Selective Detection of Mercury Ion by a Fluorescent Sensor Based on Dipeptide Containing Cysteine

Abstract

Two fluorescent peptidyl chemosensors containing cysteine and a dansyl group (DNS-γGlu-Cys, DNS-Cys-Glu) were prepared via Boc solution phase peptide synthesis for monitoring heavy metal ions on the basis of phytochelatin peptide sequence. DNS-Cys-Glu displayed a selective fluorescence turn-off response to Hg 2+ over other heavy metal ions. In contrast, the addition of various metal ions to DNS-γGlu-Cys resulted in no significant fluorescent changes. For DNS-Cys-Glu, because the thiol group of Cys is adjacent to the sulfonamide group, they can bind to Hg 2+ by cooperative electrostatic interactions. As a result, the quenching of the fluorescence intensity can be explained in terms of effective electron transfer from the excited dansyl fluorophore to the bound Hg 2+ . DNS-Cys-Glu could be applicable to homogeneous Hg 2+ detection.