Enhanced blood compatibility of polymers grafted by sulfonated PEO via a negative cilia concept

In our laboratory sulfonated PEO (PEO-SO3) was designed as a "negative cilia model" to investigate a synergistic effect of PEO and negatively charged SO3 groups. PEO-SO3 itself exhibited a heparin-like anticoagulant activity of 14% of free heparin. Polyurethane grafted with PEO-SO3 (PU-PEO-SO3) increased the albumin adsorption to a great extent but suppressed other proteins, while PU-PEO decreased the adsorption of all the proteins. The platelet adhesion was decreased on PU-PEO but least on PU-PEO-SO3 to demonstrate an additional effect Of SO3 groups. The enhanced blood compatibility of PU-PEO-SO3 in the ex vivo rabbit and in vivo canine implanting tests was confirmed. Furthermore, PU-PEO-SO3 exhibited an improved biostability and suppressed calcification in addition to the enhanced antithrombogenicity. The in vivo antithrombogenicity and biostability were improved in the order of PU < PU-PEO < PU-PEO-SO3. The calcium amounts deposited was decreased in the order of PU > PU-PEO > PU-PEO-SO3 in spite of the possible attraction between negative SO3 groups and positive calcium ions. The bioprosthetic tissue (BT) was grafted with H2N-PEO-SO3 via glutaraldehyde (GA) residues after conventional GA fixation. BT-PEO-SO3 also displayed the decreased calcification by in vivo animal models. The application of PEO-SO3 was extended by designing amphiphilic copolymers containing PEO-SO3 moiety and hydrophobic long alkyl groups as anchors. The superior effect of PEO-SO3 groups on thromboresistance compared to PEO was confirmed also in the case of copolymers coated or blended with other polymers and the systems coupled by UV irradiation, photoreaction or gold/sulfur or silane coupling technology, and therefore it might be very useful for the medical devices. (C) 2003 Elsevier Science Ltd. All rights reserved.