edoc

Micro- and nanomechanical analysis of articular cartilage by indentation-type atomic force microscopy: validation with a gel-microfiber composite

Loparic, M. and Wirz, D. and Daniels, A. U. and Raiteri, R. and Vanlandingham, M. R. and Guex, G. and Martin, I. and Aebi, U. and Stolz, M.. (2010) Micro- and nanomechanical analysis of articular cartilage by indentation-type atomic force microscopy: validation with a gel-microfiber composite. Biophysical journal, Vol. 98. pp. 2731-2740.

Full text not available from this repository.

Official URL: http://edoc.unibas.ch/dok/A5848084

Downloads: Statistics Overview

Abstract

As documented previously, articular cartilage exhibits a scale-dependent dynamic stiffness when probed by indentation-type atomic force microscopy (IT-AFM). In this study, a micrometer-size spherical tip revealed an unimodal stiffness distribution (which we refer to as microstiffness), whereas probing articular cartilage with a nanometer-size pyramidal tip resulted in a bimodal nanostiffness distribution. We concluded that indentation of the cartilage's soft proteoglycan (PG) gel gave rise to the lower nanostiffness peak, whereas deformation of its collagen fibrils yielded the higher nanostiffness peak. To test our hypothesis, we produced a gel-microfiber composite consisting of a chondroitin sulfate-containing agarose gel and a fibrillar poly(ethylene glycol)-terephthalate/poly(butylene)-terephthalate block copolymer. In striking analogy to articular cartilage, the microstiffness distribution of the synthetic composite was unimodal, whereas its nanostiffness exhibited a bimodal distribution. Also, similar to the case with cartilage, addition of the negatively charged chondroitin sulfate rendered the gel-microfiber composite's water content responsive to salt. When the ionic strength of the surrounding buffer solution increased from 0.15 to 2 M NaCl, the cartilage's microstiffness increased by 21%, whereas that of the synthetic biomaterial went up by 31%. When the nanostiffness was measured after the ionic strength was raised by the same amount, the cartilage's lower peak increased by 28%, whereas that of the synthetic biomaterial went up by 34%. Of interest, the higher peak values remained unchanged for both materials. Taken together, these results demonstrate that the nanoscale lower peak is a measure of the soft PG gel, and the nanoscale higher peak measures collagen fibril stiffness. In contrast, the micrometer-scale measurements fail to resolve separate stiffness values for the PG and collagen fibril moieties. Therefore, we propose to use nanostiffness a new biomarker to analyze structure-function relationships in normal, diseased, and engineered cartilage.
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Department of Biomedicine, University Hospital Basel > Tissue Engineering (Martin)
03 Faculty of Medicine > Bereich Operative Fächer (Klinik) > Querschnittsbereich Forschung > Tissue Engineering (Martin)
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Operative Fächer (Klinik) > Querschnittsbereich Forschung > Tissue Engineering (Martin)
03 Faculty of Medicine > Bereich Medizinische Fächer (Klinik) > Rheumatologie
03 Faculty of Medicine > Departement Klinische Forschung > Bereich Medizinische Fächer (Klinik) > Rheumatologie
05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Aebi)
UniBasel Contributors:Daniels, A.U. Dan and Martin, Ivan and Aebi, Ueli
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Biophysical Society
ISSN:0006-3495
Note:Publication type according to Uni Basel Research Database: Journal article
Related URLs:
Identification Number:
Last Modified:07 Dec 2012 13:01
Deposited On:08 Jun 2012 06:48

Repository Staff Only: item control page