Spatially controlled apoptosis induced by released nickel(ii) within a magnetically responsive nanostructured biomaterialElectronic supplementary information (ESI) available: Rheometric data, release from DOPC MNPVs, diffusion data (5/6-CF, Ni(ii)), cell responses with 7.7 mM Ni(ii) and induction coil details. See DOI: 10.1039/c2sm27379a

Magnetically patterned and responsive biomaterials have been shown to produce spatially controlled cell death in response to a magnetic signal. The responsive elements in these nano-structured biomaterials are magnetic nanoparticle-vesicle assemblies (MNPVs), which are thermally sensitive vesicles crosslinked by magnetic nanoparticles. MNPVs are nano-sized drug delivery platforms that are responsive to magnetic fields in two ways: they can be spatially manipulated by static magnetic fields, and upon exposure to an alternating magnetic field (AMF) they can release chemical messengers stored within the vesicles. Magnetically initiated release of nickel( ii ) from MNPVs immobilised in an alginate hydrogel was used to produce remotely triggered and spatially controlled apoptosis of fibroblasts cultured in the hydrogel. The ability to manipulate MNPVs with static magnetic fields was used to immobilise the MNPVs in only one region of the biomaterial; subsequent AMF-induced release of nickel( ii ) caused a wave of cellular apoptosis through the biomaterial as the nickel( ii ) slowly diffused through the hydrogel. Magnetically patterned and responsive biomaterials have been shown to produce spatially controlled cell death in response to a magnetic signal.