Cargando…

Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk

The hierarchical structure of spider dragline silk is composed of two major constituents, the amorphous phase and crystalline units, and its mechanical response has been attributed to these prime constituents. Silk mechanics, however, might also be influenced by the resistance against sliding of the...

Descripción completa

Detalles Bibliográficos
Autores principales: Patil, Sandeep P., Xiao, Senbo, Gkagkas, Konstantinos, Markert, Bernd, Gräter, Frauke
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132047/
https://www.ncbi.nlm.nih.gov/pubmed/25119288
http://dx.doi.org/10.1371/journal.pone.0104832
_version_ 1782330558613815296
author Patil, Sandeep P.
Xiao, Senbo
Gkagkas, Konstantinos
Markert, Bernd
Gräter, Frauke
author_facet Patil, Sandeep P.
Xiao, Senbo
Gkagkas, Konstantinos
Markert, Bernd
Gräter, Frauke
author_sort Patil, Sandeep P.
collection PubMed
description The hierarchical structure of spider dragline silk is composed of two major constituents, the amorphous phase and crystalline units, and its mechanical response has been attributed to these prime constituents. Silk mechanics, however, might also be influenced by the resistance against sliding of these two phases relative to each other under load. We here used atomistic molecular dynamics (MD) simulations to obtain friction forces for the relative sliding of the amorphous phase and crystalline units of Araneus diadematus spider silk. We computed the coefficient of viscosity of this interface to be in the order of 10(2) Ns/m(2) by extrapolating our simulation data to the viscous limit. Interestingly, this value is two orders of magnitude smaller than the coefficient of viscosity within the amorphous phase. This suggests that sliding along a planar and homogeneous surface of straight polyalanine chains is much less hindered than within entangled disordered chains. Finally, in a simple finite element model, which is based on parameters determined from MD simulations including the newly deduced coefficient of viscosity, we assessed the frictional behavior between these two components for the experimental range of relative pulling velocities. We found that a perfectly relative horizontal motion has no significant resistance against sliding, however, slightly inclined loading causes measurable resistance. Our analysis paves the way towards a finite element model of silk fibers in which crystalline units can slide, move and rearrange themselves in the fiber during loading.
format Online
Article
Text
id pubmed-4132047
institution National Center for Biotechnology Information
language English
publishDate 2014
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-41320472014-08-19 Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk Patil, Sandeep P. Xiao, Senbo Gkagkas, Konstantinos Markert, Bernd Gräter, Frauke PLoS One Research Article The hierarchical structure of spider dragline silk is composed of two major constituents, the amorphous phase and crystalline units, and its mechanical response has been attributed to these prime constituents. Silk mechanics, however, might also be influenced by the resistance against sliding of these two phases relative to each other under load. We here used atomistic molecular dynamics (MD) simulations to obtain friction forces for the relative sliding of the amorphous phase and crystalline units of Araneus diadematus spider silk. We computed the coefficient of viscosity of this interface to be in the order of 10(2) Ns/m(2) by extrapolating our simulation data to the viscous limit. Interestingly, this value is two orders of magnitude smaller than the coefficient of viscosity within the amorphous phase. This suggests that sliding along a planar and homogeneous surface of straight polyalanine chains is much less hindered than within entangled disordered chains. Finally, in a simple finite element model, which is based on parameters determined from MD simulations including the newly deduced coefficient of viscosity, we assessed the frictional behavior between these two components for the experimental range of relative pulling velocities. We found that a perfectly relative horizontal motion has no significant resistance against sliding, however, slightly inclined loading causes measurable resistance. Our analysis paves the way towards a finite element model of silk fibers in which crystalline units can slide, move and rearrange themselves in the fiber during loading. Public Library of Science 2014-08-13 /pmc/articles/PMC4132047/ /pubmed/25119288 http://dx.doi.org/10.1371/journal.pone.0104832 Text en © 2014 Patil et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Patil, Sandeep P.
Xiao, Senbo
Gkagkas, Konstantinos
Markert, Bernd
Gräter, Frauke
Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk
title Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk
title_full Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk
title_fullStr Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk
title_full_unstemmed Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk
title_short Viscous Friction between Crystalline and Amorphous Phase of Dragline Silk
title_sort viscous friction between crystalline and amorphous phase of dragline silk
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132047/
https://www.ncbi.nlm.nih.gov/pubmed/25119288
http://dx.doi.org/10.1371/journal.pone.0104832
work_keys_str_mv AT patilsandeepp viscousfrictionbetweencrystallineandamorphousphaseofdraglinesilk
AT xiaosenbo viscousfrictionbetweencrystallineandamorphousphaseofdraglinesilk
AT gkagkaskonstantinos viscousfrictionbetweencrystallineandamorphousphaseofdraglinesilk
AT markertbernd viscousfrictionbetweencrystallineandamorphousphaseofdraglinesilk
AT graterfrauke viscousfrictionbetweencrystallineandamorphousphaseofdraglinesilk