Efficient oral delivery of water-soluble CT contrast agent using an W1/O/W2 alginate hydrogel matrix.

ABSTRACT

HYPOTHESIS: Iohexol (IOH) is a commonly used second-generation nonionic iodinated contrast agent. However, low gastrointestinal mucosal adherence and high downstream speed limit its application in intestinal Computed tomography (CT) imaging. We hypothesize that oral IOH delivery carriers composed of environmentally responsive materials enable the intestinal targeted delivery and prolong the intestinal residence time of IOH, enhancing the intestinal disease detection efficiency. EXPERIMENTS An emulsion-filled alginate hydrogel system was developed as the intestinal targeting vehicle for IOH. The formulation optimization was determined by response surface analysis. After a thorough study of the physicochemical properties of this hydrogel matrix, the pH sensitivity and the ability to control release were investigated, followed by a vitro cell experiment evaluating its bioactivity and CT imaging capability. FINDINGS: This alginate hydrogel matrix was sparsely structured and rapidly released IOH at pH 7.4. Meanwhile the swelling degree was 4.4 times higher than that at pH 1.2, indicating a good selective responsiveness to the gastrointestinal simulated environment. It improved the CT visual contrast of A549 cells without affecting cell morphology, suggesting that it would be an effective oral administration for water-soluble nonionic contrast agents and a potential candidate for intestinal disease detection tools.