Novel graphene quantum dots modified NH2-MIL-125 photocatalytic composites for effective antibacterial property and mechanism insight

Bacterial infection threatens human health, so the design of efficient and stable photocatalytic antibacterial materials has attracted widespread attention. In this regard, a novel photocatalyst GQDs/NH2-MIL-125 (GQDs: graphene quantum dots) was prepared by the solvothermal method for photocatalytic disinfection. Since the addition of GQDs enhanced the absorption of visible light and also accelerated the transfer of photogenerated electrons, the photocatalytic performance of GQDs/NH2-MIL-125 was significantly improved. 5 wt% GQDs loading sample (2-GQDs/NH2-MIL-125) exhibited the best antibacterial properties. The killing efficiency by 2-GQDs/NH2-MIL-125 against E. coli and S. aureus (107 CFU·mL−1) increased from 40 % and 75 % by NH2-MIL-125 to 92 % and 93 % within 60 min, respectively. Moreover, through the single-wavelength antibacterial experiments, it was found that the introduction of GQDs led to a wide-range-responsive antibacterial effect. Through photocatalytic trapping experiments and ESR analysis, the dominant roles of superoxide radicals (•O2–) were confirmed in the antibacterial process. Finally, by studying the state of bacteria via TEM, confocal fluorescent images, and gel electrophoresis, it was found that the active substances not only destroyed the cell membranes but also further destroyed DNA to achieve the purpose of completely killing bacteria. This work provides a new method for the rapid disinfection of pathogenic microorganisms using GQDs-related photocatalysts.