Abstract: Bovine serum albumin(BSA) microcapsules, which have a uniform shape and size and can be well dispersed in water, were fabricated by the controlled precipitation of BSA on the surface of MnCO₃ microparticles though desolvation, followed by cross-linking and core removal. The thickness of the capsule walls were controlled by the amount of the added non-solvent(ethanol). The as-prepared microcapsules are permeable to TRITC-dextran with a molecular weight of 70000, but not up to 155000, implying that the pore size in the capsule walls is between 18.5—26.2 nm. Due to the excessive carboxylic groups on the BSA molecules, which can be fully charged at an alkaline condition, the BSA capsules expanded their size at pH>10. This method is applicable to other proteins and enzymes as well, and the pH-sensitive protein capsules may find potential applications in biomedical field because of their biodegradability and biocompatibility.

Key words: Desolvation, Controlled precipitation, Cross-linking, Protein microcapsules