Biological Propertites Of Composite Oxide Nanostructures

Due to the similar elastic modulus to bone, excellent biocompatibility and corrosion resistance under biological environment, pure Ti and its alloys have been widely used as artificial hip, orthopedic and dental implants. Moreover, Ti and its alloys bond with bone in a simple interlocking way, which cannot bond chemically to the host bone, so it can lead to the loosening of the implant and the eventual failure of the implantation. It has been accepted that the essential requirement for an artificial biomaterial to exhibit the tight chemical bonding to the host bone is the formation of a bone-like apatite layer on its surface in the body condition. It has been reported that an intermediate layer can have significant impact on the chemical bonding between a HAP coating and a metallic substrate. Fabricating a thick and stable titanium oxide nanostructures on the surface of Ti alloys are expected to improve the bioactivity and the nanostructures will enhance the bonding between the metallic substrate and apatite.The titania-based composite nanostructures can be fabricated on the surface of titanium or titanium alloys through an anodization method. This paper discusses the anode oxidation process of the pure titanium and titanium alloy (including Ti35Nb, Ti35Nb5Zr, Ti35Nb10Zr and Ti35Nb15Zr alloy, as well as the aged Ti35Nb5Zr alloy). We investigated mainly on the wettability, in vitro bioactivity, as well as stem cell interactions with the composite oxide's nanostructures, and we also made a preliminary exploration of drug-release properties of the Ti-Nb-Zr-O nano-structures. Meanwhile, this paper take a comparative study of pure titanium metallic and the Ti-O nanostructures on the differences of wettability and the interaction with the stem cell. We focused on analyzing how the alloying elements effect on the wettability and in vitro bioactivity of the composite oxide nanostructure, and then compared on a variety of different nanostructure's wettability and in vitro bioactivity.It was found that the as-anodiazed composite oxides could significantly improve the biological properties of the Ti alloy surface. Investigation on the anodization of Ti35NbxZr alloys revealed that, the existence of Nb and Zr elements in the anodic oxides could refine the diameter of the nanotubes and help to grow longer nanotubes, and with the increase of the Zr content in the original Ti35NbxZr alloys, the surface wettability could be significantly improved. The as-anodized Ti-Nb-O and Ti-Nb-Zr-O nanotubes show a highly hydrophobic behavior, which differ from the hydrophilic behavior demonstrated by the metallic substrate surface before anodization. Compared with the pure TiO2 nanostructure, the Nb, Zr-doped composite TiO2 nanotubes could induce a quicker apatite formation after immersion in simulated body fluids (SBF). Moreover, similar to undoped TiO2 nanotubes, the Nb, Zr-doped composite TiO2 nanostructures also promote mesenchymal stem cell adhesion and fast formation of extracellular matrix (ECM) materials. For the gentamicin/ Ti-Nb-Zr-O nano-structured drug-release system, studies have shown that the release process of the high content drug loading is more slowly than low content drug loading. Besides, from the view of the efficiency of drug release, the higher content of the drug loading, the more the drug residues in the nano-tubes relatively.