Biofunctionalized magnetic-vortex microdiscs for targeted cancer-cell destruction

Nanomagnetic materials offer exciting avenues for probing cell mechanics and activating mechanosensitive ion channels, as well as for advancing cancer therapies. Most experimental works so far have used superparamagnetic materials. This report describes a first approach based on interfacing cells with lithographically defined microdiscs that possess a spin-vortex ground state. When an alternating magnetic field is applied the microdisc vortices shift, creating an oscillation, which transmits a mechanical force to the cell. 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 tens of hertz applied for only ten minutes was sufficient to achieve ∼90% cancer-cell destruction in vitro. Biocompatible, lithographically defined, ferromagnetic microdiscs that have a spin-vortex ground state oscillate when activated by an alternating magnetic field. This oscillation compromises the integrity of the cell membrane and initiates programmed cell death in ∼90% of cancer cells in vitro, even with a low-frequency field applied for only ten minutes.