Effects of environment on the molecular structure and electrical conductivity of DNA

Silicon based materials are used in electronic circuits in today's electronic technology. The smaller the size of the materials, the higher the research time and cost required for the new devices in silicon based electronic technologies. Molecular electronics could be an alternative field to silicon technologies in reducing the circuit size. Molecular electronics is the study of molecular building blocks such as DNA, RNA, peptides or carbon nanotubes for design and manufacture of electronic devices. Understanding of the electronic properties of many different molecular systems is necessary to build new molecular devices. DNA is an important study material for molecular electronics based on its unique electronic and structural properties. In order to understand DNA conductance, its electronic properties have been studied over the years both theoretically and experimentally. However, controlling conductance of DNA is depending on conformational properties, chemical and environmental factors. DNA exists in different forms according to the number of bases (nucleotides) per rotation in the helix, the distance between the bases, the vertical distance between the base pairs and the helical diameter of the helix. A DNA and B DNA are the two of most common forms and are known to exhibit different electrical properties. In this study, to analyze the effect of environment (ethanol and salt concentration) on conformations of DNA, we first completed molecular dynamics simulations (Amber 16) and determined the A-B transformation path. After that, we chose representative structures from the simulations and calculated and analyzed the electronic properties of the structures using density functional theory (Gaussian 09). As a result, depending on the ethanol and salt concentrations in the solution, stable structures of DNA and the electrical conduction properties of these stable structures were determined.