Multifunctional fluorescence probe for simultaneous detection of viscosity, polarity, and ONOO− and its bioimaging in vitro and vivo

Intracellular microenvironment (viscosity and polarity) and peroxynitrite ions (ONOO−) are involved in maintaining cell morphology, cell function, and signaling so that it is crucial to explore their level changes in vitro and vivo. In this work, we designed and synthesized a mitochondria-targeted fluorescence probe XBL for monitoring the dynamic changes of viscosity, polarity, and ONOO− based on TICT and ICT mechanism. The fluorescence spectra showed obvious changes for polarity at 500 nm as well as ONOO− and viscosity at 660 nm, respectively. The XBL can image simultaneously viscosity, polarity, and ONOO− in cells, and the results showed excess ONOO− leaded to the increase of viscosity in mitochondrial. The ferroptosis process was accompanied by increase of intracellular viscosity and ONOO− levels (or decrease of polarity), which allowed us to better understand the relevant physiological and pathological processes. The XBL can distinguish normal cells and cancerous cells by the fluorescence intensity changes in green and red channels, and image viscosity in inflamed mice. Thus, XBL can provided the chemical tool to understand the physiological and pathological mechanisms of disease by simultaneous detection of viscosity, polarity and ONOO−.