Research and Development of Metallic Biomaterials Meeting Clinical Demands

Referencia Apresentador Autores
Takao Hanawa Hanawa, T.(Tokyo Medical and Dental University); Metals and alloys are widely used as biomedical materials and are indispensable in the medical field. The advantages of metals compared with ceramics and polymers are their great strength and resistance to fracture. In particular, toughness, elasticity, rigidity, and electrical conductivity are essential properties for metals used in medical devices. We are making the best effort to develop metal-based biomaterials to solve clinical problems. The problems could be soluble with two methods: The development of new alloys and surface modification techniques. To decrease MRI artifacts, metals with low magnetic susceptibility should be investigated. We have developed Zr-based alloys. Zr-1Mo alloy after large-amount melting showed large strength and elongation and low magnetic susceptibility. 3T MRI artifact of spinal instruments consisting of the alloy and implanted into sheep spine occupied in 2 mm and the vertebral canal appeared. Therefore, this alloy is a candidate of MRI compatible alloy. Here, high-pressure torsion (HPT) is a processing technique to produce ultrafine-grained structures through severe plastic deformation, even for hard and low-ductile metallic materials. HPT can enhance the strength with almost the same elongation. In this study, Ti-6Al-7Nb was deformed by HPT for strengthening of the alloy. To inhibit the adsorption of proteins, adhesion of cells and bacteria, and formation of biofilm, both terminals of poly(ethylene glycol), PEG, were terminated with –NH2 (NH2–PEG–NH2). The cathodic potential was charged to Ti. During charging, the terminated PEGs electrically migrated to and deposited on the Ti cathode. The PEG-immobilized surface inhibited the adsorption of proteins, as well as the adhesion of platelets and bacteria, indicating that this electrodeposition technique is useful for the biofunctionalization of metal surfaces. In addition, Antibacterial property is given to Ti by MAO in the addition of Ag to electrolyte. Therefore, both ability of bone formation and antibacterial property are simultaneously give to Ti surface.
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