Seeding the Self-Assembly of DNA Origamis at Surfaces

Unlike supramolecular self-assembly methods that can organize many unique components into designer shapes in a homogeneous solution (e.g., DNA origami), only relatively simple, symmetric structures consisting of a few unique components have been self-assembled at solid surfaces. As the self-assembly process is confined to the surface/interface by mostly nonspecific attractive interactions, an open question is how these interfacial interactions affect multicomponent self-assembly. To gain a mechanistic understanding of the roles of surface environment in DNA origami self-assembly, here we studied the oligonucleotide-assisted folding of a long single-stranded DNA (ssDNA scaffold) that was end-tethered to a dynamic surface, which could actively regulate the DNA-surface interactions. The results showed that even weak surface attractions can lead to defective structures by inhibiting the merging of multiple domains into complete structures. A combination of surface anchoring and deliberate regulation of DNA-surface interactions allowed us to depart from the existing paradigm of surface confinement via nonspecific interactions and enabled DNA origami folding to proceed in a solution-like environment. Importantly, our new strategy retains the key advantages of surface-mediated self-assembly. Moreover, surface-anchored oligonucleotides could sequence-specifically initiate the growth of DNA origamis of specific sizes and shapes. Our work opens up new opportunities for encoding information into a surface and expressing the information into complex DNA surface architectures for potential nanoelectronics and nanophotonics applications. In addition, our new approach to surface confinement may facilitate the 2D self-assembly of other molecular components, such as proteins, as maintaining conformational freedom may be a general challenge in the self-assembly of complex structures at surfaces.