PLANT-BASED COPPER OXIDE NANOPARTICLES: BIOSYNTHESIS, CHARACTERIZATION AND THEIR CLINICAL AND ENVIRONMENTAL APPLICATIONS

Abstract

The growing demand for sustainable, eco-friendly nanomaterials has intensified interest in green synthesis routes for metal oxide nanoparticles. This study reports the biosynthesis, comprehensive characterization and evaluation of copper oxide nanoparticles (CuO NPs) prepared using an aqueous plant extract as a combined reducing and stabilizing agent. Synthesis parameters were optimized by response surface methodology based on a central composite design, and the optimized nanoparticles were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), dynamic light scattering (DLS) and zeta potential analysis. Antimicrobial activity was assessed against Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria by agar well diffusion and broth microdilution. Cytotoxicity was determined by MTT assay on HEK-293 and HepG2 cells, and photocatalytic performance was evaluated through degradation of methylene blue and methyl orange under visible light. The optimized conditions (18% v/v extract, 1.5 mM copper salt, 70 degrees Celsius, 90 min) yielded spherical, monoclinic CuO NPs of 30.5 +/- 2.1 nm with a narrow polydispersity index (0.18) and a zeta potential of -28.5 mV. A blue-shifted optical bandgap of 2.1 eV confirmed quantum confinement. The nanoparticles showed broad-spectrum antibacterial activity (zone of inhibition 10-24 mm; MIC 25-100 microgram/mL), dose-dependent and selective cytotoxicity (IC50 85 microgram/mL for HEK-293 and 65 microgram/mL for HepG2), and efficient photocatalytic dye degradation (92% for methylene blue and 88% for methyl orange within 180 min). These findings establish plant-mediated synthesis as a viable, environmentally benign route to functional CuO NPs with promising biomedical and environmental-remediation applications