Engineers are used to combining two or more materials to make a composite with superior properties, such as the strength and lightness achieved by setting carbon fibres in an epoxy resin.

For those working at the nanoscale, however, the difficulty of combining materials at that level means there have been few composite materials to play with. Now that has changed thanks to chemists in China who have worked out a simple way to add a prime engineering property - the magnetism of iron particles - to carbon nanotubes.

Nanotubes have unique electrical, optical and mechanical properties that lend themselves to all sorts of nano-engineering applications, and because they are hollow, they can also be used to transport catalysts or drugs. However, magnetically guiding nanotubes containing drugs, say, to where they are needed has until now been difficult, as the tubes are only very weakly magnetic. Previous attempts to address this ...