Preparation and characterization of novel poly(epsilon-caprolactone)/biphasic calcium phosphate hybrid composite microspheres

Abstract

Desirably porous biodegradable hybrid composite microspheres were fabricated for use in bone graft and bone substitute applications. In this study, novel poly(epsilon-caprolactone)/biphasic calcium phosphate (70/30) composite microspheres (PCL/BCP MPs) were prepared using the emulsion solvent-evaporation method. Throughout this process, the ammonium bicarbonate (NH4HCO3) content was changed to obtain the desired porous structure. However, to maintain the spherical shape, the NH4HCO3 content should not be higher than 5%. In the optical images of the PCL/BCP MPs, almost all the microparticles had a spherical shape, and the average diameter was about 600 mu m. The scanning electron microscopy and cross-sectional optical images showed that the pore density and pore diameter of PCL/BCP MPs increased with increasing initial NH4HCO3 concentrations. In the phase-composition analysis of the PCL/BCP MPs, which was characterized by X-ray diffraction and EDS, the two crystals BCP and PCL phases were shown to be miscible in PCL/BCP MPs. When the degradation of these microspheres was characterized, PCL/BCP MPs-0, PCL/BCP MPs-2, and PCL/BCP MPs-5 were found to display a sustained biodegradability, and the rate of degradation increased at higher initial NH4HCO3 concentrations. Proliferation of cells on three different sample types was assessed and compared, and based on these results, the PCL/BCP MPs-5 was chosen to study MG-63 osteoblast-cell adhesion, growth, and proliferation. Furthermore, confocal images indicated that the cells effectively adhered, spread, and proliferated on PCL/BCP MPs-5 during a 5-day culture period. (C) 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 98B: 272-279, 2011.