Department of Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China.
Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
Chem Asian J. 2023 Sep 1;18(17):e202300562. doi: 10.1002/asia.202300562. Epub 2023 Aug 8.
A water-soluble 1,2,4,5-tetrazine-substituted carbon-dipyrromethene (C-DIPY) was synthesized from the previously reported carbonyl pyrrole dimer through a two-step procedure. Owing to the presence of a tetrazine moiety, the fluorescence emission of this compound was largely quenched in phosphate-buffered saline at pH 7.4. Upon addition of a bicyclo[6.1.0]non-4-yne (BCN) derivative, the tetrazine-based quenching component of the compound was disrupted through the inverse electron-demand Diels-Alder reaction to restore the fluorescence in up to 6.6-fold. This bioorthogonal activation was also demonstrated using U-87 MG human glioblastoma cells, in which the fluorescence intensity of this C-DIPY could be enhanced by 8.7-fold upon post-incubation with the BCN derivative. The results showed that this tetrazine-caged C-DIPY can serve as a bioorthogonally activatable fluorescent probe for bioimaging. The compound, however, was found to reside preferentially in the lysosomes instead of the mitochondria of the cells as predicted based on its cationic character, which could be attributed to its energy-dependent endocytic cellular uptake pathway, for which lysosomes are the end station.
一种水溶性的 1,2,4,5-四嗪取代的碳二吡咯甲川（C-DIPY），是通过两步法从先前报道的羰基吡咯二聚体合成的。由于存在四嗪部分，该化合物在 pH 值为 7.4 的磷酸盐缓冲盐溶液中的荧光发射被大大猝灭。当加入双环[6.1.0]壬-4-炔（BCN）衍生物时，化合物中基于四嗪的猝灭部分通过逆电子需求 Diels-Alder 反应被破坏，荧光恢复了高达 6.6 倍。这种生物正交激活也在 U-87 MG 人神经胶质瘤细胞中得到了证明，其中该 C-DIPY 的荧光强度在与 BCN 衍生物孵育后可以增强 8.7 倍。结果表明，这种四嗪笼状 C-DIPY 可以作为一种生物正交激活的荧光探针用于生物成像。然而，该化合物被发现优先存在于溶酶体中，而不是细胞的线粒体中，这与其基于阳离子特性的预测一致，这可能归因于其依赖能量的内吞细胞摄取途径，溶酶体是其终末站。
