A highly selective fluorescent probe for nanomolar detection of ferric ions in the living cells and aqueous media
Jung-Seop Lee, Shrikant Dashrath Warkad, Pramod B. Shinde, Anil Kuwar, Satish Balasaheb Nimse
Abstract
A dipodal fluorescent probe 3, with imine and hydroxyl moieties as binding sites, has been synthesized and characterized with spectroscopic methods, single-crystal X-ray techniques, and DFT. The synthesized probe 3 (φ = 0.0028) showed highly sensitive and highly specific fluorescent ‘turn-on’ effect (λem = 453 nm) for the 1:1 binding with Fe3+ ions to form probe 3.Fe3+ complex (φ = 0.203) in semi-aqueous medium (acetonitrile:water (50:50; v/v)) and live cells. The 1:1 binding stoichiometry of probe 3 and Fe3+ ions was proposed by DFT calculations and confirmed by the NMR spectroscopy, crystal structures of probe 3 and 3.Fe3+ complex, and mass spectrum of probe 3.Fe3+ complex. The stability of probe 3.Fe3+ complex in a wide pH range (pH 2–12) and reversibility for binding with Fe3+ ions in the presence of EDTA indicates that it can be an effective chemosensor for the detection of Fe3+ ions in various samples, including living cells. Importantly, with the LOD of 21.5 nM for the detection of Fe3+ ions, probe 3 did not show any interference from potentially competing ions even at a 1:3 ratio, indicates its biocompatibility. The nanomolar limit of detection (21.5 nM), cell permeability, and low cytotoxicity allows the probe 3 to be an excellent tool for the live-cell imaging and detection of ferric ions in live cells.