Dissertation > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > General issues > Biomaterial

Synthesis and Biocompatibility of different types of hydrophilic surface - modified polyurethane

Author HeChunLi
Tutor LiLi
School Nanjing Normal University
Course Polymer Chemistry and Physics
Keywords Polyurethane Hydrophilicity Surface Modification Blood Compatibility Anti-clotting Mechanism
CLC R318.08
Type Master's thesis
Year 2011
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Polyurethane materials, which could be used in biological environment,played an important role in biomedical application,and were widely used in biomedical fields for artificial organ and other medical devices.When Polyurethane materials come into contact with living organisms significant responses such as thrombus formation and unfavorable immuoresponses occur.Biocompatibility, especially blood compatibility,is the most important property with regard to Polyurethane materials.Therefore,improving blood compatibility of Polyurethane materials is an essential research task for biomaterial research and development. To improve blood compatibility properties of polyurethane (PU) films, surface modification has been considered as effective method, in this research work, three vinyl hydrophilic monomers were grafted to the surface of Polyurethane films by chemical method, in order to improve the antithrombogenicity. We chemically induced graft polymerization of 2-Hydroxyethyl Methacrylate (HEMA), Methacrylic Acid (MAA), Acrylamide(AAm) onto the surface of polyurethane films using benzoyl peroxide as initiator.The effects of grafting temperature, grafting time, monomer and initiator concentrations on the grafting rates and water absorbency were studied. The structure and hydrophilicity of the ungrafted Polyurethane films and grafted films had been characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetry (TG) and surface water contact angle measurement respectively. The results showed that the three vinyl hydrophilic monomers were successfully grafted onto the surface of PU films, the hydrophilicity of the grafted PU films were improved significantly.Moreover, the blood compatibility of the ungrafted PU films and PU-g-PHEMA, PU-g-PMAA, PU-g-PAAm films were evaluated by platelet adhesion test, hemolysis test and recalcification time test.The hemolysis rate of PU-g-PHEMA, PU-g-PMAA, PU-g-PAAm films accorded with international standard. And there were little platelet adhered on the grafted PU films. The results indicated that PU-g-PHEMA, PU-g-PMAA, PU-g-PAAm films could be expected to find wide application in the medical treatment in future.In order to study the anti-clotting mechanism of Polyurethane materials, the relationship between the hydrophilicity and antithrombogenicity of the ungrafted PU films and PU-g-PHEMA, PU-g-PMAA, PU-g-PAAm films were discussed. By means of the Ubbelodhe viscosimeter and circular dichroism, the interaction between Polyurethane materials and bovine serum albumin (BSA) solutions was investigated. The results indicated that PU-g-PHEMA films can keep the natural molecule conformation of BSA in the course of contacts. The experiments have provided evidence to the hypothesis of "Maintaining Natural Behavior"

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