Formulation of pH-responsive carboxymethyl chitosan and alginate beads for the oral delivery of insulin

pH-sensitive beads were prepared from the interpenetrating polymer networks (IPNs) of carboxymethyl chitosan (CMCTS) and alginate to study their application in oral insulin administration. CMCTS was synthesized from chitosan and was characterized by Fourier transform infrared spectroscopy and wide-angle X-ray diffraction. Calcium chloride, a relatively less toxic material, was used to crosslink both the alginate and CMCTS to prepare the IPN beads. The IPN beads were used to encapsulate insulin at different weight ratios. The swelling behavior and insulin release profile in response to simulated gastric and intestinal media of the beads were investigated. The beads observed under scanning electron microscopy were almost spherical, with an average diameter of 780 m. The bead with about a 54% insulin loading efficiency was observed to contain about 98% encapsulated insulin. The maxima of about 20% insulin retention at acidic pH (1.2) and about 94% insulin release at intestinal pH (7.4) justified the good pH-responsive nature of these IPN beads. Moreover, the insulin released from the IPN beads was stable and biologically active. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 129: 835-845, 2013