Multifunctional visible light photocatalytic carbon dots synergize with reactive oxygen species for anti-quorum sensing and anti-bacteria for salmon preservation

Quorum sensing (QS)-induced spoilage causes approximately 15–20% of annual food wastage. However, traditional natural QS inhibitors exhibit poor water solubility and no catalytic activity. Therefore, this study aimed to synthesize novel anti-QS carbon dots (RR-CDs) with good water solubility, visible light photocatalytic activity, and high biocompatibility. The RR-CDs (<200 μg mL −1 ) exhibited considerable broad-spectrum antibacterial activity by generating reactive oxygen species (ROS) to disrupt the cell membrane wall structure. Owing to the appropriate bandgap of RR-CDs, a high ROS content, including · O 2 − , 1 O 2 , and · OH, was generated via energy transfer under visible light irradiation. Furthermore, the combined effect of RR-CDs and ROS reduced the biofilm formation, swarming, swimming, and extracellular protease production of Pseudomonas fluorescens by 48.45%, 25.51%, 52.79%, and 38.67%, respectively, by inhibiting LuxI/R expression, which further decreased pgaC , tyrB , motB , and aprE expression by >50 %. Notably, RR-CDs exhibited no obvious cytotoxicity; furthermore, they could extend the shelf life of salmon by 3 d. Altogether, these results present and validate the strong ability of photocatalytic RR-CDs for QS inhibition and show their potential in aquatic product preservation.