Time-Dependent Nanomechanics of Cartilage
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Han-2011-Time-Dependent Nanom.pdf
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Author(s)
Han, Lin
Greene, Jacqueline J.
Lee, Hsu-Yi
Hung, Han-Hwa K.
Grodzinsky, Alan J.
Ortiz, Christine
Frank, Eliot
Date Issued
April 2011
Journal
Biophysical Journal
Publisher
Elsevier
Citation
Han, Lin, Eliot H. Frank, Jacqueline J. Greene, Hsu-Yi Lee, Han-Hwa K. Hung, Alan J. Grodzinsky, and Christine Ortiz. “Time-Dependent Nanomechanics of Cartilage.” Biophysical Journal 100, no. 7 (April 2011): 1846–1854. © 2011 Biophysical Society
Version
Final published version
Abstract
In this study, atomic force microscopy-based dynamic oscillatory and force-relaxation indentation was employed to quantify the time-dependent nanomechanics of native (untreated) and proteoglycan (PG)-depleted cartilage disks, including indentation modulus E[subscript ind], force-relaxation time constant τ, magnitude of dynamic complex modulus |E*|, phase angle δ between force and indentation depth, storage modulus E′, and loss modulus E″. At ∼2 nm dynamic deformation amplitude, |E*| increased significantly with frequency from 0.22 ± 0.02 MPa (1 Hz) to 0.77 ± 0.10 MPa (316 Hz), accompanied by an increase in δ (energy dissipation). At this length scale, the energy dissipation mechanisms were deconvoluted: the dynamic frequency dependence was primarily governed by the fluid-flow-induced poroelasticity, whereas the long-time force relaxation reflected flow-independent viscoelasticity. After PG depletion, the change in the frequency response of |E*| and δ was consistent with an increase in cartilage local hydraulic permeability. Although untreated disks showed only slight dynamic amplitude-dependent behavior, PG-depleted disks showed great amplitude-enhanced energy dissipation, possibly due to additional viscoelastic mechanisms. Hence, in addition to functioning as a primary determinant of cartilage compressive stiffness and hydraulic permeability, the presence of aggrecan minimized the amplitude dependence of |E*| at nanometer-scale deformation.
MIT Department
Massachusetts Institute of Technology. Center for Biomedical Engineering
Massachusetts Institute of Technology. Department of Biological Engineering
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1016/j.bpj.2011.02.031
