High-efficiency photocatalytic degradation of antibiotics and molecular docking study to treat the omicron variant of COVID-19 infection using biosynthesized ZnO@Fe₃O₄ nanocomposites

Abstract

In this study, ZnO@Fe3O4 nanocomposite (NC) was synthesized using a green synthesis method with Mentha pulegium leaf extract. Characterization techniques such as UV–vis, FTIR, SEM, TGA, and XRD were employed to confirm the formation of ZnO@Fe3O4 NC and thermogravimetric analysis to evaluate the breakdown of NC in the presence of heat. XRD analysis showed a crystallite size of about 25.59 nm and SEM images of ZnO@Fe3O4 NC revealed spherical-shaped agglomerated particles. The optical bandgap energy of the ZnO@Fe3O4 NC was estimated to be 2.51 eV for direct bandgap and 1.57 eV for allowable indirect bandgap. Photocatalytic activity of the ZnO@Fe3O4 NC was evaluated for the degradation of Amoxicillin, Cephalexin, and Metronidazole antibiotics under sunlight irradiation, showing degradation efficiencies of 71%, 69%, and 99%, respectively, suggesting the potential of ZnO@Fe3O4 NC for removal of antibiotics from waterways. First-principles theory was employed to establish the adsorption energy (Ead) of the antibiotic species, including Amoxicillin, Cephalexin, and Metronidazole, on the surface of ZnO@Fe3O4 nanocomposite, which was found to be −8.064, −8.791, and −21.385 eV, respectively, indicating strong adsorption. Furthermore, molecular docking studies were conducted to upgrade Fe3O4 nanoparticles to ZnO@Fe3O4 NC to enhance composite efficiency. Leveraging the FDA-approved use of Fe3O4 nanoparticles and their known antiviral activity, our docking experiment demonstrated promising results in the interaction between ZnO@Fe3O4 nanocomposite and the spike protein receptor-binding domain of SARS-CoV-2 S Omicron. These findings suggest that ZnO@Fe3O4 nanocomposite could potentially inhibit virus attachment to host cell receptors more stably, providing a promising avenue for further exploration in developing effective medications against SARS-CoV-2.