title: The effect of titanium dioxide (TiO2) nano-objects, and their aggregates and agglomerates greater than 100nm (NOAA) on microbes under UV irradiation.
abstract: Today, nanoparticles are used in many products. One of the most common nanoparticles is titanium dioxide (TiO2). These particles generate reactive oxygen species (ROS) upon UV irradiation. Although nanoparticles are very useful in many products, there are concerns about their biological and ecological effects when released into the environment. Thus, it was assessed that the effect of TiO2 nano-objects, and their aggregates and agglomerates greater than 100nm (NOAA) on microbes under UV irradiation by using Escherichia coli and Saccharomyces cerevisiae. ROS generation was evaluated by adding TiO2 nanoparticles and methylene blue to distilled water. We also assessed growth inhibition by adding TiO2 nanoparticles and microbes in minimal agar medium. Moreover, microbial inactivation was assessed by adding TiO2 nanoparticles and microbes to PBS. Upon UV irradiation, TiO2-NOAAs decomposed methylene blue and generated ROS. TiO2-NOAAs also decomposed methylene blue in minimal agar medium under UV irradiation; however, they did not inhibit microbial growth. Surprisingly, TiO2-NOAAs in the medium protect microbes from UV irradiation as colony formation was observed only near TiO2-NOAAs. In PBS, TiO2-NOAAs did not inactivate microbes but instead protected microbes from lethal UV irradiation. These results suggest that the amount of ROS generated by TiO2-NOAAs is not enough to inactivate microbes. In fact, our results suggest that TiO2-NOAAs may protect microbes from UV irradiations.
authors.affiliation: Division of Food Science and Life Science, Graduate School of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan. Electronic address: ikuho.yamada@gmail.com.
authors.forename: Ikuho
authors.initials: I
authors.lastname: Yamada
authors.affiliation: Division of Food Science and Life Science, Graduate School of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nomura
authors.affiliation: Division of Food Science and Life Science, Graduate School of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Iwahashi
authors.affiliation: Health Research Institute, National Institute of Advanced Industrial Science and Technology, 2217-14 Hayashimachi, Takamatsu, Kagawa 761-14, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Horie
mesh_terms: D000327:Adsorption; D000362:Agar / Q000737:chemistry; D002384:Catalysis; D002518:Ceramides / Q000737:chemistry*; D004203:Disinfection / Q000379:methods*; D004926:Escherichia coli / Q000378:metabolism; D008751:Methylene Blue / Q000737:chemistry; D050296:Microbial Viability; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D017382:Reactive Oxygen Species / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D002518:Ceramides; C056929:N-(omega-acyloxy)acylsphingosine; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D000362:Agar; D014025:Titanium; D008751:Methylene Blue
keywords: Adsorption; Escherichia coli; NOAA; Photocatalytic properties; Saccharomyces cerevisiae; TiO(2) nanoparticle