Red/NIR-I-Fluorescence Carbon Dots Based on Rhein with Active Oxygen Scavenging and Colitis Targeting for UC Therapeutics.

Ulcerative colitis (UC) is a lifelong inflammatory disease characterized by uncontrolled inflammatory response and intestinal epithelial barrier damage that continuously promote disease progression. Rhein, as an active monomer in traditional Chinese medicine, has dual biological effects of controlling inflammatory responses and promoting intestinal mucosal repair. However, their clinical application is limited by their hydrophobicity and poor bioavailability. L-arginine, as a complement to NO, has synergistic and attenuating effects. In this paper, we report red/NIR-I fluorescent carbon dots based on rhein and doped with L-arginine (RA-CDs), which were synthesized by a hydrothermal process without any organic solvents. RA-CDs preserve a portion of the functional group of the active precursor, increase rhein solubility, and emit red/NIR-I light for biological imaging. In vitro experiments showed that RA-CDs scavenged excessive reactive oxygen species, protected cells from oxidative stress, and enabled the fluorescence imaging of inflamed colons. In a DSS-induced UC mouse model, both delayed and prophylactic treatment with RA-CDs via intraperitoneal and tail vein injections alleviated UC severity by reducing intestinal inflammation and restoring the intestinal barrier. This study highlights a novel strategy to improve the clinical utility of poorly soluble small-molecule drugs, which are promising for the targeted therapy and imaging of UC. This article is protected by copyright. All rights reserved.