The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation, State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P.R. China.
Analyst. 2017 Nov 20;142(23):4522-4528. doi: 10.1039/c7an01280b.
There is increasing evidence indicating that lysosomal HO is closely related to autophagy and apoptotic pathways under both physiological and pathological conditions. Therefore, fluorescent probes that can be exploited to visualize HO in lysosomes are potential tools for exploring diverse roles of HO in cells. However, functional exploration of lysosomal HO is limited by the lack of fluorescent probes capable of compatibly sensing HO under weak acidic conditions (pH = 4.5) of lysosomes. Lower spatial resolution of the fluorescent visualization of lysosomal HO might be caused by the interference of signals from cytosolic and mitochondrial HO, as well as the non-specific distribution of the probes in cells. In this work, we developed a lysosome-locating and acidic-pH-activatable fluorescent probe for the detection and visualization of HO in lysosomes, which consists of a HO-responsive boronate unit, a lysosome-locating morpholine group, and a pH-activatable benzorhodol fluorophore. The response of the fluorescent probe to HO is significantly more pronounced under acidic pH conditions than that under neutral pH conditions. Notably, the present probe enables the fluorescence sensing of endogenous lysosomal HO in living cells without external stimulations, with signal interference from the cytoplasm and other intracellular organelles being negligible.
越来越多的证据表明，溶酶体 HO 与生理和病理条件下的自噬和凋亡途径密切相关。因此，能够可视化溶酶体中 HO 的荧光探针是探索 HO 在细胞中多种作用的潜在工具。然而，由于缺乏能够在溶酶体的弱酸性条件（pH=4.5）下兼容地感应 HO 的荧光探针，因此对溶酶体 HO 的功能探索受到限制。溶酶体 HO 的荧光可视化空间分辨率较低可能是由于来自细胞质和线粒体 HO 的信号干扰，以及探针在细胞中的非特异性分布所致。在这项工作中，我们开发了一种用于检测和可视化溶酶体中 HO 的溶酶体定位和酸性 pH 激活型荧光探针，它由 HO 响应的硼酸酯单元、溶酶体定位的吗啉基团和 pH 激活型苯并罗丹荧光团组成。该荧光探针在酸性 pH 条件下对 HO 的响应明显强于中性 pH 条件下的响应。值得注意的是，该探针能够在没有外部刺激的情况下对活细胞内的内源性溶酶体 HO 进行荧光传感，来自细胞质和其他细胞内细胞器的信号干扰可以忽略不计。
