Effect of electrical polarization and composition of biphasic calcium phosphates on early stage osteoblast interactions

In spite of having excellent biocompatibility and osteogenic property of hydroxyapatite (HAp) and beta-tricalcium phosphate (beta-TCP), concerns have been raised regarding their degradation kinetics. Complete in vivo degradation of HAp takes years because of its slow degradation rate, and fast degradation rate of beta-TCP limits its application. Biphasic calcium phosphates (BCPs) composed of both HAp and beta-TCP have controlled degradation to some extent. Here, we have prepared three different BCPs composed of beta-TCP and HAp. These BCP composites are successfully electrically polarized to generate surfaces with positive (P-poled) and negative (N-poled) charges. Thermally stimulated depolarized current measurement (TSDC) exhibits increased stored charge density with the increase in HAp percentage in the composites. Our study focuses on understanding the effect of composition variation as well as electrical polarization of these composites on early stage osteoblast-cell adhesion, proliferation, and extracellular matrix (ECM) formation capability. No matter what the composition is, N-poled (Negatively poled) surfaces show early stage osteoblast-cell adhesion, proliferation, and ECM formation when compared with U-poled (unpoled) and P-poled (positively poled) surfaces. Irrespective of the surface charge, an improved cell-material interactions are observed as the percentage of HAp content in the composites is increased. These electrically polarized BCP composites can have potential use in the area of orthopedics and dentistry. (C) 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 97B: 306-314, 2011.