Rhodamine-based fluorescent sensor for mercury in buffer solution and living cells

Abstract

A novel fluorescent sensor based on thiooxorhodamine B has been prepared to detect Hg 2+ in aqueous buffer solution. It demonstrates high selectivity for sensing Hg 2+ with about 383-fold enhancement in fluorescence emission intensity and micromolar sensitivity ( K d = 7.5 × 10 −6 mol L −1) in comparison with alkali and alkaline earth metal ions (K +, Na +, Mg 2+, Ca 2+) and other transition metal ions (Mn 2+, Ni 2+, Co 2+, Cu 2+, Zn 2+, Cd 2+, Ag +, Pb 2+, Cr 3+, Fe 3+). Meanwhile the distinct color changes and rapid switch-on fluorescence also provide ‘naked eyes’ detection for Hg 2+ over a broad pH range. Moreover, such sensor is cell-permeable and can visualize the changes of intracellular mercury ions in living cells using fluorescence microscopy.