A turn-on Schiff base fluorescent probe for the exogenous and endogenous Fe ion sensing and bioimaging of living cells

A Schiff base fluorescent probe, namely naphthalic anhydride - (2-pyridine) hydrazone ( NAH ), has been synthesized and developed for the highly selective and sensitive monitoring of Fe 3+ ions in an aqueous solution and living cells. The enhanced fluorescence emission intensity of NAH has been observed upon the introduction of Fe 3+ with a large Stokes shift of 100 nm, and the trace levels of Fe 3+ at 38.3 nM can be monitored with no interference from other existing metal ions. Moreover, the recognition mechanism of NAH with Fe 3+ has been discussed via ESI-MS, 1 H NMR and FT-IR techniques. The binding mode of NAH with Fe 3+ is found to be 1 : 1 complex with the binding constants ( K a ) of 1.77 × 10 6 M −1 . In addition, NAH has been demonstrated to be nontoxic by cytotoxicity experiments and successfully proved to be a good probe for exogenous and endogenous Fe 3+ sensing in living cells. A Schiff base fluorescent probe, namely naphthalic anhydride - (2-pyridine) hydrazone ( NAH) , has been synthesized and developed for the highly selective and sensitive monitoring of Fe 3+ ions in an aqueous solution and living cells.