关键词: Zn/g-C3N4, 光动力抗菌, 大肠埃希菌, 机制研究

Abstract: Objective: To construct an efficient photodynamic antibacterial system, this study systematically investigates the
photodynamic antibacterial properties and mechanism of Zn/g-C3N4 nanomaterials. Methods: Zn/g-C3N4 nanomaterials with Zn doping
ratios of 1%, 5%, 10%, 15%, and 20% were prepared by a calcination method. Escherichia coli （E. coli） was selected as the model
strain. The antibacterial efficacy against E. coli was assessed via the plate spreading method. The photodynamic antibacterial
mechanism was systematically studied through reactive oxygen species quenching assays and analysis of cellular component leakage.
Results: The antibacterial activity exhibited a trend of first increasing and then decreasing with the elevation of Zn doping ratio. The
10% Zn/g-C3N4 nanomaterial exhibited optimal antibacterial performance, achieving complete inhibition of E. coli within 60 minutes.
Quenching experiments identified hydroxyl radicals, superoxide anions, and singlet oxygen as the primary reactive oxygen species.
Further investigation revealed that photodynamic treatment led to substantial glutathione depletion and significant leakage of
intracellular nucleic acids and proteins in bacteria. Conclusion: Under visible light irradiation, 10% Zn/g-C3N4 nanomaterials
efficiently generate reactive oxygen species, which mediate a cascade antibacterial mechanism involving "reactive oxygen species
attack-antioxidant defense collapse-membrane structure damage-intracellular content leakage". This study provides theoretical basis
and experimental support for the design and application of novel photosensitizing antibacterial materials based on Zn/g-C3N4.

Key words: Zn/g-C3N4, photodynamic antibacterial properties, Escherichia coli, mechanism research