Green synthesis of CuO nanoparticles using Rhamnus prinoides leaf extracts, and mechanistic insights into antibacterial efficacy

Green synthesis presents a cost-effective and environmentally sustainable pathway for producing nanoparticles, particularly metal oxides. This investigation details the successful green synthesis of copper oxide nanoparticles (CuO NPs) utilizing Rhamnus prinoides leaf extracts as a reducing and stabilizing agent. Comprehensive characterization revealed a distinct nanosphere morphology confirmed via transmission electron microscopy (TEM), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), while selected area electron diffraction (SAED) and x-ray diffraction (XRD) analysis provided crystallographic patterns. Energy-dispersive X-ray spectroscopy was employed for analysis of elemental compositions, whereas Fourier-transform infrared (FTIR) spectroscopy identified a characteristic metal-oxygen vibrational bond at 608 cm −1 . Optical properties were assessed using UV–visible spectroscopy, which exhibited absorption maxima between 400 and 411 nm, indicative of electron transitions across energy bands and variations in surface conduction electrons. Cyclic voltammetry analysis revealed enhanced electrochemical activity and rapid ion transport kinetics, indicative of robust redox capabilities. Evaluation of antibacterial efficacy yielded significant results: the CuO NPs demonstrated potent activity against both Gram-positive ( Staphylococcus aureus, Streptococcus pyogenes ) and Gram-negative ( Escherichia coli, Pseudomonas aeruginosa ) pathogens, with measurable zones of inhibition ranging from 7 ± 0.1 mm to 15 ± 0.8 mm. This study underscores the potential of Rhamnus prinoides derived CuO NPs, highlighting their unique structural features, intriguing surface properties, and promising antimicrobial performance. • CuO NPs were synthesized via a biosynthetic route using Rhamnus prinoides leaf extract. • The synthesized CuO NPs were characterized by UV–Vis, SEM, HR-TEM, XRD, FTIR, and cyclic voltammetry. • The study reveals mechanistic insights into how bio synthesized CuO NPs act on bacterial cell membranes. • The biosynthesized CuO NPs exhibited remarkable antibacterial efficacy against both Gram-positive and Gram-negative strains.