Clots reveal anomalous elastic behavior of fiber networks

Abstract

The mechanical properties of many soft natural and synthetic biological materials are relevant to their function. The emergence of these properties from the collective response of the structural components of the material to external stress as well as to intrinsic cell traction, remains poorly understood. Here, we examine the nonlinear elastic behavior of blood clots by combining microscopy and rheological measurements with an elastic network model that accounts for the stretching, bending, and buckling of constituent fibrin fibers. We show that the inhibition of fibrin crosslinking reduces fiber bending stiffness and introduces an atypical fiber buckling-induced softening regime at intermediate shear, before the well-characterized stiffening regime. We also show that crosslinking and platelet contraction significantly alter force propagation in the network in a strain-dependent manner. Our mechanics-based model, supported by experiments, provides a framework to understand the origins of characteristic and anomalous regimes of non-linear elastic response not only in blood clots, but also more generally in active biopolymer networks.

Facile Determination of the Poisson’s Ratio and Young’s Modulus of Polyacrylamide Gels and Polydimethylsiloxane

“…We also note that while the assumption of incompressibility may be reasonable, this does not imply that it is a valid assumption as further discussed in the Discussion section and elsewhere. , This is especially important when we consider dynamic effects specific to mechanobiology studies on cell motility on biomimetic hydrogel surfaces. For instance, the deformation fields induced in the substrate due to the contractile and time-dependent stresses in focal adhesion regions depend crucially on Poisson’s ratio. ,, A second instance where Poisson’s ratio may play an important role is in the rate-dependent deformation of initially planar hydrogels of finite stiffness. Here, axial and normal deformations are coupled via Poisson’s ratio and together determine the time-dependent forces felt by the indenter.…”

“…For instance, the deformation fields induced in the substrate due to the contractile and time-dependent stresses in focal adhesion regions depend crucially on Poisson’s ratio. 29 , 30 , 42 A second instance where Poisson’s ratio may play an important role is in the rate-dependent deformation of initially planar hydrogels of finite stiffness. Here, axial and normal deformations are coupled via Poisson’s ratio and together determine the time-dependent forces felt by the indenter.…”

Facile determination of the Poisson’s ratio and Young’s modulus of polyacrylamide gels and polydimethylsiloxane

“…For instance, the deformation fields induced in the substrate due to the contractile and time-dependent stresses in focal adhesion regions depend crucially on the Poisson's ratio. 28,29,40 A second instance where Comparison between rheology and static tensile tests of PDMS. Next, we extended the abovedescribed approach to analyze the cross-correlation of elastic constants obtained between static tensile tests and shear rheology for PDMS rod.…”