Superparamagnetic hyperbranched polyglycerolgrafted fe3o 4 nanoparticles as a novel magnetic resonance imaging contrast agent: an in vitro assessment

Abstract

Hyperbranched polyglycerol-grafted, magnetic Fe3O4 nanoparticles (HPCgrafted MNPs) are successfully synthesized by surface-initiated ring-opening multibranching polymerization of glycidol. Reactive hydroxyl groups are immobilized on the surface of 6-9 nm Fe 3O4 nanoparticles via effective ligand exchange of oleic acid with 6-hydroxy caproic acid. The surface hydroxyl groups are treated with aluminum isopropoxide to form the nanosized macroinitiators. The successful grafting of HPC onto the nanoparticles is confirmed by infrared and X-ray photoelectron spectroscopy. The HPCgrafted MNPs have a uniform hydrodynamic diameter of (24.0 ± 3.0) nm, and are very stable in aqueous solution, as well as in cell culture medium, for months. These nanoparticles have great potential for application as a new magnetic resonance imaging contrast agent, as evidenced by their lack of cytotoxicity towards mammalian cells, low uptake by macrophages, excellent stability in aqueous medium and magnetic fields, and favorable magnetic properties. Furthermore, the possibility of functionalizing the hydroxyl endgroups of the HPG with cell-specific targeting ligands will expand the range of applications of these MNPs. ©2009 WILEY-VCH Verlag GmbH & Co. KGaA,.