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Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2
Department of Microbiology and Immunology, School of Medicine, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
Kanagawa Academy of Science and Technology, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012, Japan
Department of Urology, Graduate School of Medicine, Yokohama City University, 3-9, Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-0004, Japan
Division of Photocatalyst for Energy and Environment, Research Institute for Science and Technology, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
Department of Applied Chemistry, Faculty of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyyoo-ku, Tok 113-8656, Japan
These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 3 December 2012; in revised form: 25 January 2013 / Accepted: 6 March 2013 / Published: 21 March 2013
Abstract: Photocatalytically active titanium dioxide (TiO2) is widely used as a self-cleaning and self-disinfecting material in many applications to keep environments biologically clean. Several studies on the inactivation of bacteria and viruses by photocatalytic reactions have also been reported; however, only few studies evaluated the spectrum of the microbicidal activity with photocatalysis for various species. There is a need to confirm the expected effectiveness of disinfection by photocatalysis against multidrug-resistant bacteria and viruses. In this study, microbicidal activity of photocatalysis was evaluated by comparing the inactivation of various species of bacteria and viruses when their suspensions were dropped on the surface of TiO2-coated glass. Gram-positive bacteria, e.g., methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae, were easily inactivated by photocatalysis, whereas some gram-negative bacteria, e.g., Escherichia coli and multidrug-resistant Pseudomonas aeruginosa, were gradually inactivated by photocatalysis. Influenza virus, an enveloped virus, was significantly inactivated by photocatalysis compared with feline calicivirus, a non-enveloped virus. The effectiveness of microbicidal activity by photocatalysis may depend on the surface structure. However, they are effectively inactivated by photocatalysis on the surface of TiO2-coated glass. Our data emphasize that effective cleaning and disinfection by photocatalysis in nosocomial settings prevents pathogen transmission.
Keywords: photocatalysis; disinfection; drug resistant bacterium; virus; UV-A; TiO2
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Nakano, R.; Hara, M.; Ishiguro, H.; Yao, Y.; Ochiai, T.; Nakata, K.; Murakami, T.; Kajioka, J.; Sunada, K.; Hashimoto, K.; Fujishima, A.; Kubota, Y. Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2. Catalysts 2013, 3, 310-323.
Nakano R, Hara M, Ishiguro H, Yao Y, Ochiai T, Nakata K, Murakami T, Kajioka J, Sunada K, Hashimoto K, Fujishima A, Kubota Y. Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2. Catalysts. 2013; 3(1):310-323.
Nakano, Ryuichi; Hara, Masayuki; Ishiguro, Hitoshi; Yao, Yanyan; Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Kajioka, Jitsuo; Sunada, Kayano; Hashimoto, Kazuhito; Fujishima, Akira; Kubota, Yoshinobu. 2013. "Broad Spectrum Microbicidal Activity of Photocatalysis by TiO2." Catalysts 3, no. 1: 310-323.