Upcycling invasive plants into functional carbon dots: A sustainable reinforcement strategy for biomass food...

The development of sustainable and active food packaging derived from biomass is imperative to address global issues including food waste and plastic pollution. However, fabricating biopolymer-based packaging that integrates good barrier properties with active functions remains challenging. Herein, biomass-derived carbon dots (AA-CDs) were synthesized from the extract of invasive plant Ageratina adenophora via a facile hydrothermal method. These AA-CDs was incorporated into a natural polysaccharide-based matrix composed of gelatin/alginate (GEL/ALG) to fabricate AA-CDs/GEL/ALG composite active films. Structural and morphological characterization revealed that AA-CDs possessed a graphite-like structure with an average diameter of ~2.8 nm, and exhibited remarkable fluorescence, antibacterial activity, and UV absorption. The introduced AA-CDs served as multifunctional nanofillers, significantly enhancing the performance of GEL/ALG matrix. Specifically, the composite active film with only 1 % AA-CDs achieved a 98.7 % UV barrier at 280 nm, a 45.9 % reduction in oxygen barrier, and 84.9 % antibacterial activity against E. coli. Furthermore, preservation experiment on strawberries demonstrated that AA-CDs/GEL/ALG preservation coating effectively extended shelf life by maintaining firmness and freshness. This work presents a sustainable and circular strategy for developing active food packaging, effectively transforming an ecological burden into a valuable resource.