Magnetic measurement methods to probe nanoparticle–matrix interactions

Abstract

Magnetic nanoparticles (MNPs) are key elements in several biomedical applications, e.g., in cancer therapy. Here, the MNPs are remotely manipulated by magnetic fields from outside the body to deliver drugs or generate heat in tumor tissue. The efficiency and success of these approaches strongly depend on the spatial distribution and quantity of MNPs inside a body and interactions of the particles with the biological matrix. These include dynamic processes of the MNPs in the organism such as binding kinetics, cellular uptake, passage through cell barriers, heat induction and flow. While magnetic measurement methods have been applied so far to resolve the location and quantity of MNPs for therapy monitoring, these methods can be advanced to additionally access these particle–matrix interactions. By this, the MNPs can further be utilized as probes for the physical properties of their molecular environment. In this review, we first investigate the impact of nanoparticle–matrix interactions on magnetic measurements in selected experiments. With these results, we then advanced the imaging modalities magnetorelaxometry imaging and magnetic microsphere tracking to spatially resolve particle–matrix interactions.

Perspective: magnetic nanoparticles in theranostic applications

“…Similarly, the measured phase lag in MSI is also related to these relaxation time constants and could provide information on changes in particle dynamics and interactions for the case of small AMFs. Taking these effects into account would also result in an improved characterisation of the MNPs as this is often based on measuring the relaxation time constants without consideration for the impact of magnetic field properties and MNP interactions 88,89 .…”

COMPASS – rapid and highly sensitive medical point-of-care diagnostic

“…The characterization of ensembles of magnetic nanoparticles (MNP) is a dynamically developing eld and found various applications in many elds of research such as medicine, cancer theranostics, biosensing, catalysis, agriculture, and the environment [1][2][3]. Thus, a huge portfolio of different methods and techniques is available today to investigate the complex dynamics of MNP ensembles [4,5].…”

Interplay between steric and hydrodynamic interactions for ellipsoidal magnetic nanoparticles in a polymer suspension

“…[8][9][10][11][12][13] Also, MNPs have been employed as probe particles to experimentally assess material properties of their surroundings. [14][15][16][17][18][19][20][21] The coupling between MNPs and their environment typically is the key element in the aforementioned applications. Still, in many cases the details of these coupling mechanisms remain unknown.…”