Research On The Interaction Mechanism Between The Collagen And Bioactive Glass And Their Composite As Bone Repair Material

In present study, the interaction mechanism of bioactive glass and collagen fibers was studied. Based on this research, the bone repair material composited of collagen and bioactive was prepared. Furthermore, the mechanical property and degradation property of the scaffold were improved, by the aggregation of collagen fibers was controlled in the process of preparation, under the premise of the biocompatibility of the scaffold guaranteed. The scaffold is prepared as a new kind of biomedical materials, with good cytological performance and bone repair property.The research on the interaction between collagen and bioactive glass has an important meaning in the bionic structure for the bone scaffolds fabrication. In this study, it was revealed that the conformation of collagen changed obviously during the process of preparation in the aqueous solution with collagen and bioactive glass coexistent, in order to suit the different solution environment. When the bioactive glass was added into the solution of collagen, the equilibrium state among the collagen fibers would be changed, including the calcium ions released from bioactive glass coordinated to carbonyl groups of collagen, and silicate ion also released from bioactive glass bonded to the -C=N- groups of collagen, and also the pH value of the solution of collagen changed. In order to hold the high biocompatibility of collagen in the composite, its structure should be maintained in a maximum extent to its original structure. It was investigated that the collagen in the composite could keep in a maximum extent to the triple helix structure of collagen, when the content of collagen in the composite was 40%. This can provide theoretical basis for preparing the collagen/bioactive glass composite with higher mechanical prosperity and degradation prosperity.Basing on the control the aggregation of collagen fibers in solution, the collagen/bioactive glass scaffold was fabricated. The scaffold showed similar features with nature bone both in main component and hierarchical microstructure. The maximum compress strength of this scaffold could be 1.5469±0.0995MPa. The residual mass was 35% of original after degradation under collagenase enzymolysis duration 3days at 37 oC, and the scaffold still had enough strength to keep its profile.The results of the study of the scaffold's the bioactivity in vitro and biocompatibility showed that the biomineralization and bioactivity of the scaffold were similar, both could form a layer of apatite on their surface in a short time; and there was no statistical difference in cell proliferation between scaffold and collagen by MTT assay and SEM. Cells could grow into the pore of the scaffold and adhere to the sidewall and the surface of this scaffold.After the rMSC combined with collagen/bioactive glass composite, the scaffold was induced ectopic osteogenesis in back muscles of nude mice. In the results of the RT-PCR test, there were three kinds of gene in the scaffold expressed higher than normal bone tissues, which were the expression of collagen I (Col1a RNA), the expression of bone morphogenetic protein (BMP-2 RNA) and osteopontin (Sppl RNA). It also can promote the concrescence of 8mm loaded bone defects of rats. There were pieces of new formed bone appeared in the places of implants after 4 weeks. The composite of collagen/bioactive glass had better biocompatibility, mechanical prosperity, and biodegradation, which would be a comfortable scaffold for bone repair.