Design of biotin decorated enterocyte targeting muco-inert nanocomplexes for enhanced oral insulin delivery.

The natural mucus cover has been a major obstacle to prevent enterocyte targeting particles from contact with the receptors. Thus, mucus penetration and intestinal targeting should be designed into one system. Based on the concept that biotin specifically recognizes epithelium receptors, enterocyte targeting muco-inert nanocomplexes were designed. Firstly, biotinylated chitosan (CS-Biotin) copolymers with different degree of substitution were synthesized and characterized. The nanocomplexes between CS-Biotin and insulin were prepared via self-assembly method. Thereafter, the nanocomplexes were fabricated by coating with various molecular weight hyaluronic acid (HA), which improved penetration efficiency in the mucus layer and small intestine in a HA molecular weight dependent manner. In vivo study indicated that hypoglycemic effect of the nanocomplexes was biotin modification degree and HA molecular weight dependent, with HA (200)-coated CS-Biotin21.8%/Insulin polyelectrolyte complex presenting the best performance. In conclusion, biotin decorated muco-inert nanocomplexes with HA coating are a promising platform for oral insulin delivery.