Colon Targeting pH-Responsive Coacervate Microdroplets for Treatment of Ulcerative Colitis

Ulcerative colitis (UC), an immune-mediated chronic inflammatory disease, drastically impacts patients' quality of life and increases their risk of colorectal cancer worldwide. However, effective oral targeted delivery and retention of drugs in colonic lesions are still great challenges in the treatment of UC. Coacervate microdroplets, formed by liquid-liquid phase separation, are recently explored in drug delivery as the simplicity in fabrication, spontaneous enrichment on small molecules and biological macromolecules, and high drug loading capacity. Herein, in this study, a biocompatible diethylaminoethyl-dextran hydrochloride/sodium polyphenylene sulfonate coacervates, coated with eudragit S100 to improve the stability and colon targeting ability, named EU-Coac, is developed. Emodin, an active ingredient in traditional Chinese herbs proven to alleviate UC symptoms, is loaded in EU-Coac (EMO@EU-Coac) showing good stability in gastric acid and pepsin and pH-responsive release behavior. After oral administration, EMO@EU-Coac can effectively target and retain in the colon, displaying good therapeutic effects on UC treatment through attenuating inflammation and oxidative stress response, repairing colonic epithelia, as well as regulating intestinal flora balance. In short, this study provides a novel and facile coacervate microdroplet delivery system for UC treatment.