An ESIPT-based mitochondria-targeted ratiometric and NIR-emitting fluorescent probe for hydrogen peroxide and its bioimaging in living cells

A mitochondria-targetable ratiometric fluorescent probe, HBTPB, has been developed for the detection of H2O2 with a near infrared (NIR) emission and a large Stokes shift (357 nm). Probe HBTPB displays high selectivity toward H2O2 over other reactive oxygen/nitrogen species (ROS/RNS), biological thiols and anions. The detection limit of this probe is as low as 5.9 x 10(-7) M. The sensing process confirmed by NMR and mass spectral analysis shows that the addition of H2O2 to the solution of HBTPB triggers an oxidative hydrolysis and a subsequent elimination reaction undergoes to release an ESIPT (excited-state intramolecular proton transfer) featured fluorescent dye. Probe HBTPB is cell permeable and has been applied to sense exogenous and endogenous H2O2 in living A549 cells.