Li Xiang, Tong Xiao, Yin Yongheng, Yan Hong, Lu Changsheng, Huang Wei, Zhao Qiang
State Key Laboratory of Coordination Chemistry , School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , P. R. China . Email:
Key Laboratory for Organic Electronics & Information Displays , Institute of Advanced Materials , Nanjing University of Posts and Telecommunications , Nanjing 210023 , P. R. China . Email:
Chem Sci. 2017 Sep 1;8(9):5930-5940. doi: 10.1039/c7sc00160f. Epub 2017 May 30.
Mitochondria as vital intracellular organelles play critical roles in multiple physiological processes, and their polarity is a crucial characteristic that can reveal the intracellular environment and impact cellular events. In this work, we designed and synthesized a novel series of highly emissive and environmentally sensitive phosphorescent iridium(iii) complexes (, and ) functionalized by -carborane. These complexes showed high emission quantum yields both in solution and in solid state (up to = 0.82), long emission lifetime and tunable emission wavelength over 74 nm by introduction of a carboranyl motif in their ligands. Importantly, all the complexes have shown significant solvatochromic effects in contrast to the carborane-free control complex. Among them, complex shows the highest sensitivity to polarity of solvents with a MPPS (maximum peak phosphorescence shift) value of 42 nm and clear dependence of phosphorescence lifetime on solvent polarity. Interestingly, complex can easily penetrate into cells and preferentially distribute in mitochondria. To utilize these properties, the first phosphorescent imaging of mitochondrial polarity has been realized by photoluminescence lifetime imaging microscopy (PLIM), which can monitor mitochondria-relevant cellular processes such as cell apoptosis and distinguish cancer cells from normal cells. Compared to intensity-based sensing, lifetime-based detection is independent of the probe concentration, excitation power and photobleaching of probes, which can show high accuracy and reproducibility.
线粒体作为重要的细胞内细胞器，在多种生理过程中发挥着关键作用，其极性是一个至关重要的特征，能够揭示细胞内环境并影响细胞活动。在这项工作中，我们设计并合成了一系列新型的、具有高发射率且对环境敏感的磷光铱（III）配合物（、和），这些配合物由 -碳硼烷功能化。这些配合物在溶液和固态中均表现出高发射量子产率（高达 = 0.82）、长发射寿命，并且通过在其配体中引入碳硼烷基团，发射波长可在74 nm范围内调节。重要的是，与不含碳硼烷的对照配合物相比，所有配合物均表现出显著的溶剂化显色效应。其中，配合物对溶剂极性的敏感性最高，最大峰值磷光位移（MPPS）值为42 nm，且磷光寿命明显依赖于溶剂极性。有趣的是，配合物能够轻松穿透细胞并优先分布于线粒体中。为利用这些特性，通过光致发光寿命成像显微镜（PLIM）实现了线粒体极性的首次磷光成像，该成像能够监测与线粒体相关的细胞过程，如细胞凋亡，并区分癌细胞和正常细胞。与基于强度的传感相比，基于寿命的检测与探针浓度、激发功率和探针光漂白无关，能够显示出高准确性和可重复性。
