Mechanics of bundled semiflexible polymer networks

TL;DR

This paper investigates the microscopic origins of elasticity in bundled actin networks, revealing a transition from affine to non-affine bending behavior as actin-binding protein concentration increases.

Contribution

It demonstrates that bundled actin networks' elasticity can be explained by non-affine bending undulations, advancing understanding of cellular structural mechanics.

Findings

Bundled networks form above a critical fascin concentration.

Elasticity shifts from affine to non-affine deformation with bundling.

Non-affine bending dominates the elasticity of bundled networks.

Abstract

While actin bundles are used by living cells for structural fortification, the microscopic origin of the elasticity of bundled networks is not understood. Here, we show that above a critical concentration of the actin binding protein fascin, a solution of actin filaments organizes into a pure network of bundles. While the elasticity of weakly crosslinked networks is dominated by the affine deformation of tubes, the network of bundles can be fully understood in terms of non-affine bending undulations.