Ordered DNA origami lattices on silicon surfaces for molecular lithography

DNA origami nanostructures have

become widely employed templates for the synthesis of functional materials.

Among the numerous methods reported in literature, molecular lithography has

proven particularly versatile because it enables the transfer of the nanoscale

DNA origami shape into almost arbitrary inorganic materials. Here, the DNA

origami nanostructures are used as masks for the spatially selective removal or

deposition of material, for instance by HF etching or chemical vapor deposition

(CVD). In this way, shape transfer into various metal, oxide, and semiconductor

nanostructures was demonstrated. Many

applications in nanoelectronics, plasmonics, and sensing, however, additionally

require the controlled arrangement of the fabricated nanostructures in

predesigned arrays, lattices or circuits. Unfortunately, spatially controlled DNA

origami deposition on relevant substrate surfaces has proven rather challenging.

While highly ordered DNA origami lattices can be assembled in a straightforward

manner at mica-electrolyte interfaces by competitive cation binding, it has not

been possible so far to obtain similar lattices on technologically more

relevant substrate materials such as SiO₂. This can mostly be

attributed to the fact that mica is a very flat surface with an exceptionally

high and pH-independent surface charge density. This project thus aims at

elucidating the molecular mechanisms that control the adsorption and mobility

of DNA origami nanostructures on SiO₂ surfaces, identifying ways to

stimulate their self-assembly into ordered lattices, and demonstrating the

application of such lattices in molecular lithography. The effects of

surface potential and surface roughness on DNA origami adsorption and surface

diffusion in electrolytes of different ionic composition and pH will be

investigated in situ by high-speed

atomic force microscopy in combination with automated topological image

analysis. In this way, we will not only reveal the physicochemical factors that

govern DNA origami adsorption and mobility at SiO₂ surfaces but

rationally adjust individual parameters to promote the hierarchical

self-assembly of ordered DNA origami lattices with desired symmetry. Finally,

we will demonstrate the great potential of this approach by employing CVD to

transfer the assembled DNA origami lattices into SiO₂ etch masks for

the subsequent fabrication of nanopatterned plasmonic gold films. However, this approach may find its way also into

numerous other application fields such as nanomagnetism or catalysis. The

insights obtained in this project will furthermore be beneficial also for the

assembly of ordered DNA origami lattices on other relevant materials such as

glass, SiC or Si₃N₄.