Preparation And Characterization Of Porous Calcium Phosphate/polylactide Composites

Bioactive polymer/ceramic composite materials are one of significant biomaterials for bone defect repair with characteristic of inducing new bone. The composites can be used in many cases, such as bone tissue engineering scaffolds. Since polylactiede (PLLA) is the most widely used biomaterials in clinic application, and calcium phosphate (CP) has excellent biocompactivity and osteoconductivity. Hence, CP/PLLA composite is a promising and significant biomaterial.In this research, porous CPs/PLLA composites were prepared by a temperature induced phase separation technique with addition of PF127. The composites had interconnected pore structure with ~ 200μm pore size. CP particles were homogenously dispersed in PLLA matrix. These demonstrate that the composites obtained in this work can meet the requirements of bone tissue engineering scaffolds.For the composites with β-tricalcium phosphate (β-TCP)-PLLA system, the porous composites with β-TCP content from 30% to 80% were prepared. When the β-TCP content was 80%, the composite still had ~200μm pores and β-TCP dispersed very homogenously in PLLA matrix. This is attributed to that PF127 have roles of enlarging pores and dispersing β-TCP particles in the polymer.Degradation rate of β-TCP particles are slower than that of α-TCP, and α-TCP can transform into apatite that is very affinitive to cells. The biphasic α/β-TCP particles are used to form porous α/β-TCP/-PLLA composites in this work. These composites were soaked in PBS to evaluate changes in morphology and crystalline phase. The results showed: (1) no morphology and phase variation in β-TCP/PLLA were detected after soaking in PBS for 12 hours; (2) in α/β-TCP/PLLA composites, plate-like crystals appeared after soaking for 1 hour, and the plate-like crystals aggregated to clusters after 5 hour soaking; (3) with increase of α-TCP content in biphasic calcium phosphate, the plate-like crystals grew faster; (4) XRD patterns indicated the plate-like crystals are apatite.Amorphous calcium phosphate (ACP) has a similar structural unit to that in apatite. It can act as an important intermediate product for in vitro and in vivo apatite formation. In this research, porous ACP/PLLA composites were prepared. The ACP particles in PLLA matrix fast in situ transformed into ~ 100nm bone-like apatite. The osteoblast culture in the composite showed that osteoblasts adhered well in the composite pore wall surface, and the composite had much better cytocompatibility than PLLA.