(519f) Enhanced Magnetic Properties in Functionalized Iron Oxide Nanoparticles for Biomedical Applications

Iron oxide nanoparticles are essential components of next-generation drug delivery systems, MRI contrast agents, and cell separation systems. All of these applications involve some form of surface functionalization of the nanoparticles to either render them hydrophilic or to give them targeting capabilities. The impact of such surface functionalization techniques on the magnetic properties of these nanoparticles is, however, not well-understood. This presentation will describe changes in magnetic properties in Fe3O4 nanoparticles originally synthesized with oleic acid acting as a hydrophobic surfactant when functionalized with dopamine. These changes include a significant increase in the remanence, saturation magnetization, and blocking temperature after dopamine functionalization, even though TEM and XRD studies revealed no change in the particles' size and/or structure. The results are consistent with an increase in the magnetic size of the nanoparticle core induced by the dopamine ligand exchange process. Potential mechanisms for this change will be discussed along with implications for the use of these nanoparticles in magnet-activated microfluidic cell separation.