Eco-friendly synthesis of ZnO nanoparticles using Delonix elata extract with enhanced antibacterial activity

Abstract

In this study, zinc oxide (ZnO) nanoparticles (NPs) were successfully synthesized using a green and eco-friendly method employing the aqueous leaf extract of Delonix elata as a natural reducing and stabilizing agent. Characterization of the synthesized nanoparticles was performed using a range of techniques, including X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED). XRD analysis revealed the formation of a hexagonal wurtzite structure with an average crystallite size of 30.1 nm. FTIR spectra confirmed the involvement of phytochemicals in the stabilization process. UV-Vis spectroscopy showed an absorption peak at 311 nm, corresponding to an optical band gap of 2.7 eV. SEM and HR-TEM images demonstrated predominantly spherical NPs with a well-defined morphology. The antibacterial activity of the ZnO NPs was evaluated against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli strains. The results revealed significant inhibition against E. coli, with no inhibition observed for S. aureus. These findings suggest that green-synthesized ZnO NPs possess strong antibacterial potential, particularly against Gram-negative bacteria, and offer a sustainable and cost-effective alternative to conventional methods for NP synthesis in biomedical applications.