DNA-origami nanotubes self-align with self-organized nanoscale patterns to create nanoelectronic circuits
February 5, 2014
As we start to reach physical limits, one approach to continued miniaturization of microelectronics is with “DNA origami,” in which strands of DNA are formed into nanostructures to act as scaffolds for manufacturing nanoelectronic components, such as nanowires.
But forming entire circuits with this method requires precisely controlled positioning of these nanostructures on a surface, requiring very elaborate techniques.
Researchers at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Germany have now developed a simpler strategy that combines DNA origami with self-organized pattern formation. To align these DNA nanotubes on the surface, the researchers drew on a principle of self-organization that is common in nature. Wind, for example, forms ordered patterns on a sandy beach.
“Similar processes are at work here,” said Adrian Keller of the HZDR Institute of Ion Beam Physics and Materials Research. Low-energy ion irradiation of the silicon surface results in the spontaneous appearance of ordered nanopatterns resembling miniature sand dunes, he said.
“Electrostatic interactions between the charged DNA nanotubes and the charged surface [then] cause the nanotubes to align themselves in the valleys of the dunes.”
According to Keller, the new technique is quick, cheap, and simple. “Until now, we had to draw on lithographic techniques plus treat the surface with chemicals in order to align the DNA nanostructures. Our new technique offers a much simpler alternative.”
The DNA nanotubes could also be arranged into more complex arrays, such as electronic circuits electrically attached to individual transistors, for instance. The HZDR research plan is to eventually build electronic building blocks such as transistors that spontaneously assemble into electronic circuits.
Abstract of Nanoscale paper
The controlled positioning of DNA nanostructures on technologically relevant surfaces represents a major goal along the route toward the full-scale integration of DNA-based materials into nanoelectronic and sensor devices. Previous attempts to arrange DNA nanostructures into defined arrays mostly relied on top-down lithographic patterning techniques combined with chemical surface functionalization.
Here we combine two bottom-up techniques for nanostructure fabrication, i.e., self-organized nanopattern formation and DNA origami self-assembly, in order to demonstrate the electrostatic self-alignment of DNA nanotubes on topographically patterned silicon surfaces.
Self-organized nanoscale ripple patterns with periodicities ranging from 20 nm to 50 nm are fabricated by low-energy ion irradiation and serve as substrates for DNA origami adsorption. Electrostatic interactions with the charged surface oxide during adsorption direct the DNA origami nanotubes to the ripple valleys and align them parallel to the ripples.
By optimizing the pattern dimensions and the Debye length of the adsorption buffer, we obtain an alignment yield of 70%. Since this novel and versatile approach does not rely on any chemical functionalization of the surface or the DNA nanotubes, it can be applied to virtually any substrate material and any top-down or bottom-up nanopatterning technique. This technique thus may enable the wafer-scale fabrication of ordered arrays of functional DNA-based nanowires.