An endoplasmic reticulum-targeted near-infrared fluorescent probe for selective imaging of hypochlorous acid.

Hypochlorous acid (HClO), as a key component of endogenous reactive oxygen species, plays a critical role in endoplasmic reticulum (ER) homeostasis regulation. Its dynamic imbalance is closely associated with pathological processes such as neurodegenerative diseases and cancer. This study introduces a "turn-on" near-infrared fluorescent probe, XB-CTs, designed for the specific targeting and detection of hypochlorous acid (HClO) within the ER. It uses a dihydroxanthene-hemicyanine dye as the NIR fluorescent base, featuring an N,N-dimethylthiocarbamate group for quick, specific HClO detection, and a p-toluenesulfonamide group for ER targeting. The XB-CTs probe performs exceptionally well by emitting NIR fluorescence at 735 nm, avoiding biological autofluorescence interference. It is highly sensitive to HClO with a 0.141 μM detection limit and responds in 1 s. it specifically targets the ER in live cells, providing high signal-to-noise ratio imaging for real-time HClO detection. Additionally, it has been effectively used for stable fluorescence imaging of HClO in mice. This study provides a feasible detection tool for investigating ER oxidative stress processes, and its potential applications in biomedical research warrant further exploration and validation.