title: Fluidization and Active Thinning by Molecular Kinetics in Active Gels.
abstract: We derive the constitutive equations of an active polar gel from a model for the dynamics of elastic molecules that link polar elements. Molecular binding kinetics induces the fluidization of the material, giving rise to Maxwell viscoelasticity and, provided that detailed balance is broken, to the generation of active stresses. We give explicit expressions for the transport coefficients of active gels in terms of molecular properties, including nonlinear contributions on the departure from equilibrium. In particular, when activity favors linker unbinding, we predict a decrease of viscosity with activity-active thinning-of kinetic origin, which could explain some experimental results on the cell cortex. By bridging the molecular and hydrodynamic scales, our results could help understand the interplay between molecular perturbations and the mechanics of cells and tissues.
authors.affiliation: Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647 and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Oriola
authors.affiliation: Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647 and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain.
authors.forename: Ricard
authors.initials: R
authors.lastname: Alert
authors.affiliation: Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Avinguda Diagonal 647 and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Casademunt