Detection of Cysteine with Glutathione-capped Silver Nanoparticles in the Presence of Ni2+ Ions

Abstract

Glutathione-capped silver nano particles (AgGSH) were prepared by the reduction of silver nitrate using NaBH4, and then were used for the detection of cysteine (Cys) in aqueous solution in the presence of Ni2+ ions via absorption properties of the resulting structures. The synthesized and modified nanoparticles were characterized by IR spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and atomic force microscopy. UV-Vis spectroscopy is an effective characterization method because the AgGSH-Ni nano particles show intense surface plasmon resonance bands in the presence of Cys. The sensitivity of AgGSH-Ni nanoparticles toward other amino acids is negligible. Therefore, it is highly selective for detecting Cys in aqueous solutions. The AgGSH-Ni surface plasmon absorption linearly increases with the Cys concentrations in the range from 1 X 10(-4) to 1 X 10(-3) M. Furthermore, the detection limit of Cys is 1 x 10(-5) M.