disilver-oxide and titanium-dioxide

Nanotechnology is the creation of functional materials, devices and systems at atomic and molecular scales (1-100 nm), where properties differ significantly from those at a larger scale. The use of nanotechnology and nanomaterials in medical research is growing rapidly. Recently, nanotechnologic developments in microbiology have gained importance in the field of chemotherapy. Bacterial strains that are resistant to current antibiotics have become serious public health problems that raise the need to develop new bactericidal materials. Metal oxide nanoparticles, especially TiO(2) and Ag(2)O nanoparticles, have demonstrated significant antibacterial activity. Therefore, it is thought that this property of metal oxide nanoparticles could effectively be used as a novel solution strategy. In this review, we focus on the unique properties of nanoparticles, their mechanism of action as antibacterial agents and recent studies in which the effects of visible and UV-light induced TiO(2) and Ag(2)O nanoparticles on drug-resistant bacteria have been documented. In addition, from to previous results of our studies, antileishmanial effects of metal oxide nanoparticles are also demonstrated, indicating that metal oxide nanoparticles can also be effective against eukaryotic infectious agents. Conversely, despite their significant potential in antimicrobial applications, the toxicity of metal oxide nanoparticles restricts their use in humans. However, recent studies infer that metal oxide nanoparticles have considerable potential to be the first-choice for antibacterial and antiparasitic applications in the future, provided that researchers can bring new ideas in order to cope with their main problem of toxicity.

Topics: Anti-Infective Agents; Bacteria; Drug Resistance, Microbial; Humans; Leishmania; Metal Nanoparticles; Oxides; Silver Compounds; Titanium

Treatment of burn wounds has many requirements to ensure wound closure with healthy tissue, increased vascularization, guarantee edema resolution, and control bacterial infection. We propose that titanium oxide (TiO

Topics: Animals; Gelatin; Metal Nanoparticles; Oxides; Rabbits; Regeneration; Silver Compounds; Skin; Skin Physiological Phenomena; Titanium

The dispersion of nanoparticles having different size-, shape-, and composition-dependent properties is an exciting approach to design and synthesize multifunctional materials and devices. This work shows a detailed investigation of the preparation and properties of free-standing nanocomposite films based on cellulose nanocrystals (CNC) loaded with three different types of metal nanoparticles. CNC-based nanocomposites having zinc oxide (ZnO), titanium dioxide (TiO

Topics: Anti-Bacterial Agents; Cellulose; Escherichia coli; Metal Nanoparticles; Nanoparticles; Oxides; Silver Compounds; Staphylococcus aureus; Titanium; Zinc Oxide

Three-dimensional Ag2O and Ag co-loaded TiO2 (3D Ag2O-Ag/TiO2) composites have been synthesized through a facile method, characterized using SEM, EDX, TEM, XRD, XPS, UV-vis DRS, BET techniques, and applied to remove radioactive iodide ions (I(-)). The photocatalytic adsorption capacity (207.6 mg/g) of the 3D Ag2O-Ag/TiO2 spheres under visible light is four times higher than that in the dark, which is barely affected by other ions, even in simulated salt lake water where the concentration of Cl(-) is up to 590 times that of I(-). The capability of the composites to remove even trace amounts of I(-) from different types of water, e.g., deionized or salt lake water, is demonstrated. The composites also feature good reusability, as they were separated after photocatalytic adsorption and still performed well after a simple regeneration. Furthermore, a mechanism explaining the highly efficient removal of radioactive I(-) has been proposed according to characterization analyses of the composites after adsorption and subsequently been verified by adsorption and desorption experiments. The proposed cooperative effects mechanism considers the interplay of three different phenomena, namely, the adsorption performance of Ag2O for I(-), the photocatalytic ability of Ag/TiO2 for oxidation of I(-), and the readsorption performance of AgI for I2.

Topics: Adsorption; Iodides; Iodine Radioisotopes; Kinetics; Light; Materials Testing; Oxides; Oxygen; Photolysis; Silver Compounds; Spectrophotometry, Ultraviolet; Titanium; Waste Disposal, Fluid; Water; Water Pollutants, Radioactive; Water Purification; X-Ray Diffraction

