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1.
It has been demonstrated that Ag-TiO2 nanocomposite coatings with excellent antimicrobial activity and biocompatibility have the potential to reduce infection problems. However, the mechanism of the synergistic effect of Ag-TiO2 coatings on antibacterial efficiency is still not well understood. In this study, five types of Ag-TiO2 nanocomposited coatings with different TiO2 contents were prepared on a titanium substratum. Leaching tests indicated that the incorporation of TiO2 nanoparticles into an Ag matrix significantly promoted Ag ion release. Surface energy measurements showed that the addition of TiO2 nanoparticles also significantly increased the electron donor surface energy of the coatings. Bacterial adhesion assays with Escherichia coli and Staphylococcus aureus demonstrated that the number of adhered bacteria decreased with increasing electron donor surface energy. The increased Ag ion release rate and the increased electron donor surface energy contributed to an enhanced antibacterial efficiency of the coatings.  相似文献   

2.
Colloidal silver has been known to have unique antimicrobial activity that may be useful in the construction of antibacterial materials (self-cleaning materials) to aid in the fight against bacteria-related infections. In this study, silver-coated TiO2 (Ag/TiO2) particles prepared through the photo-reduction of Ag+ were investigated as an antibacterial agent against Escherichia coli and Staphylococcus aureus. The deposition of Ag onto the surface was confirmed with SEM and EDS analysis of the post-reaction particles. It was also determined that the initial concentration of Ag+ in solution played a significant role in the effective size of the post-irradiation particles. The antibacterial effectiveness of the Ag/TiO2 was evaluated through the determination of the minimum inhibitory concentration (MIC) of AgTiO2 for each species of bacteria. The MIC values for the Ag/TiO2, on both E. coli and S. aureus, were much lower than the MIC values for Ag metal, and quite comparable to the MIC values for AgNO3. A disc diffusion/antibiotic sensitivity test was also performed using the Ag/TiO2 particles and the results compared with the results obtained for Ag metal, AgNO3 and common antibacterial agents; tetracycline, chloramphenicol, erythromycin, and neomycin. The zone of inhibition diameters for the Ag/TiO2 particles were found to be comparable with those of the other antimicrobial agents.  相似文献   

3.
Current exanimation reports, green fabrication of silver doped TiO2 nanoparticles (Ag/TiO2) using aqueous extract of Acacia nilotica as bio-reductant and assess its potential as antimicrobial and anticancer agent. The obtained spherical Ag/TiO2 were characterized by various analytical techniques including FTIR, (XRD), (FE-SEM EDS), and (TEM). Synthesized Ag/TiO2 demonstrated broad spectrum antibacterial and anticandidal activity. The order of antimicrobial activity was found to be E. coli > C. albicans > MRSA > P. aeruginosa. In addition, cytotoxicity and oxidative stress of Ag/TiO2 nanoparticles in (MCF-7) cells was also investigated. Outcomes of MTT assay showed concentration dependent reduction in cell viability. Further, synthesized NPs reduced the level of glutathione, induced ROS generation and lipid peroxidation in the treated cells. Therefore, it is envisaged that these spherical nanoparticles may be exploited in drug delivery, pharmaceutical, and food industry.  相似文献   

4.
Ag-loaded TiO2 (Ag/TiO2) nanocomposites were prepared by microwave-assisted chemical reduction method using tetrabutyl titanate as the Ti source. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption isotherms, UV–vis absorption spectrum, X-ray photoelectron spectrum, photoluminescence spectrum, and Raman scattering spectrum, respectively. Results revealed that Ag nanoparticles (NPs) were successfully deposited on TiO2 by reduction of Ag+, and the visible light absorption and Raman scattering of TiO2 were enhanced by Ag NPs based on its surface plasmon resonance effect. Besides, Ag NPs could also effectively restrain the recombination of photogenerated electrons and holes with a longer luminescence life time. In addition, photocatalytic reduction of CO2 with H2O on the composites was conducted to obtain methanol. Experimental results indicated that Ag-loaded TiO2 had better photocatalytic activity than pure TiO2 due to the synergistic effect between UV light excitation and surface plasmon resonance enhancement, and 2.5 % Ag/TiO2 exhibited the best activity; the corresponding energy efficiency was about 0.5 % and methanol yield was 405.2 μmol/g-cat, which was 9.4 times higher than that of pure TiO2. Additionally, an excitation enhancement synergistic mechanism was proposed to explain the experimental results of photocatalytic reduction of CO2 under different reaction conditions.  相似文献   

