An Oxidative Cleavage-Based Cruciform DNA Nanostructure for In Vivo Hypochlorous Acid Visualization to Monitor Intestinal Inflammation

Ulcerative colitis is a persistent inflammatory bowel disease characterized by inflammation and ulceration in the colon and gastrointestinal tract. It was indicated that the generation of hypochlorous acid (HClO) through the enzymatic activity of myeloperoxidase is significantly linked to ulcerative colitis. In this study, by assembling two hairpins (Hpa and Hpb) onto a quadrivalent cruciform DNA nanostructure, a novel HClO-activatable fluorescent probe was developed based on DNA nanomaterials (denoted MHDNA), which is sensitive, economic, simple, and stable. In the presence of HClO, the Trigger (T) was liberated from the MHDNA probe through a hydrolysis reaction between HClO and phosphorothioate (PS), which is modified on the MHDNA probe and has proved to exhibit particular susceptibility to the HClO. The liberated T subsequently initiated the opening of Hpa and Hpb to facilitate the catalyzed hairpin assembly (CHA) reaction, resulting in the changes of fluorescence and releasing T for recycled signal amplification to achieve sensitive detection of HClO (with a limit of detection 9.83 nM). Additionally, the MHDNA-based spatial-confinement effect shortens the physical distance between Hpa and Hpb and yields a high local concentration of the two reactive hairpins, achieving more rapid reaction kinetics in comparison to conventional CHA methods. Inspirationally, the MHDNA probe was effectively utilized for imaging HClO in ulcerative colitis mice, yielding valuable diagnostic insights for ulcerative colitis.