A near-infrared fluorescent probe with ultra-large Stokes shift for the detection of HNO in cells and mice

Abstract As one of the significant reactive nitrogen species in living systems, nitroxyl (HNO) plays a paramount role in a series of physiological and pathological processes. However, completely elucidating the role of endogenous HNO in living systems remains a huge challenge due to the lack of effective detection tools for the real-time monitoring of HNO. Recently, fluorescent probe has been widely accepted as a powerful molecular tool for the non-invasive detection of active species in living systems. Hence, in this work, we developed a new NIR fluorescent probe (N-HBT-HNO) with ultra-large Stokes shift for the effective detection and bioimaging of HNO in living cells and mouse. In the design blueprint of probe, the dicyanoisophorone moiety was integrated into the benzothiazole unit to expand the emission wavelength to NIR region of 728 nm and remarkably increase the Stokes shift to ultra large of 303 nm, which could endow the probe with superiority in bioimaging. Additionally, the 2-(diphenylphosphino) benzoate served as the efficient recognition group and fluorescence quenching group. Results demonstrated that the newly developed probe possessed appreciable sensing performance, including good selectivity, large signal to noise ratio, high sensitivity and fast response toward HNO. Subsequently, this probe was successfully applied for the bioimaging of exogenous HNO in living cells and mouse, reflecting the application potential of exogenous HNO (AS).