Fig. 2. Representative DNA structures highlighting size, increasing complexity, and select properties of what some different assembly approaches can provide. (A) The nucleobases on two nucleotides hydrogen-bonded to each other (2 nm wide) and a 16 bp dsDNA sequence (B-form DNA) that is 5.3 nm long. (B) Other notable dimensions of a dsDNA include the major and minor grooves and the spacing between adjacent base pairs. (C) Top: Representative DNA tetrahedron,⁶⁴ a DNA double crossover tile (DX tile),⁵⁸ a Holliday junction (HJ),⁶⁵ and a DNA block assembled using the DNA brick approach.¹⁸ Bottom: left to right shows a wireframe polyhedral,¹⁷ a rectangular DNA origami,^15,21 and a tetraplex of linked rectangular origami. (D) Magnified inset from the rectangular DNA origami in (C) showing the typical inter-helical spacing within a DNA nanostructure.