Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Caltech scientists develop DNA origami nanoscale breadboards for carbon nanotube circuits

In (a), single-wall carbon nanotubes labeled with "red" and "blue" DNA sequences attach to anti-red and anti-blue strands on a DNA origami, resulting in a self assembled electronic switch. In (b), an atomic force microscopey image of one such structure. The blue nanotube appear brighter because it is on top of the origami; the red nanotube sits below. Scale bar is 50 nm. In (c), a diagrammatic view of the structure shown in b. The gray rectangle is the DNA origami. A self-assembled DNA ribbon attached to the origami improves structural stability and ease of handling.

Credit: Paul W. K. Rothemund, Hareem Maune, and Si-ping Han/Caltech/Nature Nanotechnology
In (a), single-wall carbon nanotubes labeled with "red" and "blue" DNA sequences attach to anti-red and anti-blue strands on a DNA origami, resulting in a self assembled electronic switch. In (b), an atomic force microscopey image of one such structure. The blue nanotube appear brighter because it is on top of the origami; the red nanotube sits below. Scale bar is 50 nm. In (c), a diagrammatic view of the structure shown in b. The gray rectangle is the DNA origami. A self-assembled DNA ribbon attached to the origami improves structural stability and ease of handling.

Credit: Paul W. K. Rothemund, Hareem Maune, and Si-ping Han/Caltech/Nature Nanotechnology

Abstract:
In work that someday may lead to the development of novel types of nanoscale electronic devices, an interdisciplinary team of researchers at the California Institute of Technology (Caltech) has combined DNA's talent for self-assembly with the remarkable electronic properties of carbon nanotubes, thereby suggesting a solution to the long-standing problem of organizing carbon nanotubes into nanoscale electronic circuits.

Caltech scientists develop DNA origami nanoscale breadboards for carbon nanotube circuits

Pasadena, CA | Posted on November 10th, 2009

A paper about the work appeared November 8 in the early online edition of Nature Nanotechnology.

"This project is one of those great 'Where else but at Caltech?' stories," says Erik Winfree, associate professor of computer science, computation and neural systems, and bioengineering at Caltech, and one of four faculty members supervising the project.

Both the initial idea for the project and its eventual execution came from three students: Hareem T. Maune, a graduate student studying carbon nanotube physics in the laboratory of Marc Bockrath (then Caltech assistant professor of applied physics, now at the University of California, Riverside); Si-ping Han, a theorist in materials science who is investigating the interactions between carbon nanotubes and DNA in the Caltech laboratory of William A. Goddard III, Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics; and Robert D. Barish, an undergraduate majoring in computer science who was working on complex DNA self-assembly in Winfree's lab.

The project began in 2005, shortly after Paul W. K. Rothemund invented his revolutionary DNA origami technique. At the time, Rothemund was a postdoctoral scholar in Winfree's laboratory; today, he is a senior research associate in bioengineering, computer science, and computation and neural systems.

Rothemund's work gave Maune, Han, and Barish the idea to use DNA origami to build carbon nanotube circuits.

DNA origami is a type of self-assembled structure made from DNA that can be programmed to form nearly limitless shapes and patterns, such as smiley faces or maps of the Western Hemisphere or even electrical diagrams. Exploiting the sequence-recognition properties of DNA base paring, DNA origami are created from a long single strand of viral DNA and a mixture of different short synthetic DNA strands that bind to and "staple" the viral DNA into the desired shape, typically about 100 nanometers (nm) on a side.

Single-wall carbon nanotubes are molecular tubes composed of a rolled-up hexagonal mesh of carbon atoms. With diameters measuring less than 2 nm and yet with lengths of many microns, they have a reputation as some of the strongest, most heat-conductive, and most electronically interesting materials that are known. For years, researchers have been trying to harness their unique properties in nanoscale devices, but precisely arranging them into desirable geometric patterns has been a major stumbling block.

"After hearing Paul's talk, Hareem got excited about the idea of putting nanotubes on origami," Winfree recalls. "Meanwhile, Rob had been talking to his friend Si-Ping, and they independently had become excited about the same idea."

Underlying the students' excitement was the hope that DNA origami could be used as 100 nm by 100 nm molecular breadboards—construction bases for prototyping electronic circuits—on which researchers could build sophisticated devices simply by designing the sequences in the origami so that specific nanotubes would attach in preassigned positions.

