Simultaneous monitoring of mitochondrial viscosity and membrane potential based on fluorescence changing and location switching of carbon dots in living cells.

Mitochondrial viscosity and mitochondrial membrane potential (MMP) are vital parameters for reflecting mitochondrial conditions and they are closely correlative in various biological events. Accordingly, simultaneous detection of mitochondrial viscosity and MMP is imperative for elucidating their interactions, further exploring the mechanism of diseases, and investigating numerous pathological procedures. However, such profound research remains a big challenge due to the lack of high-performing single fluorescent probes capable of simultaneously visualizing of these two parameters. In this study, we developed a new kind of fluorescent carbon dots (CDs) that can successfully realize simultaneous monitoring of mitochondrial viscosity and MMP in living cells. The fluorescence of CDs can be specifically turned on as the viscosity of solvents increases from 0.89 to 945 cP. Meanwhile, the CDs accumulate in mitochondria under normal MMP conditions, switch to exist in both mitochondria and nucleoli under reduced MMP, and present only in nucleoli with the vanishment of MMP. Thus, various MMP situations can be easily differentiated through the changed spatial distributions of CDs. More importantly, based on the developed CDs, an increased mitochondrial viscosity accompanying a decreased MMP was simultaneously tracked in drug-stimulated cells. We envision that the developed CDs has a great potential to be utilized as a promising fluorescent probe for mitochondrion-related biology studies. The carbon dots were elaborately designed for simultaneous determination of mitochondrial viscosity and membrane potential through their fluorescence variation and location migration from mitochondria to nucleoli. [Display omitted] • The fluorescence of Carbon Dots (CDs) was specifically turned on as the viscosity of solvents increased. • Fluctuation of mitochondrial membrane potential was visualized through migration of CDs from mitochondria to nucleoli. • An increased mitochondrial viscosity accompanying a decreased membrane potential was simultaneously monitored in cells. [ABSTRACT FROM AUTHOR]