Dresden 2009 – scientific programme
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BP: Fachverband Biologische Physik
BP 10: Biofluiddynamics
BP 10.8: Talk
Tuesday, March 24, 2009, 16:00–16:15, HÜL 186
Investigating cross-linking properties of actin structures with holographic optical tweezers in microfluidic systems — •Kai Uhrig1,2, Rainer Kurre1,2, Martin Streichfuss1,2, Friedrich Erbs1,2, Simon Schulz1,2, Anabel Clemen1,2, Tamas Haraszti1,2, Christian Böhm1,2, and Joachim Spatz1,2 — 1MPI for Metals Research, Dept. Spatz, Heisenbergstr. 3, 70569 Stuttgart — 2Univ. of Heidelberg, Biophys. Chem. Dept., INF 253, 69120 Heidelberg
The actin cortex is an adaptive chemo-mechanical polymer network located underneath the cell membrane. A multitude of factors and proteins that induce cross-linking, gelification or bundling of filaments controls its shape and mechanical properties. Recent studies on actin network mechanics were always restricted to three dimensional bulk gels, which are believed to show significantly different mechanic behaviour. We used the combination of holographic optical tweezers (HOT) with microfluidic techniques to create two dimensional network structures on trapped microbeads that could be cross-linked and probed subsequently. High-speed imaging was used to monitor force generation due to contraction of the network at all trapped beads simultaneously whilst fluorescence imaging was implemented to follow structural changes of the actin network. In another approach, HOTs and the combination of optical tweezers with PDMS micropillar substrates are used to investigate cross-linking processes in zipper-like structures between freely suspended actin filaments in detail. Force curves for zipping processes as well as for force induced unzipping could be deduced and correlated to fluorescence micrographs of the zipper structures.