Lighting up hydrogen peroxide in living cells by a novel quinoxalinamine based fluorescent probe.

Abstract Hydrogen peroxide (H2O2), a member of small-molecule reactive oxygen species (ROS), plays vital roles in normal physiological activities and the occurrence of many diseases. In this work, two off–on fluorescent probes, QX8A-H2O2 and QX9A-H2O2, were firstly designed for H2O2 detection with novel fused quinoxalines as the fluorophores and boronate moiety as the reaction sites. By comparing the optical properties, QX9A-H2O2 with better performance was selected for further studies. QX9A-H2O2 exhibited a high sensitivity to H2O2 with the detection limit as low as 46 nM, and displayed a good selectivity towards H2O2 over other reactants such as ROS, biothiols and various ions. The detection was based on the intramolecular charge transfer (ICT), proceeding through a sequential oxidative hydrolysis, 1,6-rearrangement elimination and decarboxylation process to release the fluorophore QX9A. Moreover, probe QX9A-H2O2 was cell permeable and was successfully employed in both exogenous and endogenous H2O2 imaging in living cells.