Cell guidance by magnetic nanowires.

The phenomenon of contact guidance on thin fibers has been known since the beginning of the 20th century when Harrison studied cells growing on fibers from spider's web. Since then many studies have been performed on structured surfaces and fibers. Here we present a new way to induce guidance of cells or cell processes using magnetic nanowires. We have manufactured magnetic Ni-nanowires (200 nm in diameter and 40 microm long) with a template-based electro-deposition method. Drops of a nanowire/ethanol suspension were placed on glass cover slips. The nanowires were aligned in an external magnetic field and adhered to the cover slips after evaporation of the ethanol. When the wires had adhered, the magnetic field was removed. L929 fibroblasts and dissociated dorsal root ganglia (DRG) neurons from mice were cultured on the nanowire-coated cover slips for 24 h and 72 h respectively. The fibroblasts were affected by the aligned nanowires and displayed contact guidance. Regenerated axons also displayed contact guidance on the wires. There were no overt signs of toxicity caused by Ni-wires. Aligned magnetic nanowires can be useful for lab-on-a-chip devices and medical nerve grafts.