Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
J Am Chem Soc. 2010 Jan 20;132(2):725-36. doi: 10.1021/ja908215t.
Despite considerable efforts toward the development of various sophisticated spiropyrans for metal ion sensing, less attention has been paid to organic molecule sensing. One of the major difficulties for detection of organic molecules using a spiropyran is the weak and nonspecific interaction between the spiropyran and the target. Here, we report the synthesis and molecular recognition characterization of two bis-spiropyrans for dipolar molecules and their application to in vivo glutathione (GSH) fluorescent probes. Unlike the mono-spiropyrans, the newly designed bis-spiropyran molecules feature a rigidly maintained molecular cleft and two spiropyran units as binding modules. The molecular recognition is based on multipoint electrostatic interactions and structure complementarity between the opened merocyanine form of the spiropyran and the analyte. It was observed that the spiropyran 1a binds GSH in aqueous solution with high affinity (K = (7.52 +/- 1.83) x 10(4) M(-1)) and shows strong fluorescence emission upon binding. Remarkably, fluorescence output of 1a is not significantly affected by other amino acids and peptides, especially, structurally similar compounds, such as cysteine and homocysteine. Furthermore, fluorescence anisotropy and confocal fluorescent microscopy confirmed that spiropyran 1a is a comparatively good candidate for intracellular delivery and can be accumulated intensively into cells. Thus, 1a can be utilized in vivo as a GSH probe or as a marker to show the level of intracellular GSH.
尽管人们为开发各种用于金属离子传感的复杂螺吡喃化合物做出了相当大的努力，但对有机分子传感的关注较少。使用螺吡喃检测有机分子的主要困难之一是螺吡喃与目标之间的相互作用较弱且无特异性。在这里，我们报告了两种用于偶极分子的双螺吡喃的合成和分子识别特性及其在体内谷胱甘肽 (GSH) 荧光探针中的应用。与单螺吡喃不同，新设计的双螺吡喃分子具有刚性保持的分子裂缝和两个螺吡喃单元作为结合模块。分子识别基于螺吡喃开环的菁型形式与分析物之间的多点静电相互作用和结构互补性。观察到螺吡喃 1a 在水溶液中与 GSH 高亲和力结合（K = (7.52 +/- 1.83) x 10(4) M(-1)），结合后表现出强荧光发射。值得注意的是，1a 的荧光输出不受其他氨基酸和肽的显著影响，特别是结构相似的化合物，如半胱氨酸和同型半胱氨酸。此外，荧光各向异性和共聚焦荧光显微镜证实，螺吡喃 1a 是细胞内递送的较好候选物，可以密集地积累到细胞中。因此，1a 可以在体内用作 GSH 探针或作为标记物来显示细胞内 GSH 的水平。
