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.