A method to kill cancer cells using magnetic nanodiscs is reported online in Nature Materials this week. The method uses magnetic fields only one tenth the strength of those of used in previous approaches, and at much lower frequencies, and so therefore could avoid the negative side effects associated with higher-strength fields.

Elena Rozhkova and colleagues made tiny, ultrathin discs of permalloy ― a magnetic alloy composed of iron and nickel ― in which the magnetization of all the atoms are arranged in concentric circles, creating a 'magnetic vortex'. When an alternating magnetic field is applied, the discs oscillate. In laboratory tests, the authors show that the oscillations disrupt the membranes of cancer cells and initiate programmed cell death.

This approach overcomes some of the problems that have prevented magnetic-nanoparticle therapies from being used clinically, such as high fields and accumulation of particles with permanent magnetization into clumps in the body.