Regensburg 2010 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 28: Focus: Charge Effects in Soft and Biological Matter II (joint CPP, BP, ST)
BP 28.7: Vortrag
Donnerstag, 25. März 2010, 16:15–16:30, H37
Oligolamellar Lipid Layers Under Load: A Model For Artificial Implants — •Martin Kreuzer1, Reiner Dahint1, and Roland Steitz2 — 1Universität Heidelberg, Physikalisch Chemisches Institut, 69120 Berlin, Germany — 2Helmholtz-Zentrum Berlin GmbH, 14109 Berlin, Germany
The mechanisms and physicochemical parameters to reduce friction in a natural joint are not yet clear and subject of controversial discussions. We represented the biological interface by a suitable model system and employed Neutron Reflectivity for studying the relevant structural features on the molecular scale. The model interface consisted of a lipid covered silicon disc measured against a model synovial fluid at elevated hydrostatic pressure. Measurements in a pressure cell against D2O showed, that the as-prepared lipid coating remained stable on the substrate up to a hydrostatic pressure of 900bar when the lipid molecules were in their gel-like Pβ* phase. However, the lipid main phase transition from the gel to fluid-like Lα phase at 450 bar and 38°C lead to a loss of most of the lipid bilayers and only one double layer remained on the substrate. Measurements against the model synovial fluid (3mg/ml hyaluronic acid in D2O) showed that the lipid multilayer coatings remained stable on the substrate at 450 bar and 38°C, where formerly the phase transition into the fluid-like Lα phase occurred. Beside that, a pronounced swelling of the oligo-lamellar films was observed. Therefore, we conclude that the synovial fluid not only plays an important role in the reduction of friction in the human joint, but also significantly stabilizes the lipid multilayer coating.