Polyhedra Self-Assembled from DNA Tripods and Characterized with 3D DNA-PAINT

Engineering Larger DNA Structures Several approaches now exist for the self-assembly of DNA into nanostructures. For example, three-arm DNA tripods can be assembled into larger wireframe polyhedra, but for the most complicated shapes, assembly yields can be low, apparently because the flexibility of smaller tripods allows for misassembly. Iinuma et al. (p. 65, published online 13 March) now show that larger, stiffer tripods that have controlled arm lengths and interarm angles can be designed to form a wide variety of open wireframe polyhedra—including tetrahedra, cubes, and hexagonal prisms, with edges 100 nanometers in length. Stiff DNA tripod units enabled the assembly of wireframe polyhedra with edges 100 nanometers in length. DNA self-assembly has produced diverse synthetic three-dimensional polyhedra. These structures typically have a molecular weight no greater than 5 megadaltons. We report a simple, general strategy for one-step self-assembly of wireframe DNA polyhedra that are more massive than most previous structures. A stiff three-arm-junction DNA origami tile motif with precisely controlled angles and arm lengths was used for hierarchical assembly of polyhedra. We experimentally constructed a tetrahedron (20 megadaltons), a triangular prism (30 megadaltons), a cube (40 megadaltons), a pentagonal prism (50 megadaltons), and a hexagonal prism (60 megadaltons) with edge widths of 100 nanometers. The structures were visualized by means of transmission electron microscopy and three-dimensional DNA-PAINT super-resolution fluorescent microscopy of single molecules in solution.