A non-aggregation spectrometric determination for mercury ions based on gold nanoparticles and thiocyanuric acid

We provide a highly sensitive and selective colorimetric assay to detect mercury ions (Hg(2+)) in aqueous environment using thiocyanuric acid (TCA) molecule-functionalized gold nanoparticles (AuNPs). This method is based on the thiophilicity of Hg(2+) and AuNPs as well as the unique optical properties of TCA-functionalized AuNPs. In the presence of TCA, AuNPs aggregate due to the strong attraction between thiol groups of TCA and surface-bounded AuCl4(-)/AuCl2(-) ions, which induces the visible color change from red to blue. With the addition of Hg(2+), Hg(2+) is more apt to interact with thiols than AuNPs. Thus, Hg(2+) can remove the AuNPs of the TCA-functionalized AuNPs and trigger AuNP aggregation redisperse again. This assay can selectively detect Hg(2+) with the detection limits as low as 0.5 nM in aqueous solution.