Rhodanine stabilized gold nanoparticles for sensitive and selective detection of mercury (II)

Self-assembling of rhodanine (R) on gold nanoparticles was used to construct a colorimetric sensor for detecting Hg2+ in aqueous media. Gold nanoparticles capped with R (AuNPs@R) were well dispersed in phosphate buffer (NaH2PO4-Na2HPO4) as clear wine red solutions. The presence of Hg2+ induced aggregation of AuNPs@R and resulted in a color change from wine red to blue. The experimental results indicated that formation of rhodanine-Hg2+-rhodanine (R-Hg2+-R) structure was the initial driving force of the aggregation, without the use of expensive DNA and complicated functionalization of AuNPs. This aggregation phenomenon is similar to that used for the determination of Hg2+ by thymine. The color change was successfully used for the determination of Hg2+. Under the optimum conditions, the linear relationship between the absorbance ratio A(650)/A(520) and Hg2+ concentration was in a range of 0.02-0.5 mu M, and the limit of the detection (LOD) was 6.0 nM. The color change was evident and it is possible to recognize the presence of Hg2+ as low as 0.1 mu M by the naked eye. The method avoids complicated surface modifications and tedious separation processes. Its applicability was verified by analysis of Hg2+ in tap water and lake water with the quantitative spike recoveries ranging from 94.8 to 110%. (C) 2017 Elsevier Ltd. All rights reserved.