Visualization of biothiols and HClO in cancer therapy via a multi-responsive fluorescent probe

Cancer is among the most important diseases threatening human life and health, and drug chemotherapy is an effective method which can be used to treat cancer. Last several years, although a growing anti-tumor drugs have been discovered, there still lacks direct visual evidence for reactive sulfur/oxygen species (RS/OS) during cancer therapy. Herein, a novel fluorescence probe RSS-HClO was reported for detecting Cys/Hcy, GSH and HClO at three channels with coumarin-hemicyanine moiety and NBD chloride (NBD-Cl) moiety as fluorophore and recognition group. RSS-HClO shows almost no fluorescence due to the hydroxyl group is protected by NBD. The fluorescence was significantly increased in green and red channels after the reaction with Cys/Hcy. For GSH, the fluorescence was increased in red channel while the green channel fluorescence presented no noticeable change. Conversely, the fluorescence increased only in blue channel in the presence of HClO. Additionally, RSS-HClO exhibits low detection limit with short response time toward three thiols and HClO. The multi-responsive fluorescent probe RSS-HClO allows the distinction of three biothiols and HClO in cells and zebrafish. We hope that RSS-HClO can be invoked as a potential and effective tool for investigating the pharmacological processes during cancer therapy.