Iron oxide nanoparticles for magnetic resonance imaging

Magnetic iron oxide nanoparticles (IONPs) are a class of biocompatible and safe nanomaterials attractive to many biomedical applications, including as contrast agents for magnetic resonance imaging (MRI). Given tunable magnetic properties and various surface chemistry, engineered IONPs offer superb MRI contrast enhancement and can be functionalized as biomarker-targeted molecular MRI probes. MRI contrast enhancing capability, described as relaxivities, is highly dependent on the composition, size, and surface, as well as the aggregation of IONPs. This article discusses the chemical and physical properties of engineered IONPs affecting the relaxivities and imaging contrast as well as MRI methods and applications that utilize IONPs.