Ultra-sensitive detection of mercury(II) ions in water sample using gold nanoparticles synthesized by Trichoderma harzianum and their mechanistic approach

The present study demonstrates a simple, cost effective and selective method for colorimetric detection of mercury(II) ions using gold nanoparticles (AuNPs) synthesized by non-pathogenic and agriculturally considerable fungal biomass of Trichoderma harzianum (T. harzianum). The synthesized nanoparticles were characterized by UV-vis spectroscopy (UV-vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The as-synthesized AuNPs were used further for the selective optical detection of Hg2+ ions. The color of AuNPs solution changes in the presence of Hg2+ ions and also a substantial change in the surface plasmon resonance (SPR) of nanoparticles was observed even at minute concentration of Hg2+ ions. The sensitivity and selectivity of AuNPs towards Hg2+ ions was also analyzed in the presence of Pb2+, Zn2+, Cd2+, Fe3+, Ni2+, Ca2+, Mn2+, Al3+, Co2+ and Na+ ions. The mechanism of colorimetric detection of Hg2+ ions was also discussed along with diagrammatic representation. (C) 2014 Elsevier B.V. All rights reserved.