Biodegradable poly (lactic acid)/ZnO/Pluronic composite films: Mechanical properties, antibacterial performance, and fruit preservation

In this study, composite films based on Poly(lactic acid) (PLA), Zinc Oxide (NPs) and Pluronic P123 (0.5–1.5 wt% ZnO/Plu) were fabricated and characterized with respect to structure, mechanics, antibacterial behavior, and fruit‑preservation performance. An optimum was observed at 1.0 wt% ZnO/Plu, where tensile strength (15.7 MPa), elongation at break (~0.7%), and reduced 24‑h water solubility coincided with uniformly dispersed ZnO/Plu domains confirmed by SEM/EDX and FTIR. The films exhibited strong, dose‑dependent antibacterial activity against Escherichia coli and Bacillus subtilis, with maximal inhibition at 1.0 wt% and a slight decline at 1.5 wt% due to nanoparticle aggregation. When used as active packaging for bananas, the 1.0 wt% ZnO/Plu film most effectively limited weight loss, maintained titratable acidity and vitamin C, and preserved visual quality, indicating its potential as a biodegradable active packaging material for postharvest applications.