? This Bioengineering Research Partnership proposal is submitted by a multidisciplinary collaboration of scientists primarily affiliated with the University of California (UC) system. The lead institution is Lawrence Berkeley National Laboratory, with component groups at UC Berkeley and San Francisco campuses. There is also small business collaborator from SkeleTech, Inc., in Bothell, WA. Some of the collaborators have worked together on ceramic projects for over 20 years, while others have worked together on dental research projects for over 10 years. This team has been expanded to include greater expertise in all the disciplines involved in this proposal: materials science, chemistry, biology, and dental/medical science. The research is aimed at development and testing of new implant materials by combining biomimetics with two radically new design philosophies to produce dense and strong bioactive scaffolds that are intended to be partially or completely resorbed and replaced by bone from the host in a sequence resembling bone remodeling. The ultimate goal is to develop strong and tough implant materials for load-bearing applications deriving their strength from nanoparticle hydroxyapatite and their toughness from hydrogel polymers, with the microstructural architecture scale on the order of tens of nanometers and below. Three types of materials will be developed. First, inorganic scaffolds with a dense core and a graded distribution of porosity and surface chemistry will be fabricated by stereolithography and by a novel technology developed in our laboratory based on freeze casting of calcium phosphate suspensions. Second, hydrogels and self-assembling polymers that possess anionic groups and adhesive ligands suitably positioned for the nucleation process and cellular adhesion will be used to direct templatedriven biomimetic mineralization of hydroxyapatite and other biominerals in nanoscopically and microscopically controlled fashion. Third, the resultant porous scaffolds will be used as the matrices to fabricate inorganic-organic composites with improved strength and fracture resistance. This will be achieved by infiltration of the inorganic scaffolds with hydrogels or by direct template-driven biomimetic mineralization of calcium phosphate nanoparticles on the organic scaffolds. Materials that pass the mechanical property tests will be tested in cell cultures and an animal model. Improvement of implants will result in improved health and quality of life for the millions of people who will need implants in the future. ? ?
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