general format for future development of PEC immunoanalysis.

    Topics: Ascorbic Acid; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Nanotubes; Photochemical Processes; Quantum Dots; Sulfates; Titanium

2012
The role of ascorbic acid on titanium dioxide-induced genetic damage assessed by the comet assay and cytogenetic tests.
    Experimental and toxicologic pathology : official journal of the Gesellschaft fur Toxikologische Pathologie, 2011, Volume: 63, Issue:5

    Titanium dioxide (TiO(2)) is used in several commercial products such as cosmetics, sunscreen, toothpaste and pharmaceuticals. However, some recent investigations have revealed that titanium particles generate potential harmful effects on the environment and humans. Because of its strong antioxidant activity, ascorbic acid (AA) is admitted to act as an anti-mutagenic agent. The present study was undertaken to investigate the protective effect of AA against TiO(2)-induced genotoxicity. Sister chromatid exchange (SCE), micronucleus (MN) and the comet assays were used to assess TiO(2)-induced genotoxicity and to establish the protective effects of AA. There were significant increases (P<0.05) in both SCE and MN frequencies of cultures treated with TiO(2) as compared to controls. However, co-application of AA (4.87 and 9.73 μM) and TiO(2) resulted in decreases of SCE and MN rates as compared to the group treated with titanium alone. Besides, significant reductions of primary DNA damage (comet assay) were determined when the AA was added to the cell culture medium simultaneously with TiO(2). In conclusion, the preventive role of AA in alleviating TiO(2)-induced DNA damage was indicated for the first time in the present study.

    Topics: Antioxidants; Ascorbic Acid; Cell Proliferation; Cells, Cultured; Comet Assay; DNA Damage; Humans; Lymphocytes; Micronuclei, Chromosome-Defective; Micronucleus Tests; Mutagens; Sister Chromatid Exchange; Titanium

2011
Hydrothermal preparation and electrochemical sensing properties of TiO(2)-graphene nanocomposite.
    Colloids and surfaces. B, Biointerfaces, 2011, Volume: 83, Issue:1

    A facile hydrothermal method has been developed and shown to be effective for the preparation of TiO(2)-graphene nanocomposite. The as-prepared nanocomposite was characterized using FT-IR spectroscopy, powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The TiO(2)-graphene modified glassy carbon electrode (GCE) exhibited remarkable electron transfer kinetics and electrocatalytic activity toward the oxidation of dopamine (DA). Furthermore, the oxidation of common interfering agent such as ascorbic acid (AA) was significantly suppressed at this modified electrode, which resulted in good selectivity and sensitivity for electrochemical sensing of DA. These results demonstrate that the TiO(2)-graphene hybrid material has promising potential applications in electrochemical sensors and biosensors design.

    Topics: Ascorbic Acid; Carbon; Catalysis; Dopamine; Electrochemical Techniques; Electrodes; Glass; Graphite; Nanocomposites; Oxidation-Reduction; Spectroscopy, Fourier Transform Infrared; Temperature; Titanium; Water; X-Ray Diffraction

2011
Differential toxicity of silver and titanium dioxide nanoparticles on Drosophila melanogaster development, reproductive effort, and viability: size, coatings and antioxidants matter.
    Chemosphere, 2011, Volume: 85, Issue:1

