Protein Retention in Chitosan-Alginate Microcapsules Modified for Possible Oralprotein Deliverywith Selected Excipients

The protein retention characteristics of chitosan-alginate microcapsules modified with selected excipients were evaluated in vitro for oral protein delivery using Bovine serum albumin (BSA) as the 'model' protein. The microcapsules were prepared by extruding alginate solution containing BSA and either talc, Eudragit L100, Eudragit RSPM, microcrystalline cellulose (MCC) or HPMCAS, into chitosan/calcium chloride solution. Protein retention in microcapsules at different pH of the elution medium was determined spectrophotometrically at e_max of 280 nm. Microcapsules containing MCC and talc had the highest protein retention capacity, with 68% and 60%, respectively, of protein still available in the core of the microcapsules after 9 h at pH 1.2, while HPMCAS failed to retain any protein after 9 h at the same pH. Protein retention in microcapsules modified with other additives was intermediate. At higher pH values, microcapsules containing talc still exerted the highest protein retention of 77% (pH 3) and 85% (pH 6), followed by microcapsules containing Eudragit RS PM, 65% (pH 3) and 80% (pH 6), after 9 h. This work has demonstrated that blending the core with suitable excipient enhanced protein retention capacity of chitosanalginate microcapsules. This technology can be employed in oral delivery of protein/vaccines to human and aquaculture.