Synergistic Ag/TiO2-N photocatalytic system and its enhanced antibacterial activity towards Acinetobacter baumannii

The hybrid Ag/TiO2-N photocatalyst was prepared via a supercritical solvothermal process in ethanol fluid. The simultaneous achievement of reduction of Ag+ ions and N-doping in silver-ammonia complex solution led to the uniform distribution of Ag nanoparticles stably combined with the surface of TiO2-N substrate. As a result, the visible-light photocatalytic inactivation of Acinetobacter batunannff was facilitated via the enhanced visible light harvesting and the high separation efficiency of photo-induced charge carriers. By means of the main active species of center dot O-2(-) radical, the synergistic effect of Ag nanoparticles and TiO2-N could induce the structure change of bacteria with the leakage of K+ ions as well as the mineralization of cell membrane with the elimination of self-repair function, leading to the final cell death. In comparison, the bactericidal activity of Ag nanoparticles and TiO2-N under UV light irradiation was due to the intrinsic efficiency and the high light harvesting, respectively. The photothermal effect of Ag nanoparticles in the near-IR light region could be possibly remained by TiO2-N substrate to achieve the antibacterial activity. Furthermore, Ag/TiO2-N photocatalyst played great bactericidal effect for kinds of bacteria, implying the applicable future to the medical disinfection.