Cyanine based ratio fluorescent probe and its application in hypochlorite detection.

Hypochlorite (ClO), a weakly acidic reactive oxygen species, plays a crucial role in antibacterial and anti-inflammatory defense mechanisms. However, elevated levels of ClO or disruptions in endogenous sites can lead to tissue damage and various diseases including cardiovascular disease, neuronal degeneration, and arthritis. To address this, the development of a specific fluorescent probe with a built-in self-calibration ratio mode for the analysis and biological imaging of ClO is essential. In this study, a cyanine-based fluorescent probe (Cy-H) was designed for ratiometric fluorescent detection of ClO, utilizing its aggregation behavior as a novel approach in this field. Upon exposure to ClO, the phenolic hydroxyl group in probe Cy-H was oxidized into benzoquinone, leading to the formation of cyanine products that displayed a strong tendency to aggregate. As a result, the maximum emission peak of the probe shifted from 700 nm to 485 nm. Notably, a linear relationship was observed between the peak intensity ratio (I/I) and the concentration of hypochlorite, with a limit of detection (LOD) of 0.49 μM. Furthermore, this probe was successfully employed for imaging analysis of hypochlorite in living cells and zebrafish.