Lemon peel-based fluorescent carbon quantum dots as a functional filler in polyvinyl alcohol-based films for active packaging applications

Carbonation of agro-waste into high-value-added products is becoming a promising strategy for producing functional active materials and for reducing landfills. Carbon quantum dots (CQDs) are of great attention due to their non-toxic, antibacterial, antioxidant, fluorescent, and other functional properties. The current study demonstrated the hydrothermal synthesis of dried lemon peel-based carbon quantum dots (LCQDs) and their incorporation in polyvinyl alcohol for developing active films. The developed LCQDs exhibit excellent fluorescence, antioxidant, and antibacterial activities against S. aureus, B. cereus, S. enterica, L. monocytogenes, and E. coli. Interestingly, as confirmed by FE-SEM and FTIR, LCQDs showed excellent compatibility with PVA-based films. The mechanical and water vapor barrier properties were improved by adding 3% LCQDs to the PVA film, which also resulted in improved UVC (99.9%), UVB (99.9%) and UVA (99.1%) blocking effects. Additionally, PVA film containing 3% LCQDs showed 98.9% radical scavenging activity by ABTS method and was 100% effective against S. aureus and S. enterica. Therefore, 3% LCQDs-incorporated PVA films could have excellent potential as active food packaging materials.