| The construction of designed three-dimensional structures is the ultimate goal in DNA nanotechnology. Previous data has shown that it is possible to design and self-assemble a well-ordered macromolecular 3D crystalline lattice with precise control. The model motif used for this achievement is that of the tensegrity triangle, which is a very rigid DNA motif with three-fold pseudo-symmetry.;The aim of the first project is to get a detailed picture of torsionally stressed DNA using the two-turn tensegrity triangle as a model. To achieve under-twisted motifs, additional nucleotide pairs are inserted at specific locations on the motif. Crystals grown from the design could diffract to 4.8 A and its structures have been determined by X-ray crystallography.;Secondly, a DNA analog, Locked Nucleic Acids (LNA), is used to increase the stability and ultimately the resolution of the tensegrity triangle crystals. Alpha-LNA is used since it tends to form helices with B-DNA characteristics. To reach this goal, atomic resolution of the motifs is essential. In an effort to obtain said information, a series of studies using X-ray crystallography have been undertaken to determine the structure of the designed 3-turn DNA lattices in which many parameters are varied: the amount of alpha-LNA incorporated in the triangle, the length of the sticky ends, the size of the crystal, and the addition of 5'-phosphate moieties to the strand components. DNA is a macromolecule with many appealing features for use in nanofabrication. Nano-devices, such as walkers, have been produced using tiles that contain more than one immobile junction, such as the double-crossover (DX), the triple-crossover (TX), and the paranemic-crossover (PX). Even so, the crystal structure is not known for any of these motifs. In an attempt to solve one of these problems, triple-crossover fused two-tile crystals are designed and grown.;Furthermore, other unnatural DNA bases are incorporated in the construction 3-D arrays, such as 2'-O-methyl DNA, "Z" (6-amino-5-nitro-2(1H)-pyridone), and "P" (2-amino-imidazo[1,2-a]-1,3,5-triazin-4(8H)one) bases. |
