H2O2-Activatable Peptide Nanozyme-Alginate Dual-Network Hydrogel Coating Reconciling Antibacterial and Moisture Retention in Postharvest Preservation.

Abstract

Nearly 40% of fruits spoil annually before consumption, yet reconciling the contradiction between dehydration-induced shriveling and high-humidity-facilitated microbial decay in biomass coatings without invoking antimicrobial resistance and biosafety concerns remains an unsolved challenge. We addressed this by fabricating a dip-coated dual-network hydrogel comprising self-assembling peptide nanoenzyme filaments (SPEFs) embedded in Ca2+-cross-linked sodium alginate (SPEF-CaAlg), which exhibits enhanced mechanical properties and sustained catalytic readiness. The interpenetrating network provided controlled water retention (∼300% equilibrium swelling) to prevent tissue desiccation while maintaining dimensional stability. Upon periodic spraying of dilute H2O2 solution, the embedded nanoenzymes catalytically generate •OH on demand, achieving >90% bacterial reduction against E. coli and S. aureus and inhibiting biofilm formation; concurrently, the aqueous phase replenishes transpiration-induced water losses. This creates an integrated preservation microenvironment that sustains both hydration and antibacterial protection. In strawberry preservation tests, the coating maintained by intermittent H2O2 misting reduced weight loss from 55 to 37%, maintained higher firmness (8.1 vs 6.7 N/cm2), preserved soluble solids (only 8% loss), and extended shelf life to 8 days with excellent biocompatibility. This replenishable catalytic hydrogel strategy offers a sustainable, safe, and efficient solution for postharvest fruit preservation, paving the way for active food preservation systems with on-demand functionality.