A ratiometric probe based on coumarin-quinoline for highly selective and sensitive detection of Zn2+ ions in living cells

Abstract A new fluorescent probe T2 for Zn2+, by employing coumarin and quinoline as the detection platform, was rationally designed and synthesized. Of particular significance was that T2 showed a specific colorimetric and ratiometric response towards Zn2+ without interference from other biologically important cations. T2 also displayed high affinity towards Zn2+ ions with a Kd of 0.98 μM with a visually detectable color change from yellow to pale red in absorption, and from green to yellow in emission. The detection limit for Zn2+ was estimated at 48.1 nM, which was below the threshold limit value of Zn2+ in drinking water (46 μM) according to World Health Organization. Moreover, the probe T2 displayed low cytotoxicity and good cell membrane permeability at physiological temperature. The imaging of Zn2+ in living cells and the quantitative determination of Zn2+ levels in the real water samples were successfully demonstrated. This study developed a new receptor toward Zn2+ for the further study on the qualitative and quantitative determination of Zn2+ in the biological system.