Screening of superparamagnetic iron oxide nanoparticles for their application in the human body: Influence of various coatings

Iron oxide nanoparticles (IONs) are of great interest in nanomedicine for imaging, drug delivery, or for hyperthermia treatment. Although many research groups have focused on the synthesis and application of IONs in nanomedicine, little is known about the influence of the surface properties on the particles’ behavior in the human body. This study analyzed the impact of standard coating materials (dextran, polyvinyl alcohol, polylactide-co-glycolide) with an improved experimental setting on the IONs’ cytocompatibility, degradation, and agglomeration profile and their oxidative stress. All particles, including bare IONs (BIONs), showed good cytocompatibility (>70%) with smooth muscle cells. The polyvinyl alcohol coating led to the least agglomeration over a pH range from 4 to 10 in water. Small-angle X-ray scattering profiles could visualize aggregation and primary particle sizes around 20 nm for BIONs and dextran-coated IONs. A combined experimental setup of dynamic light scattering and phenanthroline assay was used to analyze the long-term agglomeration and degradation profile of IONs in simulated body fluids, allowing fast screening of multiple candidates. All particles degraded in simulated endosomal and lysosomal fluid, confirming the pH-dependent dissolution. The degradation rate decreased with the shrinking size of particles leading to a plateau. The fastest Fe2+ release could be measured for the polyvinyl-coated IONs. The analytical setup is ideal for a quick preclinical study of IONs, giving often neglected yet crucial information about the behavior and toxicity of nanoparticles in the human body.