Transport properties of carrier-injected DNA

Abstract

Electrical and optical characterization of DNA molecules as a function of concentration in aqueous solutionWe have studied electric properties of carrier-injected deoxyribonucleic acid ͑DNA͒ molecules. First, a current (I CA ) through a single DNA molecule was measured by the two-probe dc method with varying a distance between a cathode and an anode (d CA ). The I CA -d CA curve showed that the current rapidly decreased with increasing d CA (I CA Շ0.1 nA for d CA տ6 nm) according to a hopping model. Next, we measured electric properties of DNA injected carriers by two methods; a field effect transistor ͑FET͒ arrangement and a chemical doping. In the FET arrangement, we set three electrodes on a single DNA molecule as source, drain, and gate electrodes with a source-drain distance (d DS )ϳ20 nm. When a voltage was applied to the gate, the source-drain current (I DS ) could be detected to be 0.5-2 nA. This showed that charge injection with the FET arrangement would yield a carrier transportation through DNA at least d DS ϳ20 nm. In order to flow a current through DNA over a distance ϳ100 m, we synthesized the DNA-acceptor cross-linked derivatives ͑DACD͒. In the structure of DACD, DNA molecules, which were attached acceptor molecules at guanine sites specifically, were cross-linked by linker molecules. We can modulate the carrier concentration in DACD with changing a guanine-cytosine pair content (p GC ) in a DNA double strand. We measured the current-voltage curves of DACD for various p GC . The conductivity of DACD increased nonlinearly with an increase in p GC . We explained this behavior using a percolation model, so that a two-dimensional conductive network would form in DACD.

Assembling the puzzle of superconducting elements: a review

“…Current work is laying the foundations of elemental superconductor nanowires applications and further elucidation of the low dimensionality effect on their properties. Advances in materials and nanomaterials fabrication and characterization will certainly lead to observation of superconductivity in elements at higher temperatures, creating new opportunities for applications such as spintronics [88] or DNA integrated molecular electronics [96]. As suggested by the fast pace of discoveries in this field of superconductivity, it seems the periodic table of superconducting elements will likely need updating in the near future.…”

Charge Transport in DNA-Based Devices

“…In another attempt to resolve the puzzle around the DNA conduction properties, Watanabe et al [62] and Shigematsu et al [63]. All the three experiments demonstrated currents of order 1 nA upon application of voltage of ~1 V. The experiments by Fink et al [50] and Kasumov et al [61] showed higher currents and lower resistivities over longer molecules (hundreds of nm), but they were never reconfirmed for individual molecules.…”

“…Few works have been published since 1998 describing direct electrical transport measurements conducted on single DNA molecules [12,14,33,50,[59][60][61][62][63]. In such measurements one has to bring (at least) two metal electrodes to a physical contact with a single molecule, apply voltage and measure current (or vice versa).…”

“…In a recent experiment that was mentioned above with regard to single molecules measurements, Shigematsu et al [63] prepared a more complex network that included acceptor molecules. They found a network conductivity that increased with the guanine content.…”

Direct measurement of electrical transport through single DNA molecules of complex sequence

“…We present multileveled evidence for charge transport through 26-bp-long dsDNA of a complex sequence, characterized by S-shaped current-voltage curves that show currents >220 nA at 2 V. This significant observation implies that a coherent or band transport mechanism takes over for bias potentials leading to high currents (>1 nA). molecular electronics ͉ scanning probe microscopy ͉ nanoelectronics E xperimental observations that seemed to be in dissonance raised a debate over the ability of DNA to transport charge and the nature of the conduction mechanisms through it (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). These conf licts stem from the variety of measurement approaches, sample preparations, experimental setups, and environmental conditions.…”