Thrombus formation and blood coagulation is a major problem associated with blood contacting products such as catheters, vascular grafts and artificial hearts. An intense
research is being conducted towards the synthesis of new hemocompatible materials and mdifications of surfaces with biological molecules. In this study, polyurethane
(PU) films were synthesized in medical purity from diisocyanate and polyol without using any other ingredients and the chemical, thermal and mechanical properties were
characterized by solid state NMR, FTIR, GPC, mechanical tests, DMA and TGA. The surfaces of PU films were modified by covalent immobilization of different molecular weight heparins / low molecular weight heparin (LMWH) and unfractionated heparin (UFH) and these surfaces were examined by ESCA, ATR-FTIR, AFM and contact
angle goniometer. Cell adhesion studies were conducted with whole human blood and examined by SEM. The effects of different types of heparins on blood protein adsorption and on platelet adhesion were analyzed by electrophresis and SEM, respectively. The surfaces of the UFH immobilized polyurethane films (PU-UFH) resulted in lesser red blood cell adhesion in comparison to LMWH immobilized polyurethane film surfaces (PU-LMWH). When the PU films were treated with blood
plasma, the surfaces modified with two different heparin types showed a clearly different protein adsorption behavior especially in the early stage of blood plasma
interaction. PU-LMWH samples showed about three times less protein adsorption compared to PU-UFH samples. The morphologies of platelets adhered on material
surfaces demonstrated differences / such as PU-UFH had clusters with some pseudopodia extensions, while PU-LMWH had round shaped platelets with little clustering. PU surfaces modified by immobilization of LMWH and UFH, demonstrated promising results for the improvement of non-thrombogenic devices and surfaces.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12609701/index.pdf |
| Date | 01 July 2008 |
| Creators | Aksoy, Eda Ayse |
| Contributors | Hasirci, Nesrin |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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