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

## TL;DR

A biodegradable sponge made with silver nanoparticles and chitin effectively preserves fruits by killing bacteria and breaking down safely.

## Contribution

A novel biodegradable composite sponge with immobilized silver nanoparticles for synergistic antibacterial fruit preservation is developed.

## Key findings

- The sponge showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus.
- The composite sponge demonstrated good enzymatic degradability with over 50% mass loss in 36 days.
- The sponge provided satisfactory preservation performance for fresh strawberries.

## Abstract

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 Escherichia coli and Staphylococcus aureus, 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.