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

Abstract

In our laboratory sulfonated PEO (PEO-SO 3) was designed as a “negative cilia model” to investigate a synergistic effect of PEO and negatively charged SO 3 groups. PEO-SO 3 itself exhibited a heparin-like anticoagulant activity of 14% of free heparin. Polyurethane grafted with PEO-SO 3 (PU-PEO-SO 3) 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-SO 3 to demonstrate an additional effect of SO 3 groups. The enhanced blood compatibility of PU-PEO-SO 3 in the ex vivo rabbit and in vivo canine implanting tests was confirmed. Furthermore, PU-PEO-SO 3 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-SO 3. The calcium amounts deposited was decreased in the order of PU>PU-PEO>PU-PEO-SO 3 in spite of the possible attraction between negative SO 3 groups and positive calcium ions. The bioprosthetic tissue (BT) was grafted with H 2N-PEO-SO 3 via glutaraldehyde (GA) residues after conventional GA fixation. BT-PEO-SO 3 also displayed the decreased calcification by in vivo animal models. The application of PEO-SO 3 was extended by designing amphiphilic copolymers containing PEO-SO 3 moiety and hydrophobic long alkyl groups as anchors. The superior effect of PEO-SO 3 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.