Ratiometric Near-Infrared Fluorescent Probe Monitors Ferroptosis in HCC Cells by Imaging HClO in Mitochondria.

Hypochlorous acid (HClO) is a typical endogenous ROS produced mainly in mitochondria, and it has strong oxidative properties. Abnormal HClO levels lead to mitochondrial dysfunction, strongly associated with various diseases. It has been shown that HClO shows traces of overexpression in cells of both ferroptosis and hepatocellular carcinoma (HCC). Therefore, visualization of HClO levels during ferroptosis of HCC is important to explore its physiological and pathological roles. So far, there has been no report on the visualization of HClO in ferroptosis of HCC. Thus, we present a ratiometric near-infrared (NIR) fluorescent probe Mito-Rh-S which visualized for the first time the fluctuation of HClO in mitochondria during ferroptosis of HCC. Mito-Rh-S has an ultrafast response rate (2 s) and large emission shift (115 nm). Mito-Rh-S was constructed based on the PET sensing mechanism and thus has a high signal-to-noise ratio. The cell experiments of Mito-Rh-S demonstrated that Fe2+- and erastin-induced ferroptosis in HepG2 cells resulted in elevated levels of mitochondrial HClO and that high concentration levels of Fe2+ and erastin cause severe mitochondrial damage and oxidative stress and had the potential to kill HepG2 cells. By regulating the erastin concentration, erastin induction time, and treatment of the ferroptosis model, Mito-Rh-S can accurately detect the fluctuation of mitochondrial HClO levels during ferroptosis in HCC.

A near-infrared fluorescent probe with remarkably large stokes shift for specifical imaging of peroxynitrite fluctuations in Hela cells.

Peroxynitrite (ONOO-), an endogenous reactive nitrogen species, plays an important role in maintaining intracellular homeostasis. Abnormal levels of ONOO- in cells could cause protein oxidation which is confirmed that related with Alzheimer's diseases, so accurate monitoring of ONOO- in cells is crucial. Herein, a novel fluorescent probe (XPC) based on dicyanomethylene-4H-benzothiopyran was developed by regulating its intramolecular charge transfer (ICT) effect to detect ONOO-. Once reaction with ONOO-, the fluorescence of XPC was turned on and the emission wavelength could reach up to 750 nm. Furthermore, XPC exhibited satisfactory performances for ONOO- such as large Stokes shift (200 nm), good sensitivity (Limit of detection = 13 nM), high selectivity to ONOO- over other a reactive nitrogen species (RNS)/reactive oxygen species (ROS). More importantly, XPC was successfully applied for monitoring the fluctuations of ONOO- in living cells.