Preparation and characterization of catechol-grafted chitosan/gelatin/modified chitosan-AgNP blend films

•Modified chitosan is more soluble in aqueous solutions than chitosan.•Antibacterial film is prepared using modified chitosan.•Nano silver is prepared by in-situ reduction using modified chitosan.•Mechanical properties of antibacterial film are better than those of chitosan film.•Antibacterial activity of antibacterial film is better than that of chitosan film. Due to the increasing environmental pollution caused by plastic materials, the chitosan (CS)-based biodegradable films is gradually popular. However, poor water solubility of CS, poor mechanical and water barrier properties of CS film limit its application in food packaging. In this study, new bio-based films containing catechol-modified chitosan (CSCT), catechol-modified chitosan-silver nanoparticles (CSCT-Ag NPs) and gelatin (G) were prepared to overcome the drawbacks of pure CS films. Chitosan was modified by catechol to improve the water solubility. Ag NPs were prepared by in-situ reduction using modified chitosan, which yielded particles with an average size of approximately 8 nm. An antibacterial film composed of the modified chitosan as a matrix incorporated with Ag NPs and G was prepared by the solution casting method. The addition of Ag NPs and G improved the tensile strength and water vapor resistance. The prepared membrane exhibited unique antibacterial activities against S. aureus and E. coli. In conclusion, the fabricated bio-nanocomposite indicated considerable potential for food packaging.