Facile one-pot synthesis of Fe3O4@Au composite nanoparticles for dual-mode MR/CT imaging applications

A facile one-pot hydrothermal approach to synthesizing Fe3O4@Au composite nanoparticles (CNPs) for dual-mode magnetic resonance (MR) and computed tomography (CT) imaging applications is reported. In this work, polyethyleneimine (PEI) partially modified with poly(ethylene glycol) monomethyl ether (mPEG) was used as a stabilizer to form gold NPs (mPEG-PEI.NH2-Au NPs) with the assistance of sodium borohydride reduction. The mPEG-PEI.NH2-Au NPs were then mixed with iron(II) salt in a basic aqueous solution followed by treatment under an elevated temperature and pressure. This hydrothermal process led to the formation of Fe3O4@Au-mPEG-PEI.NH2 CNPs. The remaining PEI amine groups were finally acetylated to reduce the surface positive charge of the CNPs. The formed Fe3O4@Au-mPEG-PEI.NHAc (Fe3O4@Au) CNPs were characterized via different techniques. The combined in vitro cell viability assay, cell morphology observation, flow cytometry, and hemolysis assay data show that the formed Fe3O4@Au CNPs are noncytotoxic and hemocompatible in the given concentration range. MR and CT imaging data reveal that the formed Fe3O4@Au CNPs have a relatively high r2 relaxivity (146.07 mM(-1) s(-1)) and good X-ray attenuation property, which enables their uses as contrast agents for MR imaging of mouse liver and CT imaging of rat liver and aorta. The Fe3O4@Au CNPs developed via the facile one-pot approach may have promising potential for the dual-mode MR/CT imaging of different biological systems.