A dansyl-based fluorescent probe for turn-off and turn-on detection of Hg2+ in a full water system

A dansyl-based fluorescent probe, 2-((5-dimethylamino)naphthalene-1- sulfonamido)acetic acid (DNSG), was synthesized from dansyl chloride and glycine. In HEPES buffer (20 mM, pH 6.7), DNSG could detect Hg2+ by fluorescence quenching. The maximal fluorescence intensity showed a good linear relationship with the Hg2+ concentration (0 ~ 80 μM). The detection limit was 0.33 μM. With the help of silk fibroin (0.076 g/L), DNSG could detect Hg2+ by fluorescence enhancement and blueshift. The linear concentration range for Hg2+ was 0 ~ 160 μM with a detection limit of 0.81 μM. DNSG could detect Hg2+ quickly and reversibly with excellent anti-interference ability and further could assay environmental water sample efficiently. The sensing mechanism was examined by Job’s plot, mass spectrum and 1H NMR analysis.