Chitosan coating based on antibiotic carbon dots with strong antimicrobial properties, excellent water washability...

This study developed chitosan (CS)-based antibacterial composite coating incorporated with amikacin-derived carbon dots (AK-CDs), which were synthesized through a one-pot hydrothermal treatment of amikacin sulfate (AK) and polyethyleneimine (PEI). Characterization confirmed their near-spherical morphology (6.82 nm diameter), positive surface charge (+16.8 mV), excitation-independent blue fluorescence, and abundant amino/carbonyl functional groups, endowing potent broad-spectrum antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) through membrane disruption and biofilm eradication. Uniformly incorporated into CS films (0.5-2.5 wt%), the optimal 2.5% AK-CDs composite demonstrated enhanced functionality including significant antibacterial efficacy, high optical transparency, excellent water solubility, and superior mechanical strength. When applied as a blueberry coating, it extended shelf life from 4 d (control) to 8 d at room temperature by reducing weight loss, inhibiting microbial growth, and preserving quality. Critically, the composite films exhibited eco-benign properties through full biodegradation within 3 weeks, presenting a sustainable, high-performance solution for perishable food preservation.