title: Biosynthesis and safety evaluation of ZnO nanoparticles.
abstract: The secrets gleaned from nature have led to the development of biomimetic approaches for the growth of advanced nanomaterials. Biological methods for nanoparticle synthesis using microorganisms, enzymes, and plants or plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical methods. Here, we report extracellular mycosynthesis of ZnO-NPs by Alternaria alternata (Fr.) Keissl (1912). On treating zinc sulfate solution with fungal culture filtrate, rapid reduction of ZnSO₄ was observed leading to the formation of highly stable ZnO-NPs in the solution and up-to-date literature survey showed this was the first report of biosynthesis of ZnO-NPs using this fungus. The particles thereby obtained were characterized by different analytical techniques. EDX-spectrum revealed the presence of zinc and oxygen in the nanoparticles. FTIR spectroscopy confirmed the presence of a protein shell outside the nanoparticles which in turn also support their stabilization. DLS and TEM analysis of the ZnO-NPs indicated that they ranged in size from 45 to 150 nm with average size of 75 ± 5 nm. But potential negative impacts of nanomaterials are sometimes overlooked during the discovery phase of research. Therefore, in the present study, bio-safety of mycosynthesized ZnO-NPs were evaluated by using cytotoxicity and genotoxicity assays in human lymphocyte cells, in vitro. Cytotoxicity studied as function of membrane integrity and mitochondrial dehydrogenase activity revealed significant (P < 0.05) toxicity at treatment concentration of 500 μg/ml and above. Additionally, DNA damaging potential was also studied using comet assay. The results revealed significant genotoxicity at the highest concentration (1,000 μg/ml).
authors.affiliation: Molecular and Applied Mycology and Plant Pathology Laboratory, Department of Botany, University of Calcutta, Kolkata, 700019, India.
authors.forename: Joy
authors.initials: J
authors.lastname: Sarkar
authors.forename: Manosij
authors.initials: M
authors.lastname: Ghosh
authors.forename: Anita
authors.initials: A
authors.lastname: Mukherjee
authors.forename: Dipankar
authors.initials: D
authors.lastname: Chattopadhyay
authors.forename: Krishnendu
authors.initials: K
authors.lastname: Acharya
mesh_terms: D000528:Alternaria / Q000378:metabolism; D002478:Cells, Cultured; D020552:Comet Assay; D004249:DNA Damage; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000648:ultrastructure; D053768:Metal Nanoparticles / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D015034:Zinc Oxide