Switching binary states of nanoparticle superlattices and dimer clusters by DNA strands

Nanoscale components can be self-assembled into static three-dimensional structures(1-6), arrays(7-9) and clusters(10-13) using biomolecular motifs. The structural plasticity of biomolecules and the reversibility of their interactions can also be used to make nanostructures that are dynamic, reconfigurable and responsive. DNA has emerged as an ideal biomolecular motif for making such nanostructures, partly because its versatile morphology permits in situ conformational changes using molecular stimuli(12,14-22). This has allowed DNA nanostructures to exhibit reconfigurable topologies and mechanical movement(17,18). Recently, researchers have begun to translate this approach to nanoparticle interfaces(18,23,24,) where, for example, the distances between nanoparticles can be modulated, resulting in a distance-dependent plasmonic response(18,23,25). Here, we report the assembly of nanoparticles into three-dimensional superlattices and dimer clusters, using a reconfigurable DNA device that acts as an interparticle linkage. The interparticle distances in the superlattices and clusters can be modified, while preserving structural integrity, by adding molecular stimuli (simple DNA strands) after the self-assembly processes has been completed. Both systems were found to switch between two distinct rigid states, but a transition to a flexible device configuration within a superlattice showed a significant hysteresis.