基于苯并吡喃腈的激活型半胱氨酸荧光探针

设计并合成了基于苯并吡喃腈为母体单元的近红外激活型荧光探针(E)-2-(苯并吡喃腈基)乙烯基-5-(二乙氨基)丙烯酸苯酯(DCM-AC),其结构中的丙烯酰酯键作为氨基酸激活反应的响应基团。 研究结果表明,探针分子DCM-AC对半胱氨酸具有高灵敏、选择性光谱响应,不仅能观察到明显的颜色变化,而且探针在710 nm处的荧光发射强度显著增强,相应的荧光增强比值与半胱氨酸的浓度(1.0~8.0 μmol/L)呈现良好的线性关系。 探针DCM-AC对半胱氨酸的检出限为2.8×10^-7 mol/L,能选择性检测半胱氨酸区别于结构类似的高半胱氨酸和谷胱甘肽,且不受其它氨基酸物质干扰。 通过质谱、核磁和紫外吸收光谱研究了DCM-AC检测半胱氨酸的反应激活机理:半胱氨酸先通过巯基与DCM-AC上的丙烯酰酯双键发生亲核加成,然后环化脱除内酰胺环状化合物。

A Turn-On Fluorescent Probe for Cysteine Based on Benzopyran

A benzopyran-based turn-on near-infrared probe (E)-2-(benzopyran)ethenyl-5-(diethylamino)phenyl acrylate(DCM-AC) has been successfully synthesized. Acrylate bond is specifically designed for the response units of amino acid. The results show that the spectral response of DCM-AC towards cysteine is highly sensitivity and selectivity. With increasing the concentration(1.0~8.0 μmol/L) of cysteine, a significant color change can be observed and the fluorescent intensity of DCM-AC at 710 nm increases gradually, showing a good linear relationship with concentration. The limit of detection of DCM-AC for cysteine is determined as 2.8×10^-7 mol/L. DCM-AC exhibits a highly selective probe for cysteine over homocysteine and glutathione, with no interference of other substances. The recognition mechanism of the DCM-AC to cysteine is verified by mass spectrum,¹H NMR titration and absorption spectra, indicating that cysteine thiol groups attack at acrylate double bond of DCM-AC by addition reaction, and finally removed as the cyclic lactam compound.