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

Abstract

AbstractUlcerative colitis (UC) is a chronic inflammatory disease with uncontrolled inflammation and demage to the intestinal barrier. Rhein, a bioactive compound in traditional Chinese medicine, has anti‐inflammatory and intestinal repair effect. 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, red/NIR‐I fluorescent carbon dots based on rhein and doped with L‐arginine (RA‐CDs), which are synthesized by a hydrothermal process without any organic solvents, are reported. 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 show that RA‐CDs scavenge excessive reactive oxygen species (ROS), protect cells from oxidative stress, and enable 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 alleviate UC severity by reducing intestinal inflammation and restoring the intestinal barrier. This study highlights a novel strategy for treating and imaging UC with poorly soluble small‐molecule drugs.