A highly selective near-infrared fluorescent probe for imaging HSe in living cells and .

Hydrogen selenide (HSe), a highly reactive Se species, is an important selenium metabolism intermediate involved in many physiological and pathological processes. This compound is of scientific interest with regard to the real-time monitoring of HSe in living cells and to understand the anti-cancer mechanism of selenium. However, monitoring HSe in living cells is still challenging due to the lack of straight forward, highly selective and rapid methods. Here, we developed a novel small-molecule fluorescent probe, , for imaging endogenous HSe. exhibited high selectivity toward HSe over selenocysteine (Sec), HS and small molecule thiols and was successfully used to image the HSe content in HepG2 cells during NaSeO-induced apoptosis. Increased HSe content and reduced ROS levels were observed under hypoxic conditions compared to normoxic conditions, which indicated that the cell apoptosis induced by NaSeO under a hypoxic environment is a non-oxidative stress mechanism. Thus, this probe should serve as a powerful tool for exploring the physiological function of HSe and Se anticancer mechanisms in a variety of physiological and pathological contexts.