Relaxometry and magnetometry of ferritin

Rodney A. Brooks, Josef Vymazal, Ron B. Goldfarb, Jeff W.M. Bulte, Philip Aisen

Research output: Contribution to journalArticle

Abstract

By combining nuclear magnetic relaxometry on 39 ferritin samples with different iron loading with magnetometry, results were obtained that suggest a new interpretation of the core structure and magnetic properties of ferritin. These studies provide evidence that, contrary to most earlier reports, the ferritin core is antiferromagnetic (AFM) even at body temperature and possesses a superparamagnetic (SPM) moment due to incomplete cancellation of antiparallel sublattices, as predicted by Neel's theory. This moment also provides a likely explanation for the anomalous T2 shortening in ferritin solution. However, the number of SPM moments derived from this model is less than the number of ferritin molecules determined chemically, and a similar discrepancy was found by retrospectively fitting previously published magnetometry data. In other words, only a fraction of the ferritin molecules seem to be SPM. The studies also provide evidence for paramagnetic (PM) Curie-Weiss iron ions at the core surface, where the local Neel temperature is lower; these ions are apparently responsible for the weaker T1 shortening. In fact, the conversion of uncompensated AFM lattice ions to PM ions could explain the small number of SPM particles. The apparent Curie Law behavior of ferritin thus appears to be a coincidental result of different temperature dependences of the PM and SPM components.

Original languageEnglish (US)
Pages (from-to)227-235
Number of pages9
JournalMagnetic resonance in medicine
Volume40
Issue number2
DOIs
StatePublished - Aug 1 1998
Externally publishedYes

Keywords

  • Ferritin
  • Relaxometry
  • Superparamagnetism
  • T
  • T

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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  • Cite this

    Brooks, R. A., Vymazal, J., Goldfarb, R. B., Bulte, J. W. M., & Aisen, P. (1998). Relaxometry and magnetometry of ferritin. Magnetic resonance in medicine, 40(2), 227-235. https://doi.org/10.1002/mrm.1910400208