Benzopyrylium conjugated quinolone constructing 705 nm long wavelength emission for evaluation of sulfur dioxide in brain slices

Abstract

Although sulfur dioxide shows a variety of physiological and pathological functions in the body, the lack of detection tools still limits its in situ analysis. Fluorescent probes have the advantages of visualization, non-destructive and multi-level imaging, and have potential application prospects for in-situ detection of organisms. However, fluorescent probes capable of in-situ resolution of substances need to have specific and rapid response to targets, as well as near-red and long-wavelength emission. In our study, benzopyrylium moiety as a versatile fluorophore with a built-in site for SO2, good water solubility and the ability to target mitochondria was employed to construct probe Mito-NQ together with quinoline moiety for extension of conjugate. The probe Mito-NQ exhibited a near infrared emission at 705 nm based on the designed d-π-A-π-D structure. Moreover, we have successfully applied Mito-NQ to the detection of SO2 targeting mitochondria in cells, zebrafish and nude mice. Brain slice imaging showed that long wavelength emission has deep tissue penetration compared to short wavelength emission.