A Multifunctional Chemical Probe for the Measurement of Local Micropolarity and Microviscosity in Mitochondria

The measurement of physicochemical parameters in living cells can provide information on individual cellular organelles, helping us to understand subcellular function in health and disease. While organelle‐specific chemical probes have allowed qualitative evaluation of microenvironmental variations, the simultaneous quantification of mitochondrial local microviscosity (ηm) and micropolarity (ϵm), along with concurrent structural variations, has remained an unmet need. Herein, we describe a new multifunctional mitochondrial probe (MMP) for simultaneous monitoring of ηm and ϵm by fluorescence lifetime and emission intensity recordings, respectively. The MMP enables highly precise measurements of ηm and ϵm in the presence of a variety of agents perturbing cellular function, and the observed changes can also be correlated with alterations in mitochondrial network morphology and motility. This strategy represents a promising tool for the analysis of subtle changes in organellar structure. Eine Fluoreszenzsonde für die präzise quantitative Bestimmung der lokalen Mikroviskosität und ‐polarität in Mitochondrien in Gegenwart vielfältiger störender Einflüsse auf die Zellfunktion wird vorgestellt. Beobachtete Veränderungen wurden mit wechselnder Gerüstmorphologie und Motilität der Mitochondrien korreliert.