5.
Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these requirements. Axially segmented Ag|ZnO and radially segmented (coaxial) TiO2-Ag nanowires with a diameter of 200 nm and a length of 6-20 µm were made by templated electrodeposition within the pores of polycarbonate track-etched (PCTE) or anodized aluminum oxide (AAO) membranes, respectively. In the photocatalytic experiments, the ZnO and TiO2 phases acted as photoanodes, and Ag as cathode. No external circuit is needed to connect both electrodes, which is a key advantage over conventional photo-electrochemical cells. For making segmented Ag|ZnO nanowires, the Ag salt electrolyte was replaced after formation of the Ag segment to form a ZnO segment attached to the Ag segment. For making coaxial TiO2-Ag nanowires, a TiO2 gel was first formed by the electrochemically induced sol-gel method. Drying and thermal annealing of the as-formed TiO2 gel resulted in the formation of crystalline TiO2 nanotubes. A subsequent Ag electrodeposition step inside the TiO2 nanotubes resulted in formation of coaxial TiO2-Ag nanowires. Due to the combination of an n-type semiconductor (ZnO or TiO2) and a metal (Ag) within the same nanowire, a Schottky barrier was created at the interface between the phases. To demonstrate the photocatalytic activity of these nanowires, the Ag|ZnO nanowires were used in a photocatalytic experiment in which H2 gas was detected upon UV illumination of the nanowires dispersed in a methanol/water mixture. After 17 min of illumination, approximately 0.2 vol% H2 gas was detected from a suspension of ~0.1 g of Ag|ZnO nanowires in a 50 ml 80 vol% aqueous methanol solution.  相似文献   

6.
TiO2 nanotube arrays (TiO2 NTs) were fabricated by anodic oxidation and then Ag nanoparticles (Ag NPs) were assembled in TiO2 NTs (Ag/TiO2 NTs) by microwave-assisted chemical reduction. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence spectrum (PL), UV–vis absorption spectrum (UV–vis), and Raman spectrum, respectively. The results showed that Ag NPs were well dispersed on the surface of TiO2 NTs with metallic state. The surface plasmon resonance (SPR) effect of Ag NPs could extend the visible light response and enhance the absorption capacity of TiO2. Furthermore, Ag NPs could also restrain the recombination of photo-generated electron–hole pairs of TiO2 NTs efficiently. The methylene blue photodegradation experiment proved that the SPR phenomenon had an effect on photoreaction enhancement. The results of photocatalytic water splitting indicated that Ag/TiO2 NTs samples had better photocatalytic performance than pure TiO2 NTs. The corresponding hydrogen evolution rate of Ag/TiO2 NTs prepared with 0.002 M AgNO3 solution was 3.3 times as that of pure TiO2 NTs in the test condition. Additionally, the mechanism of catalyst activity enhanced by SPR effect was proposed.  相似文献   

7.
This study is focused on the fabrication and characterization of titanium oxide (TiO2) NPs. Afterwards; the interaction of TiO2 NPs with human hemoglobin (Hb) was investigated by FTIR spectroscopy, fluorescence spectroscopy, and molecular docking studies. Also, the cytotoxic effect of fabricated TiO2 NPs against human white blood cells (WBCs) was considered by MTT assay. The antibacterial effect of synthesized NPs was examined on Pseudomonas aeruginosa (ATCC 27853); Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). TEM and DLS investigations showed that the synthesized TiO2 NPs have a narrow nano-sized distribution. XRD pattern of the fabricated NPs exhibited that the TiO2 NPs contain anatase phase. Similarity in amide I and II signal intensities showed that secondary structure of the adsorbed Hb is preserved. The intrinsic fluorescence study revealed that the fluorescence quenching of Hb was done by complex formation between Hb and TiO2 NPs trough the hydrogen bond and van der Waals interactions. Synchronous fluorescence spectroscopy determined that interaction of TiO2 NPs with Hb did not unfold the Hb structure in the vicinity of the Tyr and Trp residues. Molecular docking study depicted that Glu-95, Thr-134 and Tyr-140 are involved in the formation of hydrophilic bonds. MTT data and antibacterial assays indicated that TiO2 NPs endow distinguished antibacterial activities against Gram-negative and Gram positive strains at safe concentrations. This study may reveal that fabricated TiO2 NP can be used as a safe and potent antibacterial agent.

