Development of novel caged compounds that can report the yield of uncaged products

荧光成像是目前可用于连续观察活细胞内动态细胞内过程的最强大的技术。合适的荧光探针对于荧光成像自然是至关重要的，但由于缺乏灵活的荧光探针设计策略，目前只能显示非常有限的生物分子。目前，设计在很大程度上是经验的。我们证明了被广泛用作荧光探针核心的荧光素分子可以理解为一个直接连接的电子供体-荧光团受体系统，荧光素衍生物的荧光性质可以通过分子内光诱导电子转移来控制。基于这些光物理发现，我们可以构建第一个完全合理的新型荧光探针设计策略。到目前为止，我们可以开发以下新型荧光探针：(A)用于单线态氧的DPAX和DMAX，(B)用于一氧化氮的DAFS和DAMBOS，(C)用于包括羟基自由基和过氧亚硝酸盐在内的高活性氧物种的HPF和AIPF等。此外，我们成功地开发了新型的笼状化合物，通过使用亚硝基作为笼状保护基团和荧光素作为报告的荧光团，可以报告未笼化产物的产量作为荧光强度的增加。

Fluorescence imaging is the most powerful technique currently available for continuous observation of dynamic intracellular processes in living cells. Suitable fluorescence probes are naturally of critical importance for fluorescence imaging, but only a very limited range of biomolecules can currently be visualized because of the lack of flexible design strategies for fluorescence probes. At present, design is largely empirical. We demonstrated here that the fluorescein molecule, which has been widely employed as a core of fluorescence probes, could be understood as a directly linked electron donor -fluorophore acceptor system and that the fluorescence properties of fluorescein derivatives could be controlled by intramolecular photoinduced electron tranfer. Based on these photo-physical findings, we could construct the first and totally rational design strategy for novel fluorescence probes. We could develop so far the following novel fluorescence probes; (a) DPAXs and DMAXs for singlet oxygen, (b) DAFs and DAMBOs for nitric oxide, (c) HPF and AIPF for highly reactive oxygen species including hydroxyl radical and peroxynitrite, and so on. Further, we succeeded in developing novel caged compounds that can report the yield of uncaged products as an increase of fluorescence intensity by employing a nitrobeuzyl moiety as a caging protective group and fluorescein as a reporting fluorophore.