Preparation And Performance Research Of β-tricalcium Phosphate And Its Composites

In recent years, bone tissue engineering material has been becoming animportant choice of bone repair material for many of its merits. Ideal bone repairmaterials should be of good biocompatibility and high bioactivity. Besides, theirmechanical properties should be equivalent to natural bone. Single organic polymermaterial or inorganic ceramic material is difficult to meet the requirements forbiological properties and mechanical properties of bone repair materials. Therefore,porous composites become the development direction of bone tissue engineeringmaterials.This paper first described the preparation of β-tricalcium phosphate powders bymicrowave-assisted co-precipitation method. The effects of pH value and themicrowave specific effects including microwave heating temperature and microwaveradiation time on the formation of pure β-tricalcium phosphate were studied. Ourexperimental results indicate that the reaction condition for the synthesis of pureβ-tricalcium phosphate by co-precipitation method is optimized when the reactionpH value, the microwave reaction temperature and the microwave radiation time areset at7.0,50oC and40minutes, respectively. Compared with co-precipitation method,the main advantages of microwave processing of β-tricalcium phosphate includeextremely rapid reaction kinetics of crystallization and shorter processing timeand/or lower reaction temperature. This in turn may lead to energy savings. A fastand efficient method for the preparation of β-tricalcium phosphate is put forward.β-Tricalcium phosphate/chitosan porous composites were prepared by NaHCO₃foaming process. The results showed that a representative structure of β-tricalciumphosphate/chitosan composite scaffolds with irregular macropores and most poresize in the range of50～200μm were observed. Under high power lens it was shownthat homogeneously interconnected micropores distributed on the pore walls andβ-tricalcium phosphate particles were well distributed in chitosan matrix withoutsegregation. The porosity of the porous scaffolds was more than45%, thecompressive strength was higher than14.391MPa and the bending strength washigher than10.105MPa, which were all basically satisfied with the requirements of bone tissue engineering materials. The in vitro degradation behavior of theβ-tricalcium phosphate/chitosan composites showed that the pH of degradationmedium maintained neutrality skew alkaline, which could avoid or reduce axenicinflammation. After immersed in SBF for4weeks, there were bone-like apatitesformed on the surfaces of the scaffolds. This showed that the β-tricalciumphosphate/chitosan porous composites had good biological activity.Chitosan/β-tricalcium phosphate/wollastonite composite scaffolds were preparedby freeze-drying method. The effects of wollastonite on the degradation property andin vitro bioactivity of the composite scaffolds were investigated. The compositesscaffolds were macroporous and had interconnected pores with diameters from50to200μm, which would not only be good for cell implantation and adhesion but also beconducive to nutritional components infiltration and excretion of metabolic products.The results of in vitro degradation experiment showed that the incorporation ofwollastonite into β-tricalcium phosphate/chitosan composites could enhance both thedegradation rate and the formation ability of bone-like apatite. Compared withβ-tricalcium phosphate/chitosan composites, the mechanical performance ofchitosan/β-tricalcium phosphate/wollastonite composite scaffolds was poor, but thebioactivity and degradation property of the resultant composite were very excellent.The macroporous chitosan/β-tricalcium phosphate/wollastonite composite scaffoldsmay be a potential candidate for application in bone tissue engineering.