Visible-Light-Induced Bactericidal Activity of a Nitrogen-Doped Titanium Photocatalyst against Human Pathogens

Abstract

ABSTRACT The antibacterial activity of photocatalytic titanium dioxide (TiO 2 ) substrates is induced primarily by UV light irradiation. Recently, nitrogen- and carbon-doped TiO 2 substrates were shown to exhibit photocatalytic activities under visible-light illumination. Their antibacterial activity, however, remains to be quantified. In this study, we demonstrated that nitrogen-doped TiO 2 substrates have superior visible-light-induced bactericidal activity against Escherichia coli compared to pure TiO 2 and carbon-doped TiO 2 substrates. We also found that protein- and light-absorbing contaminants partially reduce the bactericidal activity of nitrogen-doped TiO 2 substrates due to their light-shielding effects. In the pathogen-killing experiment, a significantly higher proportion of all tested pathogens, including Shigella flexneri , Listeria monocytogenes , Vibrio parahaemolyticus , Staphylococcus aureus , Streptococcus pyogenes , and Acinetobacter baumannii , were killed by visible-light-illuminated nitrogen-doped TiO 2 substrates than by pure TiO 2 substrates. These findings suggest that nitrogen-doped TiO 2 has potential application in the development of alternative disinfectants for environmental and medical usages.