DEVELOPMENT AND CHARACTERIZATION OF NOVEL NANOMATERIALS USING GQUADRUPLEX DNA BUILDING BLOCKS

Cutting edge technologies require advanced materials that meet the challenge of integrating more functions into smaller and smaller sized devices. The current target is creation of devices and circuits with molecular level dimensions. Biocompatible materials that directly assemble into ordered and multifunctional structures are not readily available. Deoxyribonucleic acid (DNA) has emerged as a material that may fill this void. This dissertation describes basic research exploring how guanine quadruplex DNA sequences self-assemble, bind ligands, and can be formulated into novel structures of suitable size for nanodevices. Guanine quadruplex DNA (G-quadruplex) forms from four strands of DNA held together by Hoogsteen hydrogen bonding. G-quadruplexes share some properties with canonical Watson-Crick double-stranded DNA including directed self-assembly of larger structures through control of sequence. G-quadruplexes also definitely possess intriguing new properties and can create new patterns not possible with duplex DNA. We were the first to observe and systematically exploit the intrinsic fluorescence of Gquadruplexes to elucidate structural changes and monitor ligand binding. The thermal and environmental stability of G-quadruplexes were investigated along with binding of several metallocomplexes to probe the possibility of using G-quadruplexes to organize metallocomplexes in larger self-assembled structures. In addition to working with small G-quadruplexes, we attempted to assemble G-quadruplex units into bigger structures through several methods. These experiments demonstrated a synergistic effect of cations and sequence on the stability of supramolecular structures. These investigations have led to creation of a hybrid structure containing both duplex and G-quadruplex DNA regions. This new building block elegantly permits control of the sequence and the direction that the DNA strands assemble. In summary, the findings from this research contribute significantly to the emerging field of self-assembled DNA-based materials as well as to the field of nanomaterials at large