Azomethine-H as a Highly Selective Fluorescent Probe for Fe 3+ Detection in 100% Aqueous Solution and Its Application in Living Cell Imaging

A simple assay for the detection of Fe3+ in water by means of fluorescence spectroscopy was developed based on a commercially available reagent, Azomethine-H(A-H), allowing sensing trace levels of Fe3+ with high selectivity over other cations. A significant fluorescence quenching of A-H at 424 nm was found after its binding with Fe3+ in 100% aqueous solution at pH=7.0, while other physiologically relevant metal ions posed little interference. The fluorescence responses can be well described by the modified Stern-Volmer equation. A good linear relationship(R 2=0.9904) was observed up to 1.6×10–5 mol/L Fe3+ ions. The detection limit, calculated via the 3σ IUPAC(international union of pure and applied chemistry) criteria, was 1.95×10–7 mol/L. Moreover, the colorimetric and fluorescent response of A-H to Fe3+ can be conveniently detected by the naked eye, providing a facile method for visual detection of Fe3+. The proposed method was used to determine Fe3+ in water samples. Moreover, inverted fluorescence microscopy imaging using human umbilical vein endothelial cells shows that A-H can be used as an effective fluorescent probe for detecting Fe3+ in living cells.