Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration

The controlled agglomeration of superparamagnetic iron oxide nanoparticles (SPIONs) was used to rapidly switch their magnetic properties. Small-angle X-ray scattering (SAXS) and dynamic light scattering showed that tailored iron oxide nanoparticles with phase-changing organic ligand shells agglomerate at temperatures between 5 degrees C and 20 degrees C. We observed the concurrent change in magnetic properties using magnetic particle spectroscopy (MPS) with a temporal resolution on the order of seconds and found reversible switching of magnetic properties of SPIONs by changing their agglomeration state. The non-linear correlation between magnetization amplitude from MPS and agglomeration degree from SAXS data indicated that the agglomerates' size distribution affected magnetic properties.

Automated summary

Controlled agglomeration of superparamagnetic iron oxide nanoparticles can rapidly switch their magnetic properties. Changes in temperature induced reversible switching of magnetic properties, with non-linear correlation between magnetization amplitude and agglomeration degree indicating the impact of agglomerates' size distribution on magnetic properties.