Sensitive detection of mercury (II) ion using water-soluble captopril-stabilized fluorescent gold nanoparticles

In our work, a simple, facile, and green method was developed for the synthesis of water-soluble and well-dispersed fluorescent gold nanoparticles (Au NPs) within 5 min, using captopril as a capping agent. The as-prepared Au NPs showed strong emission at 414 nm, with a quantum yield of 5.5%. The fluorescence of the Au NPs can be strongly quenched by mercury (II) ion (Hg^2 +) due to the stronger interactions between thiolates (RS^?) and Hg^2 +. It was applied to the detection of Hg^2 + in water samples in the linear ranges of 0.033–0.133 μM and 0.167–2.500 μM, with a detection limit of 0.017 μM. Therefore, the as-prepared Au NPs can meet the requirement for monitoring Hg^2 + in environmental samples.