Aggregation-induced potentiation of photodynamic inactivation and its application in food preservation

Photodynamic inactivation (PDI) is a promising non-thermal food preservation strategy, while the limited antimicrobial efficacy of food-grade photosensitizers hinders practical application. Here, we identify ε-polylysine (EPL) as the first food-safe PDI potentiator by enhancing Erythrosine B (EB)'s reactive oxygen species (ROS) yield for 16-fold. Computational studies and experimental validations revealed a newly identified potentiation mechanism by inducing J-aggregation of EB molecules, which reduces the singlet-triplet energy gap, therefore augmenting intersystem crossing and ROS generation. To exploit the practical application, we incorporated EB and EPL into a starch cling film, which exhibited potent PDI activity against multiple food-spoilage microorganisms upon exposure to 520 nm LED light. Furthermore, the functionalized film effectively delayed spoilage in beef sticks and strawberries during long-term storage, outperforming commercial counterparts. This work proposes a new strategy to enhance the preservative efficacy of PDI, and presents a new J-aggregation-driven potentiation mechanism for PDI in food science.