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. Of the wide range of self-assembled DNA nanostructures reported, most are one- or two-dimensional. Examples of three-dimensional DNA structures include cubes, truncated octahedra, octohedra and tetrahedra, 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. 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 strategy can be adapted to allow the fabrication of a range of relatively complex three-dimensional structures.

A three-point-star DNA motif has been designed and constructed, which can self-assemble into hexagonal two-dimensional lattices. The resulting lattices are up to 1 mm.

Molecular self-assembly is a promising approach to the preparation of nanostructures. DNA, in particular, shows great potential to be a superb molecular system. Synthetic DNA molecules have been programmed to assemble into a wide range of nanostructures. It is generally believed that rigidities of DNA nanomotifs (tiles) are essential for programmable self-assembly of well defined nanostructures. Recently, we have shown that adequate conformational flexibility could be exploited for assembling 3D objects, including tetrahedra, dodecahedra, and buckyballs, out of DNA three-point star motifs. In the current study, we have integrated tensegrity principle into this concept to assemble well defined, complex nanostructures in both 2D and 3D. A symmetric five-pointstar motif (tile) has been designed to assemble into icosahedra or large nanocages depending on the concentration and flexibility of the DNA tiles. In both cases, the DNA tiles exhibit significant flexibilities and undergo substantial conformational changes, either symmetrically bending out of the plane or asymmetrically bending in the plane. In contrast to the complicated natures of the assembled structures, the approach presented here is simple and only requires three different component DNA strands. These results demonstrate that conformational flexibility could be explored to generate complex DNA nanostructures. The basic concept might be further extended to other biomacromolecular systems, such as RNA and proteins.icosahedron ͉ three-dimensional ͉ polyhedron ͉ cryo-EM ͉ molecular cages M olecular self-assembly provides a bottom-up approach to the preparation of nanostructures (1-3). DNA, in particular, shows great potential to be a superb molecular system (4). In the last 20 years, DNA has been explored as building blocks for nanoconstructions, including preparation of periodic and aperiodic 2D nanopatterns (5-8) and 3D polyhedra (9-14). Most of the branched DNA structures are intrinsically flexible and are not suitable building blocks for construction of well defined geometric structures. How to overcome the conformational flexibility of branched DNA structures is a major challenge in structural DNA nanotechnology. In the last decade, a series of rigid structural motifs have been successfully engineered that lead to the rapid evolution of structural DNA nanotechnology (4). However, with more experience and knowledge, it is possible to controllably introduce the conformational flexibility to prepare complex DNA nanostructures (15). In our recent study of 3D self-assembly of DNA three-point-star tiles (16), we found that DNA tetrahedra could be readily assembled, and the tetrahedra are well behaved during sample characterizations. In contrast, DNA dodecahedra and buckyballs have significantly lower assembly yields and are prone to deformation. This phenomenon can be explained by the geometrical differences of these structures. Tetrahedra consist of triangular faces, but others do not. According to tensegrity principle, triangular faces will lead to rigid s...

Inching its way forward: A DNA nanodevice is presented which can autonomously and processively move on a well‐defined track with a 7‐nm step size. The moving principle integrates DNAzyme activity and a strand‐displacement strategy, which resembles the behavior of a caterpillar eating its way through a row of plants (see picture).

Multistep synthesis in the laboratory typically requires numerous reaction vessels, each containing a different set of reactants. In contrast, cells are capable of performing highly efficient and selective multistep biosynthesis under mild conditions with all reactants simultaneously present in solution. If the latter approach could be applied in the laboratory, it may improve the ease, speed, and efficiency of multistep reaction sequences. Here we show that a DNA mechanical device— a DNA walker moving along a DNA track— can be used to perform a series of amine acylation reactions in a single solution without any external intervention. The multistep products generated by this primitive ribosome mimetic are programmed by the sequence of the DNA track, are unrelated to the structure of DNA, and are formed with speeds and overall yields significantly greater than those previously achieved by multistep DNA-templated small-molecule synthesis.

This paper reports a novel DNA six-point-star motif assembled from only three different DNA single-strands. This motif readily assembles into hexagonal two-dimensional arrays with high connectivity. Such a high connectivity could potentially improve the array stability.

DNA nanotechnology provides a versatile foundation for the chemical assembly of nanostructures. Plasmonic nanoparticle assemblies are of particular interest because they can be tailored to exhibit a broad range of electromagnetic phenomena. In this Letter, we report the assembly of DNA-functionalized nanoparticles into pentamer clusters, which consist of a smaller gold sphere surrounded by a ring of four larger spheres. Magnetic and Fano-like resonances are observed in individual clusters. The DNA plays a dual role: it selectively assembles the clusters in solution and functions as an insulating spacer between the conductive nanoparticles. These particle assemblies can be generalized to a new class of DNA-enabled plasmonic heterostructures that comprise various active and passive materials and other forms of DNA scaffolding.

The long and the short of it: A short oligonucleotide is designed to self‐assemble into micrometer‐long nanotubes, which further serve as templates to fabricate metallic nanowires. This study addresses the question: what is the minimum number of DNA strands that are required for self‐assembly of well‐defined DNA nanostructures?