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

• On the basis of FRET, a new rhodamine derivative was synthesized as a ratiometric fluorescent probe for detecting Hg2 +.
• The 1:1 stoichiometric structure between DRh and Hg2 + were supported by Job's plot, MS and DFT theoretical calculations.
• Linear response, high selectivity and sensitivity were observed. The LOD of Hg2 + is 0.008 μmol L− 1.
• The probe DRh has been successfully applied in monitoring of Hg2 + in water and biological samples.

On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg2 + in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H2O/CH3CN (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 Hg2 +. Upon the addition of Hg2 +, the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg2 + were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio (I582/I538) is proportional to the concentration of Hg2 + in the range 0–30 μmol L− 1. The limit of detection (LOD) of Hg2 + is 0.008 μmol L− 1 (base on S/N = 3). The present probe was applied to the determination of Hg2 + 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 Hg2 + detection in HeLa cells.

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