Development of copper(I) fluorescent sensors based on photoinduced electron transfer mechanism and their application to optical imaging of cells

我们开发了铜(I)选择性荧光探针，作为监测活细胞中铜离子行为的化学工具。我们首先合成了各种含硫醚的配体，并制备了相应的铜(I)配合物。这些铜(I)配合物的光谱测量和x射线晶体结构分析表明，硫醚配体的连接链长度强烈影响铜(I)离子的亲和力、结合方式和铜的氧化还原电位。接下来，我们开发了基于氧化裂解机制的新型铜(I)荧光探针。这些探针含有还原形式的荧光素和TPA四齿配体，它们通过苄醚基团连接。我们发现，将铜(I)加入到含有亚毫米谷胱甘肽的探针溶液中，可以观察到强烈的荧光。同样的反应甚至在细胞中也会发生。因此，这将是探测细胞内铜(I)离子行为的有用化学工具。

We have developed copper(I)-selective fluorescent probes as a chemical tool for monitoring behavior of copper ions in living cells. We initially synthesized various tioether-containing ligands and prepared the corresponding copper(I) complexes. Spectroscopic measurements and X-ray crystal structure analysis of these copper(I) complexes indicate that the linker chain length of the thioether ligand strongly affect the affinity toward copper(I) ion, binding fashion, and redox potential of copper. We next developed novel copper(I) fluorescent probes based on the oxidative cleavage mechanism. These probes contain a reduced form of fluorescein and TPA tetradentate ligand, those are linked through a benzyl ether group. We found that strong fluorescence is observed when copper(I) is added to the probe solution containing sub mM of gluthatione in water. The same reaction undergoes even in cells. Therefore, this will be useful chemical tool to probe intracellular copper(I) ion behavior.