When biology becomes electronics
Yuval Dror, Haaretz, voila!
Construction of an electrical switch in the D-NA molecule
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A breakthrough in the field of molecular electronics was recently recorded following research by researchers from the Technion who were able to show, for the first time, how a DNA molecule forms a basic electrical switch (transistor). The results of the research, published yesterday in Science magazine, demonstrate for the first time how molecules can be harnessed to create electrical circuits. "We were able to prove that electronics based on DNA is not fiction," said Prof. Erez Braun of the Technion Physics Faculty, who directed the research.
The research is part of Dr. Kinneret Keren's doctoral thesis with the participation of Professor Uri Sivan, Dr. Yevgeni Buchstab and Rotam Berman. In an interview with Haaretz, Prof. Brown explained that the construction of the transistor is part of a six-year project. "Our goal is to take advantage of the natural properties of the DNA molecule, so that the information encoded in it will allow self-construction of a transistor," he said. The first phase of the project took place in '98, when the researchers - in collaboration with Prof. Yoav Ishan from the Technion Faculty of Chemistry - developed a method by which they turned the DNA molecule into a wire capable of conducting electricity, by coating it with silver and gold.
However, in order to produce a transistor that acts as an electrical switch, further development was needed. The researchers used a basic biological process that naturally allows the mixing of genes and the creation of new genes. "We took the ``RecA'' protein from a bacterium whose function is to attach to a segment in the DNA molecule and replace it with a segment with a similar sequence from another DNA molecule," Brown explains. "We assembled a short strand of DNA on the protein. The protein becomes a 'driver' that drives the short strand and assembles it at a certain point on the long strand."
According to Brown, the researchers found that the protein protects the site to which it has attached. "This protection means that no metal will be formed at this site. This is how we obtained a metal thread in the middle of which appears the protein on which there is no metal. This is a significant advance because it allows us to utilize the information in the DNA sequences," says Brown.
But even this is not enough to create an electric switch. The protein is not used as a semiconductor and it was necessary to use a material that would connect to the "protein site" and transmit electricity according to an instruction. In an article published in Science, the researchers describe how they overcame the problem. They decided to use a nanometer carbon tube that has many properties, among other things it can be used as a semiconductor. "The problem is how to get the tube to coat the protein. We wouldn't want to do it manually," says Brown. The researchers used another mechanism of nature - the antibodies. An antibody is a protein that knows how to connect to another protein to neutralize it. The researchers used an antibody that knows how to connect to a protein found on DNA and connected it to the carbon tube with the help of another auxiliary protein. In doing so, they created a second time a "driver" who "drives" the handset to exactly the right point.
"Now we have a metal wire in the middle of which is a protein on which a carbon tube has settled," describes Brown. "When we put this wire on a silicon substrate and passed an electric voltage through it (the so-called "gate voltage"), we were able to make the DNA strand with the carbon tube act as an electronic switch: once it conducts electricity, which means the switch is closed, and once it does not conduct electricity, i.e. The switch is open."
The researchers' achievement is especially impressive when you consider that until now researchers around the world have succeeded in producing a molecular electronic transistor by chance: they applied a solution containing carbon tubes to a surface and hoped that some tubes would randomly connect in a way that would allow them to be used as an electric circuit. "We do something completely different," emphasizes Brown. "We pour the ingredients into the solution; a long DNA strand, a short DNA strand with protein, carbon tubes, and within a few minutes the electric circuit is formed inside the solution, and this, while taking advantage of the special properties of all the components we threw into the solution."
According to Brown, the creation of a basic electric switch that organizes independently
from proteins and carbon tubes is the first step on the way to building electric circuits and more complex electronic systems. "We have been talking about molecular electronics for 30 years. We started working on the subject six years ago and only now have we succeeded in producing the first electrical switch based on biological molecules. These are long processes, but it seems that we have succeeded in overcoming the first hurdle on the way to electronic circuits that organize themselves. Now we will try to produce complex circuits more, networks and junctions of transistors composed of d-na and also to cause another d-na molecule to be this which is responsible for the switching of the transistors, and not the silicon substrate through which the electrical voltage is transmitted. If we succeed in doing this, then there will be real progress."
The race to miniaturization
By Yuval Dror
The first generation of modern electronics began with the invention of the vacuum tube and the triode, which enabled the development of the first computers in the 30s and 40s. Later, the transistor was invented, the use of which made it possible to miniaturize electronic devices that became fast and cheap. However, electronics is quickly reaching the limit of its compression and miniaturization, so a research effort has begun to base new electronic systems on molecules.
The molecules are a natural candidate for the next generation due to their tiny size. The researchers know that if they succeed in building a transistor - which is considered the most basic component of any electronic system - in such tiny dimensions, they will give the electronic devices new properties that will allow them to work more quickly and efficiently.
DNA molecules are the most suitable for building molecular electronic circuits, as they contain large amounts of coded information. The goal of the researchers is to use this information, originally intended for the creation of biological systems, to create electronic systems.
The science expert in Israel
The input is the fuel
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