(247c) Functionalized Carbon Coated Cobalt As A Novel Magnetic Nano-Devices In Separation Technology

The miniaturization of sampling volumes in analytical chemistry and medical diagnostics requires fast and reliable separation methods. Based on the energy demand and difficulties in miniaturization, standard unit operations are often not applicable and novel separation methods have to be introduced. Magnetic separation using magnetic beads has often been proposed for a wide range of such applications. However, due to the large cost of the magnetic materials, large particle sizes (>> 1 μm), relatively poor magnetic properties, and very limited binding capacities, the wide spread use of this technology has been limited to high-value biotechnological applications.

In this contribution we present an improved magnetic nanobead material ? carbon coated cobalt ? which can be manufactured at large scale and has highly beneficial properties for applications in miniaturized separation technology. The material can be described as nanoparticles with a size ranging from 20 ? 40 nm and consisting of a metallic cobalt core which is coated with some layers of graphene carbon. The use of metallic cobalt as core material offers optimal magnetic properties and the carbon layer protects the metallic core from oxidation in a wide range of solvents, pH ranges and temperatures of up to 200°C.

The carbon layer can be covalently functionalized with amino- or chloro- groups, allowing a modification of the surface chemistry and the binding and de-binding of specific ligands. We further demonstrate the application of the material in separation technology with biotechnological relevant ligands.

The Figure shows a photograph of a suspension of carbon coated cobalt nanoparticles in water which are removed from the liquid by the use of a commercial neodymium magnet (photograph taken ~5 seconds after placing the magnet)

References:

[1] R. N. Grass, E. K. Athanassiou, W. J. Stark, Angew. Chem. Int. Ed. 2007, in print.

[2] R. N. Grass, W. J. Stark, J. Mater. Chem. 2006, 16, 1825.

[3] R. N. Grass, M. Dietiker, R. Spolenak, W. J. Stark, Nanotechnology 2007, 18, 035703.