Controlling Bovine Serum Albumin Release from Biomimetic Calcium Phosphate Coatings

Biomimetic calcium phosphate (CaP) coating has been used successfully for protein delivery, but the release of protein from CaP coating is mainly dependent on the limited dissolution of the CaP coating and the passive diffusion of the protein in the CaP coating. In the present work, our aim is to improve the release behavior of protein from CaP coating and make it more controllable. By using bovine serum albumin (BSA) as a model protein, our strategy is to tailor BSA release profiles by controlling the distribution of BSA in CaP coatings. To achieve this aim, BSA was added to a modified simulated body fluid (m-SBF) at different stages of coating formation to obtain tailored BSA release profiles. Sustained BSA release was obtained when BSA was added to m-SBF at the initial stage of the coating where the BSA was incorporated into the lattice structure of the coating. In contrast, a relatively faster release was observed when BSA was added during the later stage of coating formation where BSA was mainly adsorbed to the coating surface. As a result, the BSA release efficiency could be tailored by adding BSA into m-SBF at different coating formation stages. More importantly, the coating composition was not altered with the change of BSA adding times and all the beneficial properties of the biomimetic coating were reserved. Therefore, the BSA release from CaP coatings can be tailored by adjusting its distribution in the coating to achieve a more satisfactory release profile.