Green synthesis of copper oxide nanoparticles using Abrus precatorius leaf extract: Characterization, evaluation of biological activities and photocatalytic degradation of methylene blue dye.

The present study aimed to synthesize and characterize copper oxide nanoparticles (CuONPs) using Abrus precatorius leaf extract and to evaluate their biological and photocatalytic activities. Preliminary phytochemical screening of the leaf extract revealed the presence of alkaloids, phenols, flavonoids, tannins, saponins, terpenoids, carbohydrates, glycosides, steroids and proteins, indicating the presence of bioactive constituents that may contribute to nanoparticle formation and stabilization. UV-visible spectroscopy confirmed the formation of CuONPs with a characteristic absorption peak at 367 nm. FTIR analysis revealed hydroxyl, aromatic, amine and C-O functional groups, together with characteristic Cu-O vibrations at 612.32 and 421.84 cm-1, suggesting the involvement of plant-derived metabolites in nanoparticle formation and surface capping. XRD analysis confirmed the crystalline monoclinic CuO phase, while FE-SEM showed predominantly spherical like structures with an average particle size of 24.86 nm. DLS analysis revealed a predominant hydrodynamic diameter of 78.01 nm, and the zeta potential was -21.12 mV (mV), indicating moderate colloidal stability. The synthesized CuONPs exhibited concentration-dependent antibacterial activity against Staphylococcus aureus and Escherichia coli, with maximum inhibition zones of 33 ± 0.8 and 36 ± 0.7 mm, respectively, at 100 μg/mL. At the highest tested concentrations, the DPPH and ABTS radical-scavenging activities reached 76.92% and 65.86%, respectively, at 250 and 300 μg/mL. The nanoparticles maintained 85.4 ± 1.2% cell viability at 160 μg/mL and enhanced fibroblast migration and wound closure in the scratch assay. Furthermore, the synthesized CuONPs exhibited photocatalytic activity against methylene blue, as demonstrated by a progressive reduction in dye absorbance up to 45 min of irradiation. Overall, the novelty of this study lies in the green synthesis of CuONPs mediated by A. precatorius, which demonstrated promising antibacterial, antioxidant, wound-healing, photocatalytic and concentration-dependent cytocompatibility properties, highlighting their potential for diverse biomedical and environmental applications.