Influence of clustering on the magnetic properties and hyperthermia performance of iron oxide nanoparticles
Journal article, 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.
core-clusters
magnetic nanoparticles
numerical inversion
multi-core particles
magnetic hyperthermia
nanoflowers
Author
P. Bender
University of Luxembourg
University of Cantabria
J. Fock
Technical University of Denmark (DTU)
M. F. Hansen
Technical University of Denmark (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
Federal Institute for Materials Research and Testing
AGH University of Science and Technology
Lunjie Zeng
Chalmers, Physics, Eva Olsson Group
D. Heinke
Nanopet Pharma
N. Gehrke
Nanopet Pharma
M. T.Fernández Díaz
Institut Laue-Langevin
D. Gonzalez-Alonso
University of Cantabria
J. I. Espeso
University of Cantabria
J. Rodríguez Fernández
University of Cantabria
C. Johansson
RISE Research Institutes of Sweden
Nanotechnology
0957-4484 (ISSN) 1361-6528 (eISSN)
Vol. 29 42 425705Subject Categories
Inorganic Chemistry
Other Physics Topics
Condensed Matter Physics
Infrastructure
Chalmers Materials Analysis Laboratory
DOI
10.1088/1361-6528/aad67d