Enantioselective Circular Dichroism Sensing of Cysteine and Glutathione with Gold Nanorods

Abstract

Enantioselective analysis of biological thiols, including cysteine (Cys) and glutathione (GSH), is extremely important because of their unique role in bioentities. Here we demonstrated that the end-to-end assemblies of plasmonic gold nanorods with chiral Cys or GSH can be used as a distinctive chiroptical sensor for reliable determination of the absolute configuration of Cys and GSH at the visible light region. The end-to-end assemblies of Au nanorods induced by Cys or GSH exhibit strong circular dichroism (CD) signals in the region of 500-850 nm, which is attributed to chiral current inside Au nanorods induced by the mixed biothiols. The CD intensity of the assemblies shows good linearity with the amount of Cys and GSH. The limit of detection for Cys and GSH using end-to-end assemblies is at micromolar concentrations. In addition, the sensing system exhibits good selectively toward Cys and GSH in the presence of other amino acids.