Authors: M. Concha, S. DeLong, L. Radu, C. Kumar and P. Bidwell-Hanson
Affilation: University of New Orleans, United States
Pages: 24 - 27
Keywords: EPR, SPION, glass, phase transition
The magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) have made them useful tools in a variety of applications ranging from drug delivery to magnetorheologic valving in microfluidic systems. The structure of SPIONs is typically characterized by methods such as XRD, XAFS, SEM and high resolution TEM while the SPION magnetic properties are evaluated relative to bulk values using SQUID. These methods characterize the state of the nanoparticles; however, the methods provide limited information about the behavior of the particles in solution. Here we demonstrate that electron paramagnetic resonance (EPR) reveals the solution behavior of 13 nm SPIONs suspended in a methanol:glycerol solution as well as environmental changes around the SPIONs. For example, characteristic temperature-dependent changes in the EPR spectra detail orientation changes of the SPIONs. The data presents a new opportunity for observing the in vitro, in vivo, and solution behavior of magnetite SPIONs.