Synthesis of water well-dispersed PEGylated iron oxide nanoparticles for MR/optical lymph node imaging.

We reported the synthesis of highly water-stable iron oxide nanoparticles by a simple one-pot reaction. Non-toxic polyethylene glycol MW 600 (PEG) acted as a solvent, capping agent and reducing agent in the synthesis of iron oxide nanoparticles. As a result of the synthesis, PEGylated small-size (4.2 ± 0.39 nm average diameter and 7.2 ± 1.9 nm hydrodynamic sizes measuring by DLS) iron oxide nanoparticles (USPIO) were obtained, which show great colloidal stability in water and tolerate high salt concentration (0.75 M sodium chloride) and a wide pH range of 4 to 12. Oxidation of PEG was observed during the synthesis of iron oxide nanoparticles, which makes USPIO easy to functionalize with other molecules. Functionalization of the USPIO surface with fluorescein isothiocyanate (FITC) was conducted for investigating the possibility for multimodal imaging. Also the cytotoxicity test and lymph node imaging were performed by using the FITC labelled USPIO (FITC@USPIO). According to these results, the stable water dispersed USPIO and FITC@USPIO are expected to apply for multimodal in vivo imaging.