pH-Sensitive Fluorine-Containing Hydrogel System for Enhanced Intestinal Computed Tomography Imaging

Iohexol (IOH), a widely used nonionic contrast agent, presents limitations including prolonged circulation time and short gastrointestinal retention, which restrict its effectiveness in intestinal CT imaging. We developed an intestinal-targeting system featuring pH-sensitive hydrogels encapsulating perfluorocarbon droplets, which can serve as an intestinal targeting vehicle for IOH. The perfluorocarbon droplets demonstrate enhanced structural stability through temperature-responsive phase transition capabilities. In simulated gastric fluid (pH 1.2), only around 9% of IOH was released from the hydrogel system within 60 min. Conversely, under intestinal fluid environment (pH 7.4), the system achieved rapid 80% drug release within 30 min, significantly faster than the release rate of nonfluorinated hydrogel controls. Importantly, this formulation enhanced cellular CT contrast without changing cell morphology, demonstrating its potential as an effective oral nonionic contrast agent for intestinal disease diagnosis.