Fabrication of DNA Nanowires by Orthogonal Self-Assembly and DNA Intercalation on a Au Patterned Si/SiO2 Surface

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• 作者：Katsuaki Kobayashi ; Naoya Tonegawa ; Sho Fujii ; Jiro Hikida ; Hisakazu Nozoye ; Ken Tsutsui ; Yasuo Wada ; Makoto Chikira ; Masa-aki Haga
• 刊名：Langmuir
• 出版年：2008
• 出版时间：November 18, 2008
• 年：2008
• 卷：24
• 期：22
• 页码：13203-13211
• 全文大小：445K
• 年卷期：v.24,no.22(November 18, 2008)
• ISSN：1520-5827

文摘

A novel Ru complex bearing both an acridine group and anchoring phosphonate groups was immobilized on a surface in order to capture double-stranded DNAs (dsDNAs) from solution. At low surface coverage, the atomic force microscopy (AFM) image revealed the “molecular dot” morphology with the height of the Ru complex (∼2.5 nm) on a mica surface, indicating that four phosphonate anchor groups keep the Ru complex in an upright orientation on the surface. Using a dynamic molecular combing method, the DNA capture efficiency of the Ru complex on a mica surface was examined in terms of the effects of the number of molecular dots and surface hydrophobicity. The immobilized surface could capture DNAs; however, the optimal number of molecular dots on the surface as well as the optimal pull-up speed exist to obtain the extended dsDNAs on the surface. Applying this optimal condition to a Au-patterned Si/SiO₂ (Au/SiO₂) surface, the Au electrode was selectively covered with the Ru complex by orthogonal self-assembly of 4-mercaptbutylphosphonic acid (MBPA), followed by the formation of a Zr⁴⁺-phosphonate layer and the Ru complex. At the same time, the remaining SiO₂ surface was covered with octylphosphonic acid (OPA) by self-assembly. The selective immobilization of the Ru complex only on the Au electrode was identified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS) imaging on the chemically modified Au/SiO₂ surface. The construction of DNA nanowires on the Au/SiO₂ patterned surface was accomplished by the molecular combing method of the selective immobilized Ru complex on Au electrodes. These interconnected nanowires between Au electrodes were used as a scaffold for the modification of Pd nanoparticles on the DNA. Furthermore, Cu metallization was achieved by electroless plating of Cu metal on a priming of Pd nanoparticles on the Pd-covered DNA nanowires. The resulting Cu nanowires showed a metallic behavior with relatively high resistance.