"Before talking with these students," Winfree continues, "I had zero interest in working with carbon nanotubes or applying our lab's DNA-engineering expertise toward such practical ends. But, seemingly out of nowhere, a team had self-assembled with a remarkable spectrum of skills and a lot of enthusiasm. Even Si-Ping, a consummate theorist, went into the lab to help make the idea become reality."

"This collaborative research project is evidence of how we at Caltech select the top students in science and engineering and place them in an environment where their creativity and imagination can thrive," says Ares Rosakis, chair of the Division of Engineering and Applied Science at Caltech and Theodore von Kármán Professor of Aeronautics and professor of mechanical engineering.

Bringing the students' ideas to fruition wasn't easy. "Carbon nanotube chemistry is notoriously difficult and messy—the things are entirely carbon, after all, so it's extremely difficult to make a reaction happen at one chosen carbon atom and not at all the others," Winfree explains.

"This difficulty with chemically grabbing a nanotube at a well-defined 'handle' is the essence of the problem when you're trying to place nanotubes where you want them so you can build complex devices and circuits," he says.

The scientists' ingenious solution was to exploit the stickiness of single-stranded DNA to create those missing handles. It's this stickiness that unites the two strands that make up a DNA helix, through the pairing of DNA's nucleotide bases (A, T, C, and G) with those that have complementary sequences (A with T, C with G).

"DNA is the perfect molecule for recognizing other strands of DNA, and single-stranded DNA also just happens to like sticking to carbon nanotubes," says Han. "So we mix bare nanotubes with DNA molecules in salt water, and they stick all over the nanotubes' surfaces. However, we make sure that a little bit of each DNA molecule is protected, so that that little portion doesn't stick to the nanotube, and we can use it to recognize DNA attached to the DNA origami instead."

The scientists created two batches of carbon nanotubes labeled by DNA with different sequences, which they called "red" and "blue."

"Metaphorically, we dipped one batch of nanotubes in red DNA paint, and dipped another batch of nanotubes in blue DNA paint," Winfree says. Remarkably, this DNA paint acts like color-specific Velcro.

"These DNA molecules served as handles because a pair of single-stranded DNA molecules with complementary sequences will wrap around each other to form a double helix. Thus," he says, "red can bind strongly to anti-red, and blue with anti-blue."

"Consequently," he adds, "if we draw a stripe of anti-red DNA on a surface, and pour the red-coated nanotubes over it, the nanotubes will stick on the line. But the blue-coated nanotubes won't stick, because they only stick to an anti-blue line."

To make nanometer-scale electronic circuits out of carbon nanotubes requires the ability to draw nanometer-scale stripes of DNA. Previously, this would have been an impossible task. Rothemund's invention of DNA origami, however, made it possible.

"A standard DNA origami is a rectangle about 100 nm in size, with over 200 'pixel' positions where arbitrary DNA strands can be attached," Winfree says. To integrate the carbon nanotubes into this system, the scientists colored some of those pixels anti-red, and others anti-blue, effectively marking the positions where they wanted the color-matched nanotubes to stick. They then designed the origami so that the red-labeled nanotubes would cross perpendicular to the blue nanotubes, making what is known as a field-effect transistor (FET), one of the most basic devices for building semiconductor circuits.

Although their process is conceptually simple, the researchers had to work out many kinks, such as separating the bundles of carbon nanotubes into individual molecules and attaching the single-stranded DNA; finding the right protection for these DNA strands so they remained able to recognize their partners on the origami; and finding the right chemical conditions for self-assembly.

After about a year, the team had successfully placed crossed nanotubes on the origami; they were able to see the crossing via atomic force microscopy. These systems were removed from solution and placed on a surface, after which leads were attached to measure the device's electrical properties. When the team's simple device was wired up to electrodes, it indeed behaved like a field-effect transistor. The "field effect" is useful because "the two components of the transistor, the channel and the gate, don't actually have to touch for there to be a switching effect," Rothemund explains. "One carbon nanotube can switch the conductivity of the other due only to the electric field that forms when a voltage is applied to it."

At this point, the researchers were confident that they had created a method that could construct a device from a mixture of nanotubes and origami.

