A new quinoline-based fluorescent probe for Cd2+ and Hg2+ with an opposite response in a 100% aqueous environment and live cell imaging

Abstract

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 × 10⁻⁸ M and 9.8 × 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.