DNA nanotechnology has enabled the self-assembly of complex designer structures in the solution phase. For example, the DNA origami method programmably forms complex nanoscale shapes by folding a long single-stranded DNA with hundreds of unique short DNA staple strands. In contrast, successes in supramolecular self-assembly at surfaces have been limited to relatively simple, symmetric structures that consist of a small number of unique components. It remains unclear why it is difficult to predictably assemble complex, aperiodic surface structures, which are needed for sophisticated functions such as nanoelectronics and nanophotonic circuits. Ubiquitous to self-assembly at surfaces are attractive interactions that confine the supramolecular structures to the surface. How such interactions influence complex supramolecular self-assembly is unexplored. Here we studied the staple-assisted folding of ssDNA scaffolds end-tethered to a dynamic surface, a self-assembled monolayer that allows us to quantitatively regulate the DNA-surface interaction. Our high-resolution microscopy technique provided unique insight into how the surface interactions affect the pathways of the self-assembly process. The results provide direct evidence that attractive non-specific interactions hinder DNA origami formation by restricting conformational freedom. In the presence of short-range repulsive interactions, both the folding kinetics and pathways are similar to those in the solution phase. The knowledge has allowed the surface to mediate the site-specific formation of DNA origami for the first time. We demonstrate that a single surface-tethered molecule (seed strand) could initiate self-assembly of DNA origami of prescribed size, shape, and internal arrangement. Our results enable a new mechanism to encode sophisticated information into the surface and express the information into complex supramolecular structures at the surface.

Surface confinement: Friend or foe to complex self-assembled DNA architectures?

2019 Fall National Meeting

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