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

Hydrogen peroxide (HO), one of the reactive oxygen species (ROS), plays vital roles in diverse physiological processes. Imbalance of the HO 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 HO in vivo. In this work, a two-photon excitation (860nm) NIR fluorescent turn-on probe TPNR-HO for HO 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-HO clearly demonstrated that the probe could be applied to imaging intracellular HO 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 HO with promising biological application.