Abstract：
Two interesting benzothizolium-based D-π-A type hemicyanine dyes (3a-3b) with a diphenylamine (-NPh2) donor group were evaluated for fluorescence confocal microscopy imaging ability in live cells (MO3.13, NHLF). In sharp contrast to previously reported D-π-A dyes with alkyl amine donor (-NR2) groups (1), 3a and 3b exhibited significantly different photophysical properties and organelle selectivity. Probes 3a and 3b were nearly non-fluorescent in many polar and non-polar solvents but exhibited a bright red fluorescence (λem ≈ 630-640 nm) in stained MO3.13 and NHLF with very low probe concentrations (i.e., 200 nM). Fluorescence confocal microscopy-based co-localization studies revealed excellent lysosome selectivity from the probes 3a-3b, which is in sharp contrast to previously reported D-π-A type benzothiazolium dyes (1) with an alkyl amine donor group (-NR2) (exhibiting selectivity towards cellular mitochondria). The photostability of probe 3 was found to be dependent on the substituent (R\') attached to the quaternary nitrogen atom in the cyanine dye structure. The observed donor-dependent selectivity switching phenomenon can be highly useful in designing novel organelle-targeted fluorescent probes for live-cell imaging applications.
摘要：
评估了具有二苯胺（-NPh2）供体组的两种有趣的基于苯并噻唑的D-π-A型半鸟嘌呤染料（3a-3b）在活细胞（MO3.13，NHLF）中的荧光共聚焦显微镜成像能力。与先前报道的具有烷基胺供体（-NR2）基团的D-π-A染料（1）形成鲜明对比，图3a和3b显示出显著不同的光物理性质和细胞器选择性。探针3a和3b在许多极性和非极性溶剂中几乎无荧光，但在探针浓度非常低的染色MO3.13和NHLF中显示出亮红色荧光（λem≈630-640nm）（即，200nM)。基于荧光共聚焦显微镜的共定位研究表明，探针3a-3b具有优异的溶酶体选择性，这与先前报道的具有烷基胺供体基团(-NR2)(表现出对细胞线粒体的选择性)的D-π-A型苯并噻唑染料(1)形成鲜明对比。发现探针3的光稳定性取决于与花青染料结构中季氮原子相连的取代基（R\'）。观察到的供体依赖性选择性转换现象对于设计用于活细胞成像应用的新型细胞器靶向荧光探针非常有用。
