The effect of electron transfer channel on UV-independent antibacterial activity of Ag+ implanted TiO2

The antibacterial effect induced by photocatalysis of UV-irradiated TiO2 has been widely studied. The present work reveals that Ag+ implanted TiO2 film shows significantly enhanced antibacterial activity without the application of UV light. Density functional calculations show that the existence of the implanted Ag+ tends to change the electric field leading to a gradient band alignment of TiO2 near the interface, favoring the charge transfer from the TiO2 side to the membrane of the bacteria. Our density functional calculations clearly demonstrate the strong evidence of charge transfer channeling from the conduction band of Ag+ implanted TiO2 to the bacteria membrane which produces large amount of reactive oxygen species (ROS, including O2•–, H2O2 and •OH). The ROS lead to bacteria death by inducing physiological changes such as membrane break, leakage of intracellular components, protein denaturation and DNA lesions. This work unravels the antibacterial mechanism of Ag+ implanted TiO2, and contributes furtherly to the rational design and modification of biomaterials by Ag+ implantation.