Designing bifunctionalized gold nanoparticle for colorimetric detection of Pb2+ under physiological condition

In the present work, a kind of peptide functionalized gold nanoparticle (AuNP) has been synthesized and employed for colorimetric detection of Pb2+ in both aqueous solution and living cell. The AuNPs are capped by two peptide ligands: glutathione (GSH) and pentapeptide (CALNN). The GSH is used as a functional group for selectively sensing Pb2+ by coordination reaction, and CALNN is employed as a stabilize ligand for improving the stability of AuNPs under physiological condition, respectively. The AuNP enables to strongly interact with Pb2+ that leads to distinct color change of solution. Under the optimized molar ratio of GSH to CALNN on the AuNP surface, the colorimetric assay for detecting Pb2+ in living cell downs to 2.9 fmol Pb(2+)per cell (3 times of standard deviation, 3 sigma) with linear relationship from 2.9 to 37.7 fmol Pb2+ per cell. In addition, the method also shows highly selective detection toward Pb2+ against other common metal ions in both aqueous solution and living cell. (C) 2011 Elsevier B.V. All rights reserved.