Postbiotic-biosynthesized silver nanoparticles anchored on covalent organic frameworks integrated into carboxymethyl chitosan-based film for enhancing antibacterial packaging

Food packaging plays a vital role in guaranteeing the quality and safety of fresh products during the storage and distribution. Carboxymethyl chitosan (CMCS) is identified as a promising polymer for food packaging film owing to its film-forming ability, non-toxicity, and biodegradability. Nevertheless, the practical applications of pure CMCS film usually suffer from some limits owing to its poor antibacterial effect and mechanical strength. In this study, postbiotic-biosynthesized silver nanoparticles (AgNPs) anchored on covalent organic frameworks (COF) (namely COF-AgNP) were integrated into the CMCS film to enhance antibacterial packaging performance for preservation of fruits. Utilizing postbiotic as a reducing agent, COF-AgNPs composite nanomaterials were prepared by anchoring AgNPs on COF via in-situ reduction of Ag⁺. Furthermore, antibacterial packaging film was prepared using CMCS and COF-AgNPs (CMCS@COF-AgNPs) via a solution-casting method. Furthermore, characterization results proved that mechanical strength of CMCS@COF-AgNP films exhibited a gradual enhancement with the increased COFs-AgNPs content. Moreover, CMCS@COF-AgNP films exhibited an enhanced antibacterial activity and excellent biocompatibility. Importantly, CMCS@COF-AgNP coating can effectively preserve citrus quality and prolong its storage time. Therefore, CMCS@COF-AgNP films could be used as a promising and economically viable solution to diminish postharvest losses and prolong the shelf life of fresh products.