    Silver and titanium dioxide nanoparticles are known to induce oxidative stress in vitro and in vivo. Here we test if they impact development, mating success, and survivorship in Drosophila melanogaster, and if so, if these effects are reversible by antioxidants. Ingestion of nanotitanium dioxide during the larval stage of the life cycle showed no effects on development or survivorship, up to doses of 200 μg mL(-1). Conversely, ingestion of nanosilver had major dose, size, and coating-dependent effects on each of these aspects of life history. Each of these effects was partially or fully reversible by vitamin C. Larvae growing on nanosilver supplemented with vitamin C showed a greater than twofold increase in survivorship compared to flies reared on nanosilver alone, and a threefold increase in mating success. Vitamin C also rescued cuticular and pigmentation defects in nanosilver fed flies. Biochemical assays of superoxide dismutase and glutathione show these markers respond to nanotitanium dioxide and nanosilver induced oxidative stress, and this response is reduced by vitamin C. These results indicate that life history effects of nanosilver ingestion result from oxidative stress, and suggest antioxidants as a potential remediation for nanosilver toxicity. Conversely, the lack of nanotitanium dioxide life history toxicity shows that oxidative stress does not necessarily result in whole organism effects, and argues that nanoparticle toxicity needs to be examined at different levels of biological organization.

    Topics: Animals; Antioxidants; Ascorbic Acid; Drosophila melanogaster; Nanoparticles; Silver; Titanium

2011
High photocatalytic degradation activity of the polyvinyl chloride (PVC)-vitamin C (VC)-TiO2 nano-composite film.
    Journal of hazardous materials, 2010, Jun-15, Volume: 178, Issue:1-3

    A novel photodegradable polyvinyl chloride (PVC)-vitamin C (VC)-TiO(2) nano-composite film was prepared by embedding VC modified nano-TiO(2) photocatalyst into the commercial PVC plastic. The solid-phase photocatalytic degradation behavior of PVC-VC-TiO(2) nano-composite film under UV light irradiation was investigated and compared with those of the PVC-TiO(2) film and the pure PVC film, with the aid of UV-Vis spectroscopy, scanning electron microscopy (SEM), weight loss monitoring, and X-ray diffraction spectra (XRD). The results show that PVC-VC-TiO(2) nano-composite film has a high photocatalytic activity; the photocatalytic degradation rate of it is two times higher than that of PVC-TiO(2) film and fifteen times higher than that of pure PVC film. The optimal mass ratio of VC to TiO(2) is found to be 0.5. The mechanism of enhancing photocatalytic activity is attributed to the formation of a Ti(IV)-VC charge-transfer complex with five-member chelate ring structure and a rapid photogenerated charge separation is thus achieved.

    Topics: Ascorbic Acid; Catalysis; Microscopy, Electron, Scanning; Nanotechnology; Photochemistry; Polyvinyl Chloride; Spectrophotometry, Ultraviolet; Titanium; Ultraviolet Rays; X-Ray Diffraction

2010
Voltammetric sensor for buzepide methiodide determination based on TiO2 nanoparticle-modified carbon paste electrode.
    Colloids and surfaces. B, Biointerfaces, 2010, Jul-01, Volume: 78, Issue:2

    In this work, we have prepared nano-material modified carbon paste electrode (CPE) for the sensing of an antidepressant, buzepide methiodide (BZP) by incorporating TiO2 nanoparticles in carbon paste matrix. Electrochemical studies indicated that the TiO2 nanoparticles efficiently increased the electron transfer kinetics between drug and the electrode. Compared with the nonmodified CPE, the TiO2-modified CPE greatly enhances the oxidation signal of BZP with negative shift in peak potential. Based on this, we have proposed a sensitive, rapid and convenient electrochemical method for the determination of BZP. Under the optimized conditions, the oxidation peak current of BZP is found to be proportional to its concentration in the range of 5 x 10(-8) to 5 x 10(-5)M with a detection limit of 8.2 x 10(-9)M. Finally, this sensing method was successfully applied for the determination of BZP in human blood serum and urine samples with good recoveries.

