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Stretching and Immobilization of Photo-electro Functional Nanowires Consisting of DNA and Functional Molecules
Norihisa Kobayashi, Kazuki Nakamura, Makoto Nishizawa, Reina Son, Shintaro Inoue and Yuuki Nishiyama

DNA/functional molecules complex have attracted a lot of attention for fabricating the DNA-based functional nanowire. In this paper, we fabricated DNA-based functional nanowire stretched and immobilized between a pair of electrodes. As the photo-electro functional material, tris(bipyridine) ruthenium(II) complex (Ru(bpy)32+) was employed for fabricating the DNA-based functional molecular wire. The molecular structure and the photo-electro characteristics of the DNA/functional molecules were investigated. The Ru(bpy)32+ was associated with duplex of DNA by not only electrostatic interaction but also intercalation in the aqueous solution. The molecular structure of DNA/Ru(bpy)32+ complex on substrate was analyzed with AFM. As result we have found the network structures of DNA/Ru(bpy)32+ complex on the mica substrate without any stretching treatments, which is similar to native DNA. The height of DNA/Ru(bpy)32+ complex on the mica substrate was ranging from 0.8 to 1.6 nm, which was higher than the naked DNA (0.5-1.0 nm). This indicates that single-molecular DNA/Ru(bpy)32+ complex also connects to each other to form network structures on a mica substrate. Then, in order to stretch the DNA complex between a pair of electrodes, high frequency and high electric field stretching methods were carried out. The structures of stretched and immobilized DNA-based functional nanowires were also analyzed with AFM. The I-V characteristics of DNA single molecule between electrodes were improved by the association of Ru(bpy)32+.

Keywords: DNA, Ru(bpy)32+, Poly(aniline), Molecular stretching, Molecular wire

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