High UV-Vis-NIR Light-Induced Antibacterial Activity by Heterostructured TiO2-FeS2 Nanocomposites.

Antibiotic resistance issues associated with microbial pathogenesis are considered to be one of the most serious current threats to health. Fortunately, TiO2, a photoactive semiconductor, was proven to have antibacterial activity and is being widely utilized. However, its use is limited to the short range of absorption wavelength. In this work, heterostructured TiO2-FeS2 nanocomposites (NCs) were successfully prepared by a facile solution approach to enhance light-induced antibacterial activity over a broader absorption range. In TiO2-FeS2 NCs, FeS2 NPs, as light harvesters, can effectively increase light absorption from the visible (Vis) to near-infrared (NIR). Results of light-induced antibacterial activities indicated that TiO2-FeS2 NCs had better antibacterial activity than that of only TiO2 nanoparticles (NPs) or only FeS2 NPs. Reactive oxygen species (ROS) measurements also showed that TiO2-FeS2 NCs produced the highest relative ROS levels. Unlike TiO2 NPs, TiO2-FeS2 NCs, under light irradiation with a 515-nm filter, could absorb light wavelengths longer than 515 nm to generate ROS. In the mechanistic study, we found that TiO2 NPs in TiO2-FeS2 NCs could absorb ultraviolet (UV) light to generate photoinduced electrons and holes for ROS generation, including ⋅O2 - and ⋅OH; FeS2 NPs efficiently harvested Vis to NIR light to generate photoinduced electrons, which then were transferred to TiO2 NPs to facilitate ROS generation. TiO2-FeS2 NCs with superior light-induced antibacterial activity could be a promising antibacterial agent against bacterial infections.