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

In this study, the effects, fate and transport of ENPs in wastewater treatment plants (WWTP) were investigated using three parallel pilot WWTPs operated under identical conditions. The WWTPs were spiked with (i) an ENP mixture consisting of silver oxide, titanium dioxide and zinc oxide, and (ii) bulk metal salts. The third plant served as control (unspiked). ENP effects were evaluated for (i) bulk contaminant removal, (ii) activated sludge (AS) process performance, (iii) microbial community structure and dynamics and (iv) microbial inhibition. ENPs showed a strong affinity for biosolids and induced a specific oxygen uptake rate two times higher than the control. The heterotrophic biomass retained its ability to nitrify and degrade organic matter. However, non-recovery of ammonia- and nitrite-oxidizing bacteria such as Nitrosomonas, Nitrobacter or Nitrospira in the ENP spiked reactors suggests selective inhibitory effects. The results further suggest that ENPs and metal salts have antimicrobial properties which can reduce synthesis of extracellular polymeric substances and therefore floc formation. Scanning electron microscopy evidenced selective damage to some microbes, whereas lipid fingerprinting and 454 pyrosequencing indicated a temporal shift in the microbial community structure and diversity. Acidovorax, Rhodoferax, Comamonas and Methanosarcina were identified as nano-tolerant species. Competitive growth advantage of the nano-tolerant species influenced the removal processes and unlike other xenobiotic compounds, ENPs can hasten the natural selection of microbial species in AS.

Topics: Ammonia; Biomass; Comamonas; Heterotrophic Processes; Methanosarcina; Nanoparticles; Nitrification; Nitrites; Nitrobacter; Nitrosomonas; Oxides; Oxygen; Sewage; Silver Compounds; Titanium; Water Purification; Zinc Oxide

A versatile strategy to endow biomaterials with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat biomaterial related infection. TiO2 nanotube (NT) arrays can significantly enhance the functions of many cell types including osteoblasts thus having promising applications in orthopedics, orthodontics, as well as other biomedical fields. In this study, TiO2 NT arrays with Ag2O nanoparticle embedded in the nanotube wall (NT-Ag2O arrays) are prepared on titanium (Ti) by TiAg magnetron sputtering and anodization. Well-defined NT arrays containing Ag concentrations in a wide range from 0 to 15 at % are formed. Ag incorporation has little influence on the NT diameter, but significantly decreases the tube length. Crystallized Ag2O nanoparticles with diameters ranging from 5 nm to 20 nm are embedded in the amorphous TiO2 nanotube wall and this unique structure leads to controlled release of Ag(+) that generates adequate antibacterial activity without showing cytotoxicity. The NT-Ag2O arrays can effectively kill Escherichia coli and Staphylococcus aureus even after immersion for 28 days, demonstrating the long lasting antibacterial ability. Furthermore, the NT-Ag2O arrays have no appreciable influence on the osteoblast viability, proliferation, and differentiation compared to the Ag free TiO2 NT arrays. Ag incorporation even shows some favorable effects on promoting cell spreading. The technique reported here is a versatile approach to develop biomedical coatings with different functions.

Topics: Anti-Bacterial Agents; Escherichia; Nanotubes; Osteoblasts; Oxides; Silver Compounds; Staphylococcus aureus; Titanium

Heterogeneous nucleation of silver oxide (Ag2O) onto oxide microparticles (OMPs) followed by spontaneous thermal decomposition produce nanostructures made of OMPs decorated with silver nanoparticles (OMP|AgNPs).. Colloidal chemistry methods have been used to produce the decoration of OMPs with silver nanoparticles (AgNPs), by carrying out the Ag2O precipitation/thermal decomposition. The process is driven in water enriched acetone medium containing NaOH, NH3, AgNO3 and SiO2MPs as substrate. Optical and morphological properties of OMP|AgNPs were characterized by using STEM, EDS, HRTEM and Raman spectroscopy.. A new synthetic method to decorate OMPs (TiO2, SiO2) with metallic AgNPs in a single step/single pot reaction is proven effective to produce OMP|AgNPs either in aqueous or water enriched media.

Topics: Chemical Precipitation; Metal Nanoparticles; Oxides; Silicon Dioxide; Silver; Silver Compounds; Titanium

Infection-related complications have been a critical issue for the application of titanium orthopedic implants. The use of Ag nanoparticles offers a potential approach to incorporate antimicrobial properties into the titanium implants. In this work, a novel and simple method was developed for synthesis of Ag (II) oxide deposited TiO2 nanotubes (TiNTs) using electrochemical anodization followed by Ag electroplating processes in the same electrolyte. The quantities of AgO nanoparticles deposited in TiNT were controlled by selecting different electroplating times and voltages. It was shown that AgO nanoparticles were crystalline and distributed throughout the length of the nanotubes. Inductively coupled plasma mass spectrometry tests showed that the quantities of released Ag were less than 7 mg/L after 30 days at 37°C. Antimicrobial assay results show that the AgO-deposited TiNTs can effectively kill the Escherichia coli bacteria. Although the AgO-deposited TiNTs showed some cytotoxicity, it should be controllable by optimization of the electroplating parameters and incorporation of cell growth factor. The results of this study indicated that antimicrobial properties could be added to nanotextured medical implants through a simple and cost effective method.

