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.