Visualizing voltage in mitochondria via a unique polarity-responsive fluorescent probe

Abstract

Mitochondrial membrane potential (ΔΨm) plays key roles in important life processes such as aerobic respiration, and is also an important parameter for assessing mitochondrial health and cell status. Therefore, detecting ΔΨm is crucial for revealing important life processes and detecting cellular activity. However, the currently reported fluorescent probes for ΔΨm have inherent defects, and their signals are facilely affected by factors such as staining concentration and pH fluctuations. To overcome these shortcomings, in this work, we proposed a new strategy to construct probes for ΔΨm via subcellular migration and polarity-responsive mechanisms, and constructed a two-color fluorescent probe for detection of ΔΨm. The probe targeted mitochondria in living cells and emitted blue and red fluorescence due to the lower polarity of the inner mitochondrial membrane. After the ΔΨm decreased, the probe migrated into the RNA, giving decreased blue emission and enhanced red fluorescence due to the higher polarity of the RNA restriction of intermolecular rotation. In this manner, the probe was capable of detecting ΔΨm by two fluorescence signal changes in fluorescence color and staining position. Using this probe, the reversible change of ΔΨm was successfully observed, and the process of cellular oxidative damage and apoptosis was visualized. The probe can serve as an important molecular tool to promote the development of ΔΨm, cell damage and apoptosis and related fields.