Nanomechanics of opposing glycosaminoglycan macromolecules
Accepted 6 September 2004. published online 09 December 2004.
Abstract
In this study, the net intermolecular interaction force between a chondroitin sulfate glycosaminoglycan (GAG)-functionalized probe tip and an opposing GAG-functionalized planar substrate was measured as a function of probe tip–substrate separation distance in aqueous electrolyte solutions using the technique of high resolution force spectroscopy. A range of GAG grafting densities as near as possible to native cartilage was used. A long-range repulsive force between GAGs on the probe tip and substrate was observed, which increased nonlinearly with decreasing separation distance between probe tip and substrate. Data obtained in 0.1M NaCl was well predicted by a recently developed Poisson–Boltzmann-based theoretical model that describes normal electrostatic double layer interaction forces between two opposing surfaces of end-grafted, cylindrical rods of constant volume charge density and finite length, which interdigitate upon compression. Based on these results, the nanomechanical data and interdigitated rod model were used together to estimate the electrostatic component of the equilibrium modulus of cartilage tissue, which was then compared to that of normal adult human ankle cartilage measured in uniaxial confined compression.
aDepartment of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT 13-4022, Cambridge, MA 02139, USA
bDepartment of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT 13-4022, Cambridge, MA 02139, USA
cRiddick Laboratories, Department of Chemical Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA
dDepartment of Pharmacology and Therapeutics, College of Medicine, University of South Florida, Tampa, FL 33620, USA
eBiological Engineering Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT 13-4022, Cambridge, MA 02139, USA
fDepartment of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, MIT 13-4022, Cambridge, MA 02139, USA
1 Present address: The CBR Institute for Biomedical Research, Inc., Harvard Medical School, Boston, MA 02115, USA.
2 Present address: National Institute of Standards and Technology, Polymers Division, Polymers Building (224), Room B228, 100 Bureau Drive, Stop 8546, Gaithersburg, MD 20899-8546, USA.
ABSTRACT