Design And Fabrication Of Hydroxy Apatite/Protein-Based Bone Imitative Materials

Bone injuries always trouble people, even being a serious life-threatening. Bone-replacement materials provide an important way to solve the problem. And bone materials are one kind of the bone-replacement materials which are used to mimic the function of bone tissue. Considering that hydroxyapatite and protein are the main composition of nature bones, in this thesis, we explore the synthesis of the nano-hydroxyapatite and nanohydroxyapatite/protein composites, by introducing high-gravity technology, we also discussed their application in biomedical field as bone-replacement materials. The main contents are as follows:(1) In this thesis, nano-sized hydroxyapatite was synthesized with different sources of calcium (Ca) and phosphorous (P) under different temperatures. The hydroxyapatite nanoparticles (nHAP) was characterized via analytical methods such as XRD, FTIR, TEM and TGA to investigate the effect of different reaction temperatures and different Ca and P sources. The results showed that higher reaction temperatures led to better crystallization and larger particle sizes. Different calcium sources had little effect, while different phosphorus source changed product compositions, with some phosphate group replaced by hydrogen phosphate group. The results showed that the product synthesized from sodium hydrogen phosphate contained the most hydrogen phosphate replacement.(2) The nHAP were successfully synthesized using a high-gravity precipitation method. Crystal structures and morphology of the nHAP were confirmed by XRD and TEM. Chemical nature of the nHAP was analyzed by FTIR and ICP-AES. The characterization results demonstrated formation of nHAP with diameters of 1.9-14.2 nm and lengths of 4.0-36.9 nm and carbonated apatite structures, which were comparable to that of natural bone apatite. Moreover, potential applications of the nHAP in preparing Calcium Phosphate Cements (CPC) and Gelatin/HAP composite hydrogels were explored.(3)This thesis explored the potential use of a high-gravity co-precipitation strategy to synthesize nano-sized protein/hydroxyapatite (gelatin/silk-hydroxyapatite) composites with high protein absorption efficiencies. Physicochemical properties of the nano-composites were characterized using XRD, TEM, FTIR, TGA and BET. The characterization results confirmed formation of protein/HAP composites exhibiting carbonated apatite structures, rod-like morphologies, a high protein absorption efficiency and biocompatibility. In addition, the protein/HAP nano-composites were molded into cylindrical shaped Calcium Phosphate Cements (CPC), displaying an average compressive modulus of ?0.6 GPa. The compressive modulus was comparable with that of a human cancellous bone. The silk/HAP nanocomposites and CPC are also sythesized by this strategy which means the high-gravity co-precipitation is universal.The thesis shows many advantages of the high-gravity method, as a convenient, efficient, convenient industrialization for the preparation of bone-imitative materials.