Strain-Stiffening of Agarose Gels

Kia Bertula, Lahja Martikainen, Pauliina Munne, Sami Hietala, Juha Klefström, Olli Ikkala, Nonappa Nonappa

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)
162 Downloads (Pure)

Abstract

Strain-stiffening is one of the characteristic properties of biological hydrogels and extracellular matrices, where the stiffness increases upon increased deformation. Whereas strain-stiffening is ubiquitous in protein-based materials, it has been less observed for polysaccharide and synthetic polymer gels. Here we show that agarose, that is, a common linear polysaccharide, forms helical fibrillar bundles upon cooling from aqueous solution. The hydrogels with these semiflexible fibrils show pronounced strain-stiffening. However, to reveal strain-stiffening, suppressing wall slippage turned as untrivial. Upon exploring different sample preparation techniques and rheological architectures, the cross-hatched parallel plate geometries and in situ gelation in the rheometer successfully prevented the slippage and resolved the strain-stiffening behavior. Combining with microscopy, we conclude that strain-stiffening is due to the semiflexible nature of the agarose fibrils and their geometrical connectivity, which is below the central-force isostatic critical connectivity. The biocompatibility and the observed strain-stiffening suggest the potential of agarose hydrogels in biomedical applications.
Original languageEnglish
Pages (from-to)670-675
Number of pages6
JournalACS Macro Letters
Volume8
Issue number6
DOIs
Publication statusPublished - 18 Jun 2019
MoE publication typeA1 Journal article-refereed

Keywords

  • NEGATIVE NORMAL STRESS
  • NONLINEAR ELASTICITY
  • WALL SLIP
  • MECHANICAL-PROPERTIES
  • HYDROGELS
  • NETWORKS
  • ELASTOMERS

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  • Projects

    PreClinica: Novel Preclinical Model for Breast Cancer Theraphy

    Nonappa, N., Bertula, K. & Heilala, M.

    01/09/201731/12/2020

    Project: Business Finland: New business from research ideas (TUTLI)

    HYBER: The Academy of Finland's Centre of Excellence in Molecular Engineering of Biosynthetic Hybrid Materials research (2014-2019)

    Cherian, T., Nonappa, N., Ikkala, O., Bertula, K., Morits, M., Hynninen, V., Myllymäki, T., Toivonen, M., Sohrabi, F., Haataja, J., Sanchez Sanchez, A., Rissanen, S. & Poutanen, M.

    01/01/201730/06/2020

    Project: Academy of Finland: Other research funding

    Nanobreast

    Nonappa, N., Bertula, K., Ikkala, O. & Martikainen, L.

    01/10/201530/06/2018

    Project: Business Finland: Other research funding

    Equipment

    OtaNano

    Anna Rissanen (Manager)

    Aalto University

    Facility/equipment: Facility

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