Enzyme-like antibacterial activities of Cu9S5 nanoflowers with vacancy-type dependence

Summary: Due to the increasing drug resistance of bacteria and the limitations of antibacterial nanomaterials through photodynamical and photothermal routes, it is necessary to develop novel nanomaterials with outstanding enzyme-like activities and bacteria-binding capability to produce reactive oxygen species (ROS) to kill bacteria. Herein, we report the synthesis of two kinds of Cu9S5 nanoflowers composed of assemblies of nanosheets, abbreviated as Cu9S5-1 and Cu9S5-2, which possess predominantly VCuSCu and VCuSS vacancies, respectively, as confirmed by the positron annihilation spectra. Both experimental and theoretical calculation results reveal that Cu9S5-2 exhibits excellent enzyme-like activities because of stronger bacteria-binding ability and higher electron affinity that endow it with a superior antibacterial activity compared to Cu9S5-1. This study provides a deeper understanding of nanomaterials with vacancy-type-dependent enzyme-like activities and insights for the rational design of high-performance antibacterial agents in the future.