Visible light-responsive amine-rich porous g-C3N4-chitosan/PBAT bilayer film with high antibacterial activity for fruit preservation.

Eutrophic fruits tend to deteriorate after harvest due to suffering from dehydration, microbial infection, and senescence. Therefore, the development of multifunctional preservation material is crucial to resist these alterations. In this study, well designed amino-rich porous carbon nitride (APCN) with excellent photocatalytic antimicrobial performance was first infused into the biodegradable chitosan (CS) matrix to obtain photoactive film (APCN-CS). Then the photoactive film was further casting onto the surface of poly (butylene terephthalate-co-glycol terephthalate) (PBAT) to fabricate APCN-CS/PBAT bilayer film with improved water-blocking performance. The design of the bilayer film aimed to integrate the water-blocking properties of PBAT film with the excellent photocatalytic antibacterial properties of APCN-CS film, thereby achieving synergistic advantages to prolong the shelf life of fruits. The incorporation of 5 % APCN displayed excellent photocatalytic killing performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under visible light irradiation, with the bactericidal efficiency up to 99.96 % and 99.75 %, respectively. Also, the film exhibits excellent antibacterial activity against fungi. The excellent antimicrobial performance could be attributed to the capturing effect of CS towards bacteria and production of reactive oxygen species (ROS) from APCN. Moreover, after decorating the APCN-CS film with PBAT layer, the bilayer films are tightly connected without any delamination owing to the strong hydrogen bonding interaction, presenting significant improvements in both mechanical strength and water-blocking performance. As a result, preservation experiments demonstrated that the APCN-CS/PBAT bilayer film could effectively extend the shelf life of mango. This research provides new insights for the prevention of fruit spoilage in food industry.