Department+of+Chemical+and+Biomolecular+Engineering
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DNA based semiconductor technology developed
Professor Park Hyun Gyu’s research team from the Department of Chemical and Biomolecular Engineering at KAIST has successfully implemented all logic gates using DNA, a feat that led the research to be published as the cover paper for the international nanotechnology paper "Small".
Even with the latest technology, it was impossible to create a silicon based semiconductor smaller than 10nm, but because DNA has a thickness of only 2nm, this could lead to the creation of semiconductors with groundbreaking degrees of integration.
A 2 nm semiconductor will be able to store 10,000 HD movies within a size of a postage stamp, at least 100 times more than the current 20nm semiconductors.
DNAs are comprised of 4 bases which are continually connected: Adenine (A) with Thymine (T), and Guanine (G) with Cytosine (C).
For this research, the team used the specific binding properties of DNA, which forms its helix-shape, and a circular molecular beacon that has fluorescent signaling properties under structural changes.
The research team used input signals to open and close the circular DNA, the same principle that is applied to logic gates in digital circuits.
The output signal was measured using the increase and decrease of the fluorescent signal from the molecular beacon due to the opening and closing of the circular DNA respectively.
The team overcame the limited system problems of the existing logic gates and managed to implement all 8 logic gates (AND, OR, XOR, INHIBIT, NAND, NOR, XNOR, IMPlCATION). A multilevel circuit that connects different logic gates was also tested to show its regenerative properties.
Professor Park said that “cheap bio-electric devices with high degrees of integration will be made possible by this research” and that “there will be a large difference in the field of molecular level electronic research”
Mr. Park Gi Su, a doctoral candidate and the 1st author of this research, said that “a DNA sequence of 10 bases is only 3.4nm long and 2nm thick, which can be used to effectively increase the degree of integration of electronic devices” and that “a bio computer could materialize in the near future through DNA semiconductors with accurate logic gates”.
XOR Gate: The output signal 1 comes through the open circular DNA when either input DNA A or input DNA B is present. When both inputs are not present, the flourescent signal does not come through
2012.09.27 View 9054 -
Production of chemicals without petroleum
Systems metabolic engineering of microorganisms allows efficient production of natural and non-natural chemicals from renewable non-food biomass
In our everyday life, we use gasoline, diesel, plastics, rubbers, and numerous chemicals that are derived from fossil oil through petrochemical refinery processes. However, this is not sustainable due to the limited nature of fossil resources. Furthermore, our world is facing problems associated with climate change and other environmental problems due to the increasing use of fossil resources. One solution to address above problems is the use of renewable non-food biomass for the production of chemicals, fuels and materials through biorefineries. Microorganisms are used as biocatalysts for converting biomass to the products of interest. However, when microorganisms are isolated from nature, their efficiencies of producing our desired chemicals and materials are rather low. Metabolic engineering is thus performed to improve cellular characteristics to desired levels. Over the last decade, much advances have been made in systems biology that allows system-wide characterization of cellular networks, both qualitatively and quantitatively, followed by whole-cell level engineering based on these findings. Furthermore, rapid advances in synthetic biology allow design and synthesis of fine controlled metabolic and gene regulatory circuits. The strategies and methods of systems biology and synthetic biology are rapidly integrated with metabolic engineering, thus resulting in "systems metabolic engineering".
In the paper published online in Nature Chemical Biology on May 17, Professor Sang Yup Lee and his colleagues at the Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea present new general strategies of systems metabolic engineering for developing microorganisms for the production of natural and non-natural chemicals from renewable biomass. They first classified the chemicals to be produced into four categories based on whether they have thus far been identified to exist in nature (natural vs. nonnatural) and whether they can be produced by inherent pathways of microorganisms (inherent, noninherent, or created): natural-inherent, natural-noninherent, non-natural-noninherent, and non-natural-created ones. General strategies for systems metabolic engineering of microorganisms for the production of these chemicals using various tools and methods based on omics, genome-scale metabolic modeling and simulation, evolutionary engineering, synthetic biology are suggested with relevant examples. For the production of non-natural chemicals, strategies for the construction of synthetic metabolic pathways are also suggested. Having collected diverse tools and methods for systems metabolic engineering, authors also suggest how to use them and their possible limitations.
Professor Sang Yup Lee said "It is expected that increasing number of chemicals and materials will be produced through biorefineries. We are now equipped with new strategies for developing microbial strains that can produce our desired products at very high efficiencies, thus allowing cost competitiveness to those produced by petrochemical refineries."
Editor of Nature Chemical Biology, Dr. Catherine Goodman, said "It is exciting to see how quickly science is progressing in this field – ideas that used to be science fiction are taking shape in research labs and biorefineries. The article by Professor Lee and his colleagues not only highlights the most advanced techniques and strategies available, but offers critical advice to progress the field as a whole."
The works of Professor Lee have been supported by the Advanced Biomass Center and Intelligent Synthetic Biology Center of Global Frontier Program from the Korean Ministry of Education, Science and Technology through National Research Foundation.
Contact: Dr. Sang Yup Lee, Distinguished Professor and Dean, KAIST, Daejeon, Korea (leesy@kaist.ac.kr, +82-42-350-3930)
2012.05.23 View 11705