Evidence for fibrinogen mobility on hydrophobic surfaces

Abstract

The adsorption of the plasma protein fibrinogen on model hydrophobic surfaces has been explored using atomic force microscopy. Images of fibrinogen adsorbed on both graphite and methyl-terminated self-assembled monolayers are both observed to be highly non-uniform. On both substrates, aggregation and clustering of the fibrinogen molecules is seen. In the case of the graphite surface, we observe a strong preference for adsorption at atomic level steps in the graphite structure. In addition, a region free of protein adsorption is often observed near the step edges. Based on the size of this protein-depleted region, we estimate that the fibrinogen molecules must have diffusion lengths on the order of ∼200 nm under the conditions of these experiments. These results suggest that in the initial stages of adsorption, fibrinogen is quite mobile on a hydrophobic surface. © 2005 The Surface Science Society of Japan.