A two-photon NIR-to-NIR fluorescent probe for imaging hydrogen peroxide in living cells

Hydrogen peroxide (H₂O₂), one of the reactive oxygen species (ROS), plays vital roles in diverse physiological processes. Imbalance of the H₂O₂ is concerned with serious diseases such as cardiovascular disorders, neurodegenerative diseases, Alzheimer's disease and cancer. Therefore, it is critical to develop efficient methods for monitoring H₂O₂ in vivo. In this work, a two-photon excitation (860nm) NIR fluorescent turn-on probe TPNR-H₂O₂ for H₂O₂ based on Dicyanomethylene-4H-pyran fluorophore is reported, which can be used in solution detection with 13.2-fold NIR fluorescence enhancement, fast response (completed within 40min), excellent sensitivity (DL 72.48nM), and lower cellular auto-fluorescence interference. Importantly, the perfect photostability of TPNR-H₂O₂ clearly demonstrated that the probe could be applied to imaging intracellular H₂O₂ for a long time without photobleaching. In addition, through two-photon imaging, this probe was cell permeable and used to monitor the level of endogenous and exogenous H₂O₂ with promising biological application.