A highly sensitive and selective ratiometric fluorescent sensor for Zn2+ ion based on ICT and FRET

Abstract A ratiometric sensor ( QA ) for detecting Zn 2+ with high sensitivity and selectivity was reported. The fluorescence changes of sensor upon the addition of Zn 2+ were attributed to the conjugation of internal charge transfer and fluorescence resonance energy transfer mechanisms. There is a good linear relationship between the fluorescence ratio I 497 nm / I 420 nm and the concentrations of Zn 2+ ranging from 0 μM to 40 μM, which makes an effective ratiometric detection of Zn 2+ ion. The limit of detection (LOD) was evaluated to be 33.6 nM. The imaging experiments indicated that QA is cell-permeable and can be used to detect Zn 2+ within living cells with good selectivity over Cd 2+ .