Chitosan/calcium?alginate beads for oral delivery of insulin

Abstract

A mild chitosan/calcium alginate microencapsulation process, as applied to encapsulation of biological macromolecules such as albumin and insulin, was investigated. The microcapsules were derived by adding dropwise a protein-containing sodium alginate mixture into a chitosan-CaC12 system. The beads containing a high concentration of entrapped bovine serum albumin (BSA) as more than 70% of the initial concentration were achieved via varying chitosan coat. It was observed that approximately 70% of the content is being released into Tris-HC1 buffer, pH 7.4 within 24 h and no significant release of BSA was observed during treatment with 0.1M HC1 pH 1.2 for 4 h. But the acid-treated beads had released almost all the entrapped protein into Tris-HC1 pH 7.4 media within 24 h. Instead of BSA, the insulin preload was found to be very low in the chitosan/calcium alginate system; the release characteristics were similar to that of BSA. From scanning electron microscopic studies, it appears that the chitosan modifies the alginate microspheres and subsequently the protein loading. The results indicate the possibility of modifying the formulation in order to obtain the desired controlled release of bioactive peptides (insulin), for a convenient gastrointestinal tract delivery system. 0 1996 John Wiley & Sons, Inc.

Polymeric Hydrogels: Characterization and Biomedical Applications

“…A complex system of alginatechitosan microparticles was developed by Hari et al for the controlled release of bioactive peptides including insulin. In the study, the bioactive peptide dispersed in the cross-linked alginate formed the core with a subsequent layer of chitosan over the core [55]. Thermal cross-linking of the anionic hydrogel comprising of PVA and poly(γ -glutamic acid) was found to be pH-sensitive in nature and was found to be compatible with the 3T3 fibroblast cell line.…”

Alginate microspheres prepared by internal gelation: Development and effect on insulin stability

“…In particular, calcium-alginate microspheres were used to encapsulate insulin by using an extrusion process (Gray and Dowsett, 1988) and an encapsulation efficiency of 65% was obtained. Insulin was also encapsulated in chitosan-coated alginate microspheres (Hari et al, 1996) but the encapsulation efficiency was very low (11%). Strategies to increase the encapsulation efficiency included the complexation of insulin with ␤-cyclodextrin (Moses et al, 2000) or the incorporation of insulin in liposomes (Ramdas et al, 2000) before the encapsulation in alginate microspheres.…”

Development of Alginate–Gum Arabic Beads for Targeted Delivery of Protein

“…Alginate is a polyanionic copolymer of guluronic and manuronic acids that can form hydrogel beads through ionotropic gelation by the addition of divalent cations in aqueous liquid [8]. Besides proteins [9,10], the other bioactive agents that can be entrapped into alginate matrices are including cells and DNA [11,12]. This is due to the relatively mild gelation process.…”