  Engineering shape and interactions of nanoscopic building blocks allows for
the assembly of rationally designed macroscopic three-dimensional (3D)
materials with spatial accuracy inaccessible to top-down fabrication methods.
Owing to its sequence-specific interaction, DNA is often used as selective
binder to connect metallic nanoparticles into highly ordered lattices.
Moreover, 3D crystals assembled entirely from DNA have been proposed and
implemented with the declared goal to arrange guest molecules in predefined
lattices. This requires design schemes that provide high rigidity and
sufficiently large open guest space. We here present a DNA origami-based
tensegrity triangle structure that assembles into a 3D rhombohedral crystalline
lattice. We site-specifically place 10 nm and 20 nm gold particles within the
lattice, demonstrating that our crystals are spacious enough to host e.g.
ribosome-sized macromolecules. We validate the accurate assembly of the DNA
origami lattice itself as well as the precise incorporation of gold particles
by electron microscopy and small angle X-ray scattering (SAXS) experiments. Our
results show that it is possible to create DNA building blocks that assemble
into lattices with customized geometry. Site-specific hosting of nano objects
in the transparent DNA lattice sets the stage for metamaterial and structural
biology applications.
