Poking and pulling collagen: Nanomechanical assessment of native collagen fibrils

author: Orestis G. Andriotis, Institute of Lightweight Design and Structural Biomechanics
published: July 9, 2018,   recorded: May 2018,   views: 438
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Description

Recent advances in mechanical signaling between cells and the extracellular matrix (1), brought interest in understanding the mechanical properties of tissues at the sub-cellular level i.e. of native collagen fibrils. Nanomechanical assessment has been achieved via atomic force microscopy (AFM) on native collagen fibrils from human and murine samples (2). The versatility of AFM allows both indentation and tensile experiments to be carried out in air-dry and fully hydrated environments. When fully hydrated, collagen fibrils become three orders of magnitude softer under indentation loading, compared to air-dried state. This suggests that hydration plays an important role in collagen fibril mechanics. Partial addition of an osmotic pressure-inducing agent, namely polyethylene glycol, results in partial dehydration followed by an up to 6-fold increase in tensile stiffness. Interestingly, this partial dehydration-based tuning mechanism is reversed and could be used by cells to tune their microenvironment e.g. by secreting proteoglycans. The identification of such structure-function relationships of individual collagen fibrils in combination with biochemical and biological analyses could be used to manufacture tissue-engineered scaffolds with desired mechanical properties and help enhance our understanding of the development and progression of pathologies at the nanoscale.

1. DuFort CC, Paszek MJ, Weaver VM. Balancing forces: architectural control of mechanotransduction. Nature reviews Molecular cell biology. 2011;12(5):308-19. 2. Andriotis OG, Manuyakorn W, Zekonyte J, Katsamenis OL, Fabri S, Howarth PH, et al. Nanomechanical assessment of human and murine collagen fibrils via atomic force microscopy cantilever-based nanoindentation. Journal of the mechanical behavior of biomedical materials. 2014;39:9-26.

Financing: EPSRC, MRC

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