Simultaneous imaging of mitochondrial viscosity and polarity in cancer using a dual-channel NIR fluorescent probe

Cancer arises from normal cells through a complex transformation process, during which viscosity and polarity changes play important roles as key microenvironmental parameters. However, their specific mechanisms of action in the occurrence and development of cancer still remain to be fully elucidated. Herein, a dual-channel near-infrared (NIR) fluorescent probe, VP, features a thiophene unit that covalently bridges a triphenylamine electron donor and a benzindolium salt electron acceptor. The VP presents mitochondrial targeting capability and enables independent fluorescence responses to polarity and viscosity at 494 nm and 724 nm, respectively. The detection of polarity through the VP is accompanied by pronounced colorimetric responses, with the probe exhibiting four different colors. Owing to the absence of spectral overlap between the two channels, the probe allows highly accurate and reliable dual-parameter detection, and the VP exhibits high selectivity, excellent pH stability, photostability, and biocompatibility. Moreover, the VP efficiently localizes to mitochondria and allows real-time monitoring of polarity and viscosity changes in living cells. Notably, the VP is successfully applied to simultaneous imaging of viscosity and polarity in cancer models, providing a powerful tool for further investigation into cancer physiology and pathological mechanisms.