Communicated by Ramaswamy H. Sarma  相似文献   


8.
9.
Photocatalysis induced by TiO2 and UV light constitutes a decontamination and antibacterial strategy utilized in many applications including self-cleaning environmental surfaces, water and air treatment. The present work reveals that antibacterial effects induced by photocatalysis can be maintained even after the cessation of UV irradiation. We show that resin-based composites containing 20% TiO2 nanoparticles continue to provide a pronounced antibacterial effect against the pathogens Escherichia coli, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus mutans and Enterococcus faecalis for up to two hours post UV. For biomaterials or implant coatings, where direct UV illumination is not feasible, a prolonged antibacterial effect after the cessation of the illumination would offer new unexplored treatment possibilities.  相似文献   

10.
The antibacterial activity of photocatalytic titanium dioxide (TiO2) substrates is induced primarily by UV light irradiation. Recently, nitrogen- and carbon-doped TiO2 substrates were shown to exhibit photocatalytic activities under visible-light illumination. Their antibacterial activity, however, remains to be quantified. In this study, we demonstrated that nitrogen-doped TiO2 substrates have superior visible-light-induced bactericidal activity against Escherichia coli compared to pure TiO2 and carbon-doped TiO2 substrates. We also found that protein- and light-absorbing contaminants partially reduce the bactericidal activity of nitrogen-doped TiO2 substrates due to their light-shielding effects. In the pathogen-killing experiment, a significantly higher proportion of all tested pathogens, including Shigella flexneri, Listeria monocytogenes, Vibrio parahaemolyticus, Staphylococcus aureus, Streptococcus pyogenes, and Acinetobacter baumannii, were killed by visible-light-illuminated nitrogen-doped TiO2 substrates than by pure TiO2 substrates. These findings suggest that nitrogen-doped TiO2 has potential application in the development of alternative disinfectants for environmental and medical usages.  相似文献   

11.
Biofouling produces concentrated microbial populations with highly resistive biofilms and is considered to be a serious obstacle for a wide range of membrane technology applications. An antibacterial super-hydrophilic barrier could help to reduce biofouling by preventing direct contact between membranes and bacteria. In this study, an antibacterial super-hydrophilic barrier consisting of a layer of TiO2 nanoparticles (NPs) was developed on polyvinylidene fluoride (PVDF)-based membrane via a facile technique. The results demonstrated that the presence of TiO2 NPs eliminated the first step of biofouling, ie bacterial adhesion to the membrane. In addition, after bacterial deposition onto the membrane during ultrafiltration (UF), the TiO2 NPs significantly retarded bacterial growth and reproduction (the second step of biofouling). During UF, the membrane flux decreased due to bacterial deposition, but 85% of the flux was recovered through physical cleaning using water. This study sheds light on the potential advantages of antibacterial super-hydrophilic membranes for biofouling mitigation.  相似文献   

12.
BackgroundThe poor biological performance of zirconium implants in the human body resulting from their bio-inertness and vulnerability to corrosion and bacterial activity reflects the need for further studies on substitution or performing the surface modification. The suggestion of employing zirconia (ZrO2) bioceramic coatings for surface modification seems beneficial.ObjectivesThis systematic review aims to identify and summarize existing documents reporting the biological responses for ZrO2 coatings produced by the PEO process on zirconium implants.MethodsPubMed, Scopus, and Web of Science international databases were searched for the original and English-language studies published between 2000 and 2021. All publications reported at least one study about in-vitro (cellular and immersion studies), in-vivo (animal studies), and antibacterial topics for ZrO2-PEO coated zirconium implants.ResultsThroughout the initial search, 496 publications were found, and 296 papers remained following the elimination of duplicates. Finally, after multiple screening and eligibility assessments, 25 publications were qualified and included in the review. Among them, 25 in-vitro (cellular and immersion in SBF and Hanks’ solutions studies), one in-vivo (animal studies), and eight antibacterial studies were found.ConclusionThe ZrO2 coated samples demonstrate no cytotoxicity, high cell viability rate, and excellent biocompatibility. However, changing the solution composition and electrical parameters during the PEO procedures result in significant changes to in-vitro responses. As an instance, the ZrO2 coating surface demonstrates greater biocompatibility after irradiated by UV, which makes the surface more suitable for cell growth. Due to weak apatite-forming ability, the zirconium sample shows low bioactivity in SBF. However, most cases (13 out of 16) show that the specific morphology and chemical composition of the ZrO2 coating promote apatite-forming ability with good bioactivity in SBF. Nevertheless, few papers (three out of 16) showed that the ZrO2 coatings immersed in SBF had no apatite precipitates and so no bioactivity. These cases limit the bioactivity enhancement to treatment by UV-light irradiation, hydrothermal and chemical treatment, thermal evaporation, and cathodic polarization post-treatment on ZrO2 coatings. Both zirconium and ZrO2 coated samples do not show apatite-forming ability in Hanks’ solution. The ZrO2 coated implant with the bone together indicates a greater shear strength and rapid new bone formation ability during 12 weeks because of containing Ca-P compounds and porous structure. The UV post-treated ZrO2 coating induces faster new bone formation and firmer connection of bond with bone than those of untreated ZrO2 coatings. A stronger antibacterial activity of ZrO2 coatings is confirmed in half of the selected papers (four out of eight studies) compared to the bare zirconium samples. The antibacterial protection of ZrO2 coatings can be influenced by the PEO procedure variables, i.e., solution composition, electrical parameters, and treatment time. In three cases, the antibacterial activity of ZrO2 coatings is enhanced by deposition of Zn, Ag, or Cu antibacterial layers through thermal evaporation post-treatment.  相似文献   

