There is increasing evidence indicating that lysosomal H₂O₂ is closely related to autophagy and apoptotic pathways under both physiological and pathological conditions. Therefore, fluorescent probes that can be exploited to visualize H₂O₂ in lysosomes are potential tools for exploring diverse roles of H₂O₂ in cells. However, functional exploration of lysosomal H₂O₂ is limited by the lack of fluorescent probes capable of compatibly sensing H₂O₂ under weak acidic conditions (pH = 4.5) of lysosomes. Lower spatial resolution of the fluorescent visualization of lysosomal H₂O₂ might be caused by the interference of signals from cytosolic and mitochondrial H₂O₂, 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 H₂O₂ in lysosomes, which consists of a H₂O₂-responsive boronate unit, a lysosome-locating morpholine group, and a pH-activatable benzorhodol fluorophore. The response of the fluorescent probe to H₂O₂ 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 H₂O₂ in living cells without external stimulations, with signal interference from the cytoplasm and other intracellular organelles being negligible.

中文翻译：

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溶酶体定位和酸性pH激活型荧光探针，用于观察溶酶体中的内源性H ₂ O ₂

越来越多的证据表明，在生理和病理条件下，溶酶体H ₂ O ₂与自噬和细胞凋亡途径密切相关。因此，可以用来可视化溶酶体中H ₂ O _2的荧光探针是探索H ₂ O ₂在细胞中的多种作用的潜在工具。但是，由于缺乏在溶酶体的弱酸性条件下（pH = 4.5）能够兼容地检测H ₂ O ₂的荧光探针，对溶酶体H ₂ O _2的功能探索受到了限制。溶酶体H荧光可视化的较低空间分辨率₂ O ₂可能是由于胞质和线粒体H ₂ O ₂的信号干扰以及探针在细胞中的非特异性分布引起的。在这项工作中，我们开发了一种溶酶体定位和酸性pH激活的荧光探针，用于检测和可视化溶酶体中的H ₂ O ₂，该探针由H ₂ O ₂响应硼酸酯单元，溶酶体定位吗啉组组成。 ，以及pH值可激活的苯并Rhodol荧光团。荧光探针对H ₂ O ₂的响应在酸性pH条件下的pH值明显比在中性pH条件下的pH值明显。值得注意的是，本探针能够在活细胞中对内源性溶酶体H ₂ O ₂进行荧光感测，而无需外部刺激，而来自细胞质和其他细胞内细胞器的信号干扰则可以忽略不计。