Synthesis of Carbon Quantum Dots Derived from Coral Algae Polysaccharide and Their Application for Strawberry Preservation in Gelatin Films

In the present study, N and S co-doped carbon quantum dots (CP-CQDs) were synthesized using coral algal polysaccharide (CAP) and o-phenylenediamine (OPD) as precursors. CP-CQDs with a mean size of 4.14 ± 0.70 nm emitted yellow-green fluorescence at a wavelength of 530 nm when excited at 427 nm. CP-CQDs exhibited excellent fluorescence stability after 8 h of UV irradiation, across a pH range of 5.0–13.0, and in 1.0 mol/L NaCl solution, respectively. GEL/CP-CQDs composite films were prepared by incorporating CP-CQDs into a gelatin (GEL) matrix. The mechanical properties, barrier properties, and antibacterial activities of the films were significantly correlated with the concentration of CP-CQDs. Hemolysis assays and overall migration tests confirmed that the GEL/CP-CQDs films exhibited good biocompatibility. Moreover, the GEL/CP-CQDs3% film effectively extended the shelf life of strawberries, reducing the decay rate to 20.32 ± 1.62% at the tenth day of storage. This research offered valuable perspectives for promoting the high-value utilization of marine algal resources and their application in active packaging. Graphical