Pectin/gelatin-based bioactive composite films reinforced with sulfur functionalized carbon dots

Sulfur functionalized turmeric-derived carbon dots (S-CD) were prepared and used to fabricate pectin/gelatin-based bioactive food packaging film. FTIR and XPS analysis confirmed that turmeric-derived CDs were functionalized with sulfur. The sizes of CD and S-CD measured by TEM were 10.6 ± 1.2 nm and 8.5 ± 1.6 nm, respectively. Turmeric-derived CD showed strong antibacterial and antioxidant activity with insignificant cytotoxicity against mouse fibroblast L929 cells. The CD-added film showed high UV protection properties without significantly changing the transparency of the pectin/gelatin film. The incorporation of CD also affected the mechanical, water vapor permeability, and hydrophobicity of the film. In addition, CD-added pectin/gelatin-based films showed strong antioxidant activity as determined by the DPPH and ABTS methods. Also, the film with sulfur functionalized CD showed strong antimicrobial activity against food-borne pathogenic bacteria, E. coli and L. monocytogenes. The sulfur functionalized turmeric-derived carbon dots (S-CD) incorporated pectin/gelatin films with superior functional properties can be used in active food packaging applications to ensure food safety and extend the shelf life of foods.