Phase-Dependent MoS₂Nanoflowers for Light-Driven Antibacterial Application

The metallic phase of 1T-MoS2 nanoflowers (NFs) and the semiconducting phase of 2H-MoS2 NFs were prepared by a facile solvothermal and combustion method. The antibacterial activities, reactive oxygen species (ROS) generation, and light-driven antibacterial mechanism of metallic 1T-MoS2 NFs and semiconducting 2H-MoS2 NFs were demonstrated with the bacterium Escherichia coli (E. coli) under light irradiation. Results of the bacterial growth curve and ROS generation analyses revealed higher light-driven antibacterial activity of metallic 1T-MoS2 NFs compared to semiconducting 2H-MoS2 NFs. Electron paramagnetic resonance (EPR) spectroscopy demonstrated that the ROS of the superoxide anion radical-O2- was generated due to the incubation of 1T-MoS2 NFs and E. coli with light irradiation. Furthermore, E. coli incubated with metallic 1T-MoS2 NFs exhibited significant damage to the bacterial cell walls, complete bacterial destruction, and abnormal elongation after light irradiation. The light-driven antibacterial mechanism of metallic 1T-MoS2 NFs was examined, and we found that, under light irradiation, photoinduced electrons were generated by metallic 1T-MoS2 NFs, and then the photoinduced electrons reacted with oxygen to generate superoxide anion radical which induced bacterial death. For semiconducting 2H-MoS2 NFs, photoinduced electrons and holes rapidly recombined resulting in a decrease in ROS generation which diminished the light-driven antibacterial activity.