Development of Gold-Coated Magnetic Nanoparticles as a Potential MRI Contrast Agent

Gold-coated superparamagnetic iron oxide nanoparticles (SPIONs) coated with methylpolyethylene glycol (mPEG) are synthesized and investigated as a magnetic resonance (MR) imaging contrast agent. The synthesized mPEG-core@shells are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), vibrating sample magnetometry (VSM), zeta-potential analysis and X-ray diffraction (XRD). In addition, the transverse relaxivity of the mPEG-core@shells is measured using a 3T MRI scanner. The cytotoxicity of the mPEG-core@shells is tested in the LNCaP cell line using an 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results show that the mPEG-core@shell particles are semispherical with hydrodynamic size of similar to 65 nm and a transverse relaxivity of 162.3 mM(-1) S-1. The mPEG-core@shell particles demonstrate good stability in biological media without any significant in vitro cytotoxicity under high cellular uptake conditions. Finally, in vivo imaging shows that mPEG-core@shells are a potential contrast agent for use in early-stage detection.