Electrically conductive magnetic nanowires using an electrochemical DNA-templating route.

The fabrication of electrically conducting magnetic nanowires has been achieved using electrochemical DNA-templating of iron. In this approach, binding of the Fe(2+) cations to the DNA "template" molecules has been utilised to promote growth along the molecular axis. Formation of Fe within the product material was verified by XRD and XPS studies, which confirmed an iron/oxide "core-shell" structure. The effectiveness of the DNA duplex to direct the metal growth in one dimension was highlighted by AFM which reveals the product material to comprise high aspect ratio nanostructured architectures. These "nanowires" were observed to have morphologies consisting of densely packed linear arrangements of metal particles along the template, with wire diameters up to 26 nm. The structures were confirmed to be electrically conductive, as expected for such Fe-based materials, and to display superparamagnetic behaviour, consistent with the small size and particulate nature of the nanowires.

Magnetic and conductive magnetite nanowires by DNA-templating.

The synthesis of nanowires made of magnetite (Fe(3)O(4)) phase iron oxide was achieved using DNA as a template to direct formation of the metal oxide and confine its growth in two dimensions. This simple solution-based approach involves initial association of Fe(2+) and Fe(3+) to the DNA "template" molecules, and subsequent co-precipitation of the Fe(3)O(4) material, upon increasing the solution pH, to give the final metal oxide nanowires. Analysis of the DNA-templated material, using a combination of FTIR, XRD, XPS, and Raman spectroscopy, confirmed the iron oxide formed to be the Fe(3)O(4) crystal phase. Investigation of the structural character of the nanowires, carried out by AFM, revealed the metal oxide to form regular coatings of nanometre-scale thickness around the DNA templates. Statistical analysis showed the size distribution of the nanowires to follow a trimodal model, with the modal diameter values identified as 5-6 nm, 14-15 nm, and 23-24 nm. Additional scanning probe microscopy techniques (SCM, MFM) were also used to verify that the nanowire structures are electrically conducting and exhibit magnetic behaviour. Such properties, coupled with the small dimensions of these materials, make them potentially good candidates for application in a host of future nanoscale device technologies.