Bioreduction synthesis of zinc oxide nanoparticles using Delonix regia leaf extract (Gul Mohar) and its agromedicinal applications

The bioreduction of Zinc nitrate hexahydrate using crude leaf extract of Gulmohar, by a combustion method at 400 °C was carried out to form the ZnO nanostructures. The structural, morphological and optic properties of the nanostructures were characterized by UV- Visible spectroscopy, XRD analysis, FTIR spectroscopy, SEM, and TEM. The antibacterial activity of pure wurtzite ZnO NPs was carried out by the Resazurin plate assay method followed by antifungal evaluation utilizing the food poisoning technique using bavistin as a positive control. The anticancer potential was performed using the HeLa cell line for the quantitative evaluation of MTT and apoptosis assay. Antibacterial effect of ZnO NPs on Escherichia coli and Staphylococcus aureus was in the range 0.25–0.0025 μg/ml and antifungal effect on Fusarium oxysporum and Phomposis azadirachtae was in the range of 100–700 μg/ml. The MTT assay and apoptosis analysis on the HeLa cell line particularized optimal cell uptake and cell toxicity on 24 h of exposure. This biogenic method based ZnO NPs synthesis flags the way indicating the significant microbicidal potential against selected plant and animal pathogenic microorganisms and also proved to have an optimal cytotoxic effect against HeLa cell lines. Therefore, these nanomaterials can act as promising nanoantibiotics for application in medicine.