13.

Background

Titania dioxide (TiO2) photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved.

Methodology/Principal Findings

Using thermal reduction method, here we synthesized silver-nanostructures coated TiO2 thin films that contain a high visible-light responsive antibacterial property. Among our tested titania substrates including TiO2, carbon-doped TiO2 [TiO2 (C)] and nitrogen-doped TiO2 [TiO2 (N)], TiO2 (N) showed the best performance after silver coating. The synergistic antibacterial effect results approximately 5 log reductions of surviving bacteria of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus and Acinetobacter baumannii. Scanning electron microscope analysis indicated that crystalline silver formed unique wire-like nanostructures on TiO2 (N) substrates, while formed relatively straight and thicker rod-shaped precipitates on the other two titania materials.

Conclusion/Significance

Our results suggested that proper forms of silver on various titania materials could further influence the bactericidal property.  相似文献   

14.
The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag–TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.  相似文献   

15.

Background

Traditional antibacterial photocatalysts are primarily induced by ultraviolet light to elicit antibacterial reactive oxygen species. New generation visible-light responsive photocatalysts were discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. Recently, we found that visible-light responsive platinum-containing titania (TiO2–Pt) exerted high performance antibacterial property against soil-borne pathogens even in soil highly contaminated water. However, its physical and photocatalytic properties, and the application in vivo have not been well-characterized.

Methods

Transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, ultraviolet–visible absorption spectrum and the removal rate of nitrogen oxides were therefore analyzed. The antibacterial performance under in vitro and in vivo conditions was evaluated.

Results

The apparent quantum efficiency for visible light illuminated TiO2–Pt is relatively higher than several other titania photocatalysts. The killing effect achieved approximately 2 log reductions of pathogenic bacteria in vitro. Illumination of injected TiO2–Pt successfully ameliorated the subcutaneous infection in mice.

Conclusions

This is the first demonstration of in vivo antibacterial use of TiO2–Pt nanoparticles. When compared to nanoparticles of some other visible-light responsive photocatalysts, TiO2–Pt nanoparticles induced less adverse effects such as exacerbated platelet clearance and hepatic cytotoxicity in vivo.

General significance

These findings suggest that the TiO2–Pt may have potential application on the development of an antibacterial material in both in vitro and in vivo settings.  相似文献   

16.
We studied antibacterial and photocatalytic activity of anatase TiO2 and ZnO in phosphate buffer and saline solution. We found that the different anions in the suspension medium (chloride and phosphate) significantly affected the following suspension properties: the stability of nanoparticle suspension, the release of metal ions from the nanoparticles, and the production of the reactive oxygen species by the nanoparticles. As a result, antibacterial activity and photocatalytic dye degradation were also affected. However, the effect of the suspension medium was different for ZnO and TiO2. Obtained results are discussed.  相似文献   

