Colorimetric Sensing of Silver(I) and Mercury(II) Ions Based on an Assembly of Tween 20-Stabilized Gold Nanoparticles

摘要

We have developed a rapid and homogeneous method fornthe highly selective detection of Hg2+ and Ag+ usingnTween 20-modified gold nanoparticles (AuNPs). Citratenions were found to still be adsorbed on the Aunsurface when citrate-capped AuNPs were modified withnTween 20, which stabilizes the citrate-capped AuNPsnagainst conditions of high ionic strength. When citratenions had reduced Hg2+ and Ag+ to form Hg-Au alloysnand Ag on the surface of the AuNPs, Tween 20 wasnremoved from the NP surface. As a result, the AuNPsnwere unstable under a high-ionic-strength solution,nresulting in NP aggregation. The formation of Hg-Aunalloys or Ag on the surface of the AuNPs was demonstratednby means of inductively coupled plasma massnspectroscopy and energy-dispersive X-ray spectroscopy.nTween 20-AuNPs could selectively detect Hg2+ andnAg+ at concentrations as low as 0.1 and 0.1 μM in thenpresence of NaCl and EDTA, respectively. Moreover,nthe probe enables the analysis of AgNPs with a minimumndetectable concentration that corresponds to 1npM. This probe was successfully applied to detect Hg2+nin drinking water and seawater, Ag+ in drinking water,nand AgNPs in drinking water.