A new quinoline-based fluorescent probe for Cd(2+) and Hg(2+) with an opposite response in a 100% aqueous environment and live cell imaging.

A new quinoline-based fluorescent probe L was synthesized and characterized. Probe L showed opposite fluorescence responses toward Cd2+ (turn-on) and Hg2+ (turn-off) in a 100% aqueous environment. X-ray crystallography analysis and TD-DFT calculations showed the different mechanisms of CHEF-based for L-Cd2+ and PET-based for L-Hg2+ caused by different binding modes and different electronic transfer patterns. The detection limits for the analysis of Cd2+ and Hg2+ ions were found to be 3.9 x 10(-8) M and 9.8 x 10(-7) M, respectively. Its in vivo sensitivities to Cd2+ and Hg2+ were demonstrated in the EC9706 cell line with the use of a laser scanning fluorescence microscope.