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Mechanical and Structural Contribution of Non-Fibrillar Matrix in Uniaxial Tension: A Collagen-Agarose Co-Gel Model

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Abstract

The mechanical role of non-fibrillar matrix and the nature of its interaction with the collagen network in soft tissues remain poorly understood, in part because of the lack of a simple experimental model system to quantify these interactions. This study’s objective was to examine mechanical and structural properties of collagen-agarose co-gels, utilized as a simplified model system, to understand better the relationships between the collagen network and non-fibrillar matrix. We hypothesized that the presence of agarose would have a pronounced effect on microstructural reorganization and mechanical behavior. Samples fabricated from gel solutions containing 1.0 mg/mL collagen and 0, 0.125, or 0.25% w/v agarose were evaluated via scanning electron microscopy, incremental tensile stress-relaxation tests, and polarized light imaging. While the incorporation of agarose did not dramatically alter collagen network morphology, agarose led to concentration-dependent changes in mechanical and structural properties. Specifically, resistance of co-gels to volume change corresponded with differences in fiber reorientation and elastic/viscoelastic mechanics. Results demonstrate strong relationships between tissue properties and offer insight into behavior of tissues of varying Poisson’s ratio and fiber kinematics. Results also suggest that non-fibrillar material may have significant effects on properties of artificial and native tissues even in tension, which is generally assumed to be collagen dominated.

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Acknowledgments

The authors thank Victor Lai, Xiao Zhong, and Sadie Doggett for help with SEM acquisition, mechanical testing, and data analysis, respectively. We gratefully acknowledge the financial support of NIH Grants R01-EB005813 and F32-EB012352, and the NSF’s support of the University of Minnesota’s Characterization Facility.

Conflict of Interest

No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

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Authors and Affiliations

  1. Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN, 55455, USA

    Spencer P. Lake & Victor H. Barocas

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  1. Spencer P. Lake
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  2. Victor H. Barocas
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Correspondence to Victor H. Barocas.

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Associate Editor Michael S. Detamore oversaw the review of this article.

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Lake, S.P., Barocas, V.H. Mechanical and Structural Contribution of Non-Fibrillar Matrix in Uniaxial Tension: A Collagen-Agarose Co-Gel Model. Ann Biomed Eng 39, 1891–1903 (2011). https://doi.org/10.1007/s10439-011-0298-1

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  • DOI: https://doi.org/10.1007/s10439-011-0298-1

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