Protein absorption and ellipsometry in biomaterial research.

Ellipsometry is an optical surface-sensitive method for the investigation of various aspects of protein adsorption mainly at reflecting metal surfaces and ceramic surfaces. One interesting feature of the method is the possibility of detailed and accurate determination of real-time adsorption kinetics of proteins without labelling of the protein. It is also possible to detect protein adsorption with the use of antibodies that adsorb onto the antigen-coated surfaces and to detect antibodies by their adsorption behaviour with regard to antigen-coated surfaces. Compared to other solid phase methods such as enzyme linked immunosorbent assay (ELISA), immunofluorescence and radioimmunoassay, ellipsometry has the advantage of not involving any labelling of the reactant and it is a relatively inexpensive method to maintain. This review is a current report of 15 years of contributions in biomaterials and biochemical research. Special consideration has been given to biologically related surface phenomena such as protein conformation changes, protein displacement effects, early events in blood clotting and complement activation. Among the technical achievements given prominence are the wettability gradient method and the rational use of silicon as an experimental surface. It is clear that ellipsometry and related methods such as reflectometry and surface plasmon resonance (Biacore) are now being increasingly used in biomaterial research as well as in other areas of research.