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Abstract The programmable synthesis of rationally engineered crystal architectures for the precise arrangement of molecular species is a foundational goal in nanotechnology, and DNA has become one of the most prominent molecules for the construction of these materials. In particular, branched DNA junctions have been used as the central building block for the assembly of 3D lattices. Here, crystallography is used to probe the effect of all 36 immobile Holliday junction sequences on self-assembling DNA crystals. Contrary to the established paradigm in the field, most junctions yield crystals, with some enhancing the resolution or resulting in unique crystal symmetries. Unexpectedly, even the sequence adjacent to the junction has a significant effect on the crystal assemblies. Six of the immobile junction sequences are completely resistant to crystallization and thus deemed “fatal,” and molecular dynamics simulations reveal that these junctions invariably lack two discrete ion binding sites that are pivotal for crystal formation. The structures and dynamics detailed here could be used to inform future designs of both crystals and DNA nanostructures more broadly, and have potential implications for the molecular engineering of applied nanoelectronics, nanophotonics, and catalysis within the crystalline context. 

Abstract The combination of multiple orthogonal interactions enables hierarchical complexity in self‐assembled nanoscale materials. Here, efficient supramolecular polymerization of DNA origami nanostructures is demonstrated using a multivalent display of small molecule host–guest interactions. Modification of DNA strands with cucurbit[7]uril (CB[7]) and its adamantane guest, yielding a supramolecular complex with an affinity of order 10¹⁰m⁻¹, directs hierarchical assembly of origami monomers into 1D nanofibers. This affinity regime enables efficient polymerization; a lower‐affinity β‐cyclodextrin–adamantane complex does not promote extended structures at a similar valency. Finally, the utility of the high‐affinity CB[7]–adamantane interactions is exploited to enable responsive enzymatic actuation of origami nanofibers assembled using peptide linkers. This work demonstrates the power of high‐affinity CB[7]–guest recognition as an orthogonal axis to drive self‐assembly in DNA nanotechnology. 

Abstract DNA is an ideal molecule for the construction of 3D crystals with tunable properties owing to its high programmability based on canonical Watson–Crick base pairing, with crystal assembly in all three dimensions facilitated by immobile Holliday junctions and sticky end cohesion. Despite the promise of these systems, only a handful of unique crystal scaffolds have been reported. Herein, we describe a new crystal system with a repeating sequence that mediates the assembly of a 3D scaffold via a series of Holliday junctions linked together with complementary sticky ends. By using an optimized junction sequence, we could determine a high‐resolution (2.7 Å) structure containing R3 crystal symmetry, with a slight subsequent improvement (2.6 Å) using a modified sticky‐end sequence. The immobile Holliday junction sequence allowed us to produce crystals that provided unprecedented atomic detail. In addition, we expanded the crystal cavities by 50 % by adding an additional helical turn between junctions, and we solved the structure to 4.5 Å resolution by molecular replacement.