Batch Productions of Electrospun Janus Nanofibrous Films for Multifunctional Food-Packaging Applications

The development of intelligent packaging systems with dual monitoring and antibacterial capacities still poses one of the most substantial challenges for scientific advancement. In this study, polyvinylidene fluoride (PVDF) and grape skin extract (GSE) were employed as the carrier polymer and coloring agent in the round-side of electrospun Janus nanofibers, respectively, and titanium dioxide (TiO₂) was used as the crescent-side active component. To overcome the bottleneck of low production efficiency in traditional needle-based electrospinning, an innovative "needles-in-holes" eccentric spinneret was developed, enabling side-by-side electrospinning for the first time and batch-scale fabrication of Janus-structured nanofibrous membranes with a 20-fold yield compared to traditional needle-based electrospinning. The resulting Janus membrane demonstrates high colorimetric sensitivity; superior hydrophobicity; excellent stability; and robust mechanical, antioxidant, and antibacterial properties. It exhibits a strong linear correlation in monitoring total volatile basic nitrogen and pH levels in river perch (Perca fluviatilis). Based on the pH-responsive properties of GSE, the Janus fiber membrane exhibited a distinct color change from off-white to light blue at 4 °C. Combined with the antibacterial effect of TiO₂, the films effectively extended the shelf life of sea bass by 2 days. This work not only provides a high-performance multifunctional membrane for real-time freshness monitoring and preservation of fish products, but also demonstrates a batch-production strategy of side-by-side electrospinning, offering significant potential for intelligent food-packaging applications.