Selective colorimetric sensing of histidine in aqueous solutions using cysteine modified silver nanoparticles in the presence of Hg2+

Cysteine modified Ag nanoparticles were prepared in aqueous solution, via one-pot protocol, which were characterized by transmission electron microscopy ( TEM), Fourier transform infrared (FT-IR) and ultraviolet-visible spectroscopy (UV-vis). The nanoparticles provided a simple and rapid strategy to detect histidine (His) visually with the help of Hg2+ ions in solution. The colorimetric sensor allows a rapidly quantitative assay of histidine down to the concentration of 3 x 10(-5) M. The mechanism by which Hg2+ ions can bind with both the cysteine modified Ag nanoparticles and His molecule through cooperative metal-ligand interactions is discussed.