A quantitative study of particle size effects in the magnetorelaxometry of magnetic nanoparticles using atomic magnetometry

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:379

Article

Dolgovskiy, V.¹  Lebedev, V.¹  Colombo, S.¹  Weis, A.¹  Michen, B.³  Ackermann-Hirschi, L.³  Petri-Fink, A.^2,3 

[1] Univ Fribourg, Dept Phys, CH-1700 Fribourg, Switzerland

[2] Univ Fribourg, Dept Chem, CH-1700 Fribourg, Switzerland

[3] Univ Fribourg, Adolphe Merkle Inst, CH-1700 Fribourg, Switzerland

关键词: Magnetorelaxometry;    Superparamagnetic nanoparticles;    Atomic magnetometry;    Neel and Brownian relaxation;    Maghemite;   

DOI  :  10.1016/j.jmmm.2014.12.007

来源: Elsevier

【 摘 要 】

The discrimination of immobilised superparamagnetic iron oxide nanoparticles (SPIONs) against SPIONs in fluid environments via their magnetic relaxation behaviour is a powerful tool for bio-medical imaging. Here we demonstrate that a gradiometer of laser pumped atomic magnetometers can be used to record accurate time series of the relaxing magnetic field produced by pre polarised SPIONs. We have investigated dry in vitro maghemite nanoparticle samples with different size distributions (average radii ranging from 14 to 21 nm) and analysed their relaxation using the Neel-Brown formalism. Fitting our model function to the magnetorelaxation (MRX) data allows us to extract the anisotropy constant K and the saturation magnetisation M-s of each sample. While the latter was found not to depend on the particle size, we observe that K is inversely proportional to the (time- and size-) averaged volume of the magnetised particle fraction. We have identified the range of SPION sizes that are best suited for MRX detection considering our specific experimental conditions and sample preparation technique. (C) 2014 Published by Elsevier B.V.

【 授权许可】

Free