Ordered DNA origami lattices on silicon surfaces for molecular lithography

• Applicant: Privatdozent Dr. Adrian Keller
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469036492

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.

• DFG Programme: Research Grants