An activatable fluorescent probe enables in vivo evaluation of peroxynitrite levels in rheumatoid arthritis

An activatable probe able to detect RONS level underlying the development of rheumatoid arthritis (RA) would be far-reaching for the diagnosis and drug efficacy assessment of RA. Despite more and more evidence suggests that ONOO- is an important signaling molecule participating in the RA disease, only rare fluorescent probes can detect ONOO- in this disease with satisfying performance. To this end, we designed and synthesized a novel activatable AIE fluorescent probe (DPPO-PN) for the detection of ONOO- levels in RA. The probe linearly responds to 0-10 μM ONOO- with a significant far-red fluorescence enhancement at 632 nm in 30 s (F/F0 = 161-fold, LOD = 10 nM) upon the excitation of 490 nm, elucidating excellent sensing abilities for ONOO- in cuvettes. Moreover, the fluctuations of intracellular ONOO- levels caused by adscititious adding or stimulant provoking could be real-time captured and visualized with this probe by confocal imaging. Further, the intravital imaging of ONOO- in LPS-induced and CFA-induced RA mouse models also can be achieved with the aid of the probe, substantiating the burst of ONOO- in the RA process. Therefore, this work not only offers an auxiliary tool for the diagnosis of RA but also would benefit our understanding of the ONOO-'s roles in RA.