Antioxidant-antibacterial caffeic acid-derived carbon dots film based on pullulan/chitosan: Preparation,...

Caffeic acid-derived carbon dots (CA-CDs) were synthesized and characterized by their potent antioxidant capacity, broad-spectrum antibacterial activity, and favorable cytocompatibility. SEM analysis further elucidated the antibacterial mechanism, revealing that CA-CDs induce irreversible bacterial membrane disruption. Subsequently, these bioactive CA-CDs were integrated into a pullulan/chitosan (Pul/CS) matrix to fabricate multifunctional composite films (Pul/CS/CA-CDs). Incorporation of CA-CDs at different loadings (0.025%, 0.05%, and 0.1% w/v) led to progressively enhanced functional properties of the films, with the highest loading (Pul/CS/CA-CDs₃) producing the most pronounced improvements. In particular, compared with the pristine Pul/CS film, the addition of CA-CDs significantly enhanced UV-blocking ability, mechanical strength, and water vapor barrier performance (p < 0.05). The Pul/CS/CA-CDs3 film achieved ABTS and DPPH radical scavenging efficiencies of 92.65% and 90.53%, respectively, indicating strong antioxidant performance. It also showed superior antibacterial activity against Escherichia coli and Staphylococcus aureus. During chicken breast storage at 4 °C for 12 days, Pul/CS/CA-CDs₃ packaging significantly inhibited spoilage compared with the control, reducing total viable counts by 1.41 log CFU/g and markedly decreasing TVB-N (14.31 mg/100 g), TBARS (0.55 mg MDA/kg), and carbonyl content (2.37 nmol/mg protein). These changes indicate effective suppression of microbial proliferation and oxidative deterioration, resulting in improved meat preservation. The results confirm that CA-CDs-reinforced Pul/CS films act as effective active packaging materials for meat preservation, where their antioxidant, antimicrobial, and barrier properties synergistically suppress microbial proliferation and oxidative deterioration during storage.