Rational Design of Ratiometric Near-Infrared Aza-BODIPY-Based Fluorescent Probe for in Vivo Imaging of Endogenous Hydrogen Peroxide

Precise in vivo tracking of hydrogen peroxide is still challenging due to its dynamic complexity and intrinsic background interference. Herein, we describe a rational design strategy to construct asymmetric aza-boron-dipyrromethane derivative (BODIPY)-based ratiometric probes for in vivo tracking H2O2, which are composed of a near-infrared aza-BODIPY core, active targeting group, and H2O2-specific recognition unit. We take advantage of two terminal functionalized conjunctions in the bis-condensed aza-BODIPY by rationally introducing carbonyl group as an electrondeficiency linker for regulating intramolecular charge transfer-induced wavelength shift and by attaching hydrophilic polyethylene glycol-biotin segment as the active targeting moiety. The probe BP5-NB-OB features several striking characteristics: (i) ratiometric near infrared response in both absorption and emission spectra; (ii) active targeting ability (biotin receptor-mediated endocytosis) with excellent biocompatibility; and (iii) in vivo tracking of endogenous H2O2. It was demonstrated that the probe BP5-NB-OB was successfully utilized for tracking endogenous H2O2 in living cells and tumorbearing mice, providing opportunities to insight into H2O2 related diseases for clinical application.