Fluorescence detection of Fe(3+) ions in aqueous solution and living cells based on a high selectivity and sensitivity chemosensor.

Although ferric ion (Fe(3+)) performs critical roles in diverse biochemical processes in living systems, its physiological and pathophysiological functions have not been fully explored due to the lack of methods for quantification of Fe(3+) ions in biological system. In this work, a highly sensitive and selective fluorescence chemosensor, L, was developed for the detection of Fe(3+) ions in aqueous solution and in living cells. L was facile synthesized by one step reaction and well characterized by NMR, API-ES, FT-IR, and elementary analysis. The prepared chemosensor displayed excellent selectivity for Fe(3+) ions detection over a wide range of tested metal ions. In the present of Fe(3+) ions, the strong green fluorescence of L was substantially quenched. The 1:1 stoichiometry of the complexation was confirmed by a Job's plot. The association constant (Ka) of L with Fe(3+) was evaluated using the Benesi-Hildebrand method and was found to be 1.36×10(4) M(-1). The MTT assay determined that L exhibits low cytotoxicity toward living cells. Confocal imaging and flow cytometry studies showed that L is readily interiorized by MDA-MB-231 cells through an energy-dependent pathway and could be used to detect of Fe(3+) ions in living cells.