Magnetic flow field separation of superparamagnetic dextran coated iron oxide nanoparticles

Magnetic Particle Imaging (MPI) relies exclusively on the distinct magnetization reversal dynamics of superparamagentic iron oxide nanoparticles (SPIONs). The particles' potential performance for MPI is mainly driven by the SPION size: maximum monodisperse particles of a specific diameter are most suitable for high-quality MPI results. In medical application the SPIONs are dispersed in polymers. The in-vitro performance such as biocompatibility of the tracers is mostly dictated by the size and surface structure of the coating. Tuning the SPION-cores' size and the shells' size is both a first approach and also the key to achieving particles best-suited for MPI. While there are various ways of tailoring the particles' superparamagnetic core or the carbohydrate shell during synthesis, the resulting particles have a hydrodynamic size distribution from 40-400 nm. Further purification is necessary, but time consuming. This paper presents experiments with a magnetic flow field separation platform for a fast and effective size-dependent separation of different SPIONs after synthesis. The results indicate that it is possible to tune both the size of the shell and magnetic properties of the SPION core with the microfluidic fractionation platform.