A NIR fluorescent probe based on phenazine with a large Stokes shift for the detection and imaging of endogenous H 2 O 2 in RAW 264.7 cells.

Hydrogen peroxide (H2O2), one of the reactive oxygen species (ROS), plays vital roles in diverse physiological processes. Thus, herein, to improve the signal-to-noise ratio, a new near-infrared region (NIR) fluorophore (PCN) based on reduced phenazine was developed.PCNwas further designed as a "turn on" fluorescent probe (PCN-BP) for the detection of H(2)O(2)by introducingp-boratebenzyl. After H(2)O(2)was added, thep-boratebenzyl group inPCN-BPwas oxidized top-hydroxy benzyl; it then self-departed, formingPCN, which displayed 24-fold NIR emission at 680 nm with a large Stokes shift (more than 200 nm). This probe presented an excellent linear relation with the concentration of H(2)O(2)and good selectivity to various ions, ROS and biothiols; thus, it can be utilized as a colorimetric and fluorescence turn-on probe. More importantly, the probe was also employed for the exogenous and endogenous imaging of H(2)O(2)in RAW 264.7 cells.