Ultrasmall superparamagnetic iron oxide particles

Di Marco, M. Sadun, C. Port, M. Guilbert, I. Couvreur, P. Dubemet, C., Physicochemical characterization of ultrasmall superparamagnetic iron oxide particles (USPIO) for biomedical application as MRI contrast agents. International Journal of Nanomedicine 2007, 2, (4), 609-622. 

Beilin MF, Roy C, Kinkel K et al. (1998) Lymph node metasta-ses safety and effectiveness of MR imaging with ultrasmall superparamagnetic iron oxide particles—initial clinical... 

Superparamagnetic Iron Oxide Particles and Ultrasmall Superparamagnetic Iron Oxide Nanoparticles 533... 

Trivedi RA, King-Im JM, Graves MJ et al. (2004). In vivo detection of macrophages in human carotid atheroma temporal dependence of ultrasmall superparamagnetic particles of iron oxide-enhanced MRI. Stroke 35 1631-1635... 

K. B., Kessels, A.G., Kitslaar, P.J., Borgers, M., Frederik, P.M., Daemen, M.J., and van Engelshoven, J.M. (2003) Accumulation of ultrasmall superparamagnetic particles of iron oxide in human atherosclerotic plaques can be detected by in vivo magnetic resonance imaging. Circulation 107, 2453—2458. 

The higher anisotropy constants of magnetic metals with respect to their magnetic oxides lead to the critical size between superparamagnetic and ferromagnetic behaviors that is smaller for them. Thus, even ultrasmall iron nanoparticles can be blocked at room temperature giving rise to a hysteretic behavior. In addition, the ubiquitous oxide layer present on the surface of all metal particles could also lead to important variations of the overall magnetic behavior. 

---