Phyto-Mediated Fabrication of Zinc Oxide Nanoparticles via Citrus medica L. Extract: Physico-Chemical Characterization and Bio-Functional Properties

An aqueous phyto-assisted co-precipitation approach was employed to synthesize zinc oxide nanoparticles (ZnO NPs) using Citrus medica L. leaf extract as a natural complexing and surface-stabilizing agent. The synthesized nanoparticles were examined by UV-Vis and FTIR spectroscopy, powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and BET surface area analysis. UV-Vis and FTIR analyses provided spectroscopic evidence of ZnO NPs formation, with an estimated optical bandgap of 3.32 eV. XRD analysis confirmed the hexagonal wurtzite crystal structure. FE-SEM and TEM images revealed predominantly quasi-spherical particles with an average diameter of 59 nm. BET analysis yielded a specific surface area of 35.231 m2/g and a pore volume of 1.7268 cm3/g. The antibacterial potential of the ZnO NPs was assessed against Gram-negative bacteria (E. coli, V. cholerae and S. typhi) and Gram-positive S. aureus, with concentration-dependent inhibitory activity observed across the tested strains. Their antioxidant potential was examined through DPPH radical scavenging, hydrogen peroxide scavenging and reducing power assays, which revealed concentration-dependent antioxidant responses.