Heparin-containing block copolymers

Abstract

Newly synthesized heparin-containing block copolymers, consisting of a hydrophobic block of polystyrene (PS), a hydrophilic spacer-block of poly(ethylene oxide) (PEO) and covalently bonded heparin (Hep) as bioactive block, were coated either onto glass, poly (dimethylsiioxane), polyurethane or PS substrates. Coated surfaces were characterized by determination of the surface-bound heparin activity, adsorption of AT III, plasma recalcification time assays, adhesion of platelets and by an ex vivo rabbit A-A shunt model.It was demonstrated that heparin was available at the surface of all heparin-bound surfaces to interact with AT III and thrombin and to prevent the formation of clots. The maximum immobilized heparin activity was found to be 5.5 x 10 -3 U cm -2. Coated surfaces showed a significant prolongation of the plasma reclacification times as compared to control surfaces, due to surface-immobilized heparin. The platelet adhesion demonstrated that platelets reacted only minimally with the heparin-containing block copolymers in the test system and that the heparin-containing block copolymers seemed to passify the surface as compared to control surfaces. In the ex vivo A-A shunt experiments, which were carried out under low flow and low shear conditions, the heparin-containing block copolymers exhibited prolonged occlusion times, indicating the ability of the heparin-containing block copolymers to reduce thrombus formation at the surface.

All-solid-state hydrogen sensing microelectrodes based on novel PPy[3,3′-Co(1,2-C2B9H11)2] as a solid internal contact

“…Concerning the sterilization process, the presence of the PVC selective membrane precludes the use of high-temperature methods. An alternative sterilization method is the use of ethylene oxide gas [42]. We have successfully used this method with various types of PVC-based ion sensors, as the sterilization process has not affected the response of the devices.…”

Selective Aerobic Oxidation of Methanol in the Coexistence of Amines by Nanoporous Gold Catalysts: Highly Efficient Synthesis of Formamides

“…There have been various efforts to minimize or eliminate thrombogenicity. To design nonthrombogenic polymers, there have been many approaches including (1) the grafting of hydrophilic groups to the bulk polymer or polymer surface, which prevents platelet adhesion by giving nonthrombogenicity to the polymer;13 (2) suppression of platelet adhesion and morphologic change of the adhered platelets by microphase‐separated structures of polymers such as 2‐hydroxy ethyl methacrylate/styrene block copolymer;14–16 and (3) the immobilization of pharmaceutical reagents such as urokinase or heparin to the polymer 17–20. Urokinase decomposes fibrin to dissolve the thrombus.…”

In Situ Quantitative 1H NMR Monitoring of Monomer Consumption: A Simple and Fast Way of Estimating Reactivity Ratios

“…These methods have been checked out with the monomer pairs AMPS−DMAA and HEMA−AMPS (the structures of the monomers are represented in Figure ), which are systems of biomedical interest because of the presence of the sulfonic acid group that is recognized to be one of the responsible components of the antitrombogenic properties of heparine and heparine-like biomaterials bearing active sulfonic groups. −

1 Chemical structures of the monomer used in the copolymerizations together with the nomenclature of the acrylic and methacrylic protons.

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