Preparation of mesoporous polydopamine/thyme essential oil/fish scale gelatin photothermal antibacterial film and its application on cherry tomato preservation.

This study synthesized mesoporous polydopamine nanoparticles (MPDA) through emulsion-induced interfacial polymerization method to encapsulate thyme essential oil (TEO). The resulting mesoporous polydopamine-thyme essential oil composite (MT) was incorporated into tannic acid-fish scale gelatin (TF) matrix. Upon near-infrared irradiation, the MT-TF composite film achieved a temperature increase of up to 70.1 °C and exhibited sustained as well as tunable release of TEO. The released TEO acted synergistically with the photothermal effect, endowing the MT-TF film with strong antibacterial activity against Staphylococcus aureus and Escherichia coli, achieving a kill rate exceeding 99 %. Additionally, the film demonstrated antifungal efficacy against Botrytis cinerea. In cherry tomato preservation experiments, the 0.3 % MT-TF film effectively maintained fruit quality upon near-infrared activation, thereby demonstrating potential for shelf-life extension. This work thus provides a new strategy for developing sustained-release essential oil-based photo-thermoactive packaging systems.