Poroelasticity of cartilage at the nanoscale.

ABSTRACT: Atomic-force-microscopy-based oscillatory loading was used in conjunction with finite element modeling to quantify and predict the frequency-dependent mechanical properties of the superficial zone of young bovine articular cartilage at deformation amplitudes, ?, of ~15 nm; i.e., at macromolecular length scales. Using a spherical probe tip (R ~ 12.5 ?m), the magnitude of the dynamic complex indentation modulus, |E*|, and phase angle, ?, between the force and tip displacement sinusoids, were measured in the frequency range f ~ 0.2-130 Hz at an offset indentation depth of ?(0) ~ 3 ?m. The experimentally measured |E*| and ? corresponded well with that predicted by a fibril-reinforced poroelastic model over a three-decade frequency range. The peak frequency of phase angle, f(peak), was observed to scale linearly with the inverse square of the contact distance between probe tip and cartilage, 1/d(2), as predicted by linear poroelasticity theory. The dynamic mechanical properties were observed to be independent of the deformation amplitude in the range ? = 7-50 nm. Hence, these results suggest that poroelasticity was the dominant mechanism underlying the frequency-dependent mechanical behavior observed at these nanoscale deformations. These findings enable ongoing investigations of the nanoscale progression of matrix pathology in tissue-level disease.

SUBMITTER: Nia HT 

PROVIDER: S-EPMC3207157 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature