Hierarchical self-assembly of DNA into symmetric supramolecular polyhedra

Supramolecular structures A variety of patterned materials and nanostructures have been made from DNA, by exploiting its programmability to control molecular interactions. But making larger, more complex three-dimensional structures with current fabrication methods would require hundreds of unique DNA strands, an impractical proposition. Help is at hand. A team from Purdue University has developed a modular approach that can be likened to a DNA equivalent of Lego bricks. A few DNA molecules are programmed to fold into a basic structural unit, with four, twenty or sixty copies of that unit then assembling according to reaction conditions into tetrahedra, dodecahedra or buckyballs, respectively. Other complex structures should also be accessible using this strategy. DNA molecules have been programmed to fold into a basic structural unit, with four, twenty or sixty copies of that unit then assembling according to reaction conditions into either tetrahedra, dodecahedra or buckyballs, respectively. Other complex structures should also be accessible using this strategy. DNA is renowned for its double helix structure and the base pairing that enables the recognition and highly selective binding of complementary DNA strands. These features, and the ability to create DNA strands with any desired sequence of bases, have led to the use of DNA rationally to design various nanostructures and even execute molecular computations 1 , 2 , 3 , 4 . Of the wide range of self-assembled DNA nanostructures reported, most are one- or two-dimensional 5 , 6 , 7 , 8 , 9 . Examples of three-dimensional DNA structures include cubes 10 , truncated octahedra 11 , octohedra 12 and tetrahedra 13 , 14 , which are all comprised of many different DNA strands with unique sequences. When aiming for large structures, the need to synthesize large numbers (hundreds) of unique DNA strands poses a challenging design problem 9 , 15 . Here, we demonstrate a simple solution to this problem: the design of basic DNA building units in such a way that many copies of identical units assemble into larger three-dimensional structures. We test this hierarchical self-assembly concept with DNA molecules that form three-point-star motifs, or tiles. By controlling the flexibility and concentration of the tiles, the one-pot assembly yields tetrahedra, dodecahedra or buckyballs that are tens of nanometres in size and comprised of four, twenty or sixty individual tiles, respectively. We expect that our assembly stra