Synthesis of highly magnetic graphite-encapsulated FeCo nanoparticles using ahydrothermal process

Abstract

The graphite encapsulation of metal alloy magnetic nanoparticles has attracted attentionfor biological applications because of the high magnetization of the encapsulatedparticles. However, most of the synthetic methods have limitations in terms ofscalability and economics because of the demanding synthetic conditions and lowyields. Here, we show that well controlled graphite-encapsulated FeCo core–shellnanoparticles can be synthesized by a hydrothermal method, simply by mixingFe/Co with sucrose as acarbon source. Various Fe/Co metal ratios were used to determine the compositional dependence of the saturationmagnetization and relaxivity coefficient. Transmission electron microscopy indicated thatthe particle sizes were 7 nm. In order to test the capability of graphite-encapsulated FeConanoparticles as magnetic resonance imaging (MRI) contrast agents, these nanoparticleswere solubilized in water by the nonspecific physical adsorption of sodium dodecylbenzenesulfonate.