A H₂O₂ responsive self-activatable fluorescent probe and pro-photosensitizer based on a pyridine-chalcone skeleton

Hydrogen peroxide (H₂O₂) is closely associated with various physiological and pathological processes, particularly in tumor microenvironment. It has been designed for the activation and release of fluorescent probes and tumor-related drugs. In this work, we proposed a self-activatable fluorescent probe and pro-photosensitizer (pro-PS) MN-BP based on a pyridine-chalcone photosensitizer (PS) MN and a H₂O₂ responsive boronate moiety. The endogenous H₂O₂ in tumor cells triggers partial release of PS MN from the pro-PS MN-BP. Under light irradiation, the generated PS MN can produce Reactive oxygen species (ROS) and be partially converted to H₂O₂ to proceed the self-activatable process. The generated H₂O₂ can be used as an activator to accelerate the release of PS MN, thus amplifying the effect of photodynamic therapy (PDT) by generating more ROS. In addition, the enhanced fluorescence of pro-PS MN-BP can be used for the detection of H₂O₂ and the visualization of photosensitizer, so as to realize the real-time monitoring and regulation of the PDT process.