An anthracene-quinoline based dual-mode fluorometric-colorimetric sensor for the detection of Fe and its application in live cell imaging

An anthracene-quinoline based dual-mode chemosensor, anthracene-9-carboxylic acid quinoline-8-ylamide ( HAQ ), has been synthesized and fully characterized using elemental analysis, different spectroscopic methods, and single crystal X-ray diffraction analysis. HAQ acts as an "On-Off" fluorescent sensor toward Fe 3+ ions in DMSO solution with high selectivity and sensitivity over all other competitive metal ions. The limit of detection (LOD) for Fe 3+ and the binding constant ( K a ) for the resulting complex are 1.3 × 10 −6 M and 3.7 × 10 8 M −1 , respectively. Furthermore, HAQ displays a strong color change from colorless to bright yellow when exposed to Fe 3+ , which can be easily observed by the naked eye. The sensing mechanism and 1 : 1 binding stoichiometry of AQ − and Fe 3+ are confirmed using Job's plot, ESI-MS data, and computational studies. The in vitro cytotoxicity of the probe has been tested against the human breast cancer cell line MCF-7 using the MTT assay, showing a cell viability of more than 95% in the concentration range of 1.25-100 μM. The fluorescence imaging study revealed the good cell permeability of HAQ and its efficient cell staining ability; thus, the probe could be used to detect the accumulation of Fe 3+ in living cells. A highly sensitive anthracene-quinoline based dual-mode sensor has been synthesized and used for the fluorometric and colorimetric detection of Fe 3+ and in live cell imaging.