l characteristics , biocompatibility , and MRI applicability of novel monodisperse PEG-modi fi ed magnetic Fe 3 O 4 & SiO 2 core – shell nanoparticles †

Monodisperse, superparamagnetic oleic acid-stabilized Fe3O4 nanoparticles of different sizes were prepared by thermal decomposition of Fe(III) oleate. The particles were subsequently coated by silica shells of different thicknesses (yielding Fe3O4&SiO2) using a water-in-oil (w/o) reverse microemulsion technique and/or were decorated with amino groups by reaction with (3-aminopropyl)triethoxysilane. The resulting Fe3O4&SiO2-NH2 nanoparticles were then modified with poly(ethylene glycol) (PEG) via reaction with its succinimidyl ester yielding Fe3O4&SiO2-PEG particles. The in vitro biocompatibility and biosafety of the Fe3O4&SiO2 and Fe3O4&SiO2-PEG particles were investigated in a murine neural stem cell model in terms of oxidative stress response and cell viability, proliferation, and uptake. Finally, the potential of both nanoparticle types for application in magnetic resonance imaging (MRI) visualization was evaluated.