Ferrite particles and polymers loaded with iron oxides have been used in chemical and biological separation tasks for more than 50 years. Although metals (iron, nickel, cobalt & alloys) usually show highly enhanced magnetic properties, their use as magnetic micro- or even nano- particle has been hampered by their lack of oxidation-stability under most operation conditions. This limitation has however been circumvented by coating metallic nanoparticles with carbon coatings only 1-2 nm thick. [1]

We present advantages, possibilities and challenges of carbon coated metallic nanoparticles, which have recently been commercialized by TurboBeads Llc [2]. The high functional loading of these structures in combination with very responsive magnetic properties proposes applications in magnetic polymers, water purification, immunoprecipitation and chemical catalysis. These applications will be discussed in terms of chemical reactivity, dispersion stability and time of operation. We will use this discussion to highlight the opportunities as well as possible pitfalls of this novel technology in comparison with ferrite nanoparticles.

Figure 1 shows a photograph of an air-stable carbon coated nanopowder (left) and a TEM image of the same material (right) illustrating the core-shell structure of the material.

References: [1] R. N. Grass, E. K. Athanassiou, W. J. Stark, Angew. Chem. Int. Ed. 2007, 46, 4909.

[2] R. N. Grass, W. J. Stark, PCT Patent Application, Nov 2006.