Topics: Animals; Anti-Infective Agents; Cell Line; Cell Proliferation; Electrochemical Techniques; Escherichia coli; Metal Nanoparticles; Mice; Microbial Sensitivity Tests; Microbial Viability; Nanotechnology; Nanotubes; Oxides; Silver Compounds; Titanium

Iodine radioisotopes are released into the environment by the nuclear industry and medical research institutions using radioactive materials. The (129)I(-) anion is one of the more mobile radioactive species due to a long half-life, and it is a great challenge to design long-term management solutions for such radioactive waste. In this study, a new adsorbent structure with the potential to efficiently remove radioactive iodine anions (I(-)) from water is devised: silver oxide (Ag2O) nanocrystals firmly anchored on the surface of titanate nanotubes and nanofibers via coherent interfaces between Ag2O and titanate phases. I(-) anions in fluids can easily access the Ag2O nanocrystals and be efficiently trapped by forming AgI precipitate that firmly attaches to the adsorbent. Due to their one-dimensional morphology, the new adsorbents can be readily dispersed in liquids and easily separated after purification; and the adsorption beds loaded with the adsorbents can permit high flux. This significantly enhances the adsorption efficiency and reduces the separation costs. The proposed structure reveals a new direction in developing efficient adsorbents for the removal of radioactive anions from wastewater.

Topics: Adsorption; Anions; Iodine; Iodine Radioisotopes; Nanofibers; Nanotubes; Oxides; Silver Compounds; Titanium; Water; Water Pollutants, Chemical

Ag(2)O/TNBs were fabricated by depositing Ag(2)O nanoparticles on the surface of TiO(2) nanobelts (TNBs). The disinfection activities of Ag(2)O/TNBs on two representative bacterial types: Gram-negative Escherichia coli ATCC15597 and Gram-positive Bacillus subtilis, were examined under both dark and visible light conditions. Ag(2)O/TNBs exhibited stronger bactericidal activities than Ag(2)O nanoparticles and TNBs under both dark and light conditions. For both cell types, disinfection effects of Ag(2)O/TNBs were greater under light conditions relative to those under dark conditions. The bactericidal mechanisms of Ag(2)O/TNBs under both dark and light conditions were explored. Ag(+) ions released from Ag(2)O/TNBs did not contribute to the bactericidal activity of Ag(2)O/TNBs under dark conditions, whereas the released Ag(+) ions showed bactericidal activity under visible light irradiation conditions. Active species (H(2)O(2), O(2)(-)·, and e(-)) generated by Ag(2)O/TNBs played important roles in the disinfection processes under both dark and visible light irradiation conditions. Without the presence of active species, the direct contact of Ag(2)O/TNBs with bacterial cells had no bactericidal effect.

Topics: Anaerobiosis; Anti-Bacterial Agents; Bacillus subtilis; Darkness; Disinfection; Escherichia coli; Hydrogen Peroxide; Light; Microbial Sensitivity Tests; Nanoparticles; Oxides; Silver Compounds; Titanium

A highly active photocatalyst, silver loaded mesoporous WO(3), was successfully synthesized by an ultrasound assisted insertion method. The photodegradation of a common air pollutant acetaldehyde was adopted to evaluate the photocatalytic performance of the as-prepared sample under visible-light irradiation. The photocatalytic activity was about three and six times higher than that of pure mesoporous WO(3) and nitrogen-doped TiO(2), respectively. The photocatalytic mechanism was investigated to understand the much enhanced photocatalytic activity, which was mainly attributed to the largely improved electron-hole separation in the Ag-WO(3) heterojunction.

