Photocatalytic Antibacterial Activity of TiO2, TiO2+CuO, and WO3 +CuO -Evaluation of Codoping Effect

Abstract

Antibacterial efficiency of the photocatalysts, TiO₂, TiO₂+CuO and WO₃+CuO, were tested against E. coli, K. pneumoniae, MRSA and P. aeruginosa under UV irradiation to irritate active oxygen from the agents. Analytic criteria were drawing bacterial growth curve, colony counting on cultivated Petri dish, measuring generation time in liquid medium, and survival rate of bacteria by Step One Plus Realtime PCR. Tungsten oxide co-doped with copper (WO₃+CuO) was the most effective in growth inhibitive activity, followed by TiO₂+CuO and TiO₂ alone. Bacteria killing potency (survival rate) of WO₃+CuO was the strongest among the agents tested, and co-doped TiO₂+CuO and TiO₂ alone were less activity than WO₃+CuO. Photocatalysts exposed bacteria took unusual behavior in growth curve at 3 hurs incubation period such as re-growth again after growth inhibition. K. pneumoniae seemed resisting to photocatalysts effect in growth, suggesting emergence of the radical oxygen resistant bacteria. More detailed analysis should be done to clarify this unacceptable phenomenon to avoid appearance of the active oxygen resistant bacteria.