Development of CuO-enhanced soybean protein isolate biofilms with antioxidant, photocatalytic, and antimicrobial properties for food packaging applications

This work aimed to combine the unique properties of Soybean Protein Isolate (SPI) with CuO nanoparticles (NPs) at different concentrations (1 %, 3 %, and 5 %). Three different composite biofilms comprised of SPI/CuO NPs were fabricated by the solution casting method. The CuO NPs lead to a denser, tougher, and flexible biofilm. Fourier transform infrared spectroscopic characterization validated the interaction between the NPs and the SPI matrix. CuO NPs enhanced the mechanical characteristics of the SPI-based biofilm. The XRD and SEM predicted 80–100 nm size of CuO NPs and 540 μm thickness of the film. The SPI-based film exhibited antioxidant activity due to the inclusion of CuO NPs. The biofilm also shows 86.02 % photocatalytic activity against methyl red dye. The biofilm exhibited concentration dependent bacteriostatic effects on S. aureus, E. coli, and C. albicans bacteria with a comparable zone of inhibition to standard antibiotics. In comparison to non-cancerous cells, CuO-based SPI films demonstrated higher cytotoxicity against malignant cells. A rise in the CuO NPs concentration greatly enhanced the photocatalytic, antioxidant, and anticancer activity. CuO NPs increase the endurance of biofilm that can be used to preserve or store food susceptible to microbial deterioration and hence a possible use in the food packaging, storing, and transport sector.