A FRET-based fluorescent probe for mercury ions in water and living cells.

Abstract On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg 2 + in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H 2 O/CH 3 CN (9:1, v / v ; Tris-HCl 50 mmol L − 1 ; pH = 7.0) solution by the UV–Vis spectrophotometry and the fluorescence spectrophotometry. The results showed that the probe DRh exhibited the selective recognition of Hg 2 + . Upon the addition of Hg 2 + , the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg 2 + were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio ( I 582 / I 538 ) is proportional to the concentration of Hg 2 + in the range 0–30 μmol L − 1 . The limit of detection (LOD) of Hg 2 + is 0.008 μmol L − 1 (base on S/N = 3). The present probe was applied to the determination of Hg 2 + in neutral water samples and gave recoveries ranging from 104.5 to 107.9%. Furthermore, the fluorescent probe also can be applied as a bioimaging reagent for Hg 2 + detection in HeLa cells.