Entanglement Density Tunes Microscale Nonlinear Response of Entangled Actin
| Autor: | Rae M. Robertson-Anderson, Bekele Gurmessa, Robert Fitzpatrick, Tobias T. Falzone |
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| Rok vydání: | 2016 |
| Předmět: |
Resistive touchscreen
Materials science Yield (engineering) Polymers and Plastics Condensed matter physics Organic Chemistry Relaxation (NMR) FOS: Physical sciences 02 engineering and technology Quantum entanglement Condensed Matter - Soft Condensed Matter 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics Inorganic Chemistry Protein filament Nonlinear system 0103 physical sciences Materials Chemistry Soft Condensed Matter (cond-mat.soft) 010306 general physics 0210 nano-technology Scaling Microscale chemistry |
| Zdroj: | Macromolecules. 49:3948-3955 |
| ISSN: | 1520-5835 0024-9297 |
| Popis: | We optically drive a microsphere at constant speed through entangled actin networks of 0.2 - 1.4 mg/ml at rates faster than the critical rate controlling the onset of a nonlinear response. By measuring the resistive force exerted on the microsphere during and following strain we reveal a critical concentration $c^{*}\simeq0.4$ mg/ml for nonlinear features to emerge. For $c>c^{*}$, entangled actin stiffens at short times with the degree of stiffening $S$ and corresponding timescale $t_{stiff}$ scaling with the entanglement tube density, i.e. $S\sim t_{stiff}\sim d_t^{-1}\sim c^{3/5}$. The network subsequently yields to a viscous regime with the yield distance $d_y$ scaling linearly with yield force $f_y$ and inversely with the entanglement length ($f_y\sim d_y\sim l_{e}^{-1} \sim c^{2/5}$). Stiffening and yielding dynamics are consistent with recent theoretical predictions for nonlinear cohesive breakdown of entanglements. We further show that above $c^{*}$ force relaxation proceeds via slow filament disengagement from dilated tubes coupled with $\sim$10x faster lateral hopping, with the corresponding concentration dependences in agreement with recent theoretical predictions for entangled rigid rods. |
| Databáze: | OpenAIRE |
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