A Multifunctional Chemical Probe for Local Micropolarity and Microviscosity in Mitochondria

The measurement of physicochemical parameters in living cells can provide information specific to individual cell organelles, helping us to understand subcellular function in health and disease. While organelle-specific chemical probes have allowed qualitative measurements of micropolarity or microviscosity in organelles such as the mitochondria, the simultaneous quantification of mitochondrial local microviscosity (η m ) and micropolarity (ε m ), along with structural concurrent structural variations, has remained an unmet need. Here, we describe a new multifunctional mitochondrial probe ( MMP ) for simultaneous monitoring of η m and ε m . This new probe enabled highly precise, quantitative measurements of local mitochondrial microviscosity and micropolarity in the presence of a variety of agents perturbing cellular function, and the changes observed using the probe could also be correlated with alterations in mitochondrial network morphology and motility. The strategy described represents a promising tool for the analysis of subtle changes in organellar structure. A new fluorescent probe enables highly precise, quantitative measurements of local mitochondrial microviscosity and micropolarity in the presence of a variety of agents perturbing cellular function, where the observed changes could also be correlated with alterations in mitochondrial network morphology and motility.