We present a variant of the template-assisted electrodeposition method that enables the synthesis of large arrays of nanowires (NWs) on flat and curved substrates. This method uses ultra-thin (50 nm-10 μm) anodic aluminum oxide membranes as a template. We have developed a procedure that uses a two-polymer protective layer to transfer these templates onto almost any surface. We have applied this technique to the fabrication of large arrays of Ni and segmented composition Ni/Au NWs on silicon wafers, Cu tapes, and thin (0.2 mm) Cu wires. In all cases, a complete coverage with NWs is achieved. The magnetic properties of these samples show an accentuated in-plane anisotropy which is affected by the form of the substrate (flat or curve) and the length of the NWs. Unlike current lithography techniques, the fabrication method proposed here allows the integration of complex nanostructures into devices, which can be fabricated on unconventional surfaces.

Magnetic hyperthermia has been studied for the past two decades in cancer treatments as the local heat generated by magnetic nanoparticles under applied alternating magnetic fields is sufficient to kill cancer cells. More recently, it has been explored for controlling biological signaling through heat-sensitive transmembrane channels. It is of great interest to produce magnetic nanoparticles with high heat transducing efficiency to minimize potential off-target heating effects. Here, we describe shape anisotropy and particle hybridization as possible routes to augment magnetic hyperthermia in ferrite nanoparticles. Zinc substituted magnetite core and core-shell cubic nanoparticles with different sizes were synthetized. It was found that nanoparticles shape and composition are altered from cubic to flower-like, and to a more franklinite rich phase as size increased. Hybridization with a cobalt shell allowed to enhance nanoparticle magnetic coercivity and specific power loss. The optimized core-shell nanoparticles were tested to induce cellular activity in hippocampal neurons.

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