Paper NS-TuP6
Influence of Preparation Condition on Electrical Properties of Cobalt(Co2+)-Metallic-DNA Molecules

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Recent works have showed many attractive interests in the formation of nanowires to make nano-device using the deoxyribonucleic acid (DNA) molecules. Because of DNA molecule has narrow width (2nm) and the length of DNA easy to control. Metallic DNA (M-DNA) is a modified DNA by incorporating divalent metallic ions (i.e., Zn²⁺, Co²⁺, Ni²⁺, etc.) to the each base pair of B-DNA. It is one of the methods to form the metallic nanowires with metallic electrical conductivity by contrast with B-DNA of semiconductor like electrical properties. M-DNA has the higher and the more stable current-voltage (I-V) characteristic than B-DNA. Most experiments of electrical properties of M-DNA were made up by Zn-M-DNA. Cobalt and nickel divalent ions are generally known to be also possible to make M-DNA. Particularly, cobalt (Co²⁺) is comparatively easy to make M-DNA because of its good synthesis rate and fast incorporating speed. In this work, Co-M-DNA could be made using poly(dG)-poly(dC), poly(dA)-poly(dT) or lambda DNA. The Co-M-DNA was prepared with the various conditions such as concentration of divalent metallic ions, preparation pH and temperature. The Co-M-DNA was prepared with heating processes, which contributed to decrease of incorporating time. The prepared Co-M-DNA molecules were attached on Au electrodes with the nanometer size gap. The current through Co-M-DNA measured on vacuum (10^-2torr) to minimize humidity effects by HP4145 semiconductor parameter analyzer. The current through Co-M-DNA showed the metallic electrical properties and larger conductivity than B-DNA. The conductivity of Co-M-DNA became larger by preparation over pH 8. Furthermore, the conductivity of M-DNA was affected by Co²⁺ concentration.