Plant-mediated synthesis, characterization, and evaluation of a copper oxide/silicon dioxide nanocomposite by an antimicrobial study

Abstract

This study presents an innovative, environmentally friendly method for biosynthesizing copper oxide–silica (Cu2O/SiO2) nanocomposites (CSNCs) utilizing an aqueous leaf extract of Callistemon viminalis (C. viminalis). The goal of this work is to fabricate CSNCs using a less hazardous and sustainable synthesis approach. Copper acetate and sodium metasilicate were used as precursors, whereas the C. viminalis green leaf extract was used as the reducing and stabilizing agent. Analysis of the plant extract using Fourier transform infrared spectroscopy indicated the presence of polyphenolic compounds, primarily phenolic acids, which functioned as both reducing and stabilizing agents in the synthesis of CSNCs. A combination of energy dispersive X-ray spectroscopy and scanning electron microscopy was used to study the formation of spherical copper–silica hybrid nanostructures. Powder X-ray diffraction analysis revealed the successful integration of silica with copper(i) oxide (Cu2O) through the presence of distinct Cu2O peaks and a broad amorphous SiO2 peak at 2θ = 22.77°. The thermal stability of the nanocomposites (NCs) was assessed using thermogravimetric analysis and differential thermal analysis under a nitrogen atmosphere. The biogenic NCs also successfully inhibited pathogenic strains of Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans); however, S. aureus was found to be more susceptible to the biocidal activity of the NCs than P. aeruginosa. These findings suggest that this simple, cost-effective, and eco-friendly method for producing biologically active hybrid nanomaterials holds significant promise for future applications in both biological and materials sciences.