The near equiatomic intermetallic nickel titanium (NiTi) has remarkable properties. It is a shape memory alloy that exhibits considerable super-elasticity. Super-elastic NiTi is of special interest as it has elastic properties which are far closer to bone than conventional metallic materials. Although concerns have been expressed regarding the high quantity of potentially toxic nickel in the metal; a wide range of studies have shown that nickel release from these alloys is low and poses little risk to patients.
The biocompatibility of NiTi is attributed to the formation of a highly corrosion resistant titania surface film. In recent years considerable research has been carried out into mechanisms for increasing the biocompatibility of titanium by modifying the surface chemistry of the metal to enhance the growth of hydroxyapatite phases on the surface. It has been shown that a wide variety of surface modification techniques may be employed to this end.
This proposal aims to extend the work carried out on Ti to NiTi surfaces. The modification procedures proposed are combined alkali and heat treatments and calcium ion implantation. It is vital that any surface modification does not compromise the passive titanium oxide film resulting in increased ion release. Therefore, it is proposed to monitor the properties and form of the oxide film using X-ray photoelectron spectroscopy (conventional and depth profiling), secondary ion mass spectrometry (static and dynamic), white light interferometry, goniometry and ion-chromatography. Bioactivity of the resulting surfaces will be assessed by measuring the ability to precipitate calcium phosphates from simulated body fluid and the performance of osteoblast cells on the surfaces.
Call for proposal
See other projects for this call