Synergistic Antibacterial Performance of a Cu/WO₃-Added PTFE Particulate Superhydrophobic Composite under Visible-Light Exposure

Yanyan Yao, Kentaro Yamauchi, Goro Yamauchi, Tsuyoshi Ochiai, Taketoshi Murakami, Yoshinobu Kubota

Collaborative Research Centre, Daido University, Nagoya, Japan.
Department of Information Design, Daido University, Nagoya, Japan.
Department of Urology and Molecular Science, Graduate School of Medicine, Yokohama City University, Yokohama, Japan.
Kanagawa Academy of Science and Technology, Kawasaki, Japan.

DOI: 10.4236/jbnb.2012.34042                

Abstract

Addition of TiO₂ to a polytetrafluoroethylene (PTFE) particle-dispersed composite contributes to the self-cleaning properties of the water-repellent composite. However, its application is limited to outdoor usage or under ultraviolet (UV) irradiation. In this study, a novel visible-light-sensitive photocatalytic and superhydrophobic material was developed by adding Cu/WO₃ to a PTFE particulate composite material to overcome this deficit. A remarkable property of this novel composite material is the synergistic antibacterial performance against Escherichia coli (E. coli), Staphylo-coccus aureus, and methicillin-resistant Staphylococcus aureus compared with the addition of Cu/WO₃ without PTFE particles material. During 24-h exposure in visible light at 2000 lx, the number of viable cells of the three strains on the surface of the 8wt% Cu/WO₃-added PTFE particulate composite decreased from 2 – 4 × 10⁵ colony-formation units (CFUs) to less than 10, the limit of detection. This bactericidal rate is four times higher than that of 8wt% Cu/WO₃ without PTFE particles material, which is attributed to the air trapped in the rough surface of the novel material providing additional oxygen to the photocatalytic reaction. Even for exposure to visible light at 100 lx, the decrease in CFUs of E. coli on the 12wt% Cu/WO₃-added PTFE particulate composite reached nearly 2.0 logs. The characterization of the Cu/WO₃-added PTFE particulate composite indicated that the composite material containing 80wt% PTFE maintained a superhydrophobic or water-repellent property with a water contact angle >150^。, although the Cu/WO₃ in the composite material remained hydrophilic under visible light. The Cu/WO₃-added PTFE particulate composite displayed photo-catalytic reactions to decompose oleic acid adsorbed on its surface and gaseous acetaldehyde under UV-A and visible-light illumination. All results demonstrate that the Cu/WO₃-added PTFE particulate composite material may be used in sterilization, as a water repellent, for self-cleaning, and in the oxidative decomposition of volatile organic compounds (VOC) both indoors and outdoors.

Keywords

Cu/WO₃ Photocatalyst; PTFE-Hydrophobicity; Particulate-Composite; Synergistic Antibacterial Performance; Escherichia Coli; MRSA

Conflicts of Interest

The authors declare no conflicts of interest.

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