Protein adsorption and platelet adhesion onto ion-containing polyurethanes

Protein adsorption and platelet adhesion properties of polyurethane biomaterials are important considerations for blood-contacting applications. Although the presence of ionic groups on the surface of biomaterials is believed to influence their blood response, their exact role is not known. The objective of this work was to study the protein adsorption and platelet adhesion properties of ion-containing polyurethane biomaterials. Thus, we prepared polyurethanes that contained ions either on the soft segment or hard segment and investigated their in vitro protein adsorption and platelet adhesion. The presence of ions increased the amount of adsorbed proteins and adhered platelets on the synthesized polyurethanes. Whereas albumin and lysozyme adsorption were independent of the location of the ions (soft vs. hard segments), fibrinogen adsorption was strongly dependent on the location of the ions. Platelet adhesion, on the other hand, was found to be less dependent on the location of the ions within the polyurethane structure. This is the first evidence to unequivocally demonstrate the exact role of ions on protein adsorption and platelet adhesion. Taken together, our study suggests that in the absence of known biocompatible chains such as polyethyleneoxide, ion-containing polyurethanes do not demonstrate improved blood compatibility. Therefore, we conclude that ion incorporation into polyurethanes may not be a viable approach to design polyurethane biomaterials for blood-contacting applications.