Sensitive detection and imaging of endogenous peroxynitrite using a benzo[d]thiazole derived cyanine probe

Peroxynitrite is a short-lived endogenous reactive species and plays important roles in many physiological and pathological processes. In this work, we synthesized a near-infrared probe based on the structure of benzothiazole derived cyanine for determination of peroxynitrite (ONOO^-). The designed probe specifically reacted with ONOO^- through oxidative cleavage of conjugated C˭C double bonds and generating the non-fluorescent product. Meanwhile, the characteristic absorption of the probe at 630 nm greatly decreased after reaction with ONOO^-, accompanied by drastic color change from bright blue to green yellow, which exhibited a distinct visual feature. It was demonstrated that the probe could be used to measure ONOO^- in a dose-response manner and had a detection limit lower as 26 nM. Furthermore, the probe Cy-SN was applied for the imaging of endogenous ONOO^- in living cells by confocal microscopy, which showed good cell permeability and low cytotoxicity. Successful application of probe for exogenous colorimetric detection and endogenous fluorescence imaging of ONOO^- is suggesting its great potential applications in biological analysis.