First-Principles Studies of Conformation and Solution Effects on DNA Transport

DNA charge transport (CT) has attracted considerable attention by the scientific community over the past 20 years. This interest reflects the potential of DNA CT to provide a sensitive route for signaling, whether in the construction of a nano-scale biosensor or as an enzymatic tool to detect damage in the genome. Research in DNA CT began as a quest to determine whether the DNA double helix with pi-stacked base pairs might share the conductive characteristics of pi-stacked solids. Physicists carried out sophisticated experiments to measure the conductivity of DNA. But the means to connect DNA to the electrodes, as well as the conditions under which the conductivity was measured are different among many experiments, as the results of the current measurements. DNA CT was seen to depend upon the connection between electrodes and DNA, and coupling between the DNA base pair stacks. Importantly, for those studies that utilized well-characterized connections to the DNA and preserved the duplex native conformation in buffered solution, significant electron conductivities were achieved. Certainly, the debate among researches has shifted from "Is DNA CT possible?" to "How does it work?".;To investigate the remarkable characteristics of the double-helix molecule, we use a first-principle technique combined with molecular dynamics simulations to calculate the transport properties of B-DNA sandwiched between carbon nanotubes via alkane linkers. The quantum results using the NEGF method are calculated from snapshots recorded in MD trajectories. In chapter 1, we will go through the basic quantum and classic theories on which our calculations are based. The subject of DNA structure, electronic properties and its potential application in many fields will be introduced in chapter 2. In chapter 3, we discuss our results towards the understanding of the mechanism of DNA charge transport.