Synergistic antibacterial food packaging enabled by photothermal cinnamaldehyde release from mesoporous polydopamine...

Postharvest microbial contamination poses a significant challenge to fruit preservation. In this study, CMCTD films were fabricated by incorporating cinnamaldehyde-loaded mesoporous polydopamine nanocarriers with a phase-change shell into a chitosan matrix, producing a denser microstructure with enhanced mechanical strength and improved water vapor barrier properties. Upon near-infrared irradiation, the films rapidly induced photothermal temperature rise above 60 °C within 5 min, which simultaneously triggered controlled release of cinnamaldehyde at a cumulative amount of 4 mg/g over 24 h. At the microstructural level, the synergistic antibacterial effect arose from the combination of photothermal temperature rise and sustained cinnamaldehyde release, effectively inhibiting Escherichia coli and Staphylococcus aureus. The films exhibited high biocompatibility, with cell viability exceeding 96% and hemolysis rates below 5%, confirming their safety for food-contact applications. Application tests on strawberries demonstrated effective suppression of microbial growth, reduced moisture and nutrient loss, and prolonged shelf life by 2-4 days. These results illustrate how microstructural design and functional integration within CMCTD films can be harnessed to achieve controlled antimicrobial activity, providing a practical strategy for postharvest fruit preservation.