Single-step synthesis of ZnO nanoparticles using a phytosynthesis route and its characterization

Green synthesis of nanoparticles (NPs) is superior to conventional physical and chemical methods and increasingly becoming the preferred mode of synthesis nowadays. We report a method for phytosynthesis of ZnO NPs and their characterization for plausible diverse applications. ZnO NPs was synthesized using an extract of the leaves of Tagetes erecta L. (marigold), with optimum synthesis at a ratio of 1:150 for the leaf extract and salt solution (v/v), 150 mM zinc acetate at 85 °C and pH 6. The NPs were characterized using UV–vis spectrophotometer, FESEM, EDX, FT-IR, XRD, AFM, XPS, and ζ potential techniques. The band gap energy of the NPs was 3.44 eV. The IR spectrum confirmed the involvement of different phenolic and aromatic components of the plant extract as capping agents. The mean size of the NPs was ∼25 nm, using XRD and AFM techniques. The SEM image showed that the NPs were elongate with a rough surface. The EDX profile confirmed the purity of the preparation. UV–vis spectrophotometry and ζ potential data showed the NPs to be stable. SDS-PAGE of Saccharomyces cerevisiae cells exposed to 200 and 400 μg/mL NPs showed that expression levels of a few proteins were affected. The effect of the NPs on some microbes analyzed using agar well diffusion assay showed its antimicrobial potency indicating its potential use as an antimicrobial agent, especially against Gram-positive bacteria.