Study On The Fabrication Of Organic/Inorganic Composite Biomaterials

As an important research field of tissue engineering, biomaterials are widely used in the clinic. They have many kinds and different characters, although they are useful some extent, disadvantages such as less strength, unsuitable degradation compared with tissue growth can't be overcame by themselves. Based on this, two different materials are selected as basic to fabricate composite materials, this can make full use of advantages of each other and improve integrated property.As a kind of biomaterials, Calcium sulfate (CaSO4) was used long ago. CaSO4 has good biocompatibility and biodegradability, but its degradation rate is too quick and can't match with the growth of new tissue. Polymer with good biocompatibility and biodegradability is always used as biomaterials, more important, they possess cell recognition signal. But mechanical properties and degradation rate can't be adjusted easily. In this article, we choose CaSO4 and polymer as basic materials, and exert template technique and biomineralization method to fabricate composite biomaterials. By this way, the performance of materials will be optimized. Main contents are followed.Firstly, sulfochitosan is synthesized and its properties are discussed. The factors which influence sulfur content and the degree of substitution are analyzed, these include doses of chloride sulfuric acid, reaction temperature and time. In addition, the interrelation between sulfur content and solubility is discussed, and the quality of the solution of chitosan and sulfochitosan is studied. By sulfonation reaction, active group of –SO3- can be introduced to chitosan molecule, this offer the possibility of the following biomineralization .Secondly, colloidal crystal templates of different materials and sizes are prepared. Monodisperse polystyrene (PS) particles are synthesized by emulsion polymerization and dispersion polymerization, the influence of doses of emulsifier and monomer, polarity of solvent is discussed. Monodisperse silicon dioxide (SiO2) particles are synthesized by Stober method. The influence of doses of ammonia is studied. Through gravity sedimentation, PS particles or SiO2 particles turn into colloidal crystal templates of opal structure respectively, their similarities and differences are compared.Thirdly, porous templates of polymer are prepared. According to different characters of given polymer, PS or SiO2 colloidal crystal templates are chosen, polymer is filled in the pore canal of the template. When the filling is finished, PS or SiO2 is removed selectively, and porous polymer templates with inverse opal structure are obtained. Some factors such as filling degree, solution concentration and polarity which influence the filling effect are discussed. Fourthly, by biomineralization, composite biomaterials are prepared. The porous polymer offers the premise of biomineralization. Through alternate soak, Ca2+ and SO42- enter the pore and combine each other to change into CaSO4 crystals. During the growth of crystal, they are confined in the pore and can not grow free, and the crystals interlace polymer to form a integrate network. The composite materials of organic and inorganic compounds are created by this way.