Influence of Nanoroughness and Detailed Surface Morphology on Structural Properties and Water-Coupling Capabilities of Surface-Bound Fibrinogen Films

Adsorption of fibrinogen onto nanorough platinum surfaces was investigated using radiolabeling and quartz crystal microbalance with dissipation (QCM-D). In total, four surface topographies were studied with a root-mean-square (rms) roughness value ranging from 1.49 to 9.01 nm, including one surface with sharp whiskerlike surface protrusions and three surfaces with more smoothly shaped surface features. From the radiolabeling results, it is concluded that the fibrinogen adsorption process is influenced by surface roughness, and by combining radiolabeling with QCM-D, we found that the water content of the fibrinogen layers formed on respective surfaces depends significantly on the detailed surface morphology in question. Furthermore, from plots of the dissipation versus frequency shift obtained with QCM-D, the presence of several distinct adsorption phases on nanorough surfaces with more smoothly shaped surface features was observed. This type of multiphased adsorption behavior was not observed on flat reference surfaces or the surface with whiskerlike surface nanofeatures. The results demonstrate that adsorption of fibrinogen onto nanorough topographies is affected by mechanisms which go beyond simple scaling with rms roughness, and that the specific type of surface morphology associated with surface roughness can have a unique impact on the protein adsorption process as well as on the hydration level in the protein films.