A yolk-shell structured calcium phosphate modified with Eu for oral drug delivery

Abstract

Ulcerative Colitis (UC) is a non-specific chronic inflammatory disease affecting the rectum and colon, and may cause irreversible damage to the structure and function of intestine. However, there are still many challenges in the treatment of UC. For instance, the enzyme-responsive oral colon drug delivery system (OCDDS) relying on the gut flora metabolites-azo reductase is commonly used in clinical treatment, but the susceptibility of the microbiota in the gut during onset limits its further application. Besides, time-dependent OCDDS is also vulnerable to different individual gastrointestinal functions and pathophysiological conditions, which results in early or late drug-release, thus limiting its bioavailability. Therefore, in this work, a pH responsive OCDDS was designed based on the pH change pattern of human digestive tract. Calcium phosphate carrier was synthesized by phosphorus source adenosine triphosphate (ATP) and calcium source calcium gluconate monohydrate (CG). Moreover, the pH responsive materials Eu (the mixture of Eudragit L100 and Eudragit S100) were successfully coated by emulsion solvent evaporation method. The final OCCDDS achieved pH-controlled drug delivery in simulate gastrointestinal environment. Good biocompatibility of OCCDDS has been demonstrated by MTT assay.