Characterization of MPI tracer nanoparticle interactions via imaging

Magnetic particle imaging (MPI) is an emerging technology with significant potential in biomedical applications; the locations of nanoparticle tracers are detected using alternating magnetic fields to form 3D images. One concern with MPI is that the tracer particles may have varying properties and interactions depending on their environment. One such interaction is chaining, as applied fields cause the particles to form linear chains; it is poorly understood how changes in magnetic fields (direction and strength over time) will affect chaining, especially under AC fields which have been the focus of fewer studies. The variable properties of the particles can lead to artifacts in MPI images, but they also may enhance MPI signals. Using scanning electron microscopy (SEM) and optical microscopy to analyze samples of nanoparticles, we investigate these possible structural and functional variations. SEM samples were made of Perimag dextran iron oxide composite particles, dried in varying directions and strengths of AC magnetic fields, while samples for optical microscopy were imaged in colloidal suspension under DC fields. We characterize the interactions of MPI-relevant magnetic nanoparticles to understand their dynamics and contribute to the optimization of MPI techniques.