Visual Detection of Hg²⁺ with High Selectivity Using Thymine Modified Gold Nanoparticles

Abstract

Here, we describe a colorimetric sensor for detecting Hg²⁺ in aqueous media, which is simply constructed by the self-assembly of thymine acetamidoethanethiol (T-SH) on gold nanoparticles (AuNPs). Based on the specific interaction of Hg²⁺ with two thymines (T), the T-SH modified AuNPs can be induced to aggregate through the formation of a stable T-Hg-T complex in the presence of Hg²⁺, resulting in a color change from red to blue-gray. As low as 0.5 μM of Hg²⁺ can be easily monitored by the naked eye using this sensor. Other metal ions, including Zn²⁺, Cd²⁺, Pb²⁺, Ni²⁺, Cu²⁺, Co²⁺, Mn²⁺, Ba²⁺, Fe²⁺, Ca²⁺, Mg²⁺, Al³⁺, and Fe³⁺, could not cause any response, even at concentrations 100-fold higher than Hg²⁺. The high selectivity, high stability and easy operation enable this sensor suitable for the rapid on-site detection of Hg²⁺ pollution.