Investigating the effect of magnetic dipole–dipole interaction on magnetic particle spectroscopy: implications for magnetic nanoparticle-based bioassays and magnetic particle imaging

Abstract

Superparamagnetic iron oxide nanoparticles (SPIONs), with comparable size to biomolecules (such as proteins, nucleic acids, etc.) and unique magnetic properties, good biocompatibility, low toxicity, potent catalytic behavior, are promising candidates for many biomedical applications. There is one property present in most SPION systems, yet it has not been fully exploited, which is the dipole-dipole interaction (also called dipolar interaction) between the SPIONs. It is known that the magnetic dynamics of an ensemble of SPIONs are substantially influenced by the dipolar interactions. However, the exact way it affects the performance of magnetic particle-based bioassays and magnetic particle imaging (MPI) is still an open question. The purpose of this paper is to give a partial answer to this question. This is accomplished by numerical simulations on the dipolar interactions between two nearby SPIONs and experimental measurements on an ensemble of SPIONs using our lab-based magnetic particle spectroscopy (MPS) system. Our results show that even moderate changes in the SPION concentration may have substantial effects on the magnetic dynamics of the SPION system and the harmonic signal magnitudes can be increased or decreased by 60%, depending on the values of MPS system parameters.

Dynamics of interacting magnetic nanoparticles: effective behavior from competition between Brownian and Néel relaxation

“…However, since the magnetic properties of interacting MNPs are much less understood, [23][24][25] we here address the question about the validity and form of eqn (1) for interacting MNPs. In ref.…”

Anisotropic Magnetic Supraparticles with a Magnetic Particle Spectroscopy Fingerprint as Indicators for Cold-Chain Breach

“…Thus, the signal intensification is not related to intrinsic nanoparticle properties but must be related to the formation of the superstructures, i.e., the supraparticles. However, it needs to be determined whether the signal change is caused by modified interactions between individual iron oxide nanoparticles within the assembly, as was described for nanoparticle dispersions 16 and supraparticles, 14 or by its anisotropic structural arrangement.…”

Displacement Patterns in Magnetomotive Ultrasound Explored by Finite Element Analysis

“…Unfortunately, only the saturation magnetization of the particle suspension was known, not the magnetization curve. While dipoleÀdipole interactions are not prominent at the concentrations used here (Wu et al 2019), it would be preferable to use data collected on the study system for the non-linear model. Here, the non-linear magnetization model was based on normalized data from a similar particle that was scaled by the saturation magnetization.…”