The regulation of cellular activities in a controlled manner
is one of the most challenging issues in fields ranging from cell biology to
biomedicine1, 2. Nanoparticles have the potential of becoming useful tools for
controlling cell signalling pathways in a space and time selective fashion3, 4.
Here, we have developed magnetic nanoparticles that turn on apoptosis cell
signalling by using a magnetic field in a remote and non-invasive manner. The
magnetic switch consists of zinc-doped iron oxide magnetic nanoparticles5
(Zn0.4Fe2.6O4), conjugated with a targeting antibody for death receptor 4 (DR4)
of DLD-1 colon cancer cells. The magnetic switch, in its On mode when a
magnetic field is applied to aggregate magnetic nanoparticle-bound DR4s,
promotes apoptosis signalling pathways. We have also demonstrated that the
magnetic switch is operable at the micrometre scale and that it can be applied
in an in vivo system where apoptotic morphological changes of zebrafish are
successfully induced.