A cyanine carbazole oxime fluorescent probe selectively detects hypochlorite in Hi5 cells and C. elegans

Quantitative detection and visualization of hypochlorous acid (HClO) in biological samples has emerged as a hot topic in biochemical research because of the important role of this biomolecule in live organisms. In this contribution, a novel hemicyanine-based fluorescence probe, CVDI (1-ethyl-2-((E)-2-(9-ethyl-6-((E)-(hydroxyimino)methyl)-9H-carbazol-3-yl)vinyl)-3,3-dimethyl-3H-indol-1-ium), was designed and synthesized for HClO detection in aqueous solutions and in biological systems. In the presence of HClO, significant changes in absorption and fluorescence spectra were observed and the fluorescence response has increased by a factor of nine, which allow for the quantitative detection of HClO in PBS buffer. CVDI has excellent fluorescence properties: fast response time (20 s) and remarkable stability at wide pH range (7.0–10.0). The detection limit for HClO was determined to be 1.304 μM. Imaging of exogenous HClO in live Hi5 cells and C. elegans was then successfully performed using CVDI. We anticipate that CVDI could be employed for the diagnosis of pathological inflammation in clinic in near future.