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

► Water-soluble fluorescent Au NPs stabilized by captopril ► The synthesis procedure was simple, fast and facile. ► The fluorescence of the Au NPs can be strongly quenched by Hg2 +. ► The Au NPs were used to the assay of Hg2 + in water samples with high sensitivity and selectivity.