Gold Nanoparticles: Microbial Synthesis and Application in Water Hygiene Management

TLDR

The study presents a green chemical method for synthesizing a nanogold‑bioconjugate aimed at purifying contaminated waters. Gold nanoparticles (~10 nm) were biosynthesized on Rhizopus oryzae via in‑situ reduction of HAuCl₄, and their interaction with contaminants and microbes was characterized by AFM, SEM, and fluorescence microscopy. The nanogold‑bioconjugate strongly adsorbs organophosphorous pesticides, confirms adsorption by EDXA, exhibits broad antimicrobial activity, and successfully produces potable water free of pathogens and pesticides in a single operation.

Abstract

A green chemical method to synthesize nanogold-bioconjugate and its eco-friendly promising role to purify contaminated waters has been described. Gold nanoparticles of 10 nm average diameter are produced on the surface of Rhizopus oryzae , a fungal strain, by in situ reduction of chloroauric acid (HAuCl(4)). The nanogold-bioconjugate (NGBC) showed strong adsorption capacity toward different organophosphorous pesticides. The EDXA study confirms adsorption of pesticides on the conjugate material surface. Morphological changes of the NGBC material after adsorption of organophosphorous pesticides were detected by atomic force micrographs. NGBC shows high antimicrobial activity against several Gram-negative and Gram-positive pathogenic bacteria as well as the yeasts Saccharomyces cerevisiae and Candida albicans . The treatment of microbial cells with NGBC caused rupture of cell membrane as revealed in scanning electron and fluorescence micrographs. These unique characteristics of NGBC have been successfully utilized to obtain potable water free from pathogens and pesticides in a single operation.