Development of poly(lactic acid)/polyvinyl alcohol-based temperature-responsive shell-core nanofibers: Controlled...

With the increasing demand for sustainable and effective food preservation methods, the development of novel smart preservation materials has become a pressing need. A temperature-responsive smart nanofiber material with a shell-core structure, polyvinyl alcohol/poly(N-isopropylacrylamide)/polylactic acid/lemon essential oil (PPPL), was developed by incorporating lemon essential oil as a core-layer preservative and poly(N-isopropylacrylamide) as a temperature-responsive shell layer. Transmission electron microscopy confirmed the shell-core structure of the fibers. When the temperature exceeded the lower critical solution temperature, the water contact angle increased from 56° to 91°, confirming that PPPL was temperature-responsive. Infrared spectroscopy revealed interactions between the core and shell layers, which contributed to the tensile strength of 4.31 MPa and enhanced the material's water vapor barrier properties. Release studies indicated that the fibers effectively regulated lemon essential oil release, achieving a radical scavenging rate of 42 % within 24 h. Analysis of the release kinetics revealed temperature-dependent control and effective inhibition of Staphylococcus aureus and Escherichia coli growth. Additionally, the PPPL fibers exhibited significant natural degradation after three months of incubation and showed no toxicity to zebrafish or BV2 mouse glial cells, confirming their environmental and biological safety. A raspberry preservation experiment further demonstrated that under fluctuating temperature conditions, the nanofiber membrane slowed postharvest deterioration in fruit quality. This coaxial nanofiber material enables the sustained release of antibacterial agents triggered by temperature variations, offers long-term preservation for food storage, and supports the use of electrospinning technology in smart food packaging.