Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.21.262139v1?rss=1 Authors: Li, R., Chen, H., Choi, J. H. Abstract: Architectured materials exhibit negative Poisson's ratios and possess enhanced mechanical properties compared with regular materials. Their auxetic behaviors emerge from periodic cellular structures rather than chemistry. The majority of such metamaterials are constructed by top-down approaches and macroscopic with unit cells of microns or larger. On the other extreme, there are molecular-scale auxetics including naturally-occurring crystals which are not designable. There is a gap from few nanometers to microns, which may be filled by bottom-up biomolecular self-assembly. Here we demonstrate two-dimensional (2D) auxetic nanostructures using DNA origami. Structural deformation experiments are performed by strand displacement and complemented by mechanical deformation studies using coarse-grained molecular dynamics (MD) simulations. We find that the auxetic properties of DNA nanostructures are mostly defined by geometrical designs, yet materials' chemistry also plays a role. From elasticity theory, we introduce a set of design principles for auxetic DNA materials which should be useful for diverse applications. Copy rights belong to original authors. Visit the link for more info