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BP: Fachverband Biologische Physik
BP 19: Biological Membranes II
BP 19.1: Talk
Tuesday, March 15, 2011, 14:00–14:15, ZEU 260
Lipid Bilayer Membranes on Multistimuli-Responsive Poly(N-isopropylacrylamide) Copolymer Cushions — •Martin Kaufmann1, Yunfei Jia1, Carsten Werner1,2, and Tilo Pompe1 — 1Leibniz Institute for Polymer Research Dresden, Germany — 2Center of Regenerative Therapies Dresden, Germany
To mimic the native environment of a lipid bilayer in respect to the extracellular matrix or intracellular structures, we pursue the approach to use a thin polymer film as bilayer cushion support in order to prevent transmembrane proteins from pinning to the support. With the aim to actively tune transmembrane protein mobility, we first studied the characteristics of a bilayer membrane formed on a stimuli-responsive polymer cushion. Swelling characteristics of thin films of poly(N-isopropylacrylamid-co-carboxyacrylamid) were probed by ellipsometry and quartz crystal microbalance (QCM) and found to switch in thickness between 15 nm and 150 nm depending on monomer composition, pH and temperature. The mobility of lipid bilayer on top of the cushions, as analyzed by fluorescence recovery after photobleaching (FRAP), yielded higher lipid diffusion coefficients ((6.3 - 9.6) µm2s−1) in comparison to solid glass supports ((3.0 - 5.9) µm2s−1) independent of the swelling state of the polymer cushion. This finding revealed a very weak coupling of the lipid bilayer with the polymer cushion. Further, focus of interest is set on the impact of the tunable frictional drag between transmembrane adhesion receptors (integrins) and cushion support, which is expected to influence mobility, activation, and receptor clustering.