(297d) Colloidal Stability of Polyether-Stabilized Magnetite Nanoparticles In Aqueous Media

Magnetic nanoparticles have many interesting applications in biological systems, particular as MRI contrast agents. In this study, we examine the effect of different polyether stabilizers with charged end groups adsorbed to magnetite nanoparticles and how particle interactions change based on the media in which they are dispersed. Some polyether stabilizers were found to be ineffective in phosphate buffered saline (PBS). This is due to the strong adsorption of phosphate to the iron oxide surface, as evidenced by highly negative zeta potentials over wide pH ranges and particle instability over time in PBS. Additionally, magnetite/polymer complex diameters were predicted with reasonable accuracy using an adapted version of the Density Distribution model by Vagberg, et. al., that is based on a model for star polymers. The model was then used to predict the half-life for flocculation for each complex depending upon its magnetite content. This half-life was then correlated to the complex diameter as measured via dynamic light scattering and the effect of particle clustering on magnetic resonance imaging processes ? specifically T2 relaxivity - was examined.