CCX-2B, a Biotin-Modified Near Infrared Probe Enable Tumor-Specific Imaging of Viscosity and Sulfite

Aberrant viscosity and sulfur dioxide (SO2) metabolism are closely associated with cancer. Nevertheless, there remains a scarcity of near-infrared probes that can monitor the in-vivo dynamics of both viscosity and SO2-derived sulfite (SO32−) while exerting cancer-targeting performance. Herein, we report the development of CCX-2B, a biotin-modified hemicyanine probe constructed through the condensation of indolium and coumarin analogues. CCX-2B displays high sensitivity and selectivity toward both viscosity and sulfite, with limits of detection of 1.67 cP (viscosity) and 8.9 nM (sulfite), respectively. Moreover, it can distinguish cancer cells from normal cells, monitor drug-triggered intracellular viscosity fluctuations, enable intracellular visualization of exogenous and endogenous sulfite, and preferentially accumulate in tumor tissues following intravenous administration. Collectively, CCX-2B represents a promising near-infrared probe for tracking both viscosity and sulfite dynamics, featuring favorable tumor-targeting capability for bioimaging applications.