Mechanical response of active gels

¹  Department of Mathematics, University of Bristol - University Walk, Clifton, Bristol BS8 1TW, UK, EU
²  Physics Department and Syracuse Biomaterials Institute, Syracuse University - Syracuse, NY 13244, USA
³  Physicochimie Curie (CNRS-UMR168), Institut Curie, Section de Recherche - 26 rue d'Ulm, 75248 Paris Cedex 05, France, EU
⁴  ESPCI - 10 rue Vauquelin, 75231 Paris Cedex 05, France, EU

Received: 14 July 2008
Accepted: 27 November 2008

Abstract

We study a model of an active gel of cross-linked semiflexible filaments with additional active linkers such as myosin II clusters. We show that the coupling of the elasticity of the semiflexible filaments to the mechanical properties of the motors leads to contractile behavior of the gel, in qualitative agreement with experimental observations. The motors, however, soften the zero-frequency elastic constant of the gel. When the collective motor dynamics is incorporated in the model, a stiffening of the network at high frequencies is obtained. The frequency controlling the crossover between low- and high-frequency network elasticity is estimated in terms of microscopic properties of motors and filaments, and can be as low as 10^-3 Hz.