Cysteine Interactions in Glutathione Mediated Assembly of Silver Nanoparticles in the Presence of Metal Ions

Abstract

We report herein results of an investigation of the assembly of silver nanoparticles mediated by glutathione (GSH) and cysteine (Cys) interaction in the presence of metal ions: Ag+, Cd2+, Co2+, Cu2+, Fe3+, Hg2+, Ni2+, Pb2+, Zn2+. The silver nanoparticles produce well-ordered structures upon interaction with glutathione in variable acidic pH condition and exhibit pronounced changes in their optical properties arising due to electromagnetic interaction. The effect of selected metal ions on the nature of complexation as well as the variation in the optical response due to variable degree of complex formation amongst the particles have been investigated. The changes in optical properties of the silver nanoparticles have been accounted for the complex formation among the AgGSH, Cys and metal ions. The complexes have been characterized by UV-vis spectroscopy, FTIR, and AFM studies. It has been observed that the new absorption peaks appear and intensifies depending on the Cys and metal ion interaction. The AgGSH nanoparticles provided a simple and rapid strategy to detect Cys with the aid of metal ions in aqueous solution. Different metal ions give different UV-vis spectra profile and show different sensitivity. This new material allows a quantitative assay of Cys down to the concentration of 1x 10(-5) M in Co2+ ion complexation. The mechanism by which metal ions can bind with both the GSH modified Ag nanoparticles and Cys molecule through cooperative metal ligand interactions is discussed.