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

A novel fluorescent sensor based on thiooxorhodamine B has been prepared to detect Hg2+ in aqueous buffer solution. It demonstrates high selectivity for sensing Hg2+ with about 383-fold enhancement in fluorescence emission intensity and micromolar sensitivity (K-d = 7.5 x 10(-6) mol L-1) in comparison with alkali and alkaline earth metal ions (K+, Na+, Mg2+, Ca2+) and other transition metal ions (Mn2+, Ni2+, Co2+, Cu2+, Zn2+, Cd2+, Ag+, Pb2+, Cr3+, Fe3+). Meanwhile the distinct color changes and rapid switch-on fluorescence also provide 'naked eyes' detection for Hg2+ 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. (C) 2011 Elsevier Ltd. All rights reserved.