Mechanical response of active gels

TL;DR

This paper models active gels composed of semiflexible filaments and motor proteins, revealing how motor activity influences gel elasticity, contractility, and frequency-dependent stiffening, aligning with experimental findings.

Contribution

It introduces a theoretical model linking motor activity to the mechanical properties of active gels, including contractility and frequency-dependent elasticity.

Findings

Motors induce contractile behavior in the gel.

Motor activity softens low-frequency elastic response.

High-frequency stiffening is predicted and estimated.

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.