2D Auxetic DNA Origami: Mechanics, Deformation Behaviors and Design Recommendations

Auxetic materials have unconventional mechanical properties which are believed to emerge from their periodic cellular structures rather than the chemical composition. Poisson’s ratio characterizes their properties distinct and different from those of regular materials. Auxetic structures have negative Poisson’s ratios, whereas regular materials show positive values. The auxetic behaviors offer significantly improved indentation resistance, greater shear modulus, and enhanced fracture toughness. In this work, we demonstrated architectured 2D auxetic metastructures using DNA origami, a bottom-up self-assembly method. We constructed several wireframe configurations, characterized their auxetic properties, and investigated relevant mechanics. Given their nanoscale dimensions, we achieved the auxetic deformations via 2-step DNA reactions. Coarse-grained molecular dynamics simulations were also performed to study mechanical deformation upon external loading, from which we extracted structural properties. We found that (1) structural behaviors by DNA reactions and mechanical loads are consistent and that (2) the auxetic behaviors are largely defined by structures, yet the DNA properties must be considered. Our elastic model suggests design guidelines for auxetic DNA metastructures.