Facile one-pot synthesis of different surfactant-functionalized water-soluble Fe3O4 nanoparticles as magnetic resonance imaging contrast agents for melanoma tumors

A facile and efficient solvothermal strategy is described to synthesize modified Fe3O4 nanoparticles (NPs) as magnetic resonance (MR) imaging contrast agents. In this study, glycerine was used not only as a solvent but also as a reducing agent due to its nontoxicity and high viscosity, which result in the advantages of good dispersibility and narrow size distribution of the Fe3O4 NPs. In addition, sodium citrate, L-asparagine and polyvinylpyrrolidone were employed as surfactants for the surface modification of Fe3O4 NPs on account of their non/low-toxicity, water-solubility and biocompatibility. The modification process was completed by one step rather than complicated grafting approaches. Moreover, the resultant aqueous solution of the modified Fe3O4 NPs turned out to be stable for more than 6 months with no flocculates or precipitates appearing in the stock fluids. Then, T-2 weighted images and T-2 relaxation times of the modified Fe3O4 NPs were examined to investigate their biological applications for magnetic resonance (MR) imaging as T-2 contrast agents. As a consequence, the sodium citrate-modified Fe3O4 NPs exhibit a higher r(2) relaxivity than that of sodium citrate combined with PVP and L-asparagine-modified Fe3O4 NPs. Furthermore, in order to investigate their contrast effect for melanoma tumors, we also carried out a study of in vitro cytotoxicity and an observation of the tissue sections. The results suggest that these modified Fe3O4 NPs may be potential contrast agents for detecting melanoma tumors.