Influence of clustering on the magnetic properties and hyperthermia performance of iron oxide nanoparticles
Artikel i vetenskaplig tidskrift, 2018

Clustering of magnetic nanoparticles can drastically change their collective magnetic properties, which in turn may influence their performance in technological or biomedical applications. Here, we investigate a commercial colloidal dispersion (FeraSpin™R), which contains dense clusters of iron oxide cores (mean size around 9 nm according to neutron diffraction) with varying cluster size (about 18-56 nm according to small angle x-ray diffraction), and its individual size fractions (FeraSpin™XS, S, M, L, XL, XXL). The magnetic properties of the colloids were characterized by isothermal magnetization, as well as frequency-dependent optomagnetic and AC susceptibility measurements. From these measurements we derive the underlying moment and relaxation frequency distributions, respectively. Analysis of the distributions shows that the clustering of the initially superparamagnetic cores leads to remanent magnetic moments within the large clusters. At frequencies below 105rad s-1, the relaxation of the clusters is dominated by Brownian (rotation) relaxation. At higher frequencies, where Brownian relaxation is inhibited due to viscous friction, the clusters still show an appreciable magnetic relaxation due to internal moment relaxation within the clusters. As a result of the internal moment relaxation, the colloids with the large clusters (FS-L, XL, XXL) excel in magnetic hyperthermia experiments.


magnetic nanoparticles

numerical inversion

multi-core particles

magnetic hyperthermia



P. Bender

Université du Luxembourg

Universidad de Cantabria

J. Fock

Danmarks Tekniske Universitet (DTU)

M. F. Hansen

Danmarks Tekniske Universitet (DTU)

Lara K. Bogart

University College London (UCL)

P. Southern

University College London (UCL)

Frank Ludwig

Technische Universität Braunschweig

F. Wiekhorst

Physikalisch-Technische Bundesanstalt (PTB)

W. Szczerba

Bundesanstalt für Materialforschung und -prüfung (BAM)

Akademia Gorniczo-Hutnicza im. Stanislawa Staszica w Krakowie

Lunjie Zeng

Chalmers, Fysik, Eva Olsson Group

D. Heinke

Nanopet Pharma

N. Gehrke

Nanopet Pharma

M. T.Fernández Díaz

Institut Laue-Langevin

D. Gonzalez-Alonso

Universidad de Cantabria

J. I. Espeso

Universidad de Cantabria

J. Rodríguez Fernández

Universidad de Cantabria

C. Johansson

RISE Research Institutes of Sweden


0957-4484 (ISSN) 1361-6528 (eISSN)

Vol. 29 42 425705


Oorganisk kemi

Annan fysik

Den kondenserade materiens fysik


Chalmers materialanalyslaboratorium



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