Optimization of silver nanoparticle biosynthesis process using cell-free filtrate of Aspergillus niger

Abstract

Nanotechnology and nanoparticle (NPs) research has attracted a lot of interest in recent decades, and there is growing attention to find more effective ways for their synthesis. The use of biological organism as bionanofactories provides a clean and promising alternative process for the fabrication of silver nanoparticles. This study confirmed the production of silver nanoparticles (SNPs) by a cost effective, safe and environment-friendly technique using silver nitrate and cell free filtrate of the fungus Aspergillus niger as the reducing agent. The optimization of different parameters, including the culture media, pH, reaction temperature, concentration of silver nitrate solution and reduction time, were carried out to achieve better control of size, shape, stability, and to increase the yield of SNPs production. The UV-visible spectrophotometric analysis of the biosynthesized silver nanoparticles by Aspergillus niger cell-free filtrate showed characteristic surface plasmon absorption peak at 420 nm. The presence of proteins as viable reducing agents for the formation and stability of SNPs was recorded using Fourier transform infrared spectroscopic analysis (FTIR) .Further scanning electron microscopy (SEM) micrograph showed the formation of spherical, well-dispersed nanoparticles with size ranging between 15 and 50 nm in diameter. The element composition of the mixture sample was obtained from the Energy Dispersive Analysis of X-ray (EDX). It concluded that the optimum condition for biosynthesis of SNPs were the use of Potato dextrose broth medium at pH 9, 30°C for 120 h with 1mM silver nitrate.