5. Conclusions
The present study shows that PE-UHMW is highly affected by protein adsorption after interaction with SF. The presented incubation experiments allowed studying whether protein adsorption is competitive if PE-UHMW materials of differ- ent types are exposed to complete SF proteomes and lipids as well as other SF components. It was observed in MSI and by gel electrophoretic experiments that all high abundance proteins in fact adsorb to PE-UHMW. The observation of homogeneous protein layers allows the conclusion that virgin PE-UHMW is completely covered with a protein layer supporting lubrication shortly after contact with SF.However, morphologically modified or rough PE-UHMW surface regions are highly affected by protein adsorption. Proteins obviously tend to adsorb on uneven surfaces. In vivo this behavior might induce enhanced lubrication on damaged polymer material surfaces and can result in acompensation mechanism to ensure the articulating process. Despite the expectation that Vitamin E doped UHWM-PE would be less affected, we found higher protein concentration sand comparable adsorption. Vitamin E might change the surface properties especially for preferred adsorption of either lipid or glycan species,which have not been investigated in the present study. Homogeneous layer formation has been found for both materials, which is absolutely favorable for lubrication and reduced shear stress. Nevertheless it has to be mentioned that the presented model is only astatic in vitro model and that temperature, mechanical forces and cell stress affect protein conformation and might change in vivo adsorption behavior. Further investigation is necessary to evaluate protein adsorption behavior under mechanical stress to understand the interaction between PE-UHMW and SF compounds in more detail