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

• The sensor can be applied to perform Hg2+ determination in tap water samples and lake water.
• The colorimetric aptasensor presented a high specificity for Hg2+ determination.
• The sensor exhibited low detection limit (0.5 nM) and wide linear range to Hg2+ determination (0.5–300 nM).

We provide a highly sensitive and selective colorimetric assay to detect mercury ions (Hg2+) in aqueous environment using thiocyanuric acid (TCA) molecule-functionalized gold nanoparticles (AuNPs). This method is based on the thiophilicity of Hg2+ 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 Hg2+, Hg2+ is more apt to interact with thiols than AuNPs. Thus, Hg2+ can remove the AuNPs of the TCA-functionalized AuNPs and trigger AuNP aggregation redisperse again. This assay can selectively detect Hg2+ with the detection limits as low as 0.5 nM in aqueous solution.

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