A nuclear magnetic resonance study of water in aggrecan solutions

Richard J. Foster, Robin A. Damion, Thomas G. Baboolal, Stephen W. Smye, Michael E. Ries*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

6 Citations (Scopus)
176 Downloads (Pure)

Abstract

Aggrecan, a highly charged macromolecule found in articular cartilage, was investigated in aqueous salt solutions with proton nuclear magnetic resonance. The longitudinal and transverse relaxation rates were determined at two different field strengths, 9.4 T and 0.5 T, for a range of temperatures and aggrecan concentrations. The diffusion coefficients of the water molecules were also measured as a function of temperature and aggrecan concentration, using a pulsed field gradient technique at 9.4 T. Assuming an Arrhenius relationship, the activation energies for the various relaxation processes and the translational motion of the water molecules were determined from temperature dependencies as a function of aggrecan concentration in the range 0–5.3% w/w. The longitudinal relaxation rate and inverse diffusion coefficient were approximately equally dependent on concentration and only increased by upto 20% from that of the salt solution. The transverse relaxation rate at high field demonstrated greatest concentration dependence, changing by an order of magnitude across the concentration range examined. We attribute this primarily to chemical exchange. Activation energies appeared to be approximately independent of aggrecan concentration, except for that of the low-field transverse relaxation rate, which decreased with concentration.

Original languageEnglish
Article number150705
Number of pages10
JournalRoyal Society Open Science
Volume3
Issue number3
Early online date9 Mar 2016
DOIs
Publication statusPublished - Mar 2016

Keywords

  • Activation energy
  • Aggrecan
  • Chemical exchange
  • Diffusion
  • Glycosaminoglycan
  • Relaxation

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