Biomedical applications of imidazolium cation-modified iron oxide nanoparticles

We report the synthesis of N-methylimidazolium chloride-modified iron oxide nanoparticles (MImCl-NPs) by condensation of an imidazolium cation-containing silane coupling agent (1) with the iron oxide nanoparticles which were prepared by the coprecipitation of FeCl2 and FeCl3 by alkaline hydrolysis. The modified iron oxide nanoparticles exhibited a superparamagnetic behavior at the room temperature. For a given weight concentration, MImCl-NPs showed a darker (T-2-weighted) image than Resovist , which is commercially available and used for MRI imaging in practice. When mice were given a daily intravenous injection of 5% glucose aqueous solution of MImCl-NPs for two weeks, MImCl-NPs showed no significant difference in body weight and blood biochemistry of serum in all samples compared to controls. DLS measurements of the aqueous solutions of the modified iron oxide nanoparticles after the addition of NaPF6 and Nal indicated the presence of particle aggregates. In contrast, no aggregation was observed after the addition of NaCl. A higher degree of adsorption of DNA onto MImCl-NPs was observed in comparison to that onto amino-functionalized magnetic nanoparticles (NH2-NPs). Copyright (C) 2008 John Wiley & Sons, Ltd.