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The effect of water on radiation-induced modifications of a heparin conjugate studied by high pressure photoelectron spectroscopy
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
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Manuscript (Other academic)
URN: urn:nbn:se:uu:diva-94389OAI: oai:DiVA.org:uu-94389DiVA: diva2:168221
Available from: 2006-04-27 Created: 2006-04-27 Last updated: 2010-01-13Bibliographically approved
In thesis
1. Characterization of Surfaces Designed for Biomedical Applications
Open this publication in new window or tab >>Characterization of Surfaces Designed for Biomedical Applications
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In order to develop blood biocompatible materials a heparin surface and a phosphorylcholine (PC) functionalized polymer surface were characterized using photoelectron spectroscopy (PES). The formation of the heparin surface was studied by quartz crystal microbalance with dissipation monitoring (QCM-D). This heparin surface consists of heparin conjugates deposited on a conditioning layer, applied once or twice. The PC functionalized polymer, poly(trimethylene carbonate), was linked to a silicon substrate through 3-amino- propyltrimethoxysilane (APTMS), also studied using PES.

Synchrotron radiation based PES showed that the thicker heparin film resulted in complete coverage of the substrate, while the thinner did not. This could explain the difference in blood biocompatibility between the two films, as observed by others. It was also found that the heparin chains bend down towards the substrate (under vacuum).

For the thinner heparin film the modifications, resulting from extensive irradiation of the sample, were studied with synchrotron radiation based PES. This was done at a pressure of about 10-7 mbar and in 0.5 mbar water vapor. It was found that the modification is slower under water vapor than at low pressures and that the damaged film incorporates water upon exposure.

The heparin coating was found to be stable and wear resistant enough to still be present on artificial heart valves after three weeks testing in circulating plasma. It then had about the same antithrombin uptake as a non-tested surface. The film was, however, partly destroyed by the durability test and plasma proteins were deposited.

The PC functionalized, APTMS linked polymer was found to be much shorter than could be expected from random reactions. One plausible explanation is an interaction between the PC group and the silane surface, favoring aminolysis close to the PC group. This is consistent with our finding that the PC group bends down towards the surface.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 55 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 171
Physics, heparin, photoelectron spectroscopy, phosphorylcholine, biomaterial, quartz crystal dissipation, Fysik
Research subject
urn:nbn:se:uu:diva-6827 (URN)91-554-6546-3 (ISBN)
Public defence
2006-05-19, Polhemssalen, Ångströmlaboratoriet, Hus 1, Lägerhyddsvägen 1, Uppsala, 10:15
Available from: 2006-04-27 Created: 2006-04-27Bibliographically approved

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