<p>High UV-Vis-NIR Light-Induced Antibacterial Activity by Heterostructured TiO<sub>2</sub>-FeS<sub>2</sub> Nanocomposites</p>

Abstract

Purpose: Antibiotic resistance issues associated with microbial pathogenesis are considered to be one of the most serious current threats to health. Fortunately, TiO 2 , 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. Methods: In this work, heterostructured TiO 2 -FeS 2 nanocomposites (NCs) were successfully prepared by a facile solution approach to enhance light-induced antibacterial activity over a broader absorption range. Results: In TiO 2 -FeS 2 NCs, FeS 2 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 TiO 2 -FeS 2 NCs had better antibacterial activity than that of only TiO 2 nanoparticles (NPs) or only FeS 2 NPs. Reactive oxygen species (ROS) measurements also showed that TiO 2 -FeS 2 NCs produced the highest relative ROS levels. Unlike TiO 2 NPs, TiO 2 -FeS 2 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 TiO 2 NPs in TiO 2 -FeS 2 NCs could absorb ultraviolet (UV) light to generate photoinduced electrons and holes for ROS generation, including ⋅O 2 − and ⋅OH; FeS 2 NPs efficiently harvested Vis to NIR light to generate photoinduced electrons, which then were transferred to TiO 2 NPs to facilitate ROS generation. Conclusion: TiO 2 -FeS 2 NCs with superior light-induced antibacterial activity could be a promising antibacterial agent against bacterial infections. Keywords: antibacterial agent, antibacterial mechanism, reactive oxygen species, light harvester, light-induced antibacterial activity

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