High-performance iron oxide nanoparticles for magnetic particle imaging – guided hyperthermia (hMPI)

TLDR

MPI is an emerging imaging modality that quantitatively maps iron oxide nanoparticles, and tailored tracers are essential for high sensitivity and spatial resolution, yet most clinical candidates are spherical undoped magnetite particles. The study systematically investigates how changes in chemical composition and shape anisotropy influence MPI performance of iron oxide nanoparticle tracers. Selective heating is achieved by saturating nanoparticles outside the field‑free region with a static field, enabling targeted hyperthermia within the MPI test sample. Zinc‑doped cubic magnetite nanoparticles produced a two‑fold increase in MPI signal and a five‑fold boost in specific absorption rate compared to undoped spherical particles, demonstrating that MPI‑guided hyperthermia can deliver high‑performance, focused heating.

Abstract

Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).