Smartphone-integrated ratiometric fluorescent probe for on-site hydroxyl radical detection and arthritis imaging.

The hydroxyl radical (·OH), the most reactive oxygen species, significantly contributes to oxidative diseases but is difficult to detect in real-time due to its ultrashort half-life. Herein, we present a novel ratiometric fluorescent probe YCF for selective monitoring of ·OH. The probe YCF combines a tricyanofuran acceptor and dihydroquinoline donor, featuring an acetyl recognition site. Upon ·OH oxidation, YCF shows a distinct spectral shift: emission decreases at 608 nm and increases at 522 nm (λex = 425 nm), enabling self-calibrated detection (I522/I608). It exhibits high sensitivity (LOD = 0.401 μM), selectivity, and good stability. Fluorescence imaging confirmed that YCF could monitor the exogenous/LPS-induced endogenous ·OH in 4T1 cells and track ·OH dynamics in zebrafish. Furthermore, YCF is employed in the evaluation of ·OH in carrageenan-induced arthritic mice model, revealing the 2.8-fold higher green-channel intensity in inflamed joints versus controls. These results establish probe YCF as a robust tool for real-time ·OH imaging across models, advancing oxidative stress research in disease mechanisms.