Eco-friendly lignin nanocomposite films as advanced UV protective and antimicrobial sustainable packaging materials

Lignin is a renewable, biodegradable, and cost-effective biopolymer present in agri-biomass. This bioresource could be utilized as a sustainable alternative for biomaterial development. Bio-based and biodegradable polymers are ideal for sustainable polymer packaging too. In this study, lignin was extracted from wheat straw using the soda method with 18-20% yield followed by its characterization. The purified soda lignin was utilized for the synthesis of lignin nanoparticles (PNSL) and copper oxide nanoparticles (L@CuONPs) followed by their incorporation into the PVA-PEG film (PVA-PEG-PNSL-L@CuONPs nanocomposite films). The antimicrobial activity against Escherichia coli, Bacillus megaterium, and Candida albicans of nanocomposite films reached up to 5 log reduction (-99.999%). Furthermore, the UV protective activity of these lignin-based biodegradable nanocomposite films was validated which paves its way as an eco-friendly, cost-effective, and sustainable biomaterial. Moreover, lignin-based films derived from renewable sources have potential applications in the food packaging industry because of their low cost, biocompatibility, flexibility, and transparency.