Monitoring mitochondrial pH with a hemicyanine-based ratiometric fluorescent probe

• Published in: Analyst (London) Vol. 144; no. 1; pp. 3422 - 3427
• Main Authors: Xiao, Haibin, Dong, Yaqi, Zhou, Jin, Zhou, Ziyan, Wu, Xiaozhong, Wang, Rongzhou, Miao, Zhichao, Liu, Yuying, Zhuo, Shuping
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 21.05.2019
• Subjects: Apoptosis; Apoptosis - physiology; Cell Line, Tumor; Colorimetry - methods; Fluorescent Dyes - chemical synthesis; Fluorescent Dyes - chemistry; Fluorescent Dyes - radiation effects; Fluorescent Dyes - toxicity; Fluorescent indicators; Humans; Hydrogen-Ion Concentration; Indoles - chemical synthesis; Indoles - chemistry; Indoles - radiation effects; Indoles - toxicity; Light; Metabolism; Microscopy, Confocal - methods; Microscopy, Fluorescence - methods; Mitochondria; Mitochondria - metabolism; Mitochondrial Degradation - physiology; Monitoring; Organelles; Pathogenesis; Phenols - chemical synthesis; Phenols - chemistry; Phenols - radiation effects; Phenols - toxicity; Pi-electrons; Reagents; Toxicity
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/c9an00422j

Mitochondria as essential organelles play critical roles in cellular metabolism. Mitochondrial pH is a vital parameter that directly affects the unique function of mitochondria. Herein, we present a new ratiometric fluorescent probe M-pH for monitoring the pH within the mitochondria. M-pH consists of a stable and large π-electron conjugated merocyanine system. The lipophilic cationic benzyl group will facilitate the accumulation of M-pH in mitochondria. The phenol unit is the recognition moiety, achieving the ratiometric sensing of pH changes. The experimental results indicate that M-pH displays ratiometric fluorescence response to different pH values. Meanwhile, M-pH shows negligible response to common species, and has high stability and low cytotoxicity. In biological experiments, M-pH can solely accumulate in mitochondria and visualize the pH changes during mitophagy and cell apoptosis. We thus believe that M-pH has great potential as a practical tool for real-time monitoring of pH changes of mitochondria, contributing to revealing the pathogenesis of mitochondrial pH associated diseases. We describe a new ratiometric fluorescent probe for monitoring mitochondrial pH.