Designing robust xylan/chitosan composite shells around drug-loaded MSNs: Stability in upper GIT and degradation in the colon microbiota

Long residence times, near-neutral pH values, and release triggered by the enzymatic action of the resident microbiota offer unique opportunities for improved drug delivery in the colon. The fact that a delivery agent must also pass through the complete GI tract without degradation presents a challenge due to widely changing pH conditions. In this study, a promising colon-targeted drug delivery system was composed of a xylan/chitosan composite shell formed on curcumin-loaded mesoporous silica nanoparticles (MSNs). A novel synthesis approach was employed to facilitate precipitation of negatively charged xylan on negatively charged MSNs by concurrent chitosan polymerization. Curcumin-loaded xylan/chitosan-coated MSNs (C-MSNs) were determined to contain nearly 42% xylan by the inclusion of chitosan in a one-to-one ratio with xylan. The xylan/chitosan composite shell demonstrated excellent stability in the acidic upper GI tract. The hydrolysis of glycosidic bonds by resident microbiota was the triggering mechanism for xylan degradation and curcumin release in the colon. The presence of xylan has the further benefit of increasing the number of beneficial bacteria and improving short-chain fatty acid production for improved colon health. • Developing an efficient colon-targeted drug delivery system is still challenging. • The xylan-based delivery system utilizes xylan degradation by colon microbiota. • Xylan is stable through the physiological environment of the stomach and small intestine. • The Xylan-based delivery system may increase the beneficial bacteria and improve colon health. • The xylan-based delivery strategy seems very promising in pharmaceutical applications.