Invited paperA water soluble, highly sensitive and selective fluorescent probe for Al3+ ions and its application in live cell imaging

- A simple, fluorescent aminothiazole based Al3+ sensor has been synthesized.
- Characterized by IR, NMR, UV-vis and ESI-mass spectral analysis.
- The sensor is selective for Al3+ over other competitor cations.
- Detection limit in Tris-HCl buffer (10 mM, pH ∼ 7.4) is 1.09 × 10−9 M.
- The accumulation of Al3+ in the cytoplasm of live cells can be detected.

An efficient, aminothiazole based, fluorescent probe (E)-2-(2-aminothiazol-5-yl)-N'-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide (NTH) for the detection of Al3+ ions was synthesized and characterized by different physico-chemical and spectroscopic tools. An attractive glowing blue color was observed in the presence of Al3+ with single channel emissions for NTH (λem 451 & λex 391 nm). NTH, selectively detected Al3+ ions among various other ions without any significant interference in Tris-HCl buffer solution (10 mM, pH ∼ 7.4). The >CN isomerization was responsible for the turn 'on' fluorescence response after Al3+ binding. The stoichiometry of NTH with Al3+ was determined to be 1:1 by Job's plot. The binding constant and limit of detection (LOD) were observed as 3.65 × 109 M−1 and 1.09 × 10−9 M, respectively. The 1H NMR titration and DFT studies were also performed in support of binding details of NTH-Al3+ complex. MTT assay on live A549 cells suggested viability of the probe to A549 cells even at higher concentration (100 μM) with no serious cytotoxicity in cells. Live cell imaging study clearly indicated that the accumulation of Al3+ in the cytoplasm of cells could be detected by NTH.

(E)-2-(2-aminothiazol-5-yl)-N'-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide (NTH) has been synthesized and characterized. This acts as highly selective fluorescent sensor for Al3+ over other cations. The binding constant (KB) and detection limit for Al3+ are determined.170