Self-clearance efficiency and mechanisms of photodynamic-driven antibacterial films against Vibrio parahaemolyticus biofilms

This study explored the self-removal efficiency and mechanisms of a photodynamically mediated 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized chitin grafted with 5-aminolevulinic acid (ALA) film against Vibrio parahaemolyticus biofilms via an endogenous photosensitization pathway. Results showed that the grafted ALA induced the production of endogenous protoporphyrin IX (PpIX), which in situ generated much reactive oxygen species (ROS) under blue LED irradiation. The ROS damaged the structural integrity and induced the unfolding of extracellular proteins, key component of extracellular polymeric substances (EPS), as well as decreased their hydrophobicity and adhesion work by 43.3%, which attenuated the interfacial adhesion of proteins. All the changes caused significant reduction in the colloidal stability and adhesive strength of EPS matrix on the surfaces of films, which eventually disintegrated the biofilms. Consequently, the films achieved over 99.6% inactivation of viable cells and 78.0% reduction of biofilm biomass. This study fabricated a novel antibacterial packaging film that initiates attacks from internal cells to eradicate biofilms.