Superparamagnetic iron oxide nanoparticles (SPIONs) as therapeutic and diagnostic agents

Abstract Superparamagnetic iron oxide nanoparticles (SPIONs) are emerging nanomaterials, in part due to their superparamagnetic property. At room temperature, they can be readily magnetized under the influence of an external magnetic field and yet return to an apparently nonmagnetic state in its absence, with closed (no hysteresis) magnetization curves resulting in zero magnetic remanence and coercivity. Their high surface to volume ratio due to the nanometer length scale and subsequent high surface area enables them to be used in a range of applications that includes targeted drug delivery, magnetic contrasting agents in MRI scans for medical diagnosis, and in localized heating induced by an alternating magnetic field (AMF) for targeted therapy with minimum side effects. In this chapter, we systematically introduce the concept of magnetic nanomaterials, superparamagnetic materials such as SPIONs, various syntheses routes, various core-shell SPIONs, surface functionalization of core-shell SPIONs, main characterization techniques, and application of SPIONs in medical diagnosis and therapy. We have also summarized the current state of commercially available SPIONs and their applications in nanomedicine including information of clinical trials. Finally, we have provided an overview of the potential theranostics application of SPIONs in various diseases.