A near-infrared fluorescent probe based on phosphorus-substituted rhodamine for deep imaging of endogenous hypochlorous acid in vivo

Fluorescence imaging with tailored fluorecent probes are vital for the non-invasive analysis of sophisticated activities in the innate immune system. Fluorescent scaffold with deep tissue penetration are also urgently required for fluorescence imaging in vivo. A phosphorus-substituted rhodamine fluorescent probe PR−HOCl was designed with maximal emission wavelength at 730 nm. The developed probe PR−HOCl exhibits fast response (20 s) and high sensitivity towards HOCl (detection limit, 10 nM) with relatively wide linear range (0.15 μM to 13.5 μM) in vitro. Both endogenic and exogenous hypochlorous acid were sensitively monitored with high selectivity by the developed probe PR−HOCl in living RAW 264.7 cells. Substantial tissue penetrating ability of PR−HOCl has been manifested in the fluorescence imaging of endogenous hypochlorous acid in inflamed nude mice model.