Monitoring the Fluctuation of Hydrogen Peroxide in Diabetes and Its Complications with a Novel Near-Infrared Fluorescent Probe

Diabetes is one of the metabolic diseases marked by hyperglycemia and is often accompanied by the occurrence of some complications. As a biomarker of oxidative stress, hydrogen peroxide (H2O2) has close association with the occurrence and development of diabetes and its complications. Unfortunately, there is no fluorescent probe reported for imaging H2O2 in diabetic mice. Here, a novel near-infrared (NIR) fluorescent probe named QX-B was designed and synthesized to detect H2O2. For the probe, the quinolinium-xanthene dye is used as the fluorophore and borate ester is chosen as the response group. After the addition of H2O2, a strong NIR fluorescence signal at 772 nm is observed. The probe not only shows high sensitivity with 10-fold enhancement but also displays excellent selectivity to H2O2 over other possible interfering species. In the meantime, the possible response mechanism of QX-B toward H2O2 was proposed and verified by the high-performance liquid chromatography (HPLC) experiment, mass spectra (MS) experiment, and density functional theory (DFT) calculation. Furthermore, based on the low cell cytotoxicity of QX-B, it has been applied in imaging exogenous and endogenous H2O2 in HeLa cells, HCT116 cells, 4T1 cells, and zebrafish successfully. More importantly, inspired by the performance of NIR fluorescence, QX-B has been used in monitoring H2O2 in diabetic mice for the first time. This provides very important information for the diagnosis and treatment of diabetes and its complications.