Polymeric systems based on derivatives of ethylene-vinyl alcohol copolymers

To obtain polymers with improved hemocompatibility properties, commercial ethylene-vinyl alcohol copolymers (EVAL) were chemically modified, by the introduction of stearoyl groups to bind albumin and quaternary ammonium groups to bind heparin. These novel polymer composites were characterized by FT-IR and H-1-NMR spectroscopy. The amount of heparin and albumin bonded by these polymers were determined and the influence of the adsorption sequence (heparin + albumin or vice versa) was evaluated. The amount of adsorbed albumin was proportional to the stearoyl content of the polymer. When heparin was exposed to polymer surfaces containing quaternary ammonium groups, the amount of bonded heparin was proportional to the content of positively charged groups. An in vitro evaluation of the anti-clotting properties and of the adhesion characteristics of the polymer surfaces containing both stearoyl groups and quaternary ammonium groups exhibited, after heparinization, good anticoagulant activity. This activity was retained after the albuminization. Platelet adhesion tests showed that albuminization of polymer films containing only stearoyl residues improved their behavior towards platelet adhesion.