Structural characterization and evaluation of mycogenic zinc oxide nanoparticles from the cell-free culture-extract of <i>Aspergillus niger</i>

Abstract

Advances in the biological synthesis of nanoparticles have attracted decisive research attention in recent years. This is due to their eco- friendliness, nontoxicity and large spectra of applications. In this work, the structural characteristics and the purity of biogenic zinc oxide  (ZnO) nanoparticles were assessed. Zinc oxide (ZnO) nanoparticles were synthesized extracellularly using the culture filtrate of  Aspergillus niger, in the presence of zinc acetate dihydrate, as a precursor. The structural characteristics and purity of the nanoparticles  were examined using standard characterization methods viz UV-visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transmission infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). Results revealed a peak at  311nm and whitish and spherical particles with particulate sizes between 30 and 40 nm for the UV- -1 visible spectroscopy and SEM  respectively. On the FT-IR scale, absorption peaked at 548 cm in the spectra region known for the functional groups of ZnO nanoparticles;  while the average crystalline size was 21 nm based on XRD analysis. Findings in this study revealed that the ecofriendly  biogenic nanoparticles synthesized by common fungi, such as Aspergillus niger, possess desirable qualities comparable to those from  non-ecofriendly and costly chemical processes, which are currently employed for an array of applications.