A sensitive Hg(II) colorimetric sensor based on synergistic catalytic effect of gold nanoparticles and Hg

An ultrasensitive colorimetric assay for Hg2+ detection was presented based on synergistic catalytic effect of gold nanoparticles (AuNPs) and Hg. The AuNPs could catalyze the reduction of Hg2+ by surface-capping citrate. The effect of Hg2+ uptake implied amalgam formation and increased the surface area of AuNPs, leading to remarkable catalytic amplification of the peroxidase-like activity of AuNPs. On the basis of this effect, 3,3',5,5'-tetramethylbenzidine (TMB) as colorimetric probes could be catalyzed into a black blue product in the presence of H2O2. The detection limit of the colorimetric assay for Hg2+ is 0.1 nM. Furthermore, the detection limit of Hg2+ in river water samples and tap water samples are 0.66 nM, and 0.43 nM, respectively. The results are far below the World Health Organization (WHO) permissible limit (30 nM). The assay is highly sensitive, specific, and able to detect Hg2+ rapidly without requiring sophisticated equipment. In addition, our strategy could also be used as a promising and convenient approach for detection of the target in environmental protection. (c) 2016 Elsevier B.V. All rights reserved.