Flexibility defines structure in crystals of amphiphilic DNA nanostars

DNA nanostructures with programmable shape and interactions can be used as building blocks for the self-assembly of crystalline materials with prescribed nanoscale features, holding a vast technological potential. Structural rigidity and bond directionality have been recognised as key design features for DNA motifs to sustain long-range order in 3D, but the practical challenges associated with prescribing building-block geometry with sufficient accuracy have limited the variety of available designs. We have recently introduced a novel platform for the one-pot preparation of crystalline DNA frameworks supported by a combination of Watson-Crick base pairing and hydrophobic forces [Nano Lett., 17(5):3276-3281, 2017]. Here we use small angle X-ray scattering and coarse-grained molecular simulations to demonstrate that, as opposed to available all- DNA approaches, amphiphilic motifs do not rely on structural rigidity to support long-range order. Instead, the flexibility of amphiphilic DNA building-blocks is a crucial feature for successful crystallisation.