Superparamagnetic iron-oxide nanoparticles (SPIONs), composed of a magnetic iron-oxide core and a tunable non-magnetic coating, exhibit rapid magnetic response along with exceptional stability and biocompatibility [1], [2]. These characteristics have fostered their applications in diverse medical fields including drug delivery [3], diagnostic imaging [4], and hyperthermia therapy [5].
The characteristics of nanoparticles are closely related to their structure. Their structure is well layered. Crystals, iron oxide nuclei, aggregates, clusters and agglomeration are gradually formed as the scale increases. The formation of these different hierarchical structures determines the macroscopic properties of the final nanoparticle.