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A novel fabrication process was developed for a single silver nanowire using DNA metallization in a nanochannel, and the electrical properties of this nanowire were evaluated using electrochemical impedance spectroscopy. After being isolated using a nanochannel measuring 500 nm in depth and 500 nm in width, a single λDNA molecule was electrostatically stretched and immobilized between two electrodes separated by a gap of 15 μm by applying an AC voltage of 1 MHz and 20 Vp‐p. Then, naphthalene diimide molecules terminally‐labeled with galactose moieties were intercalated into the λDNA, and the reduction of silver ions along the λDNA led to its metallization with silver. Scanning electron microscopy observations revealed that two nanowires having different average widths of 154 nm and 250 nm were formed in two individual nanochannels. The nanowires showed the linear current‐voltage characteristics, and their combined resistance was estimated to be 45.5 Ω. The complex impedance of the nanowires was measured, and an equivalent circuit was obtained as a series connection of a resistance and a parallel resistance‐constant phase element circuit. Impedance analysis revealed that the nanowire included silver grain boundaries, and the bulk resistivity of silver grain was estimated to be 8.35×10−8 Ωm.

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We demonstrated that the DNA metallization technique using reducing group-labeled intercalator molecules permits dsDNA (double-stranded DNA) molecules to be specifically metallized while not permitting metallization of ssDNA (single-stranded DNA) molecules. First, dsDNA and ssDNA molecules were stretched on a mica surface using spin-coating technique, and metallization process was conducted. AFM observation showed that only dsDNA molecules were metallized, resulting in formation of nanowires with a diameter of about 11 nm. Secondly, dsDNA and ssDNA molecules were stretched and immobilized between two microelectrodes. Impedance analysis showed that the electrical conductivity of only dsDNA was drastically increased after the metallization process.

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