A, B, and C illustrate the three main magnetic properties of MIONs used in biomedical applications. A. Magnetic force generated by the interaction of MIONs with a nonuniform magnetic field. B. Magnetic resonance imaging (MRI) contrast due to the effect of MIONs on the relaxation of water protons. C. Magnetic heating generated by MIONs in an alternating magnetic field. D. TEM images of MIONs of 10, 15, 25 and 40 nm respectively. Scale bars equal 100 nm. E. A single MION coated with phospholipid-PEG and functionalized with targeting antibody, fluorescent dye, and drug molecules.