Topics: Acetaldehyde; Air Pollutants, Occupational; Carbon Dioxide; Catalysis; Light; Microscopy, Electron, Transmission; Nanoparticles; Oxidation-Reduction; Oxides; Photochemistry; Porosity; Silver Compounds; Titanium; Tungsten; X-Ray Diffraction

Three copolymers containing the functional groups P=O, S=O and C=O were prepared, and upon the introduction in calcium phosphate aqueous solutions at physiological conditions, "in vitro" were induced the precipitation of calcium phosphate crystals. The investigation of the crystal growth process was done at constant supersaturation. It is suggested that the negative end of the above functional groups acts as the active site for nucleation of the inorganic phase. In order to obtain the copolymer further antimicrobial activity, titania (TiO(2)) nanocrystals were incorporated in the polymer matrix after silver coverage by UV radiation. The antimicrobial resistance of the composite material (copolymer-titania/Ag) was tested against Staphylococcus epidermidis (SEM), Staphylococcus aureus (SAM), Candida parapsilosis (CAM) and Pseudomonas aeruginosa (PAM), microorganisms, using cut parts of "pi-plate" that covered with the above mentioned composite. The antimicrobial effect increased as the size of the nanocrystals TiO(2)/Ag decreased, the maximum achieved with the third polymer that contained also quartenary ammonium groups.

Topics: Biofilms; Calcium Phosphates; Coloring Agents; In Vitro Techniques; Nanoparticles; Oxides; Polymers; Pseudomonas aeruginosa; Silver; Silver Compounds; Staphylococcus aureus; Staphylococcus epidermidis; Titanium

Titanium dioxide nanoparticles codoped with nitrogen and silver (Ag(2)O/TiON) were synthesized by the sol-gel process and found to be an effective visible light driven photocatalyst. The catalyst showed strong bactericidal activity against Escherichia coli (E. coli) under visible light irradiation (λ > 400 nm). In X-ray photoelectron spectroscopy and X-ray diffraction characterization of the samples, the as-added Ag species mainly exist as Ag(2)O. Spin trapping EPR study showed Ag addition greatly enhanced the production of hydroxyl radicals (•OH) under visible light irradiation. The results indicate that the Ag(2)O species trapped e(CB)(-) in the process of Ag(2)O/TiON photocatalytic reaction, thus inhibiting the recombination of e(CB)(-) and h(VB)(+) in agreement with the stronger photocatalytic bactericidal activity of Ag(2)O/TiON. The killing mechanism of Ag(2)O/TiON under visible light irradiation is shown to be related to oxidative damages in the forms of cell wall thinning and cell disconfiguration.

Topics: Anti-Infective Agents; Catalysis; Crystallography, X-Ray; Disinfection; Electron Spin Resonance Spectroscopy; Escherichia coli; Hydroxyl Radical; Kinetics; Light; Microbial Sensitivity Tests; Microbial Viability; Nitrogen; Oxidation-Reduction; Oxides; Silver; Silver Compounds; Spectrophotometry, Ultraviolet; Spin Trapping; Time Factors; Titanium

Ag(2)O/TiO(2) heterostructure with high photocatalytic activity both in ultraviolet and visible-light region was synthesized via a simple and practical coprecipitation method by using surface-modified TiO(2) nanobelts as substrate materials. The as-prepared heterostructure composite included Ag(2)O nanoparticles assembled uniformly on the rough surface of TiO(2) nanobelts. Comparing with pure TiO(2) nanobelts and Ag(2)O nanoparticles, the composite photocatalyst with a wide weight ratio between TiO(2) and Ag(2)O exhibited enhanced photocatalytic activity under ultraviolet and visible light irradiation in the decomposition of methyl orange (MO) aqueous solution. On the basis of the characterization by X-ray diffraction, photoluminescence and UV-vis diffuse reflectance spectroscopies, two mechanisms were proposed to account for the photocatalytic activity of Ag(2)O/TiO(2) nanobelts' heterostructure.

Topics: Air Pollutants; Azo Compounds; Light; Metal Nanoparticles; Nanotechnology; Oxides; Photochemistry; Silver Compounds; Titanium; Ultraviolet Rays; Waste Management; Water Pollutants

Electrostatic self-assembled Ag(2)O/TiO(2) nanobelts heterostructure was synthesized via simple physical mixing of Ag(2)O nanoparticles and TiO(2) nanobelts. The morphologies and microstructures of Ag(2)O/TiO(2) nanobelt heterostructure were characterized by high resolution transmission electron microscopy. The interface dominated high UV photocatalytic activity and degraded photoluminescence strength of composite catalyst confirmed the heterostructure effect between Ag(2)O nanoparticles and TiO(2) nanobelts. X-ray photoelectron spectroscope provided direct evidence of charge transfer on the heterostructures between them.

