Electric poling of cement composites of hydroxyapatite whiskers with chitosan and their chemical properties in simulated body fluid

Abstract

Cement composite of calcium phosphate was developed as a novel bioceramic material having biocompatibility, macro-porous structure, resorbability in vivo. The purpose of this study was to prepare and characterize the polarized calcium phosphatecitric acid-chitosan composite and to evaluate the effects of electrical polarization on bioactivity in order to enhance their biocompatibility. The characterization of the cement composite revealed that the surface is consisted with mixed phases of hydroxyapatite and CaHPO 4 ·2H 2 O, having porous microstructure. The thermal analysis indicated that the appropriate temperature for electrical poling is below 100°C to inhibit the degradation of each component. The electrical measurements revealed that the cement composite has poling ability at 100°C through the proton migration among the lattice sites of OH, HPO 4 and H 2 O molecules. The bioactivity was assessed by immersing the cement composites with or without electrical poling in simulated body fluid and evaluating the deposit and growth of bone-like apatite crystals on each surface. The negatively charged surface was accelerated compared to positively charged and non-poling surfaces.