Green Synthesis of Zinc Oxide Nanoparticles from Vernonia amygdalina Leaf Extract and Evaluation of their Antioxidant, Antimicrobial, and Photocatalytic Activities

aims: The purpose of this research was to synthesize zinc oxide nanoparticles (ZnO NPs) using Vernonia amygdalina leaf extract (VAE) and evaluate its antioxidant, photocatalytic, and antibacterial activities. background: Vernonia amygdalina belongs to the family Asteraceae, and the leaf extract has been used ethnobotanically in the treatment of gastrointestinal disorders, malaria, diabetes mellitus, and hiccups. objective: The purpose of this research was to synthesize zinc oxide nanoparticles (ZnO NPs) using Vernonia amygdalina leaf extract (VAE) and evaluate its antioxidant, photocatalytic, and antibacterial activities. method: Antioxidant activities of VAE and ZnO NPs were evaluated through their inhibitory action on 2,2-diphenylpicrylhydrazyl (DPPH) radical, with ascorbic acid being the positive control. The green-synthesized ZnO NPs were evaluated using UV-VIS spectroscopy, FTIR, XRD, EDX, and SEM. result: Antioxidant activities of VAE and ZnO NPs were evaluated through their inhibitory action on 2,2-diphenylpicrylhydrazyl (DPPH) radical, with ascorbic acid being the positive control. The green-synthesized ZnO NPs were evaluated using UV-VIS spectroscopy, FTIR, XRD, EDX, and SEM. The synthesis of ZnO NPs was validated with the UV-VIS absorption spectra at 390 nm. The morphology of formulated ZnO NPs was smooth and spherical with a mean particle size of 78.25 nm. FTIR spectroscopy revealed distinct functional groups that played a vital role in the synthesis and stability of the nanoparticles. The XRD results showed three (3) characteristic peaks at 2θ angles of 24°, 28°, and 35°. The result of the antioxidant assay showed that the free radical scavenging effect of the synthesized ZnO NPs was significantly greater than that of the extract VAE (P < 0.05). The result of the EDX analysis revealed the composition of the synthesized NPs, which contained 44.4% oxygen and 55.6% zinc. The green synthesized ZnO NPs demonstrated the highest methylene blue (MB) dye degradation rate at 75 conclusion: The biosynthesized Vernonia amygdalina ZnO NPs demonstrated significant photocatalytic, antibacterial, and antioxidant activities. other: The biosynthesized Vernonia amygdalina ZnO NPs demonstrated significant photocatalytic, antibacterial, and antioxidant activities.