Development of novel types of bone-like polymer-ceramics composites using self-organized patterns

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This research project aimed proposal of novel routes for preparation of polymer-ceramic composite materials having three-dimensionally hierarchical structures and development of new types of bioactive materials. The results of this project is categorized into two parts ; study of self-organized spatial pattern of inorganic crystals in gel matrix as model cases for various practical materials and preparation of hierarchical and nanostructures hydroxyapatite and its composite materials using the spatial patterning in gel matrix.In part I of this project, we found that the control of mass transport in gel matrix and the adsorption of organic molecules specific on specific surfaces of inorganic crystals the essential factors for the self-organized spatial patterns of inorganic crystals. Moreover, the strong interaction between inorganic crystals and organic gelling agents produced hierarchically organized architecture from nano to macroscale. These findings are effective in the controlled … More synthesis of new types of organic-inorganic composite having three-dimensional structures because natural biominerals are also composed of nanoscale building blocks similar to the artificial system.In part II of this project, we developed a new type of hydroxyapatite-polymer composite having a hierarchically organized architecture similar to that of natural bone. The macroscopic periodic structure of HAp was successfully controlled from laminated layers to a cellular porous form by the reaction condition. The laminated HAp-polymer composites have potential for new types of biocompatible materials, because their mechanical properties are similar to those of natural bone. This study also provided another preparation route through the topotactic transition of precursor crystals for the formation of a hierarchical architecture. Novel types of nanotextured and nanofibrous hydroxyapatite were successfully produced through the topotactic transition of dicalcium phosphate dehydrate containing gelatin molecules. Nanotextured hydroxyapatite with an oriented framework of ca. 20 nm grains and nanofibrous hydroxyapatite elongated along the c axis with a diameter of ca. 50 nm were formed from nanostructured dicalcium phosphate prepared by dehydration through the specific interaction with gelatin molecules. The hierarchical architectures of the nanostructured hydroxyapatite providing a high specific surface and macroscopic pores would be applicable for various biomedical applications. The hierarchical porous hydroxyapatite architectures could be useful as an adsorbent and as a scaffold for tissue engineering. Less