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Issue 24, 2019
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The mechanics of single cross-links which mediate cell attachment at a hydrogel surface

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Abstract

The response of cultured cells to the mechanical properties of hydrogel substrates depends ultimately on the response of single crosslinks to external forces exerted at cell attachment points. We prepared hydrogels by co-polymerization of poly(ethylene glycol diacrylate) (PEGDA) and carboxy poly(ethylene glycol) acrylate (ACPEG-COOH) and confirmed fibroblast spreading on the hydrogel after the ACPEG linker was functionalized with the RGD cell adhesive motif. We performed specific force spectroscopy experiments on the same ACPEG linkers in order to probe the mechanics of single cross-links which mediate the cell attachment and spreading. Measurements were performed with tips of an atomic force microscope (AFM) functionalized with streptavidin and ACPEG linkers functionalized with biotin. We compared hydrogels of varying elastic modulus between 4 and 41 kPa which exhibited significant differences in cell spreading. An effective spring constant for the displacement of single cross-links at the hydrogel surface was derived from the distributions of rupture force and molecular stiffness. A factor of ten in the elastic modulus E of the hydrogel corresponded to a factor of five in the effective spring constant k of single crosslinks, indicating a transition in scaling with the mesh size ξ from the macroscopic Eξ−3 to the molecular kξ−2. The quantification of stiffness and deformation at the molecular length scale contributes to the discussion of mechanisms in force-regulated phenomena in cell biology.

Graphical abstract: The mechanics of single cross-links which mediate cell attachment at a hydrogel surface

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Supplementary files

Article information


Submitted
27 Feb 2019
Accepted
31 May 2019
First published
03 Jun 2019

Nanoscale, 2019,11, 11596-11604
Article type
Paper

The mechanics of single cross-links which mediate cell attachment at a hydrogel surface

A. Çolak, B. Li, J. Blass, K. Koynov, A. del Campo and R. Bennewitz, Nanoscale, 2019, 11, 11596
DOI: 10.1039/C9NR01784D

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