Super Fe3+ competing ability, high biocompatibility, and mild antibacterial carbon dots for food preservation

Food spoilage caused by bacteria led to about 600 million people suffering from foodborne diseases in 2020, and the diseases kill approximately 400,000 people annually. Traditional food preservatives, antibiotics, and nanomaterials have problems such as high dosage, bacterial resistance, and low biocompatibility. In this study, mild antibacterial carbon dots (TM-CDs) with Fe3+ nutritional competitiveness were prepared. TM-CDs specifically chelated Fe3+ and formed Fe-O. The maximum chelating capacity of TM-CDs for Fe3+ was 154.56 mg mL−1. TM-CDs exhibited a much stronger chelating ability for Fe3+ than traditional iron chelators and even siderophores secreted by Pseudomonas fragi. The minimum inhibitory concentration of TM-CDs against Pseudomonas fragi was 0.25 mg mL−1. The antibacterial mechanism of TM-CDs was the existence of Fe3+ competition between TM-CDs and siderophores secreted by Pseudomonas fragi, which ultimately led to the death of Pseudomonas fragi due to iron deficiency. Notably, no obvious cytotoxicity of TM CDs was observed. In addition, the experimental results of freshness showed that TM-CDs effectively prolonged the shelf-life of salmon by 3–4 d. Therefore, this study provides insight into developing a competitive approach to depriving bacteria of nutrients for antibacterial purposes, with potential applications in seafood storage and preservation.