Preparation of a Lotus-Leaf-Inspired PVA–Grape Seed Extract Biomimetic Gel Film and Its Application in Active Packaging for the Postharvest Preservation of Agaricus bisporus

This study reports the fabrication of a biomimetic PVA–GSE film featuring a lotus-leaf-like hierarchical micro/nanostructure, and its application as a gel-based active packaging material for the post-harvest preservation of Agaricus bisporus (A. bisporus). A lotus-leaf negative template was prepared using soft etching and a polydimethylsiloxane (PDMS) secondary transfer method; the PVA/GSE solution was then cast onto this template and subjected to repeated freeze–thaw cycles for physical cross-linking to induce PVA hydrogelation. The resulting biomimetic gel film reproduces the hierarchical lotus-leaf surface morphology and forms a continuous polymer gel network composed of interconnected gel pores, which serve as reservoirs for grape seed extract (GSE). This gel network structure enhances the properties of PVA. Although BPG-40 exhibited the strongest preservation performance during storage owing to its highest GSE loading, BPG-30 was selected as the optimal formulation, because it achieved the best overall balance of mechanical strength, water-vapour barrier and optical quality while retaining 91–93% of the BPG-40 antioxidant and antibacterial activity; beyond 30% loading, the marginal gains in bioactivity were outweighed by a 12.6% decrease in tensile strength, severe colour darkening (L* = 6.07) and surface cracks observed by SEM. An experiment was conducted to evaluate the effects of the biomimetic composite film on A. bisporus over a 12 days storage period at 4 °C. Storage results demonstrate that this film effectively reduces the weight loss rate of A. bisporus, lowers their respiration rate, enhances the polyphenol retention rate, and significantly extends the storage life of A. bisporus. This study simulates the surface structural regulation mechanism of lotus leaves and represents an innovative approach that synergistically integrates active ingredients with material structure for use in fresh-keeping packaging materials.