TiO2 nanotubes/Ti plates modified by silver–benzene with enhanced photocatalytic antibacterial properties

Abstract

A novel Ag/Benzene-Mod/TiO₂ nanotubes/Ti plate was fabricated via photo-modification by benzene, followed by electrodeposition of Ag on the TiO₂ nanotubes/Ti plate. The antibacterial property and related mechanism of the prepared plates for the Escherichia coli (E. coli) as model bacteria were investigated in dark, UV and visible light irradiation conditions. Bactericidal tests showed that the antibacterial efficiency was the highest for Ag/Benzene-Mod/TiO₂ nanotubes/Ti plates under both UV and visible light irradiation. However, this modified plate did not exhibit any antibacterial properties in the dark. The enhanced antibacterial activity of the modified plates indicated that not only the plasmonic properties but also effective charge separation were responsible for overall bacteria-death. Scanning electron microscopy (SEM) observation provided evidence of the cellular internalization as well as the loss of integrity of cell walls in the presence of the most active plates. Collectively, the antibacterial mechanism of Ag/Benzene-Mod/TiO₂ nanotubes/Ti plate could be related to the photoabsorption properties (broader LSPR) of Ag under visible light irradiation, and subsequent formation of free radicals, which destroy the integrity of cell walls, resulting in the death of bacteria.