AVS 46th International Symposium
    Biomaterial Interfaces Group Tuesday Sessions
       Session BI-TuM

Paper BI-TuM1
Functionality of a Model Protein at Nanostructured Surfaces

Tuesday, October 26, 1999, 8:20 am, Room 613/614

Session: Protein Solid-Surface Interactions II
Presenter: D.S. Sutherland, Chalmers and Gothenburg University, Sweden
Authors: D.S. Sutherland, Chalmers and Gothenburg University, Sweden
M. Broberg, Gothenburg University, Sweden
H. Nygren, Gothenburg University, Sweden
B. Kasemo, Chalmers and Gothenburg University, Sweden
Correspondent: Click to Email
Nanofabricated surfaces can be used to study the influence of surface topographic features on the behaviour of a model protein. Colloidal lithography was used with simple lift-off steps to create surfaces with defined nanotopography. The functionality of equal-quantities of fibrinogen molecules bound at surfaces containing pits of 40nm diameter or 110nm diameter was probed. The kinetics of binding of unactivated platelets to these surfaces from a static albumin-containing buffer was used as a measure of the functionality/conformation of the fibrinogen molecules. Two sets of samples were prepared, one where the surfaces were chemically homogeneous (titanium oxide) and one where the surfaces additionally contained nanodomains of gold coated in a methyl-terminated self-assembled monolayer at the base of the pits. Platelet binding on fibrinogen adsorbed at flat surfaces and surfaces with 110nm diameter pits showed relatively low binding rates which were not significantly different than that found at control surfaces (with no adsorbed fibrinogen). By contrast platelet binding on fibrinogen adsorbed at surfaces containing 40nm diameter pits gave significantly higher binding rates than both other test surfaces and control surfaces. For these samples with 40nm diameter pits similar results were obtained for both surfaces with homogeneous chemistry and for chemically nanodomained surfaces. These results are interpreted to mean that fibrinogen molecules bound at surfaces with 40nm diameter pits have altered conformation or orientation (compared to flat surfaces or surfaces with larger pits) to make available platelet-binding sites. These pits are smaller that the reported characteristic size of fibrinogen molecules (46-55nm length) and it appears that the effect is the result of topography rather than surface chemistry. These model experiments indicate that the conformation/orientation of individual protein molecules can be influenced by like-sized surface features.