Ca-p Bioceramic Surface / Interface Formation, Characterization And Material Bone Induction

The basic principle for the design of modern biomaterials is to take advantage of the body's natural ability to heal, especially to endow biomaterials with the biological function to induce tissue or organ regeneration. As the main inorganic composition of body's hard tissue, calcium phosphate biomaterials have excellent biocompatibility and the ability bonding with bone after implantation and are not only osteoconductivity, but also osteoinductivity.Weather the non-living biomaterials has the ability to induce bone formation has not be accepted as a general phnomena; one of the key reason is that the mechanisum of osteoinduction is still unclear. After implantation in vivo, the reaction between the materials and the doner is happenend fisrt at the surface/interface, so the properties of surce/interface are important to the biological property of the materials, including its osteoinductivity. In this thesis we focused on the surface/interface, by the research of the formation and the characterilization of the surface/interface of calcium phosphate biomaterials and the related affecting factors, including the micro-biological environment and the materials related factors, to discuss the relationship between the surface/interface characteristics and the osteoinduction of calcium phosphate ceramics.It's a complex course with so much related factors to refer to the interaction between the materials and the doners. To simplify the study model and outstand the infuluences of key factors, this thesis is focuesed on the key materials and bio-micro-envirnment factors, which have effects to the formation and characteristics of calcium phosphate ceramics surface/interface. Secondly, by the study of the effects of calcium phosphate with different surface/interface characteristics to the adhension and difffirenration and prolifferation of bone tissue cells, to study the surface/interface characteristics which is related with biological factors; and lastly, by in vivo study, to correct the results in vitro and give the conclusions.By in vitro biomemetic study, it has been founded that in the aqueous system, almost all of the Ca-P ceramics can form a second nuclean apatite layer by disolution-reprecipitate. The forming ability and the characteristic of the surface apatite are effected by the composition of the materials, micro-structure and thesolutions be used. Calcium and phosphate ions and carbonate ions are necessary for the carbonate apatite formation. At the same time, carbonate, sodium and others ions were incoparated into the apatite to induce the formation of bone like apatite, this kind of apatite is corresponding with the bone apatite. The key factor is the solubility of the ceramics, the phase composition, microstructure and the sintering temperature of the porous ceramics also have strong effects to the ability of bone like apatite formation. The ability of bone-like apatite formation of calcium phosphate ceramics is: HA/TCP> HA sintered imperfectly >HA sintered on high temperature. The order of the ability of bone-like apatite formation is corresponding with the order of osteoinduction of Ca-P ceramics.By the studies in vitro and in vivo, it has been demonstrated that the composition of the media and the composition and the structure of the materials has strongly affect the characteristics of the bone-like apatite layer. The formation of the net-like bone like apatite with the coporation of protein molecules is suitable for the adsorption and attachment and proliferation of the protens and cells. Contraray to that, the plate-like bone like apatite without the coparation of protein molecules, although has almost the same constructure of bone apatite, could still be recoganized as the un-real biomimimal matrix, the ability to protein and cells attachment, proliferation is not so good. Based on the results, the bone like apatite could be denificated as: the nonstomichemical amophase apatite layer formed by incoparation of carbonate and the corporation and manipulation of proteins.By the study in vivo,...