Bioreduction of Gold Ions from Anisotropic to Isotropic Nanostructures by NADPH‐Dependent Reductase from Bipolaris oryzae

Abstract

AbstractHere, we report an eco‐friendly, benign and rapid mycogenic synthesis of gold nanoparticles of various shapes using cell‐free extract of the fungus Bipolaris oryzae (B. oryzae). Three different volumes of cell‐free extract of the fungus were exposed to an aqueous solution of gold chloride and in all three cases, there is a gradual color change from light yellow to pink indicating the formation of gold nanoparticle. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) dependent enzyme present in the cell‐free extract of the fungus B. oryzae leads to the rapid reduction of Au3+ to Au0 within 5–10 min when incubated with an aqueous solution of gold chloride. UV‐visible and fourier transform infra red (FTIR) spectroscopy measurements show the presence of aminoacids, such as tyrosine/phenylalanine and proteins as the possible capping agent. High‐resolution transmission electron microscopy (HR‐TEM) revealed the morphology of the structures were anisotropic triangles, hexagons, decahedrals and isotropic spheres. Isotropic spherical nanoparticles and anisotropic nanoparticles such as triangles, hexagons and decahedrals were produced at higher and lower volumes of the fungal extract, respectively. Rapid and sustainable approach for the production of gold nanoparticles of various shapes such as the one reported has a plethora of applications in the field of life‐sciences and medicine.