GREEN SYNTHESIS AND COMPARATIVE BIOLOGICAL EVALUATION OF ZINC OXIDE AND SELENIUM DIOXIDE NANOPARTICLES USING AEGLE MARMELOS LEAF EXTRACT

Abstract

The present study explored a simple plant-based route for synthesizing Zinc oxide nanoparticles (ZnONPs) and Selenium dioxide nanoparticles (SeO₂NPs) using Aegle marmelos leaf extract. The work combined phytochemical screening with physicochemical characterization and two biological assays, antioxidant and antibacterial activity. The synthesized materials were examined by UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and zeta potential analysis. The leaf extract contained phenolic compounds, alkaloids, reducing sugars, saponins, terpenoids, flavonoids, steroids and glycosides. ZnONPs showed an absorption maximum in the 340–350 nm region, whereas SeO₂NPs showed a maximum around 240 nm. The zeta potentials were −30.3 mV for ZnONPs and −29.7 mV for SeO₂NPs. Total phenolic content was 6.99 ± 0.59, 2.31 ± 0.17 and 2.92 ± 0.13 μg/mL for the plant extract, ZnONPs and SeO₂NPs, respectively. In the DPPH assay, SeO₂NPs gave the lowest IC₅₀ (45.82 μg/mL), followed by ZnONPs (50.52 μg/mL) and the plant extract (56.37 μg/mL). SeO₂NPs also produced the largest inhibition zones against Bacillus subtilis (30 mm) and Escherichia coli (22 mm). Taken together, the results suggest that A. marmelos leaf extract can serve as a useful biological medium for nanoparticle synthesis and that the resulting SeO₂NP preparation showed the strongest biological activity among the materials tested.