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Chemoviscoelasticity of the interfibrillar matrix of the dermis of the black sea cucumber Holuthuria atria

DOI: 10.1016/j.mechmat.2022.104252 DOI Help

Authors: Ettore Barbieri (Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Center for Mathematical Science and Advanced Technology (MAT), Yokohama Institute for Earth Sciences (YES)) , Jingyi Mo (University of Surrey) , Himadri Gupta (Queen Mary University of London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Mechanics Of Materials , VOL 52

State: Published (Approved)
Published: February 2022
Diamond Proposal Number(s): 11806

Abstract: Mutable connective tissues of the sea cucumbers’ dermis can assume three different mechanical states (soft, standard and stiff) according to the chemical changes in the water. There is broad consensus that variable cross-linking of the extracellular matrix is responsible for such changes. This paper uses Small-angle X-ray Scattering (SAXS) measurements, a micromechanical viscoelastic model, and a molecular extended reptation theory to look for other causes beyond cross-linking. We conclude that in potassium-ions enriched seawater, the interfibrillar matrix stiffens due to increased cross-linking, but this must also imply macromolecular chain scission change in molecular weight and increased friction between the chains. In softening water solution (calcium-ions deprived seawater), the interfibrillar matrix softens because of decreased cross-linking, and simultaneously macromolecules chain recombine and friction between the chains decreases. These findings allow us to conclude that the zero-shear viscosity increases more than five times during stiffening and reduces to 3% of its standard value during softening. Also, we find that the fibril strains measured through SAXS seem to suggest that, in reference conditions, the interfibrillar matrix (artificial sea water) behaves similarly to a covalently cross-linked gel; instead, during softening and stiffening, it appears that the matrix shows stress relaxation akin to an ionic cross-linked gel.

Journal Keywords: Chemomechanics; Viscoelasticity; Sea cucumber; Shear-lag; SAXS; Reptation

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I22-Small angle scattering & Diffraction

Added On: 01/03/2022 13:10

Discipline Tags:

Biochemistry Chemistry Biophysics Life Sciences & Biotech

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)