| Abstract
| - To evaluate the influence of substratum surface characteristics on protein adsorption processes, we haveinvestigated the adsorption (adsorbed amount, supramolecular organization) of collagen on model substrataexhibiting controlled topography and surface chemistry. Substrata were prepared in two steps: (i) golddeposition onto silicon wafers (smooth substrata) and onto a support with nanoscale protrusions createdby colloidal lithography (rough substrata); (ii) functionalization with CH3 (hydrophobic) and OH (hydrophilic)groups, using alkanethiol self-assembly. Atomic force microscopy (AFM) images were recorded underwater, prior to and after collagen adsorption, and the images were analyzed quantitatively using twoindependent approaches. On smooth substrata, collagen formed a ∼6 nm thick, homogeneous layer withlow roughness on hydrophilic surfaces, and a ∼20 nm thick layer exhibiting elongated aggregated structureson hydrophobic surfaces. Film thickness measurements (AFM) together with X-ray photoelectronspectroscopy (XPS) revealed larger adsorbed amounts on hydrophobic surfaces compared to hydrophilicones. On rough substrata, the adsorbed amounts were similar to those found on smooth substrata; however,the collagen molecules no longer formed aggregated structures on the hydrophobic surfaces. It is concludedthat while the adsorbed amount is only affected by the surface chemistry, the supramolecular organizationof the adsorbed layer is controlled both by surface chemistry and topography. The approach presented herewill have great value in biophysics for investigating bioadsorption and bioadhesion processes on substrataof defined surface properties.
|
