Versatile DNA origami subunit design for self-assembled structures*

Self-assembly of nanoscale synthetic subunits is a promising bottom-up strategy for making functional materials. However, people typically design and fabricate specific subunits for a single desired structure, posing problems in efficiency and cost. By contrast, we introduce a design principle, exploiting a modularity concept, to make a versatile subunit that can target an abundant variety of self-assembled structures. Here, we synthesize a universal “core brick” made of DNA origami. Independently-replaceable “bond modules” composed of an array of single-stranded DNA overhangs are then decorated around the three core brick sides, encoding information of interaction valence and structural geometry. Though the joints between adjacent subunits are designed to swing freely in solution, they surprisingly degenerate into different locally-desired dihedral angles once subunits settle on the final assembly product. With quantitative insight provided by Cryo-EM and multi-body refinement technique, the feature indeed expands our design capacity and tolerates larger design/fabrication error. Overall, we demonstrate that any chosen set of bond modules gives a completely new subunit species, readily self-assembling into rich architectures with various Gaussian curvatures, including sheets, hollow spheres, and tubes. The proposed principle offers an economic strategy for self-assembly, facilitating construction of complex structures by subunits that are as simple as possible.