Orientation Of The Collagen Material Preparation And The Factor Of Influence

As a biomacromolecules, collagen has a rich source in various of tissues which can be separated and purified from these tissues. Removing the telopeptide with antigenicity, collagen can be processed to prepare biomaterials with excellent biocompatibility. Collagen is the predominant component of extracellular matrices existing in all multicellular animals, which can not only maintain structural integrity of tissues and organs, but also participate physiological processes in endosomatic, such as cell adhesion, proliferation, migration and differentiation, signal transduction of cells, tissue construction and regeneration, and so on.In many tissues and organs, collagen fibers aligned with a special orientation. The orientation of collagen fibers determined the construction features of these tissues and organs, and then affect their biomechanics, performed as a basis for the tissues and organs to execute their physiologic function. The destroy of collagen fiber orientation can result in the destroy of tissue structure, making it lose the intrinsical biomechanics property and influencing the normal physiologic function. At present, when repairing the destroyed tissues, how to maintain the orientation of collagen fibers and realize the reconstruction and fusion of these tissues, has become one of the research directions in biomaterials, tissue engineering and regenerative medicine fields. The main thread is to construct implant materials with the same orientation of target tissue in vitro.In this thesis, we reviewed the research evolution of the construction of collagen materials with special orientation and analysised some of the influence factors which affect the orientation in the build process of collagen materials. We researched the mechanism of collagen fibers formation and orientation, and carried out biomineralizaion of collagen materials on this basis.1. Research on collagen fiber formation mechanismWe chose sigma type I collagen from tendon of bovine to prepare collagen solution. First we investigated the physical and chemical properties of collagen. IR, UV, CD and DSC results showed that the characteristic triple helix structure of collagen remain intact with chosen experimental concentration and temperature. Then we investigated the self-assembly of collagen in presence of PBS buffer. The DLS, UV and ITC results showed that the self-assembly of collagen is a complex multistep process. AFM results showed that collagen can assembled into fibers with typical D-period under the effect of PBS buffer. In this research we found that the self-assembly process of collagen could be affected by concentration, temperature, pH, ionic strength and some other factors, the dimension and D-period of collagen fibers changed with the factors above. 2. Research on collagen fibers orientationWe built an experimental facility which can control the air strength, direction and temperature. With this facility we investigated the influence of surface property of substrate material, temperature, concentration, air strength, air direction and air action time on the orientation of collagen fibers, and explored the mechanism of collagen fibers orientation with the effect of air flow. SEM and AFM results showed that in the collagen materials prepared in this research, the collagen fibers aligned in a determinate orientation and the D-period is integral.3. Research on collagen biomineralizationWe simulated the biomineralization of collagen to prepare materials and then carried out representation on them. SEM and AFM results showed that in these materials, collagen could be mineralized in a certain degree and formed crystals distributed regularly. SAED and XRD results showed the crystals were mainly polycrystal hydroxyapatite. IR results showed collagen structure remain stable during the mineralization.