Facile green synthesis of CuO NPs using Citrus sinensis peel extract for potential antibacterial applications and banana shelf-life extension

Abstract Antibacterial-caused diseases and banana preservation are now challenging the globe due to drug resistance as well as rapid ripening and microbial spoilage caused by ethylene gas production, physical damage, and fungal infections. Green synthesis of nanoparticles (NPs) provides a promising solution for such worldwide challenges. Copper oxide nanoparticles (CuO NPs) synthesized through a green method using C. sinensis peel extracts offered a promising solution. CuO NPs were biosynthesized using C. sinensis peel extracts within various ratios, followed by characterization. XRD profiling revealed average crystallite sizes of 28.34, 28.36, and 19.94 nm for the 1:1, 1:2, and 2:1 precursor-to-extract ratios, respectively. FTIR spectroscopic analysis confirmed that plant-derived phytochemicals directly mediated the reduction and stabilization of the NPs. UV-Vis spectrophotometric analysis of the biosynthesized CuO NPs revealed a prominent absorption pick in the region of 450–480 nm, characteristic of intrinsic band-edge absorption in monoclinic CuO NPs. The SEM result was validated as the synthesized NPs were pure, crystalline CuO NPs, and FTIR confirmed the successful formation of CuO NP as well as the role of the peel. TEM-HRTEM with SAED proves that CuO NPs were spherical in shape with homogeneous morphology. The antimicrobial efficacy of the biosynthesized NPs was evaluated against drug-resistant bacterial strains. The CuO (1:2) ratio proves enhanced performance, closely approaching the effectiveness of the standard antibiotic ampicillin at 100 µg/mL. The antimicrobial efficacy of these NPs suggested their potential use as a biocidal agent in controlling bacterial contamination associated with food spoilage. During the 14-day study, banana samples coated with a 75% concentration of CuO NPs at a 1:1 ratio achieved the most effective preservation with a weight loss of only 21.1%, whereas the water-treated control group exhibited the highest weight loss at 53.0%.