Antibacterial properties and mechanism of biopolymer-based films functionalized by CuO/ZnO nanoparticles against Escherichia coli and Staphylococcus aureus

•Nanocomposite film are fabricated by incorporating CuONPs/ZnONPs into SA/CS matrix.•Packaging properties of SA/CS film are improved by incorporation of CuONPs/ZnONPs.•SA-CS@CuO/ZnO film inhibits growth of bacteria and regulates their gene expression.•SA-CS@CuO/ZnO film regulates cellular antioxidant pathway of E. coli and S. aureus.•SA-CS@CuO/ZnO film affects bacterial gene guiding repair of cell membranes and DNA.