Biosynthesis of ZnO nanoparticles using Melia azedarach seed extract: Evaluation of the cytotoxic and antimicrobial potency

ZnO nanoparticles (NPs) synthesized by using an aqueous extract of Melia azedarach seed are reported in this paper. The structural, morphological, compositional, and optical properties of the NPs were evaluated. A hexagonal phase with spherical morphology and an average crystallite size of 57.74 nm was obtained. Optical studies indicated a maximum absorption peak around 296 nm and bandgap energy of 3.88 eV. Cytotoxicity assay of both the plant extract and the as-prepared ZnO nanoparticles against the human hepatoma (HepG2) cell line showed that the M. azedarach seed-mediated ZnO nanoparticles were less toxic compared to ZnO synthesized by the conventional method, while the plant itself showed dose-dependent low toxicity. ZnO nanoparticles by the green route also exhibited good antibacterial activity, with higher efficiency for Gram-negative bacteria than Gram-positive bacteria.