Cartilage-targeting fluorophores for early detection of arthritis in the NIR-II window

Early diagnosis is crucial for the effective treatment of rheumatoid arthritis because continuing inflammation can lead to irreversible joint damage. However, current diagnostic methods lack tissue-specific guidelines to monitor the progressive course of degenerative joint diseases. Here, we demonstrate that cartilage-targeting fluorophores (CARFs) exhibit a remarkable cartilage-specific affinity and offer advanced imaging capabilities in the near-infrared II (NIR-II) window, characterized by minimal tissue scattering and negligible autofluorescence. CARFs show little to no toxicity, both in vitro (up to 100 μM) and in vivo (3 μmol/kg via intravenous injection), suggesting clinical potential. Furthermore, CARFs in the NIR-II window enable the precise visualization of cartilage lining, serving as a reliable diagnostic indicator for the early detection of arthritis in preclinical mouse models. CARFs are NIR fluorescence-emitting targeted contrast agents for prognostic imaging of joint tissue, with the potential to revolutionize applications in tissue engineering, joint surgery, and drug development for inflammatory diseases.