Dual-functional Zn@melanin nanoparticles for enhanced antibacterial activity and prolonged fruit preservation

Mitigating food spoilage from microbial infections remains a critical challenge in food preservation. Although Zn²⁺ ions are used as chemical bactericides, their use alone often requires high doses. A novel nanomaterial, Zn@MNPs, combining photothermal properties with the controlled release of Zn²⁺, was synthesized through a coordination of Zn²⁺ with melanin nanoparticles (MNPs) derived from cuttlefish ink. Zn@MNPs were capable of attaching onto the bacterial surfaces, enabling high-efficiency release of Zn²⁺ under mildly acidic conditions typically associated with bacterial infections. This leads to sustained antibacterial activity, causing bacterial membrane rupture and leakage of intracellular components. Incorporating Zn@MNPs into polyvinyl alcohol (PVA)-based films improved their ability to block UV light and reduce oxygen and water vapor permeability. These films effectively reduced dehydration, preserved nutritional content, and extended fruit shelf life. This study highlights the potential of Zn@MNPs-based PVA films as biodegradable, bioactive packaging materials for enhancing food preservation and safety.