The Biomimetic Synthesis Of Organic/Inorganic Nano-composite Materials And Study Of Adhesive Property Of Osteocyte

The research on bone tissue engineering materials which are used for replacing damaged tissues has extensive implications since the bone tissue which is lost or damaged as a result of injury, infection and ageing becomes increasingly serious. Due to the self-assembly and biomineralization in the long term evolution, natural biomaterials become a kind of material which have a simple component but complicated structures, excellent adaptabilities and self-adjusting abilities. In a sense, the study of composition and structure of natural biomaterials is of great importance to the development of biomimetic materials. As the implant materials, biomimetic materials must possess excellent biocompatibility, biodegradability, bone inductivity, mechanical property and perfect topography to combine well with the host tissue and provide location for the growth of implanted tissue. A mass of organic/inorganic composites have been studied to prepare scaffolds with the similar structure and composition of natural bone tissue. In order to obtain implant materials with excellent biodegradability, polymer composites were begun to studied and prepared.According to the above research background, the hierarchical fabrication of the Chinese sturgeon bone was firstly investigated and the chitosan/hydroxyapatite composite was obtained by bionic preparation. In order to get a biomaterial with significant property of biocompatibility, PDLLA/gelatin composite has been prepared. The structures and functions of these two composites were investigated. Furthermore, in order to estimate if these two composites were appropriate to be the implant materials, osteoblast were cultured with the composite materials. Content is as follows:(1) The Chinese sturgeon bone is a kind of natural biological mineralized material with excellent mechanical performance. We detailedly studied the composition and interior structure of Chinese sturgeon bone and the reason of its high mechanical performance were revealed. The results showed that the bone was composed of nanocrystals and nanofibers. At the same time, inorganic crystals integrated into organic matrices tightly. In order to confirm the structures of organic matrices, decalcified samples were investigated. It showed that the decalcified samples were composed of organic layers which were regularly hierarchical fabricated and every layer was consisted of innumerable long and straight nanofibers. The special structures were responsible for the good mechanical properties of Chinese sturgeon bone. Therefore, the Chinese sturgeon bone was a kind of natural nanocomposite with high mechanical properties. And for the first time, the stereo hierarchical fabrication and high mechanical strength of the Chinese sturgeon bone was elucidated. From this research, a new inspiration that we can synthetically mimic the special structure of the Chinese sturgeon bones to develop a new material was obtained.(2) Chitosan/hydroxyapatite composite was prepared according to the inspiration of the first work. The microstructure, the action between organic matrix and inorganic crystals, degradation ability and compatibility of the composite were studied. The compatibility of the material was estimated by culturing cells on it. The results showed that the amount of cells, the cell adhesion and spreading rates and the viability of cells on the prepared composite were all more excellent than those on the pure chitosan material. In general, the composite we prepared showed excellent biocompatibility. Meanwhile, via the degradation test we found that the degradation ability ofthe composite we prepared was better than that of the chitosan material. In conclusion, the chitosan/hydroxyapatite composite is a biomaterial of excellent biocompatibility and biodegradability.(3) In order to improve the biodegradability of bone tissue alternative materials, we prepared another PDLLA/gelatin porous composite. The composite was polymerized of two kinds of macromolecules which all have remarkable biodegradability. And the excellent biodegradability of the prepared composite was also proved by our experimental study. In the paper, the composites with different PDLLA/gelatin ratios (1:0,1:1,1:2,1:3,2:1and0:1) were prepared. We found that the composite with the PDLLA/gelatin ratio of2:1exhibited a uniform porous structure with high connectivity and porosity. This structure will ensure the flow of nutriment and the excretion of metabolic which can provide an excellent environment for cells to adhere, proliferate and differentiate. The results indicated the composites with the PDLLA/gelatin ratio of2:1had the most superior biodegradability. From the above, the PDLLA/gelatin porous polymer composite has a potential application in the biomedicine fields.