pH dual responsive electrospun fiber loading anthocyanin and nisin for food preservation and monitoring: Regulation in dynamic schiff base networks based on different oxidized sodium alginate

A green schiff base-mediated crosslinking strategy was developed by modulating the oxidation degree of sodium alginate (OSA) without additional crosslinker to regulate fiber network structure in electrospun films. Nisin and anthocyanins were co-encapsulated into OSA–carboxymethyl chitosan (CMCS) nanofibers to construct a pH dual-responsive film. The optimized OSA2-N/A-CMCS film (30 % oxidation) exhibited ideal mechanical properties, rapid pH-triggered color change, and pH-responsive controlled diffusive release of nisin (Ritger-Peppas model, n < 0.45). At pH 5.8, the film achieved about 100 % inhibition against E. coli and S. aureus by disrupting cell membranes. Moreover, the film visually indicated strawberries spoilage and reduced decay by 40 % within five days. This study highlights the application of a green, oxidation-tunable crosslinking strategy to achieve efficient integration of multifunctional responses like simultaneously triggering real-time visual monitoring and sustained antimicrobial controlled release under single pH stimulus, and offer a novel design reference for intelligent food packaging.