Fabrication of Dual Photodynamic Enhanced Antimicrobial CDs@ZIF-8/Polycaprolactone/Ethyl Cellulose Nanofibrous Films for Fruit Preservation

Carbon dots (CDs) have elicited attention in photodynamic antimicrobial applications, but their susceptibility to aggregation limits their effectiveness. Herein, CDs@ZIF-8 nanocomposites are synthesized. The results reveal that they have superior dual photodynamic enhanced antimicrobial properties, specifically 7.63 log₁₀ CFU mL⁻¹ (lg) elimination for Escherichia coli (only 3.12 lg with CDs and 4.18 lg with ZIF-8) and 7.27 lg elimination for Staphylococcus aureus (only 4.17 lg with CDs and 2.94 lg with ZIF-8). Optoelectronic property analysis and density functional theory calculations show that the enhanced photodynamic antimicrobial properties of CDs@ZIF-8 can be attributed to their narrow bandgap and higher binding affinity for O₂, which facilitates the photo-generated e⁻–h⁺ pairs separation and promotes the generation of ¹O₂ and •O₂⁻. Furthermore, the CDs@ZIF-8/polycaprolactone/ethyl cellulose nanofibrous films are prepared by microfluidic-blow-spinning, which have prominent antimicrobial properties and extend the shelf life of strawberries from 6 to 12 d. Overall, this study provides a novel idea for designing synergistically enhanced photodynamic antimicrobial materials and photodynamic preservation of perishable fruits.