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

Abstract

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. DNA nanowires | capillary forces | wrinkling | folding | instability A ssembling biomolecules and microorganisms (e.g., virus and DNA) into a desired architecture has offered new routes to the fabrication of nanomaterials (1, 2). In particular, DNA nanowires have proven useful as a template to fabricate functional nanomaterials and as a platform for genetic analysis (3-5). Molecular combing and its derivatives have been used widely to obtain such nanowires using an aqueous solution of DNA molecules, where capillary forces of the solution at a receding meniscus act to stretch and immobilize the molecules on a solid surface (6). To manipulate the size, geometry, and alignment of nanowires, much effort has been devoted to controlling the evaporation of the solutions by adjusting experimental parameters, such as concentration and temperature, or applying external forces that move the droplets in a desired direction (7-9). However, these approaches require careful handling only to generate nanowires that are randomly positioned and oriented. Templates whose surfaces are decorated with patterns, such as microwells (10), nanogratings (11), and micropillars (12, 13), have been shown to guide the location of nanowires. However, the experimental approaches for creating such patterns largely rely on lithography-based methods, which involve complex processes that are not readily accessible.Mechanical instabilities that occur in response to external stimuli (e.g., loading and heat) and geometric constraints cause surface wrinkling and folding of skin-substrate systems, which are ubiquitous in nature and have been harnessed to create wrinkled and folded materials for versatile applications (14). The transition from wrinkling to folding occurs when the misma...

Buckling of thermalized elastic sheets

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In-plane aligned assemblies of 1D-nanoobjects: recent approaches and applications

“…20k). 242 The orienting power of fluidic flow has been further exploited to align a large variety of nanoobjects, e.g., the capillary separation of colloidal 243 capillary flow orientation of AgNWs, 244,245 CdS NWs 246 and DNA molecules, 247 the flow alignment of AgNWs, 248,249 or of V2O5 NWs, 250 the hydro-tweezers flow orientation of AgNWs 251 and the horizontal-dip flow orientation of AgNWs. 252 To summarize, a large variety of approaches, often based on the use of directional flow-induced shear forces, have been described for the oriented assembly of diverse 1D building blocks.…”

Stepwise Evolution of Crease Patterns on Stimuli‐Responsive Hydrogels for the Production of Long‐Range Ordered Structures

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