A novel long excitation/emission wavelength fluorophore as platform utilized to construct NIR probes for bioimaging and biosensing

Near-infrared (NIR) fluorophores, especially dicyano-based fluorophores and xanthene-based hemicyanines, have been put high expectation in bioimaging application due to their excellent optical properties. However, they suffer from inherent shortages such as short excitation/emission wavelength (less than 700 nm) or small Stokes shift (20–50 nm). Herein, we constructed a novel NIR dicyano-based fluorophore (DCO-HBTN). To our knowledge, it is the first reported dicyano-based fluorophore of which the excitation/emission wavelength is more than 650 nm and Stokes shift is more than 100 nm. To demonstrate the feasibility of our efforts, we developed two NIR fluorescent probes (Probe-Cys and Probe-H2S) based on the fluorophore, Probe-Cys displayed good selective and highly sensitive (LOD = 0.28 μM) recognition of Cys over Hcy and GSH, which was used to visualize endogenous Cys in tumor tissue. Probe-H2S exhibited an. excellent specific and sensitive (LOD = 0.11 μM) response to H2S, which was applied in monitoring H2S releasing from the prodrug in vitro and in vivo.