University of Oulu

J. Phys. Chem. B 2022, 126, 13, 2538–2551,

Dipolar relaxation of water protons in the vicinity of a collagen-like peptide

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Author: Karjalainen, Jouni1; Henschel, Henning1; Nissi, Mikko J.2,1;
Organizations: 1Research Unit of Medical Imaging Physics and Technology, University of Oulu, P.O. Box 5000, Oulu 90014, Finland
2Department of Applied Physics, University of Eastern Finland, Kuopio 70210, Finland
3Department of Diagnostic Radiology, Oulu University Hospital, Oulu 90014, Finland
4Medical Research Center, University of Oulu and Oulu University Hospital, Oulu 90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.9 MB)
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Language: English
Published: American Chemical Society, 2022
Publish Date: 2022-04-26


Quantitative magnetic resonance imaging is one of the few available methods for noninvasive diagnosis of degenerative changes in articular cartilage. The clinical use of the imaging data is limited by the lack of a clear association between structural changes at the molecular level and the measured magnetic relaxation times. In anisotropic, collagen-containing tissues, such as articular cartilage, the orientation dependency of nuclear magnetic relaxation can obscure the content of the images. Conversely, if the molecular origin of the phenomenon would be better understood, it would provide opportunities for diagnostics as well as treatment planning of degenerative changes in these tissues. We study the magnitude and orientation dependence of the nuclear magnetic relaxation due to dipole–dipole coupling of water protons in anisotropic, collagenous structures. The water–collagen interactions are modeled with molecular dynamics simulations of a small collagen-like peptide dissolved in water. We find that in the vicinity of the collagen-like peptide, the dipolar relaxation of water hydrogen nuclei is anisotropic, which can result in orientation-dependent relaxation times if the water remains close to the peptide. However, the orientation-dependency of the relaxation is different from the commonly observed magic-angle phenomenon in articular cartilage MRI.

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Series: The journal of physical chemistry. B
ISSN: 1520-6106
ISSN-E: 1520-5207
ISSN-L: 1520-5207
Volume: 126
Issue: 13
Pages: 2538 - 2551
DOI: 10.1021/acs.jpcb.2c00052
Type of Publication: A1 Journal article – refereed
Field of Science: 217 Medical engineering
Funding: The authors would like to thank Jane and Aatos Erkko Foundation for funding this work. CSC – IT Center for Science is thanked for providing the computation resources.
Copyright information: © 2022 The Authors. Published by American Chemical Society. Published under CC-BY.