Topics: Catalysis; Nanoparticles; Oxides; Photoelectron Spectroscopy; Silver Compounds; Static Electricity; Titanium; Ultraviolet Rays

Superoxide anion radical (O(2)(-*)) and OH radical generations in suspensions of Ag metal-, Ag(2)O-, or AgO-loaded TiO(2) and BiVO(4) photocatalysts in alkaline conditions (pH 12.0) were examined by means of a luminol chemiluminescence (CL) technique and a spin-trapping fluorescence one in which terephthalic acid reacts with an OH radical to afford the highly fluorescent 2-hydroxyterephthalic acid (TAOH), respectively. The observed luminol CL intensity was remarkably enhanced by the AgO loading on TiO(2) as well as BiVO(4). This can be explained by enhancement of O(2)(-*) production on the AgO-loaded photocatalysts caused by the synergetic effects on the thermocatalytic activity upon the AgO surface and the efficient electron-hole separation at the photocatalyst/AgO interface. On the other hand, loading effects of AgO on the TAOH formation were not so significant compared to those on the CL observation, though the TAOH formation rates for the TiO(2) samples were much larger than those for the BiVO(4) ones by about three orders of magnitude. The properties of O(2)(-*) and OH radical generations on these photocatalysts are discussed on the basis of the luminol CL kinetics and approximate band edge positions of TiO(2), BiVO(4), and silver oxides.

Topics: Bismuth; Catalysis; Electron Spin Resonance Spectroscopy; Fluorescence; Hydrogen-Ion Concentration; Hydroxyl Radical; Luminescent Measurements; Luminol; Molecular Structure; Oxides; Photochemistry; Phthalic Acids; Reactive Oxygen Species; Semiconductors; Silver Compounds; Time Factors; Titanium; Vanadates

Degradation of implanted ceramics allows for bone in-growth and eventual replacement with natural tissue. Calcium phosphate-based materials have gained the most significant attention because of their excellent biocompatibility and compositional similarities to natural bone. Adding various dopants to these ceramics significantly influences critical properties. In this study, tricalcium phosphate (TCP) compacts were fabricated via uniaxial compression with four compositions: (i) pure TCP, (ii) TCP with 1.0 wt % TiO(2), (iii) TCP with 0.5 wt % Ag(2)O, and (iv) ternary of TCP and 1.0 wt % TiO(2), and 0.5 wt % Ag(2)O. These compacts were sintered at 1250 degrees C for 4 h to obtain dense ceramic structures. Phase analyses were carried out using an X-ray diffractometer. The presence of TiO(2) in TCP improved densification and increased compression strength from 70 (+/-25) to 145 (+/-40) MPa. The ternary composition had the highest density and compression strength of 180 (+/-15) MPa. Human osteoblast cell growth behavior was studied using an osteoprecursor cell line (OPC 1) to assure that the biocompatibility of these ceramics was not altered due to the dopants. For long-term biodegradation studies, density, weight change, surface microstructure, and uniaxial compression strength were measured as a function of time in a simulated body fluid (SBF). Weight gain in SBF correlated strongly with precipitation viewed in the inter-connected pores of the samples. After 3 months in SBF, a 35% drop in compression strength was noticed for pure TCP, but for doped compositions, no strength loss was noticed.

Topics: Absorbable Implants; Biocompatible Materials; Biomechanical Phenomena; Calcium Phosphates; Cell Line; Ceramics; Compressive Strength; Humans; Materials Testing; Microscopy, Electron, Scanning; Osseointegration; Osteoblasts; Oxides; Silver Compounds; Surface Properties; Titanium; X-Ray Diffraction

The combined effect of titanium dioxide and silver oxide on the in situ formation of biphasic calcium phosphate ceramics was investigated. Titania (5-20 mol%) was mixed with pure hydroxyapatite (HA) or HA containing Ag2O (10-20 mol%) and was heated to 900 degrees C for 12 h. The sintered samples were found to contain tricalcium phosphate (beta-TCP) and other phases along with HA depending upon the amount as well as the type of the additives used as evidenced by X-ray powder diffraction (XRD) and fourier transform infrared (FT-IR) spectroscopic studies. Enhanced TCP formation with reduced impurity phases was observed with TiO2-Ag2O addition. In vitro solubility study in phosphate buffer at physiological conditions shows the resorbable nature of these materials. A functionally graded material (FGM) structure was formed by spreading TiO2-Ag2O mixture on the surface of the HA green compact and heating at 900 degrees C. The FGM shows gradient structure of TCP and HA from the surface to the interior of the pellet in addition to titania and silver phases.

Topics: Biocompatible Materials; Calcium Phosphates; Ceramics; Durapatite; Hot Temperature; Oxides; Silver Compounds; Thermodynamics; Titanium; X-Ray Diffraction