Temperature-controllable antibacterial film mediated by a photoresponsive metal-polyphenol framework for long-term food preservation

Global microbial spoilage highlights the pressing need for advanced packaging solutions. This study introduces a novel Cu-Chlorogenic acid nanoparticles (Cu-CGA NPs) packaging film system, which demonstrates exceptional photothermal antibacterial properties aimed at enhancing fruit preservation. The system utilizes a photoresponsive metal-polyphenol framework (Cu-CGA NPs) synthesized through a spontaneous chelation process under alkaline conditions, and seamlessly integrated with a carrageenan/gelatin (CG) film matrix. This integration capitalizes on the synergistic effects between the photothermal capabilities of Cu-CGA NPs and its inherent chemical antibacterial properties, resulting in the Cu-CGA 0.15 -CG film-where 0.15 denotes the proportion of Cu-CGA in the solution. This film demonstrates enhanced antibacterial efficacy, achieving 99% bacterial killing rates for both Escherichia coli and Staphylococcus aureus under brief near-infrared light (NIR) exposure. Additionally, the CGA component imparts significant antioxidant capacity to the Cu-CGA 0.15 -CG film, with a DPPH radical scavenging rate exceeding 60%. The inclusion of Cu-CGA NPs also enhanced the mechanical strength of Cu-CGA 0.15 -CG film to 25.8 MPa and improved the water contact angle (WCA) to 84.087°. These combined attributes result in a threefold extension of cherry tomato storage life, while maintaining product quality. Safety evaluations, including migration and cytotoxicity tests, confirm the suitability of the Cu-CGA 0.15 -CG film for food contact. Overall, the development of Cu-CGA NPs films represents a substantial advancement in food preservation technologies, offering robust protection for perishable items.