Spontaneous formation of aligned DNA nanowires by capillarity-induced skin folding.

Although DNA nanowires have proven useful as a template for fabricating functional nanomaterials and a platform for genetic analysis, their widespread use is still hindered because of limited control over the size, geometry, and alignment of the nanowires. Here, we document the capillarity-induced folding of an initially wrinkled surface and present an approach to the spontaneous formation of aligned DNA nanowires using a template whose surface morphology dynamically changes in response to liquid. In particular, we exploit the familiar wrinkling phenomenon that results from compression of a thin skin on a soft substrate. Once a droplet of liquid solution containing DNA molecules is placed on the wrinkled surface, the liquid from the droplet enters certain wrinkled channels. The capillary forces deform wrinkles containing liquid into sharp folds, whereas the neighboring empty wrinkles are stretched out. In this way, we obtain a periodic array of folded channels that contain liquid solution with DNA molecules. Such an approach serves as a template for the fabrication of arrays of straight or wrinkled DNA nanowires, where their characteristic scales are robustly tunable with the physical properties of liquid and the mechanical and geometrical properties of the elastic system.