Triazine-pyridine covalent organic frameworks integrated cellulose films for sweet cherry photodynamic antibacterial preservation.

Post-harvest sweet cherries are prone to spoilage, while conventional plastic packaging lacks biodegradability and antibacterial function. Herein, a novel photodynamic antimicrobial film was engineered by embedding triazine-pyridine covalent organic frameworks (TZP-COF) within hydroxypropyl methylcellulose (HPMC). This strategy innovatively introduces photodynamic antibacterial functionality into a cellulose matrix for the first time. Hydrogen bonding and van der Waals interactions anchored TZP-COF as cross-linking bridges. TZP-COF significantly enhanced the film of mechanical strength by 45.3 %, increased water contact angle from 45.12° to 81.15°, and reduced water vapor permeability by 31.44 %. The photocatalytic activity of TZP-COF endowed the film with excellent antibacterial properties, achieving high antibacterial (99.75 % and 98.78 % towards Staphylococcus aureus and Escherichia coli) within 20 min under visible light (100 mW cm-2). The film demonstrated excellent biosafety (4.15 % hemolysis; >95 % cell viability) and extended the shelf-life of sweet cherries to 9 days, offering a promising green approach for active food packaging.