Porous hydroxyapatite-polyhydroxybutyrate composites fabricated by a novel method via centrifugation

Porous hydroxyapatite-polyhydroxybutyrate (HA-PHB) composites were fabricated by infiltrating PHB micro-/nanoparticles into rigid HA scaffolds via centrifugation, followed by subsequent heating at 175°C to melt the PHB into the scaffolds. HA scaffolds were obtained by heating trabecular bovine femur bone at 1350°C to remove the organic and sinter the HA. PHB particles were recovered and purified from microbial cells by two different chemical methods, which either filled the apparent porosity of the scaffolds or coated the trabecular network of the scaffolds after heating. The mechanical properties, porosity, HA/PHB volume fractions and surface adhesion of the resulting HA-PHB composites were investigated and compared to the original HA scaffolds. The final porosities of the filled and coated composites were ~54% and ~67%, respectively. All of the HA-PHB composites showed a slight increase in strength with the addition of PHB. The filled composites showed no change in stiffness from the addition of PHB, while the coated composites showed an increase in stiffness over the original HA scaffolds from ~ 35 MPa to ~ 105 MPa. The enhanced stiffness in the coated composites was due to strong interactions between its HA and PHB constituent phases. Very little inter-constituent adhesion was observed in the filled composites.