Preparation and characterization of agar/lignin/silver nanoparticles composite films with ultraviolet light barrier and antibacterial properties

Lignin was used to prepare silver nanoparticles (AgNPs), and they were incorporated into agar-based films. The composite films were characterized using UV–visible spectroscopy, FE-SEM, FTIR, XRD, and TGA. The color, mechanical, water vapor barrier, and antibacterial properties of the composite films were also evaluated. The composite films exhibited characteristic light absorption peaks at 250–300 nm and 430 nm due to the lignin and AgNPs, respectively. The interaction of lignin and AgNPs with agar biopolymer was analyzed using FTIR. XRD results showed the characteristic peaks of crystalline AgNPs. Incorporation of lignin and AgNPs increased the mechanical, UV-light barrier, and water vapor barrier properties of the composite films. The loading of 1 wt% of AgNPs was the optimum concentration to improve the mechanical and water vapor barrier properties of the films. The films containing AgNPs exhibited antibacterial activity against food-borne pathogenic bacteria, Escherichia coli and Listeria monocytogenes.