A near-infrared and two-photon ratiometric fluorescent probe with a large Stokes shift for sulfur dioxide derivatives detection and its applications in vitro and in vivo

As a critical gaseous signaling molecule, SO2 is involved in multiple physiological and pathological processes. However, the pathogenesis of many serious diseases including lung cancer, cardiovascular diseases and neurological disorders caused by excessive inhalation of SO2 is still unknown. Hence, the development of reliable analytical methods for efficiently and specifically monitoring SO2 in living systems is of significance. In this work, a novel near-infrared and two-photon ratiometric fluorescent probe NIR-SO2-TP was first proposed for optical SO2 sensing. The newly synthesized fluorescent probe NIR-SO2-TP, which is based on coumarin-benzopyrylium π-conjugated platform, exhibited high selectivity, rapid response time, lower detection limit and a large Stokes shift (185 nm). Importantly, the novel probe has been successfully applied to sense SO2 in living cells, tissues, zebrafish and living mice at both near-infrared and two-photon modes.