Self-assembly pH-sensitive chitosan/alginate coated polyelectrolyte complexes for oral delivery of insulin

Polyelectrolyte complexes (PEC) provide new opportunities for controlled release system of drugs, and have potentials to address challenges on the way to effective oral insulin delivery. Here, an innovative pH-sensitive PEC for insulin oral administration was developed, which was formed by self-assembly of two oppositely charged nanoparticles (chitosan-coated nanoparticles and alginate-coated nanoparticles) through electrostatic interaction via optimised double emulsion method. The encapsulation efficiency of insulin-loaded alginate-coated and chitosan-coated nanoparticles were 81.5 ± 7.4% and 55.2 ± 7.0%, respectively, and the particle size of these nanoparticles were in 200–300 nm range. The pH-dependent morphology of PEC was observed by transmission electron microscopy. The PEC exhibited insulin release profile triggered by pH in vitro and was non-cytotoxicity against Caco-2 cell. The insulin-loaded PEC could decrease blood glucose levels effectively and prolong insulin release after oral administration to diabetic rats. The results illustrated that the as-prepared PEC may be employed as a potential oral insulin delivery system.