A Flavone-Based Long-Wavelength Fluorescent Probe to Detect Biothiols in vitro and in vivo

Biothiols, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) play crucial roles in physiological and pathological processes.GSH, especially, is overexpressed in numerous types of tumor cells and could be considered as a biomarker.However, owing to the difficulty and challenge in sensing normal and cancer cells simultaneously, it is important to solve this problem in biological processes.Herein, a naked-eye visible, "off-on" long-wavelength fluorescent probe (4) based on N,N-(dimethylamino)naphthalenyl flavone (3) was designed and synthesized.This probe showed high selectivity for biothiols and low detection limits.The mechanism study revealed that biothiols catalyzed the cleavage of the ester bond, and strongly fluorescent flavone 3 was released.Probe 4 could be used for the imaging of biothiols in living cells and mice.In addition, the probe was optimized to achieve the selective imaging of normal hepatocyte HL-7702 and heptocarcinoma cell HepG2.