Fabrication of CuO–NiO Nanocomposites Using Hybanthus enneaspermus Leaf Extract: Optical and Broad-Spectrum Antibacterial Activity
Author : T Nandhini, T Lurthu Pushparaj and S Harikrishnan
Abstract :
The present study reports an eco-friendly and sustainable approach for the green synthesis of CuO–NiO nanocomposites using the aqueous leaf extract of Hybanthus enneaspermus as a natural reducing and stabilizing agent. The phytochemicals present in the plant extract facilitated the formation of CuO–NiO nanocomposites with a high synthesis yield of approximately 95% after calcination at 450 °C. UV–Visible spectral analysis confirmed nanoparticle formation through a characteristic absorption peak at 354 nm, indicating the semiconducting nature of the synthesized nanocomposites. The average particle size was found to be in the nanoscale range (22–35 nm, depending on the characterization method used). The antibacterial activity of the synthesized CuO–NiO nanocomposites was evaluated against both Gram-positive and Gram-negative bacterial strains using the agar disc diffusion method. The nanocomposites exhibited excellent antibacterial activity, producing maximum inhibition zones of 24 mm against Staphylococcus aureus and 22 mm against Escherichia coli, while inhibition zones of 20 mm, 18 mm, and 15 mm were observed against Bacillus cereus, Bacillus subtilis, and Pseudomonas aeruginosa, respectively. The enhanced antimicrobial activity is attributed to the synergistic interaction between CuO and NiO, leading to increased reactive oxygen species generation and disruption of bacterial cell membranes. The findings demonstrate that H. enneaspermus-mediated green synthesis provides a simple, cost-effective, and environmentally benign route for producing multifunctional CuO–NiO nanocomposites with promising applications in antimicrobial coatings, photocatalysis, environmental remediation, and biomedical materials.
Keywords :
Green synthesis, Hybanthus enneaspermus, CuO–NiO nanocomposites, Metal oxide nanoparticles, UV–Visible spectroscopy, Antibacterial activity.
