N-1-(2-Mercaptoethyl)thymine modification of gold nanoparticles: a highly selective and sensitive colorimetric chemosensor for Hg2+

An approach for mercury ions (Hg2+) sensing based on the Hg2+-induced aggregation of thymine (T)–SH-functionalized gold nanoparticles (AuNPs) has been reported. The T–SH ligands that we synthesized can easily be coupled to the surface of AuNPs through the Au–S bond and can recognize Hg2+ with high selectivity by forming a T–Hg–T complex with strong affinity. For the T–SH-functionalized AuNPs (T–S-AuNPs) sensor, upon addition of Hg2+, the formation of the T–Hg–T complex induces aggregation of T–S-AuNPs and results in a significant change of color and UV-Vis absorption spectra. Thus, our method can be used for the rapid, easy and reliable screening of Hg2+ in aqueous solution, with high sensitivity (2.8 nM) and selectivity over competing analytes. The developed method is successfully applied to the sensing of Hg2+ in real environmental samples.