Green Synthesis, Characterization, and Antimicrobial Activities of Copper Oxide Nanoparticles (CuONPS) Using Bitter Leaf (Vernonia amygdalina) Aqueous Extract

Abstract

Nanotechnology, a rapidly evolving field, focuses on designing, synthesizing, and utilizing materials at the nanoscale, offering revolutionary applications across industries. This study investigates the synthesis, characterization, and application of nanoparticles for specific functional applications, employing ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) for detailed analysis. Nanoparticles were synthesized through the green method and subjected to comprehensive characterization. UV-Vis spectroscopy was used to evaluate the optical properties, confirming the surface plasmon resonance (SPR) indicative of nanoparticle formation. FTIR analysis identified functional groups and chemical interactions, while SEM provided detailed morphological insights and subjected to antimicrobial screening. UV-Vis spectra confirmed a characteristic SPR peak at 250 nm, correlating with the desired particle size and uniformity. FTIR analysis revealed FTIR analysis identified functional groups, including hydroxyl (-OH), carboxyl (C=O), and amine (C-N), which reflect the presence of flavonoids, phenols, and proteins from the Vernonia amygdalina extract. These functional groups likely play a vital role in reducing and stabilizing Cu ions, enhancing nanoparticle bioactivity, and highlighting successful chemical bonding and stability of the nanoparticles. SEM images depicted uniform morphology and size distribution with an average particle size of 20nm, supporting consistent synthesis. CuONPs showed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against several organisms: Staphylococcus aureus (S.a) (MIC 6.25 µg/ml, MBC 12.5 µg/ml), Bacillus subtilis (B.s) (MIC 3.125 µg/ml, MBC 50 µg/ml), Escherichia coli (E.c) (MIC 12.5 µg/ml, MBC 50 µg/ml), and others. Compared to controls like ciprofloxacin, CuONPs demonstrated broader efficacy, especially against resistant strains like Pseudomonas aeruginosa (PS.a) (MIC 6.25 µg/ml).