Mutation effects and thermoelectric properties of DNA molecules

The idea of incorporating DNA molecules in designing nanoscale electronic devices has drawn the attention of several researchers due to the unique properties of DNA, such as selfassembly and self-recognition. As the number of theoretical and experimental studies expanded, researchers also became interested in the use of DNA molecules in designing nanoscale thermal and thermoelectric devices. In this thesis, we theoretically explore the electron transport properties through double-helix DNA strands by using the tight-binding (TB) Hamiltonian method. We also present graphical outputs of the transmission, contour plots of transmission, localization lengths, and current-voltage characteristics. Our results showed that higher electron conductivity could be observed in an ordered DNA system with a single type of base-pair, with the GC base-pair performing greater conductivity than AT base-pairs. We investigated the native and methylated DNA strands, wherein the electron transmission in the native DNA strand provided a higher electrical conductance. Variations in electron transmission spectrum depending on the contact coupling energies were also observed. As the applied temperature increased, thermal fluctuations destroyed the system and hence, reduced transport in the methylated DNA strand. By employing the phonon transport theory using the equation of motion of the system, the transmission coefficient in the single-stranded DNA model showed a number of resonant transmission peaks depending on the number of the DNA bases, while antiresonance behavior showed in the double-stranded DNA models due to the disorder of masses. The doublehelix DNA placed under different heat sources with different temperatures displayed the characteristics of a poor heat conductor. The thermopower values also indicated that the DNA strand serves as an n-type material. Poly(A)–poly(T) chain performed lower ZT figure of merit, while its thermal conductivity remained higher compared to the poly(G)–poly(C) chain.Department of Physics and AstronomyThesis (M.S.