Enhanced photostability of vitamin B2 incorporated nanofibrous membrane via covalent modification for antimicrobial photodynamic inactivation.

Vitamin B2 (VB2), a natural photosensitizer, continuously generates biocidal reactive oxygen species (ROS) under light exposure, making it a promising candidate for controlling foodborne pathogen contamination. However, the photoinduced self-degradation of VB2 limited its long-term antimicrobial application. In this work, the ribityl side chain of VB2 was covalently linked to a poly(vinyl alcohol-co-ethylene) (EVOH) nanofibrous membrane. This covalent immobilization increased the Gibbs free energy of intramolecular hydrogen abstractions, thereby hindering the photodegradation of the VB2. The obtained VB2-EVOH exhibited continuous and stable ROS generation under both D65 and UVA irradiation across multiple light exposure cycles, with ·OH, H2O2, and 1O2 yields maintained at 209.89, 208.82, and 204.41 μg g-1 h-1, respectively. The effective ROS generation resulted in approximately a 6-log reduction of Escherichia coli and Listeria monocytogenes within 60 min of photoirradiation, and this promising antimicrobial efficiency was maintained over five consecutive antimicrobial cycles without noticeable decline. Moreover, the VB2-EVOH demonstrated the ability to reduce various pathogenic bacteria on packaged strawberries without significantly compromising their quality, highlighting its potential application in the food-related area.