Fabrication And Study Of Novel Composite Calcium Phosphate Ceramic Bone Scaffold

Bone tissue engineering method is a novel and promising method for the repair and reconstruction of diseased or damaged parts of the musculo-skeletal system, using biomaterials, cells, and factors alone or in combination. The first and key step is to manufacture a bone tissue engineering scaffold with desired structure and properties, of which, the major issues are (1) the use of appropriate matrix material, (2) its biocompatibility and biodegradability, (3) the control of pore structure and porosity, (4) the sufficient mechanical strength and bioactivity, etc. In this study, Calcium polyphosphate (CPP) was initiatively combined with biological Hydroxyapatite (HA) with the purpose of improving the sintering property, optimizing the mechanical strength and adjusting the degradability of HA. And rheological method has been applied to investigate and control the rheological properties of foaming ceramic slurry, with the purpose of control the pore morphology of the dried and sintered bodies. Both dense and porous bodies have been fabricated using HA/CPP mixed powders. The effects of CPP content and calcination temperature on the phase compositions, the sintering property, the compressive strength and the microstructure of the final products have been discussed in details. Amorphous CPP would react with HA and produceβ-calcium phosphate (β-TCP) and H2O. A small dosage of CPP (<10wt %) can promote the sintering of HA and finally obtain a traditional Biphasic Calcium Phosphate (BCP), HA andβ-TCP. Excessive CPP dosage (>10wt %) would obtain a novel BCP,β-TCP and amorphous-CPP. High compressive strength could be achieved either at high sintering temperature(>1300℃) with no more than 20wt% CPP dosage or at high CPP content (>20wt %) with intermediate calcination temperature (1800℃~1250℃). Rheology study has illustrated the effects of the solid to liquid ratio (S/L), the additives and their content on the slurry rheological properties, such as slurry viscosity, thixotropy and modulus, etc, and uncovered the relation between slurry viscosity and pore morphology of the dried and sintered products. The porous composite scaffolds (HA/β-TCP andβ-TCP/a-CPP) with an average macropore diameter in range of 200~600μm and a total porosity in a wide range of 60~90% have been obtained by a combined slurry foaming method. The compressive strength of porous bodies varied from 0.2 to 6.7MPa. Evident degradation of porousβ-TCP/a-CPP has been proved by SEM and degrading weight loss.