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Nonmetallic Inorganic Materials
 
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Interactions of proteins with metal oxide surfaces

Contact: K. Rezwan

Protein adsorption to surfaces of medical implants is an essential aspect of the cascade of biological reactions taking place at the interface between synthetic material and biological environment. The types and amounts of adsorbed proteins mediate subsequent adhesion, proliferation and differentiation of cells as well as deposition of mineral phases.

Therefore, the nature of this adsorption process became of great interest in order to better understand the biointegration of implant materials, with the long-term objective of synthesising either fully biocompatible materials or, in the ideal case, truly bio-active materials to replace current materials. This would bring the advantages of improved patient recovery and subsequent quality of life. With an ageing population, this subject has naturally become one of great academic and industrial interest over recent years. But synthesizing full biocompatible materials requires more understanding of the fundamental aspects of protein adsorption.

Whilst metal oxides are directly used for applications where their extreme hardness is necessary (e.g. femoral head replacement), most metallic biomaterials are themselves covered by a protective, stable oxide film such as titanium oxide on titanium. In these cases proteins only interact with the oxide film and not with the underlying metal. Closer investigations of the protein - oxide interface are therefore vital to the biomaterials field as it strives to make the transition from merely bio-inert to fully bioactive implant materials.

In the past, many people have investigated protein adsorption and desorption on different types of planar surfaces. But to date, a complete understanding of the various protein adsorption mechanisms has not been established yet. Influences of the system parameters on the adsorption mechanisms such as pH, ionic strength, buffer solution and temperature in combination with the material properties such as surface charge, electrical conductivity, chemical composition, isoelectric point of the protein and the oxide are not clear or even known. Moreover, shape and conformational changes upon adsorption for varying proteins on different surfaces are mostly unknown.

We are studying the protein adsorption behavior on the parameters mentioned above. By using colloidal spherical particles - instead of planar surfaces - and applying colloid chemistry analysis methods (CVP, XDC and UV) we can obtain new information about protein - particle systems. The higher degrees of freedom for particle systems - like mobility and curvature - are the valuable sources for more data. See also Interaction of organic molecules with powder surfaces.

 

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© 2014 ETH Zurich | Imprint | Disclaimer | 29 December 2005
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