Peptide adsorption on metal oxide surfaces. Investigating the biomaterial/biological interface with synchrotron radiation.

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The interaction between biological molecules and inorganic material surfaces is of importance in a number of areas from biomedical devices for implantation, sensors and bioreactors. The required behaviours for each of these applications are slightly different, for example in biomedical implants it is thought that a protein conditioning layer is formed at the surface, prior to cell attachment and growth of new tissue. On the other hand, in pharmaceutical applications where protein therapeutics may be manufactured, interactions with the reactor material surfaces can lead to denaturation or agglomeration of the proteins. This may have the effect of removing the desired action protein, or in the worse case, causing unwanted side effects such as protein aggregation.Studies of molecular adsorption on well-characterised surfaces using synchrotron techniques have led to an improved understanding of protein-metal interactions. However, in most cases the surface of a metal implant or pipeline will be terminated with a native oxide layer. In addition, these studies are often carried out under vacuum conditions, thus the effect of water on the adsorption process is not well understood. Obviously in a real biomedical device or pharmaceutical plant, water will be a major component of the surrounding media. Recent advances in photoelectron spectroscopy now allow measurements to be made in the presence of water and water vapour. Photoelectron spectroscopy is an extremely powerful probe of surface chemistry and the adsorption mechanism of molecules, since it is capable of studying just the top 1 - 10 nm of a material surface.In this proposal we will study the adsorption processes of five different amino acids which exhibit varying degrees of acidity/basicity and two small peptides on idealised titanium dioxide surfaces. Rutile titanium dioxide is the native oxide formed on titanium which is widely used both as a metal and alloy in biomedical implants, and is believed to be a key factor in the success of these devices.