A simple and sensitive colorimetric method for detection of mercury ions based on anti-aggregation of gold nanoparticles

A simple and sensitive method for the colorimetric detection of mercury ions (Hg2+) has been proposed by using anti-aggregation of gold nanoparticles (AuNPs) based on the co-ordination between thymine and mercury ions. The thymine can bind to the AuNPs through Au–N bonds and induce aggregation of AuNPs. In the presence of Hg2+, the thymine was released from the surface of AuNPs via the formation of a thymine-Hg2+ coordination complex, leading to the dispersion of AuNPs. The detection reagent can be simply prepared by mixing thymine with citrate-capped AuNPs. This method is not only cost-effective, but also avoids complicated surface modifications and tedious separation processes.