Antioxidant-antibacterial caffeic acid-derived carbon dots film based on pullulan/chitosan: Preparation, characterization, and application in chicken breast preservation

Synthesized multifunctional carbon dots (CA-CDs) from caffeic acid, exhibiting antioxidant and antibacterial properties. • Developed a novel, fully bio-based food packaging film by incorporating CA-CDs into a pullulan/chitosan matrix. • Extended the shelf life of chilled chicken breast by 4 days by effectively inhibiting microbial growth and oxidation. 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-CDs 3 ) 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-CDs 3 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. Scheme 1. Synthesis of CDs; composite film-forming mechanism and chicken breast preservation principle. Pul: pullulan; CS: chitosan; CA-CDs: Caffeic acid-derived carbon dots; Pul/CS: Pullulan-chitosan blended film; Pul/CS/CA-CDs: Pullulan-chitosan blended film added with CA-CDs. Download: Download high-res image (329KB) Download: Download full-size image