Synthesis and characterization of magnetic dextran nanogel doped with iron oxide nanoparticles as magnetic resonance imaging probe.

Magnetic hybrid nanogels composed of magnetic nanoparticles and polymer hydrogel matrix have drawn much attention because of their unique superparamagnetic properties and biocompatibility as biomaterials. In this study, a facile method was developed for the preparation of iron oxide nanoparticle-loaded magnetic dextran nanogel as magnetic resonance imaging (MRI) probe. Water soluble superparamagnetic iron oxide nanocrystals (Fe3 O4 ) was pre-synthesized and physically doped into a Schiff base-containing dextran nanogel formed using W/O microemulsion as nanoreactor. Magnetic dextran nanogel (Fe3 O4 @Dex) with particle size of 300-1000 nm was obtained with multiple Fe3 O4 nanoparticles randomly encapsulated in the hydrogel networks. Magnetization and T2 relaxivity study shows that the resulted magnetic nanogel has similar superparamagneitc behaviors with single Fe3 O4 nanocrystals, and relatively higher T2 relaxivity (277.2 mMFe -1 ·s-1 ) as MRI probe. Notably, Schiff base linkages and aldehyde groups on the dextran hydrogel matrix endow the magnetic nanogel with pH-sensitiveness and reactive groups for further modifications, which make the magnetic dextran nanogel a promising nanoplatform as MRI-guided drug delivery system with acid environment-responsiveness.