Antimicrobial Activity in Thin Films of Pseudobrookite-Structured Titanium Oxynitride under UV Irradiation Observed for Escherichia coli (original) (raw)
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Coatings, 2014
In damp environments, indoor building materials are among the main proliferation substrates for microorganisms. Photocatalytic coatings, including nanoparticles of TiO 2 , could be a way to prevent microbial proliferation or, at least, to significantly reduce the amount of microorganisms that grow on indoor building materials. Previous works involving TiO 2 have already shown the inactivation of bacteria by the photocatalysis process. This paper studies the inactivation of Escherichia coli bacteria by photocatalysis involving TiO 2 nanoparticles alone or in transparent coatings (varnishes) and investigates different parameters that significantly influence the antibacterial activity. The antibacterial activity of TiO 2 was evaluated through two types of experiments under UV irradiation: (I) in slurry with physiological water (stirred suspension); and (II) in a drop deposited on a glass plate. The results confirmed the difference in antibacterial activity between simple drop-deposited inoculum and inoculum spread under a plastic film, which increased the probability of contact between TiO 2 and bacteria (forced contact). In addition, the major effect of the nature of the suspension on the photocatalytic disinfection ability was highlighted. Experiments were also carried out at the surface of transparent coatings formulated using nanoparticles of TiO 2 . The results showed significant antibacterial activities after 2 h and 4 h and suggested that improving the formulation would increase efficiency.
Bactericidal effects of titanium dioxide-based photocatalysts
Chemical Engineering Journal, 2005
The photocatalytic degradation of E. coli in water by various catalysts was investigated in a batch spiral reactor. Commercial Degussa P25 (P25), as well as novel magnetic and hydrothermally prepared photocatalysts (MPC and HPC) were investigated in a slurry system. P25 was found to be the most effective catalyst, followed by the HPC and the MPC. Cell destructions followed first order kinetics. Non-buffered samples displayed a greater bactericidal efficiency which was attributed to a decrease in electrostatic repulsions between TiO 2 and E. coli and also elevated stress on E. coli at acidic pH. Buffered (NaHCO 3 ) samples showed a decrease in bactericidal efficiency due to HCO 3 − ions competing with oxidising species and blocking (by adsorption) the TiO 2 particles. The optimum catalyst loading for P25 and HPC was 1 and 2 g/L for MPC and was attributed to mass transfer effects (bulk diffusion, available active site and shadowing). An immobilised P25 system was found to be more efficient than the MPC and comparable with the HPC in suspension. The addition of silver to the immobilised system was found to enhance the photocatalytic degradation.
Songklanakarin Journal of Science and Technology
Titanium dioxide photocatalysts were synthesized by sol-gel process, by varying the reaction conditions, acids, water content, and trivalent (Al, B) dopants. The characterizations of products were determined by XRD, SEM, BET, and UV-vis spectroscopy. The samples were mainly amorphous with a small amount of anatase, rutile, or a mixture of anatase and rutile, with a crystallite sizes of about 5-10 nm. The antibacterial activity of the synthesized TiO2 samples were investigated qualitatively and semi-quantitatively. Five types of bacteria, Escherichia coli ATCC25922, Psudomonas aeruginosa ATCC27853,Bacillus subtilis BGA, Staphylococcus aureus ATCC25923, and methicillin-resistant S. aureus (MRSA) DMST 2054, were used for the inactivation experiment employing the agar dilution method. All the synthesized samples showed inactivation activity with varying degree of efficiency. Two of them showed a much higher activity than Degussa P25.
Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, 2015
Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and covered with a thin film of nanocrystalline titanium dioxide by dip coating. The films were then photosensitized by titanium(iv) surface charge transfer complexes formed by impregnation with catechol. The photoactivity of the coatings up to 460 nm was confirmed by photoelectrochemical measurements. The photoinactivation of Escherichia coli and Staphylococcus aureus was evaluated by a glass adhesion test based on ISO 27447:2009(E) in the presence of visible light. The coating showed good antimicrobial activity induced by light from a light-emitting diode (405 nm), in particular towards E. coli ATCC 25922 strain. Adaptation of ISO 27447:2009(E) to assess bacterial photoinactivation by photocatalytic coatings will allow this procedure to be applied for the comparison of photoactivity under a range of irradiation conditions.
Photobactericidal effects of TiO2 thin films at low temperatures—A preliminary study
Journal of Photochemistry and Photobiology A: Chemistry, 2010
The efficacy of TiO 2 photocatalysis for the destruction of pathogenic bacteria has been demonstrated by a number of groups over the past two decades. Pathogenic bacteria represent a significant hazard for the food and drink industry. Current practices in this industry dictate that rigorous sanitizing regimes must be regularly implemented resulting in lost production time. The incorporation of a TiO 2 antibacterial surface coating in this setting would be highly desirable. In this paper we report a preliminary study of the efficacy of a TiO 2 coating, doped with the lanthanide, neodymium, at low temperature conditions such as those utilised in the food and drink sector. The rapid destruction of Staphylococcus aureus, a common foodborne pathogen, was observed using TiO 2 films coated to glass and steel substrates.
Photochemistry and Photobiology, 2018
Structural, microstructural and bactericidal surface properties of TiO2‐coated glass substrates elaborated by reactive Radiofrequency sputtering are investigated. As pathogenic bacteria in biofilms are a major concern in food industries due to their growing resistance to cleaning and sanitizing procedures, the development of photoactive surfaces exhibiting bactericidal properties is acknowledged as an effective approach to tackle bacterial contaminations. Our principal aim concerns the study of the photoactive top‐layer thickness impact (from 80 nm to ~500 nm) on Listeria monocytogenes. Structural characterization of the TiO2 layers demonstrates that anatase and rutile phases are both present, depending on the film thickness. Photocatalytic activity of the samples has been evaluated through the degradation of aqueous methylene blue (MB) solutions under UVA light illumination for various time periods. The results show an efficiency rating increase according to TiO2 film thickness up ...
Applied and Environmental Microbiology, 2006
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Journal of Biomedical Science, 2009
Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2.
Beilstein Journal of Nanotechnology, 2013
Pure anatase, nanosized and Sn 4+ ion doped titanium dioxide (TiO 2 ) particulates (TiO 2 -Sn 4+ ) were synthesized by hydrothermal process. TiO 2 -Sn 4+ was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn 4+ doping to TiO 2 against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO 2 -Sn 4+ in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO 2 -Sn 4+ is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO 2 -Sn 4+ from 10 to 50% in the coating solution increased antibacterial effect.