Phyto-mediated synthesis of zinc oxide nanoparticles using aqueous plant extract of Ocimum americanum and evaluation of its bioactivity

Bionanotechnology has gained wide attention in the research field of modern materials science over the past decade. Biogenic synthesis of zinc oxide nanoparticles (ZnO NP) has been focused by researchers due to their non-toxicity and a broad range of applications. In the present work, spherical shape nanoparticles (average 21 nm size) were obtained using plant extract of Ocimum americanum. The biosynthesized ZnO NPs showed a strong absorption peak at 316 nm which is a characteristic feature of ZnO NPs. Further, biophysical characterization of synthesized ZnO NPs was carried out using Fourier transform infrared spectroscopy in comparison with plant extract to determine the possible functional groups involved in ZnO NPs formation, X-ray diffraction and confirmed the crystalline nature which is in accordance with JCPDS ID for ZnO NPs, scanning electron microscopy and dynamic light scattering for shape and size. Evaluation of antimicrobial efficacy of the biosynthesized ZnO NPs was found to be significant against four Gram-positive, four Gram-negative bacteria and two human pathogenic fungi. These results affirm that plant mediated ZnO NPs are potential for effective antioxidant and antimicrobial therapeutics.