Henary Maged M, Wu Yonggang, Fahrni Christoph J
School of Chemistry and Biochemistry, Georgia Institute of Technology, 770 State Street, Atlanta, GA 30332, USA.
Chemistry. 2004 Jun 21;10(12):3015-25. doi: 10.1002/chem.200305299.
To develop a zinc(II)-selective emission ratiometric probe suitable for biological applications, we explored the cation-induced inhibition of excited-state intramolecular proton transfer (ESIPT) with a series of 2-(2'-benzenesulfonamidophenyl)benzimidazole derivatives. In the absence of Zn(II) at neutral pH, the fluorophores undergo ESIPT to yield a highly Stokes' shifted emission from the proton-transfer tautomer. Coordination of Zn(II) inhibits the ESIPT process and yields a significant hypsochromic shift of the fluorescence emission maximum. Whereas the paramagnetic metal cations Cu(II), Fe(II), Ni(II), Co(II), and Mn(II) result in fluorescence quenching, the emission response is not altered by millimolar concentrations of Ca(II) or Mg(II), rendering the sensors selective for Zn(II) among all biologically important metal cations. Due to the modular architecture of the fluorophore, the Zn(II) binding affinity can be readily tuned by implementing simple structural modifications. The synthesized probes are suitable to gauge free Zn(II) concentrations in the micromolar to picomolar range under physiological conditions.
为了开发一种适用于生物应用的锌（II）选择性发射比率探针，我们用一系列2-（2'-苯磺酰胺基苯基）苯并咪唑衍生物探索了阳离子诱导的激发态分子内质子转移（ESIPT）抑制作用。在中性pH且不存在锌（II）的情况下，荧光团发生ESIPT，从质子转移互变异构体产生高度斯托克斯位移发射。锌（II）的配位抑制了ESIPT过程，并使荧光发射最大值发生显著的紫移。虽然顺磁性金属阳离子铜（II）、铁（II）、镍（II）、钴（II）和锰（II）会导致荧光猝灭，但毫摩尔浓度的钙（II）或镁（II）不会改变发射响应，这使得该传感器在所有生物学上重要的金属阳离子中对锌（II）具有选择性。由于荧光团的模块化结构，通过进行简单的结构修饰可以很容易地调节锌（II）的结合亲和力。合成的探针适用于在生理条件下测量微摩尔到皮摩尔范围内的游离锌（II）浓度。
