Green Synthesis, Characterization, and Antimicrobial Activity of ZnO Nanoparticles Using Zanthoxylum gilletii Leaf Extract

The green synthesis of zinc oxide (ZnO) nanoparticles has attracted significant attention as an eco-friendly alternative to conventional chemical methods. In this study, ZnO nanoparticles were synthesized using aqueous leaf extract of Zanthoxylum gilletii , where plant phytochemicals acted as reducing and stabilizing agents. Key synthesis parameters, including precursor concentration, reaction pH, and temperature, were systematically optimized to obtain nanoparticles with desirable physicochemical properties. Optimal synthesis conditions were achieved at 0.7 M precursor concentration, pH 10, and 60°C, resulting in well-defined and stable nanoparticles. The synthesized ZnO nanoparticles were characterized using UV–Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and photoluminescence (PL) analysis. UV–Vis results showed a characteristic absorption peak at 356 nm with a band gap of 3.12 eV, confirming ZnO formation. FTIR analysis revealed a Zn–O stretching vibration at ~410 cm -1 , while XRD confirmed a hexagonal wurtzite structure with an average crystallite size of 29.70 nm. PL spectra exhibited an emission peak at 401 nm, indicating defect-related optical behaviour. The antimicrobial activity of the synthesized nanoparticles was evaluated against Escherichia coli , Staphylococcus aureus , Pseudomonas aeruginosa , and Candida albicans using the agar disc diffusion method. The nanoparticles exhibited significant antimicrobial activity, with mean zones of inhibition ranging from 18.67 mm to 22.00 mm. Statistical analysis (one-way ANOVA, p > 0.05) indicated no significant difference among the tested microorganisms, demonstrating consistent broad-spectrum antimicrobial performance. These findings demonstrate that Zanthoxylum g illetii -mediated green synthesis provides an effective and sustainable approach for producing ZnO nanoparticles with controlled structural and optical properties and strong antimicrobial potential.