November 30, 2009 – Researchers at Argonne National Laboratory and the University of Chicago have created a new way to target cancer cells with nanotechnology: tiny magnetic discs that deliver a 90% cell destruction rate.

Their work, published online in Nature Materials, involves fabricating 60nm-thick nickel-iron discs with a spin-vortex ground state. Applying an alternating magnetic field shifts the vortices, creating an oscillation that basically rips up the cancer cell membranes, causing them to die.

Details of the microdisc fabrication process, described as "low-cost" and resulting in "uniformly sized microdiscs":

– Optical lithography: Photoresist (N-1410 negative-tone) spin-coated onto a 2-in. silicon wafer, a mask placed in contact with the prebaked photoresist and illuminated with UV light, and unexposed resist removed via organic solvent;
– Deposition of a 5nm underlayer gold via magnetron sputtering, followed by 60nm of permalloy and another 5nm of gold layer;
– Lift-off process in acetone.

Fabrication of MDs by optical lithography and magnetron sputtering. (Source: Nature Materials)

From the journal paper abstract:

Because reduced sensitivity of cancer cells toward apoptosis leads to inappropriate cell survival and malignant progression, selective induction of apoptosis is of great importance for the anticancer therapeutic strategies. We show that the spin-vortex-mediated stimulus creates two dramatic effects: compromised integrity of the cellular membrane, and initiation of programmed cell death.

A low-frequency field of a few 10s of hertz applied for only 10min was enough to destroy ~90% of cancer-cells in vitro, they claim. And the system also works with much less heat/energy than other cancer cell-busting methods, they note.