Synthesis of novel chalcone/lipoic acid derivatives and cross-linked chitosan for preparation of multi-functional packaging film

Chitosan is a bio-based material that is more environmentally friendly than traditional petroleum-based materials, but its biofilms often suffer from brittleness and limited antioxidant and antibacterial properties. To overcome these challenges, chemically modified chitosan is a key solution. Herein, a novel CS-LA/CHA films were prepared through a radical reaction of chitosan (CS), lipoic acid/chalcone derivative (LA/CHA) and N,N-methylene bisacrylamide (MBA). Experimental results indicate that the tensile strength of the CS-LA/CHA film is 65 % greater than that of the standard chitosan film following radical cross-linking modification. Additionally, the chalcone ester structure elevates the water contact angle of the CS-LA/CHA film by 18 %, and its antioxidant activity improves to 81 ± 0.01 % (p < 0.01). Concurrently, the water absorption rate (WA) and water vapor permeability (WVP) exhibited significant reductions. Given the remarkable antibacterial properties of chalcone, the CS-LA/CHA film effectively inhibits the proliferation of Escherichia coli and Staphylococcus aureus, which containing 15 wt% LA/CHA can kill >94.1 ± 0.09 % (p < 0.01) of S. aureus and 98.1 ± 0.07 % (p < 0.01) of E. coli. Furthermore, this film can extend the shelf life of fish by an additional 6 to 8 days. The CS-LA/CHA film exhibits substantial potential for application in food preservation.