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What can discrete network models tell us about the (visco-)elasticity of biopolymers?
The mechanical properties of the cytoskeleton inside a cell play a key role in its biological function. The actin network —one of the components of the cytoskeleton— can be strong/stiff as well as fluidic depending on its location in the cell and its function at that moment. This variability in properties is mediated by the density of cross-linking molecules, their properties as well as the dynamics of cross-linking. The general objective of this work is to understand the role of these aspects in determining theelastic as well as viscoelastic properties of actin networks.
For this purpose we employ a network model in which the semi-flexible filaments as well as the cross-links are represented by discrete interconnected entities. Firstly, we will summarise the findings of large-scale three-dimensional simulations of a statically cross-linked network and show that both the linear and the stiffening response can be captured by simple scaling laws. Subsequently, we will report the results of a single unit, two-filament model with cross-links that can bind, unbind and rebind. This simple model provides elementary insight in the visco-elasticity of biopolymer networks, as characterised by the dependence of both the storage and the loss moduli on loading frequency.
Author(s):
Erik Van der Giessen
University of Groningen
Netherlands