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Spring 2007

March 01, 2007 (Thursday)

Christine Selhuber-Unkel

Heidelberg University
"Adhesion Force Spectroscopy of Single Cells on Nanopatterned Substrates"

Abstract: Cell adhesion is a highly complex biological process and a crucial step for many cell activities. In order to understand the physical principles of cell adhesion at the molecular level, surfaces of defined adhesion properties are required. In our experiments biofunctionalized nanopatterns are employed to position adhesion ligands in aquasi-hexagonal lattice. This allows cooperative interactions between cellular adhesion receptors to be studied, for example between integrins. Integrin-mediated cell adhesion is a highly complex biological process and essential for numerous cell functions. With nanopatterns, the distance between adjacent integrin binding sites is precisely defined. Recent cell culture experiments have revealed that the distance between the integrin binding sites strongly affects cell spreading, cell motility and the formation of adhesion clusters, known as focal contacts. To quantify the adhesion cluster formation for different integrin binding site spacings, we studied cell adhesion forces with magnetic tweezers and atomic force microscopy (AFM). We found that an integrin binding site spacing of 70nm and more prevents the cooperative formation of early adhesion clusters already in the first five minutes of cell-substrate contact. Additionally, experiments on mature focal contacts showed that the focal contact formation cooperatively increases the local adhesion strength. Our results were related to theoretical models and make a contribution to understanding the formation and stability of cell adhesion clusters.

Time: 11:00 am

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