Active microrheology determines scale-dependent material properties of Chaetopterus mucus

We characterize the lengthscale-dependent rheological properties of mucus from the ubiquitous Chaetopterus marine worm. We use optically trapped probes (2-10 μm) to induce microscopic strains and measure the stress response as a function of oscillation amplitude. Our results show that viscoelastic p...

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Bibliographic Details
Published in:PloS one 2017-05, Vol.12 (5), p.e0176732-e0176732
Main Authors: Weigand, W J, Messmore, A, Tu, J, Morales-Sanz, A, Blair, D L, Deheyn, D D, Urbach, J S, Robertson-Anderson, R M
Format: Article
Language:English
Subjects:
Animals
Biology and Life Sciences
Biophysics
Biopolymers
Continuum mechanics
Displacement
Elasticity
Marine biology
Medicine and Health Sciences
Mucus
Oceanography
Parchment worm
Physical Sciences
Polychaeta - metabolism
Probes
Rheological properties
Rheology
Rheology - methods
Strain
Stress
Stress response
Stresses
Viscoelasticity
Worms
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Summary:We characterize the lengthscale-dependent rheological properties of mucus from the ubiquitous Chaetopterus marine worm. We use optically trapped probes (2-10 μm) to induce microscopic strains and measure the stress response as a function of oscillation amplitude. Our results show that viscoelastic properties are highly dependent on strain scale (l), indicating three distinct lengthscale-dependent regimes at l1 ≤4 μm, l2≈4-10 μm, and l3≥10 μm. While mucus response is similar to water for l1, suggesting that probes rarely contact the mucus mesh, the response for l2 is distinctly more viscous and independent of probe size, indicative of continuum mechanics. Only for l3 does the response match the macroscopic elasticity, likely due to additional stiffer constraints that strongly resist probe displacement. Our results suggest that, rather than a single lengthscale governing crossover from viscous to elastic, mucus responds as a hierarchical network with a loose biopolymer mesh coupled to a larger scaffold responsible for macroscopic gel-like mechanics.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0176732