17.
A new type of nitrogen and chloride co-doped carbon dots (N/Cl-CDs) based on choline chloride–urea–glycine ternary deep eutectic solvents (DESs) was synthesized using a one-step hydrothermal method. The prepared N/Cl-CDs exhibited oxidase-like activity and excellent antibacterial activity against Escherichia coli, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). The addition of silver nanoparticles (Ag NPs) (i.e. N/Cl-CDs + Ag NPs) to the N/Cl-CDs also significantly enhanced the oxidase and antibacterial activities. The nanocomposite (1·8 mg ml−1) completely inactivated 105 CFU per ml of MRSA in 90 min. E. coli and S. aureus were labelled with the N/Cl-CDs, enabling multicolour fluorescence imaging at different excitation wavelengths. The nanocomposites have high antibacterial efficiency as a new bactericidal agent, as well as application potential with good biocompatibility and low toxicity.  相似文献   

18.
New types of organic-inorganic hybrid nanocomposites based on nanosized titanium oxide(IV) (TiO2, particle size <100 nm) and carbon nanotubes (CNT, outer diameter of 10–15 nm, inner diameter of 2–6 nm, and length of 0.1–10 μm) and phosphatidylcholine were elaborated for improvement of analytical characteristics of screen printed electrodes. These nanomaterials were employed as an interface for immobilization of skeletal myoglobin. Electroanalytical and electrokinetic behavior of myoglobin on such interfaces was characterized with cyclic voltammetry (CV) and square wave voltammetry (SWV). Direct unmediated electron transfer between heme of immobilized myoglobin and electrodes modified with titanium oxide or carbon nanotubes was registered. The midpoint (redox) potential of the myoglobin Fe3+/Fe2+ E 1/2 = ?0.263 V for electrodes modified with CNT and E 1/2 = ?0.468 V for electrodes modified with TiO2 was observed (vs. Ag/AgCl reference electrode).  相似文献   

19.
Despite great efforts in tissue engineering of the ureter, urinary bladder, and urethra, further research is needed in order to improve the patient’s quality of life and minimize the economic burden of different lower urinary tract disorders. The nanostructured titanium dioxide (TiO2) scaffolds have a wide range of clinical applications and are already widely used in orthopedic or dental medicine. The current study was conducted to synthesize TiO2 nanotubes by the anodization method and TiO2 nanowires and nanospheres by the chemical vapor deposition method. These scaffolds were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. In order to test the urologic applicability of generated TiO2 scaffolds, we seeded the normal porcine urothelial (NPU) cells on TiO2 nanotubes, TiO2 nanowires, TiO2 nanospheres, and on the standard porous membrane. The viability and growth of the cells were monitored everyday, and after 3 weeks of culturing, the analysis with scanning electron microscope (SEM) was performed. Our results showed that the NPU cells were attached on all scaffolds; they were viable and formed a multilayered epithelium, i.e., urothelium. The apical plasma membrane of the majority of superficial NPU cells, grown on all three different TiO2 scaffolds and on the porous membrane, exhibited microvilli; thus, indicating that they were at a similar differentiation stage. The maximal caliper diameter measurements of superficial NPU cells revealed significant alterations, with the largest cells being observed on nanowires and the smallest ones on the porous membrane. Our findings indicate that different nanostructured TiO2 scaffolds, especially nanowires, have a great potential for tissue engineering and should be further investigated for various urologic applications.  相似文献   

20.

In this report, Ag nanoparticles were fabricated using the single-step glancing angle deposition (SS-GLAD) technique upon In2O3/TiO2 thin film. Afterward, a detailed analysis was done for the two samples such as In2O3/TiO2 thin film and In2O3/TiO2 thin film/Ag nanoparticles, to inspect the field emission scanning electron microscopy (FESEM), energy-dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), ultraviolet (UV) spectroscopy, and electrical properties. The reduction in bandgap energy for the samples of In2O3/TiO2 thin film/Ag nanoparticles (~4.16 eV) in comparison with the In2O3/TiO2 thin film (~4.28 eV) was due to trapped e–h recombination at the oxygen vacancies and electron transmission of Ag to the conduction band of the In2O3/TiO2 thin films. Moreover, under irradiation of photons Ag nanoparticles generated inorganic Ag–O compound attributable to the localized surface plasmon resonance (LSPR). Also, a?~90% high transmittance,?~60% and?~25% low reflectance in UV and visible region, fill factor (FF) of 53%, as well as power conversion efficiency (PCE) of 15.12% was observed for In2O3/TiO2 thin film/Ag nanoparticles than the In2O3/TiO2 thin film. Therefore, the use of Ag nanoparticles textured In2O3/TiO2 thin film–based device is a promising approach for the forthcoming photovoltaic applications.

  相似文献   

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