Spatiotemporally Tracking the Programmable Mitochondrial Membrane Potential Evolutions by a Robust Molecular Rotor.

Mitochondrial membrane potential (MMP) represents an essential parameter of cellular activities, and even a minute MMP variation could significantly affect the biological functions of living organisms. Thus, convenient and accurate MMP detection is highly desirable since conventional MMP probes are always constrained by photobleaching, inconvenience, and irreversibility. Herein, a spatial-dependent fluorescent molecular rotor Mito-Cy is introduced for efficiently tracking the varied MMP status through its restricted intramolecular rotation in mitochondria and nucleus compartments. Based on a systematic investigation, the specifically lit up fluorescent Mito-Cy enables us to explore different MMP situations by determining their varied distributions. Accordingly, Mito-Cy concentrates in mitochondria under normal MMP status. Yet Mito-Cy starts to migrate gradually from mitochondria to the nucleus in decreasing MMP status, as represented by the increasing distribution levels of fluorescent Mito-Cy in the nucleus. Mito-Cy exclusively accumulates in the nucleus at ultimate vanishing MMP status. The facile operation of Mito-Cy, together with its high photostability and sensitivity, facilitates the monitoring of the reversible and programmable MMP evolutions in living cells. The Mito-Cy-involved logic control over MMP, e.g., AND and OR gates, indicates that the robust and versatile Mito-Cy holds great potential for illuminating mitochondrial viscosity-related bioprocesses.