Photocatalytically Activated Cu-N1S3 Single-Atom Nanozyme: Enhancing Enzyme Activities and Antibacterial Synergy for Highly Efficient Fruit Preservation

Postharvest preservation urgently demands innovative solutions bridging atomic precision with practical scalability. Here, a distinctive photocatalysis-driven self-assembly strategy is presented that fundamentally diverged from conventional high-temperature syntheses by enabling precise single-atom coordination under ambient conditions. This approach, utilizing α-lipoic acid (α-LA) as coordination ligand, achieved the mild assembly of S-coordinated Cu single-atom nanozymes (Cu/CNS) while significantly enhancing their enzymatic activity. The resulting material demonstrated unprecedented multi-enzyme mimetic activities (catalase-, oxidase-, and glutathione oxidase-like) with catalytic efficiency surpassing conventional nanozymes by orders of magnitude. The Cu/CNS exhibits near-perfect antimicrobial efficacy against Escherichia coli ( E. coli ), Staphylococcus aureus ( S. aureus ), and Botrytis cinerea ( B. cinerea ) through synergistic mechanisms. When integrated into chitosan-gelatin films (Cu/CNS@CS-Gel), it forms active packaging with pH-responsive behavior, exceptional barrier properties, and mechanical strength. Crucially, the synthesis is simple, scalable, and environmentally adaptable. Using strawberries and kiwifruits as representative examples, Cu/CNS@CS-Gel more than doubled the shelf life while efficiently maintaining nutritional quality. Beyond food packaging, this coordination chemistry platform is generalizable to other metal-ligand systems, offering a versatile toolbox for sustainable agriculture. By bridging atomic-level design with practical feasibility, the work advances sustainable nanozyme implementation in food systems.