A mitochondria-targeted dual-response sensor for monitoring viscosity and peroxynitrite in living cells with distinct fluorescence signals

Viscosity and peroxynitrite (ONOO−) are two significant indicators to affect and evaluate the mitochondrial functional status, which are nearly relational with pathophysiological process in many diseases. Developing suitable analytical methods for monitoring mitochondrial viscosity changes and ONOO− is thus of great importance. In this research, a new mitochondria-targeted sensor DCVP-NO2 for the dual determination of viscosity and ONOO− was exploited based on the coumarin skeleton. DCVP-NO2 displayed a red fluorescence "turn-on" response toward viscosity along with about 30-fold intensity increase. Meanwhile, it could be used as ratiometric probe for detection of ONOO− with excellent sensitivity and extraordinary selectivity for ONOO− over other chemical and biological species. Moreover, thanks to its good photostability, low cytotoxicity and ideal mitochondrion-targeting capability, DCVP-NO2 was successfully utilized for fluorescence imaging of viscosity variations and ONOO− in mitochondria of living cells through different channels. In addition, the results of cell imaging revealed that ONOO− would lead to the increase of viscosity. Taken together, this work provides a potential molecular tool for researching biological functions and interactions of viscosity and ONOO− in mitochondria.