Facile green synthesis of gold nanostructures by NADPH-dependent enzyme from the extract of Sclerotium rolfsii

In this paper, we report the facile environmental friendly “greener synthesis” of anisotrophic nanostructures and isotrophic spherical gold nanoparticles using the cell-free filtrate of fungus, Sclerotium rolfsii. We found that NADPH-dependent enzyme present in the cell-free filtrate of S. rolfsii, when incubated with the aqueous chloroauric acid solution has the ability to synthesize gold nanoparticles within 10–15 min at ambient temperature. The morphologies of synthesized nanoparticles were anisotrophic like triangles, hexagonals, decahedrals, and rods and isotrophic sphericals. The synthesized isotrophic spherical nanoparticles were in the average size of ca. 25 nm and stable in aqueous solution up to 2 months. The shape and size of gold nanoparticles were modulated by the change in the ratio of metal salt and cell-free filtrate of S. rolfsii. Spherical and anisotrophic shapes like triangles, decahedrals, hexagonals and rods nanoparticles were produced at higher and lower concentrations of filtrate respectively. The controlled synthesis of well-defined size, shape and composition has enormous applications in the fields of biolabeling, biosensing, drug delivery, cancer therapy and catalysis.

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► Synthesis of AuNPs using the cell-free filtrate of Sclerotium rolfsii was described.
► UV–Vis absorption spectra showed facile formation of AuNPs in 10–15 min.
► XRD analysis showed intense peaks corresponding to the fcc structure of AuNPs.
► HR-TEM analysis confirmed the formation of stable anisotrophic and isotrophic AuNPs.
► SDS-PAGE showed NADPH-dependent enzyme may be responsible for the formation of AuNPs.