Zinc(II)-selective ratiometric fluorescent sensors based on inhibition of excited-state intramolecular proton transfer
Zinc(II)-selective ratiometric fluorescent sensors based on inhibition of excited-state intramolecular proton transfer
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DOI：
10.1002/chem.200305299
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发表时间：
2004-06-21
影响因子：
4.3
通讯作者：
Fahrni, CJ
中科院分区：
文献类型：
--
作者：
Henary, MM;Wu, YG;Fahrni, CJ
为了开发一种适合于生物应用的锌（II）选择性发射比探针，我们研究了一系列2-（2'-苯磺酰胺苯基）苯并咪唑衍生物对激发态分子内质子转移（ESIPT）的阳离子诱导抑制。在中性pH没有Zn-II的情况下，荧光团经过ESIPT从质子转移互变异构体中产生高度斯托克斯位移发射。Zn-II的配位抑制了ESIPT过程，并产生了荧光发射最大值的显着的次色移。顺磁性金属阳离子Cu-II、Fe-II、Ni-II、Co-II和Mn-II会导致荧光猝灭，而发射响应不会因Ca-II或Mg-II的毫摩尔浓度而改变，这使得传感器在所有重要的生物金属阳离子中对Zn-II具有选择性。由于荧光团的模块化结构，Zn-II的结合亲和力可以很容易地通过实施简单的结构修改来调整。所合成的探针适用于生理条件下测量游离Zn-II浓度在微摩尔到皮摩尔范围内。
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'-benzene-sulfonamidophenyl)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.