The team, which includes scientists from the Nano-Bio Fusion Research Center, is focused on the development of nanomaterials for molecular imaging and biocompatible structures. A simple hydrothermal reaction and heat-treatment process is used to form the graphite encapsulated FeCo core-shell nanoparticles.

In a typical reaction, a mixture, consisting of Fe, Co species and sucrose as a carbon source, is stirred vigorously to form a clear solution. The contents are then placed in a 45 ml capacity Teflon-lined stainless steel autoclave, which is heated in an oven to 190 °C for 9 h. This method provides well controlled graphite-encapsulated FeCo core-shell nanoparticles and offers high production yields with reduced production costs. The technique also benefits from the use of simple equipment, readily available source materials, an absence of explosive or corrosive gases, and the use of de-ionized water as the reaction medium.

Contrast agent

In their study, the researchers describe the potential use of graphite-coated FeCo nanoparticles as MRI contrast agents in terms of various Fe/Co metal ratios. To make the graphite-encapsulated nanoparticles soluble in water, the material was surface functionalized with a surfactant – sodium dodecylbenzene-sulfonate (NaDDBS).

The magnetization values and relaxivity coefficients of the nanoparticles are dependent on the Fe/Co ratio. FeCo/C nanoparticles with a Fe/Co ratio of 0.6/0.4 showed the largest magnetization value (230 e.m.u./g) and relaxivity coefficient (392 mM–1S–1).

More details can be found in the journal Nanotechnology.