Self-Assembly of DNA Rings from Scaffold-Free DNA Tiles

We report a scaffold-free approach in which four- and six-helix DNA bundle units, assembled from a small number of single stranded DNA oligonucleotides precisely arranged in networks of contiguous and semicrossover strands, are connected into DNA nano rings. Nearly uniform structures with well-defined diameters of 53 +/- 7, 81 +/- 9, 85 +/- 8, and 166 +/- 13 nm were achieved by introducing uniform, in-plane curvature to the repeating units. We demonstrate that precise higher order assemblies can be achieved by fine tuning the particular features of the individual building blocks.