TEMPO-Oxidized Nanocellulose In Situ-Immobilized AgNPs-Modified Chitin-Based Composite Sponge for Synergistic Antibacterial Fruit Preservation

Sponge-based preservative packaging is an emerging approach to mitigate mechanical damage to fruits and vegetables during transportation, storage, and retail. However, conventional polyurethane sponges generally lack durable antibacterial activity and are neither biodegradable nor readily recyclable. Herein, to address these limitations, silver nanoparticles immobilized on TEMPO-oxidized cellulose nanofibers (TCNF@AgNPs) were incorporated into a quaternized chitin matrix to construct a synergistic antibacterial composite sponge (QCH/TCNF@AgNPs) for fruit preservation. The composite sponge exhibited strong antibacterial efficacy against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>, together with a low cumulative release of silver species of 2.49% after 336 h. In addition, the sponge showed >50% mass loss after 36 days in lysozyme solution, indicating good enzymatic degradability. Cytocompatibility assays further confirmed favorable biocompatibility and biosafety. Notably, the composite sponge provided satisfactory preservation performance for fresh strawberries. Overall, this work demonstrates the potential of QCH/TCNF@AgNPs as a biodegradable antibacterial packaging sponge for fruit preservation.