Dynamics of magnetic nanoparticle assemblies in magnetic particle imaging

Magnetic nanoparticles (MNPs) are becoming increasingly important as tracers for non-invasive, in vivo magnetic particle imaging (MPI¹), magnetic hyperthermia², and thermometry³. For these applications, MNP tracers are driven by AC magnetic fields and detected by their modulated magnetic moments. Iron oxide nanoparticles with strong dipolar interactions exhibit enhanced MPI performance due to rapid magnetization reversal along strongly coupled chains of MNPs⁴. The chaining and magnetization dynamics span broad timescales and are governed by a complex set of parameters, including magnetic field amplitude, frequency, and temperature. We are using magnetic and physical characterization to investigate a number of strongly interacting iron oxide nanoparticle systems synthesized by our group. Here, we present mechanistic characterization using time-resolved magnetometry and electron microscopy for our synthesized ferrite iron oxide nanoparticles over a range of temperatures (275-320 K), magnetic field amplitudes (1-20 mT_RMS), and timescales (20 ns to 10 seconds) to elucidate chaining dynamics.

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[2] Liu et al. Theranostics, 10, P. 3793 (2020)

[3] Bui et al. J. Appl. Phys., 128, 224901, p. 1-9 (2020); Bui et al. Appl. Phys. Lett. 120, p.012407 (2022)

[4] Tay et al. Small Methods, 5, 2100796 (2021)