Abstract: Conventional synthetic packaging materials contribute significantly to environmental pollution and the accumulation of solid waste, intensifying the demand for biodegradable, functional alternatives with intrinsic antimicrobial properties. This study presents a multifunctional chitosan/polyvinyl alcohol (CS/PVA) composite film engineered through dual-role tannic acid (TA) crosslinking and TA-mediated surface functionalization of MgO–TiO₂ photocatalysts, targeting both environmental engineering and food preservation applications. TA establishes extensive hydrogen-bonding and metal–phenolic coordination networks that anchor MgO–TiO₂ nanoparticles within the biopolymer matrix, suppressing particle aggregation while inducing ligand-to-metal charge transfer (LMCT). This interfacial engineering broadens light absorption into the visible region and reduces charge recombination, thereby promoting the generation of reactive oxygen species (ROS: •OH and ¹O₂) under ambient light. The optimized TA-crosslinked CS/PVA/MgO–TiO₂ film achieved a 99% increase in tensile strength, a 21% reduction in water vapor permeability, a 38% improvement in oxygen barrier performance, and a 5.5-fold increase in antioxidant activity relative to the pristine CS/PVA film. Visible-light-activated ROS production imparted pronounced antibacterial efficacy, achieving 5.8- and 5.9-log CFU mL⁻¹ reductions against Escherichia coli and Staphylococcus aureus, respectively. Application trials on bananas demonstrated effective delay of surface browning, reduced weight loss, and extended shelf life of 10 days under ambient storage conditions. This work highlights polyphenol–metal coordination as a viable strategy for constructing light-responsive active packaging with integrated photocatalytic, antimicrobial, and barrier functionalities, offering a sustainable pathway toward cleaner production and circular-economy-aligned material design.

Biography: Professor Yao-Tung Lin is a globally recognized expert in environmental engineering, with over three decades of academic and professional experience spanning carbon sequestration, high-value material innovation from agricultural and fishery waste, and advanced synchrotron-based characterization. As a principal investigator and lead scientist, Professor Lin has pioneered novel methods to transform waste into multifunctional materials with antimicrobial, antioxidant, and environmental applications. His research integrates nanotechnology, photocatalysis, and AI-driven material sensing, with special emphasis on chromatic pH-responsive indicators for wound diagnostics and food freshness. In his leadership role, Professor Lin serves as Director of the Taiwan Science and Technology Office for Net-Zero Emission under the Executive Yuan. He is responsible for developing strategies, formulating R&D budgets, and steering technological innovation to meet Taiwan’s 2050 Net-Zero goals. He is also renowned for pioneering work using synchrotron X-ray imaging to visualize the 3D inactivation process of bacteria and intracellular stress responses under environmental stimuli. Professor Lin’s integrative leadership connects science, policy, and sustainability toward a circular, carbon-neutral future.