Hindawi Publishing Corporation Journal of Nanotechnology Volume 2011, Article ID 380979, 7 pages doi:10.1155/2011/380979 Research Article Antibacterial Activity of Hydrophobic Composite Materials Containing a Visible-Light-Sensitive Photocatalyst Kentaro Yamauchi, 1 Yanyan Yao, 2, 3 Tsuyoshi Ochiai, 2, 4 Munetoshi Sakai, 2 Yoshinobu Kubota, 3 and Goro Yamauchi 5 1 Collaborative Research Center, Daido University, 10-3 Takiharu-cho, Minami-ku, Nagoya 457-8530, Japan 2 Kanagawa Academy of Science and Technology, 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012, Japan 3 Department of Urology and Molecular Science, Graduate School of Medicine, Yokohama City University 3-9 Fukuura, Kanazawa-ku, Yokohama 236-004, Japan 4 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 5 Department of Information Design, Daido University, 10-3 Takiharu-cho, Minami-ku, Nagoya 457-8530, Japan Correspondence should be addressed to Goro Yamauchi, gyamauch@daido-it.ac.jp Received 15 March 2011; Revised 25 August 2011; Accepted 7 September 2011 Academic Editor: J. Anthony Byrne Copyright © 2011 Kentaro Yamauchi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The conventional superhydrophobic surface offered by PTFE provides no sterilization performance and is not sufficiently repellent against organic liquids. These limit PTFE’s application in the field of disinfection and result a lack of durability. N-doped TiO 2 photocatalyst added PTFE composite material was developed to remedy these shortcomings. This paper reports the surface characteristics, and the bactericidal and self-cleaning performance of the newly-developed composite material. The material exhibited a contact angle exceeding 150 degrees consistent with its hydrophobicity despite the inclusion of the hydrophilic N- doped TiO 2 . The surface free energy obtained for this composite was 5.8mN/m. Even when exposed to a weak fluorescent light intensity (100 lx) for 24 hours, the viable cells of gram-negative E. coli on the 12% N-doped TiO 2 -PTFE film were reduced 5 logs. The higher bactericidal activity was also confirmed on the gram-positive MRSA. Compared with the N-doped TiO 2 coating only, the inactivation rate of the composite material was significantly enhanced. Utilizing the N-doped TiO 2 with the PTFE composite coating could successfully remove, by UV illumination, oleic acid adsorbed on its surface. These results demonstrate the potential applicability of the novel N-doped TiO 2 photocatalyst hydrophobic composite material for both indoor antibacterial action and outdoor contamination prevention. 1. Introduction It is well known that the conventional superhydrophobic surface offered by polytetrafluoroethylene (PTFE) provides no sterilization performance and is not sufficiently repellent against organic matters. Thus, there is potential risk for bacteria to adhere to its surface more readily in ambient air, as well as organic matters is considered to reduce the durability of the superhydrophobic performance. To remedy this shortcoming, anatase titanium dioxide (TiO 2 ), a UV light-sensitive photocatalyst added water repellent composite material has been developed in our previous study [1–5]. TiO 2 was used to demonstrate the inactiva- tion of various bacteria, such as Escherichia coli (E. coli), methicillin-resistant Staphylococcus aureus (MRSA), Pseu- domonas aeruginosa (P. aeruginosa), Legionella pneumophila (L. pneumophila)[6–8], and Clostridium difficile spores [8]. The inclusion of TiO 2 to the PTFE coating is expected to generate antimicrobial and self-cleaning properties, which would expand its scope of application. Anatase TiO 2 -added PTFE composite material is not only water-repellent but also exhibits self-cleaning properties. However, because anatase