DNA-silica nanolattices as mechanical metamaterials

Mechanical metamaterials consist of periodic structures with enhanced material properties. The best additive manufacturing techniques have resolutions of 100s of nanometers, which cannot fully realize material size effects. Further, they cannot easily combine disparate materials (e.g., soft, biological polymers with hard ceramics). Here, DNA origami is used to construct octahedral-based isotropic and anisotropic nanolattices, which are coated with silica. These DNA nanolattices have features two orders of magnitude smaller than additively manufactured lattices and obtain material properties comparable to the best nanolattices due to material size effects. Atom probe tomography confirms the nanoscale distribution of DNA and silica in the octahedral lattice. Finite element modeling reveals two dominate failure modes: buckling at lower coating thicknesses and tensile fracture at higher thicknesses. Molecular dynamics simulations reveal that the DNA suppresses global buckling modes in favor of surface buckling, which delays failure and contributes to increased strength at large strains.