Antimicrobial nanocomposite films based on MOF-embedded copper nanoclusters for fruit preservation

The proliferation of multidrug-resistant (MDR) bacteria poses a severe threat to food safety and public health, driving the urgent need for advanced packaging solutions that go beyond conventional methods. Herein, we present a nanocomposite film engineered to tackle this challenge. Its active core is a rationally designed CuNCs@ZIF-67/CNF composite, where copper nanoclusters (CuNCs) are embedded in a ZIF-67 matrix and anchored onto chitosan nanofibers (CNF). This design enables synergy: CNF captures bacteria, ZIF-67 provides sustained ion release, and CuNCs generate reactive oxygen species, jointly disrupting biofilms, membranes, and metabolism. The composite demonstrates exceptional, broad-spectrum antibacterial activity, achieving >99% inactivation against Gram-positive/negative bacteria and key MDR pathogens like Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Processed into a polyvinyl alcohol film, it shows excellent flexibility, strength, and biocompatibility. In practical tests on cherry tomatoes, the film effectively inhibited MDR bacteria on surfaces, reduced weight loss to <6% (control >25%), and preserved freshness over 7 days. This work offers a high-performance, sustainable strategy for next-generation active food packaging to combat spoilage and antimicrobial resistance.