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2019-11-18 - Article/Dans un journal avec peer-review - Anglais - 9 page(s)

Henrard Daniel , Vuong Quoc Lam , Delangre Sébastien , Valentini Xavier, Nonclercq Denis , Gonon Maurice , Gossuin Yves , "Monitoring of Superparamagnetic Particle Sizes in the Langevin Law Regime" in Journal of Nanomaterials, 2019, 6409210, https://doi.org/10.1155/2019/6409210

  • Edition : Hindawi Publishing Corporation (Egypt)
  • Codes CREF : Résonance magnétique nucléaire (biophysique) (DI131B), Physique du spin (genre RMN) (DI1234), Biophysique (DI3113)
  • Unités de recherche UMONS : Physique biomédicale (M104)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Physique des matériaux (CRPM)
Texte intégral :

Abstract(s) :

(Anglais) In this work, aqueous solutions of magnetite nanoparticles (NPs) are studied. Magnetite NPs are very useful in biomedicine for magnetic resonance imaging (MRI), for drug delivery therapy, and also for hyperthermia. In order to predict the NP efficiency in these applications, it is crucial to accurately characterize their size distribution and their magnetization. Magnetometry, through the dependence of NP magnetization on the magnetic induction (MB curve), can provide interesting information on these physical properties. In this work, the extraction of the NP size distribution and magnetization from experimental MB curves of aqueous solutions of magnetite NPs is discussed. The results are compared to TEM and XRD characterizations. It is shown that an expression taking into account the size distribution better fits the results than the commonly used simple Langevin function. The size distributions obtained by magnetometry seem comparable to those obtained by TEM measurements. However, a closer look at the results shows some nonnegligible discrepancies: the size distributions obtained by magnetometry vary with the temperature and are closer to the TEM ones at room temperature. Our study suggests that it could be explained by the nonnegligible anisotropy energy of the NPs at low temperature and the lack of NP Brownian rotation below the freezing point of water. This demonstrates that care must be taken when interpreting the results obtained by magnetometry of magnetite NPs: only the size and size distribution obtained at room temperature should be used.