David Kirkpatrick

June 15, 2010

Organic nanoelectronics

As the title of this release puts it, “one step closer.”

The release:

Organic nanoelectronics a step closer

Researchers use metal crystal to organize organic materials, overcoming key stumbling block

This release is avaiable in French.

IMAGE: This image shows the polymers that were created at a resolution of 5 nanometers (the average strand of human hair is 80,000 nanometers wide).

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Although they could revolutionize a wide range of high-tech products such as computer displays or solar cells, organic materials do not have the same ordered chemical composition as inorganic materials, preventing scientists from using them to their full potential. But an international team of researchers led by McGill’s Dr. Dmitrii Perepichka and the Institut national de la recherche scientifique’s Dr. Federico Rosei have published research that shows how to solve this decades-old conundrum. The team has effectively discovered a way to order the molecules in the PEDOT, the single most industrially important conducting polymer.

Although Dr. Perepichka is quick to point out that the research is not directly applicable to products currently in the market, he gives the example of a possible use for the findings in computer chips. “It’s a well known principle that the number of transistors in a computer chip doubles every two years,” he said, “but we are now reaching the physical limit. By using molecular materials instead of silicon semiconductor, we could one day build transistors that are ten times smaller than what currently exists.” The chips would in fact be only one molecule thick.

The technique sounds deceptively simple. The team used an inorganic material – a crystal of copper – as a template. When molecules are dropped onto the crystal, the crystal provokes a chemical reaction and creates a conducting polymer. By using a scanning probe microscope that enabled them to see surfaces with atomic resolution, the researchers discovered that the polymers had imitated the order of the crystal surface. The team is currently only able to produce the reaction in one dimension, i.e. to make a string or line of molecules. The next step will be to add a second dimension in order to make continuous sheets (“organic graphite”) or electronic circuits.

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Perepichka is affiliated with McGill University’s department of chemistry and Rosei is affiliated with Institut national de la recherche scientifique – Énergie Matériaux Télécommunications Center, a member of the Université du Québec network. Their research was published online by theProceedings of the National Academy of Sciences and was funded by the Natural Sciences and Engineering Research Council of Canada, the Air Force Office of Scientific Research and Asian Office of Aerospace Research and Development of the USA, the Petroleum Research Fund of the American Chemical Society, the Fonds québécois de recherche sur la nature et les technologies, and the Ministère du Développement économique, de l’Innovation et de l’Exportation of Quebec.

May 12, 2010

Semi-conductor nanocrystals and quantum computing

Another step toward quantum computing.

The release:

Quantum move toward next generation computing

McGill researchers make important contribution to the development of quantum computing

This release is available in French.

IMAGE: These images show the electrostatic energy given off when electrons are added to a quantum dot. They were made with an atomic-force microscope.

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Physicists at McGill University have developed a system for measuring the energy involved in adding electrons to semi-conductor nanocrystals, also known as quantum dots – a technology that may revolutionize computing and other areas of science. Dr. Peter Grütter, McGill’s Associate Dean of Research and Graduate Education, Faculty of Science, explains that his research team has developed a cantilever force sensor that enables individual electrons to be removed and added to a quantum dot and the energy involved in the operation to be measured.

Being able to measure the energy at such infinitesimal levels is an important step in being able to develop an eventual replacement for the silicon chip in computers – the next generation of computing. Computers currently work with processors that contain transistors that are either in an on or off position – conductors and semi-conductors – while quantum computing would allow processors to work with multiple states, vastly increasing their speed while reducing their size even more.

Although popularly used to connote something very large, the word “quantum” itself actually means the smallest amount by which certain physical quantities can change. Knowledge of these energy levels enables scientists to understand and predict the electronic properties of the nanoscale systems they are developing.

“We are determining optical and electronic transport properties,” Grütter said. “This is essential for the development of components that might replace silicon chips in current computers.”

IMAGE: These images show the electrostatic energy given off when electrons are added to a quantum dot. They were made with an atomic-force microscope.

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The electronic principles of nanosystems also determine their chemical properties, so the team’s research is relevant to making chemical processes “greener” and more energy efficient. For example, this technology could be applied to lighting systems, by using nanoparticles to improving their energy efficiency. “We expect this method to have many important applications in fundamental as well as applied research,” said Lynda Cockins of McGill’s Department of Physics.

The principle of the cantilever sensors sounds relatively simple. “The cantilever is about 0.5 mm in size (about the thickness of a thumbnail) and is essentially a simple driven, damped harmonic oscillator, mathematically equivalent to a child’s swing being pushed,” Grütter explained. “The signal we measure is the damping of the cantilever, the equivalent to how hard I have to push the kid on the swing so that she maintains a constant height, or what I would call the ‘oscillation amplitude.’ ”

Dr. Aashish Clerk, Yoichi Miyahara, and Steven D. Bennett of McGill’s Dept. of Physics, and scientists at the Institute for Microstructural Sciences of the National Research Council of Canada contributed to this research, which was published online late yesterday afternoon in the Proceedings of the National Academy of Sciences. The research received funding from the Natural Sciences and Engineering Research Council of Canada, le Fonds Québécois de le Recherche sur la Nature et les Technologies, the Carl Reinhardt Fellowship, and the Canadian Institute for Advanced Research.

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March 17, 2010

DNA nanotubes as a drug delivery system

Medical nanotech news from McGill University.

The release:

DNA nanotechnology breakthrough offers promising applications in medicine

McGill researchers create DNA nanotubes able to carry and selectively release materials

This release is available in French.

A team of McGill Chemistry Department researchers led by Dr. Hanadi Sleiman has achieved a major breakthrough in the development of nanotubes – tiny “magic bullets” that could one day deliver drugs to specific diseased cells. Sleiman explains that the research involves taking DNA out of its biological context. So rather than being used as the genetic code for life, it becomes a kind of building block for tiny nanometre-scale objects.

Using this method, the team created the first examples of DNA nanotubes that encapsulate and load cargo, and then release it rapidly and completely when a specific external DNA strand is added. One of these DNA structures is only a few nanometres wide but can be extremely long, about 20,000 nanometres. (A nanometre is one-10,000th the diameter of a human hair.)

Until now, DNA nanotubes could only be constructed by rolling a two-dimensional sheet of DNA into a cylinder. Sleiman’s method allows nanotubes of any shape to be formed and they can either be closed to hold materials or porous to release them. Materials such as drugs could then be released when a particular molecule is present.

One of the possible future applications for this discovery is cancer treatment. However, Sleiman cautions, “we are still far from being able to treat diseases using this technology; this is only a step in that direction. Researchers need to learn how to take these DNA nanostructures, such as the nanotubes here, and bring them back to biology to solve problems in nanomedicine, from drug delivery, to tissue engineering to sensors,” she said.

The team’s discovery was published on March 14, 2010 in Nature Chemistry. The research was made possible with funding from the National Science and Engineering Research Council and the Canadian Institute for Advanced Research.

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On the Web: http://www.hanadisleiman.com

Video link: http://snurl.com/uw2q1