Berlin 2008 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 13: Biopolymers

BP 13.2: Vortrag

Dienstag, 26. Februar 2008, 17:30–17:45, PC 203

Morphological and Mechanical Characterization of Reconstituted Collagen Type I Networks — •Stefan Münster¹, Thorsten Koch¹, Philip Kollmannsberger¹, Louise Jawerth², David Vader², Gerd Schroeder-Turk¹, and Ben Fabry¹ — ¹Department of Physics, University of Erlangen-Nuremberg, Germany — ²Department of Physics, Harvard University, Cambridge, USA

Collagen is the most abundant extracellular matrix (ECM) protein and serves as 3D culture environment for cell biology assays. Cell behavior in 3D sensitively depends on the mechanical properties of the ECM. Moreover, for computing cell tractions from the matrix deformations around invaded cells, knowledge of the matrix rheology is necessary.

Confocal images of collagen gels (2.4 mg/ml) show a narrowly distributed pore size of Ø1 µm. Macrorheology using a parallel-plate rheometer revealed predominantly elastic behavior that was approximately linear for strains <5%, with a shear modulus G’ of 80 Pa, a loss modulus G” of 11 Pa, and a weak frequency dependency of both moduli according to a power-law with exponent 0.09. Microrheological behavior was measured by applying a 21 nN ’point’ force to a ferrimagnetic Ø4.5 µm bead, and tracking the resulting 3D displacements of Ø1 µm fluorescent beads dispersed in the gel. Local strain fields were also determined by indenting the gel surface with a sphere and by shearing the bulk between two parallel glass plates. Under all conditions, the microscopic gel deformations for small strains closely followed that of an affine, predominantly elastic, isotropic and homogeneous continuum.