Near-infrared fluorescence probe with a large stokes shift for visualizing hydrogen peroxide in ulcerative colitis mice

Ulcerative colitis (UC), as the main inflammatory disease in the colon, is regarded as one of the most refractory diseases by World Health Organization. Hydrogen peroxide (H2O2) is a kind of reactive oxygen species (ROS) and is closely associated with the development of UC. Unfortunately, there is no an excellent fluorescence probe was designed for monitoring H2O2 in UC mice. Herein, a near-infrared (NIR) fluorescence probe (DCX-B) with large stokes shift (158 nm) is designed and synthesized, which displays good sensitivity and selectivity toward H2O2. The probe itself is non-fluorescent because intramolecular charge transfer (ICT) effect is blocked by the borate ester group. After DCX-B reacting with H2O2, the ICT process is restored and a strong fluorescence signal is released. Meanwhile, the possible reaction mechanism of DCX-B towards H2O2 is studied and proved by HPLC, MS and DFT calculation. Due to the low cytotoxicity of the probe, it is successfully applied in the image of H2O2 in two cell lines (HCT116 and HepG2 cells). Furthermore, enlightened by the properties of NIR emission and large stokes shift, DCX-B has been applied in monitoring the dynamic change of H2O2 in the diagnosis and treatment of UC mice.