One Stone, Three Birds: pH Triggered Transformation of Aminopyronine and Iminopyronine Based Lysosome Targeting Viscosity Probe for Cancer Visualization.

The lysosomes of cancer cells have lower pH and higher viscosity than those of normal cells. These features can be used as sensitive and selective markers for cancer diagnosis. In this work, a pH and viscosity dual responsive lysosome targeting fluorescent probe 1 was designed based on the transformation of amino- and imino- forms of pyronine and the twisted intramolecular charge shuttle (TICS) sensing mechanism. Live cancer cells and tumors were effectively distinguished from normal cells and organs through fluorescence imaging of probe 1, which indicated that probe 1 could serve as an effective tool for visualization of tumors at organ level with high selectivity.