    Topics: Algorithms; Ascorbic Acid; Azepines; Biosensing Techniques; Calibration; Carbon; Electrodes; Glucose; Humans; Hydrogen-Ion Concentration; Metal Nanoparticles; Potentiometry; Reproducibility of Results; Sucrose; Titanium

2010
Dissolution studies on TiO2 with organics.
    Chemosphere, 2005, Volume: 61, Issue:4

    In this work the effect of organic reducing reagents, namely, ascorbic acid, oxalic acid and L-cysteine on dissolution of commercial TiO(2) has been investigated. Kinetic studies showed that a maximum of about 45% of TiO(2) was dissolved by ascorbic acid in 4h when oxide:acid molar ratio was kept at 1:2. The dissolution of TiO(2) increased with increase in ascorbic acid and oxalic acid concentration up to 0.15M in 4h (corresponding to molar ratio of oxide to acid of 1:3) and further addition did not affect the dissolution. Nearly 45% TiO(2) dissolution was obtained with ascorbic acid alone while oxalic acid yielded 40% dissolution. When oxalic acid was added along with ascorbic acid in equi-molar concentrations, dissolution of TiO(2) was enhanced to 60% in 2.5h but when cysteine was added to ascorbic acid the dissolution was about 50% in just 1h.

    Topics: Ascorbic Acid; Cysteine; Oxalic Acid; Oxidation-Reduction; Solubility; Titanium

2005
Effect of the photocatalytic activity of TiO(2) on plasmid DNA.
    Mutation research, 2000, Mar-03, Volume: 466, Issue:1

    We investigated the photodynamic DNA strand-breaking activity of TiO(2). A solution of super-coiled pBR 322 DNA was irradiated with 5 J/cm(2) of UVA in the presence of TiO(2) and the products were analyzed by using gel electrophoresis. The ratio of open-circular DNA to super-coiled circular DNA was calculated from the resulting peak areas as a DNA strand-breaking index (SBI). The SBI of anatase-structure TiO(2) (band gap=3.23 eV) was greater than that of rutile structure (band gap=3.06 eV), and the level of SBI correlated with the photocatalytic activity for degradation of 2-propanol. The inhibitory effects of active oxygen scavengers, including DMSO, glutathione and histidine, on the DNA strand-breaking activity were examined. All of the scavengers except ascorbic acid showed inhibitory effects, as did several polyhydric alcohols including mannitol, a well-known hydroxyl radical scavenger. These results suggest that the photodynamic DNA strand-breaking activity of TiO(2) is due to active oxygen species, especially hydroxyl radicals. Polyhydric alcohols showed an inverse correlation between the inhibitory effect on DNA strand-breaking activity and the octanol/water partition coefficient (logP).

    Topics: Ascorbic Acid; Dimethyl Sulfoxide; DNA; DNA Damage; Dose-Response Relationship, Drug; Free Radical Scavengers; Glutathione; Histidine; Mannitol; Photosensitizing Agents; Plasmids; Sugar Alcohols; Titanium; Ultraviolet Rays

2000
Evaluation of the micronucleus test in vitro using Chinese hamster cells: results of four chemicals weakly positive in the in vivo micronucleus test.
    Environmental and molecular mutagenesis, 1995, Volume: 26, Issue:3

    A rapid and simple procedure for the micronucleus test (MNT) in vitro using Chinese hamster ovary (CHO) cells was established in our laboratory. The assay is intended to quickly screen chromosomal aberrations in vitro within the framework of industrial genotoxicity studies. To test the sensitivity of the assay in the experiments described here, four substances, classified as noncarcinogens but reported as weak inducers of micronuclei (MN) in bone-marrow cells of mice, were evaluated in the MNT in vitro. Of the four compounds, ascorbic acid, phenol, and 2,6-diaminotoluene proved to be genotoxic in the MNT in vitro. Titanium dioxide, which could not be dissolved in the culture medium, did not induce MN. The MNT in vitro proved to be quick and relatively simple and to yield highly reproducible results when testing the four chemicals.

    Topics: Animals; Ascorbic Acid; Bleomycin; Bone Marrow; CHO Cells; Cricetinae; Cricetulus; Cyclophosphamide; Mice; Micronucleus Tests; Mutagens; Phenol; Phenols; Phenylenediamines; Reproducibility of Results; Titanium

1995
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