"It worked," Winfree says. "I can't say perfectly—there's lots of room for improvement. But it was sufficient to demonstrate the controlled construction of a simple device, a cross-junction of a pair of carbon nanotubes."

"We expect that our approach can be improved and extended to reliably construct more complex circuits involving carbon nanotubes and perhaps other elements including electrodes and wiring," Goddard says, "which we anticipate will provide new ways to probe the behavior and properties of these remarkable molecules."

The real benefit of the approach, he points out, is that self-assembly doesn't just make one device at a time. "This is a scalable technology. That is, one can design the origami to construct complex logic units and to do this for thousands or millions or billions of units that self-assemble in parallel."

The work in the paper, "Self-assembly of carbon nanotubes into two-dimensional geometries using DNA origami templates," was supported by the National Science Foundation, the Office of Naval Research, and the Center on Functional Engineered Nano Architectonics.

####

For more information, please click here

Contacts:
Kathy Svitil

626-395-8022

Copyright © California Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Seeking Nanoscale Defenses for Biological and Chemical Threats: WPI co-organizes a NATO workshop to improve the detection and decontamination of biological and chemical agents September 13th, 2014

New pricing report for bulk graphene materials September 13th, 2014

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Iranian Nano Scientists Create Flame-Resistant Polymers September 13th, 2014

Chip Technology

UT Arlington research uses nanotechnology to help cool electrons with no external sources September 11th, 2014

Excitonic Dark States Shed Light on TMDC Atomic Layers: Berkeley Lab Discovery Holds Promise for Nanoelectronic and Photonic Applications September 11th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

Development of Algorithm for Accurate Calculation of Average Distance Travelled by Low-Speed Electrons without Energy Loss that Are Sensitive to Surface Structure September 11th, 2014

Self Assembly

Molecular self-assembly controls graphene-edge configuration September 10th, 2014

Rice chemist wins rare NSF Special Creativity Award: Grant extension will bolster Zubarev's effort to produce gold nanorods September 8th, 2014

Magnetic nanocubes self-assemble into helical superstructures September 4th, 2014

Peptoid Nanosheets at the Oil/Water Interface: Berkeley Lab Reports New Route to Novel Family of Biomimetic Materials September 3rd, 2014

Nanotubes/Buckyballs

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Global Energy Systems Signs Master Sales Agreement with China Aviation Supplies Group September 4th, 2014

Breakthrough for Carbon Nanotube Solar Cells: Polychiral carbon nanotube mixture absorbs more sunlight September 3rd, 2014

SouthWest NanoTechnologies CEO Dave Arthur to Discuss “Carbon Nanotubes and Automotive Applications” at The Automotive Composites Conference and Expo 2014 (ACCE2014) August 28th, 2014

Nanoelectronics

Excitonic Dark States Shed Light on TMDC Atomic Layers: Berkeley Lab Discovery Holds Promise for Nanoelectronic and Photonic Applications September 11th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

Material development on the nanoscale: Doped graphene nanoribbons with potential September 8th, 2014

Nano-pea pod model widens electronics applications: A new theoretical model explains how a nanostructure, such as the nano-pea pod, can exhibit localised electrons September 4th, 2014

Discoveries

Iranian Nano Scientists Create Flame-Resistant Polymers September 13th, 2014

Boosting armor for nuclear-waste eating microbes September 12th, 2014

Ceramics don't have to be brittle: Caltech materials scientists are creating materials by design September 11th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

Announcements

Seeking Nanoscale Defenses for Biological and Chemical Threats: WPI co-organizes a NATO workshop to improve the detection and decontamination of biological and chemical agents September 13th, 2014

New pricing report for bulk graphene materials September 13th, 2014

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Iranian Nano Scientists Create Flame-Resistant Polymers September 13th, 2014

Nanobiotechnology

NanoStruck has a High Recovery Rate on Mine Tailings: retrieval of up to 96% of Gold, 88% of Silver and 86% of Palladium September 12th, 2014

Boosting armor for nuclear-waste eating microbes September 12th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

UO-Berkeley Lab unveil new nano-sized synthetic scaffolding technique: Oil-and-water approach from Richmond's UO lab to spark new line of versatile peptoid nanosheets September 2nd, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE