Retained integrity of protein encapsulated in spray-dried chitosan microparticles

Chitosan microparticles for delivery of proteins were prepared by spray-drying technique. The effects of formulation (molecular weight and concentration of chitosan) and process variables (inlet drying air temperature and spray rate) on size and morphology of microparticles were characterized. Size of microparticles was mainly controlled by formulation variables, while particle morphology was influenced by both formulation and process variables investigated in this study. Bovine serum albumin (BSA), as a model protein, was loaded into microparticles at different levels. BSA-loaded chitosan microparticles were characterized in terms of physicochemical properties and integrity of encapsulated protein, which was studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and circular dichroism. Size of microparticles ranged between 3.760-8.681 microm, of which BSA-loaded microparticles were larger in size than their corresponding blank microparticles. All microparticles showed dented or distorted surface, especially when BSA was incorporated, with positive surface charge exposed. Burst release of protein was observed. The effect was more pronounced as BSA loading level was increased. Integrity of entrapped protein could be retained when BSA was incorporated at high loading level. In conclusion, chitosan microparticles for delivery of protein could be efficiently prepared by spray-drying technique. The encapsulated protein was capable of retaining its integrity after the preparation process.