Chem
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Prof. Lee"s Team Pioneers Biotechnological Production of Chemical Using Renewable Materials
A research team led by Prof. Sang-Yup Lee of the Bio and Brain Engineering Department at KAIST has succeeded in engineering the bacterium E. coli to produce the industrial chemical putrescine, university authorities said on Monday (Aug. 31).
Putrescine, a four carbon chain diamine, is an important platform chemical with a wide range of applications for the pharmaceutical, agrochemical and chemical industries. It is currently used to synthesize nylon-4,6, a widely used engineering plastic.
The research result, published in the Biotechnology and Bioengineering journal, proviDrdes a renewable alternative to the traditional process using fossil fuels.
Currently the production of putrescine on an industrial scale relies on chemical synthesis, which requires non-renewable petrochemicals and expensive catalyst systems. This process is highly toxic and flammable with potentially severe repercussions for both the environment and human health.
"For the first time we have developed a metabolically engineered E. coli strain that efficiently produces putrescine," said Professor Lee. "The development of a bio-refinery for chemicals and materials is very important in a world where dependency on fossil fuels is an increasing concern."
The team developed a strain of E.coli capable of producing putrescine through metabolic engineering. This is where a cell"s metabolic and regulatory networks are enhanced in order to increase production of a needed material.
First the team weakened or deleted competing metabolic pathways within the E. coli strain before deleting pathways which cause putrescine degradation. They also amplified the crucial enzyme Spec C, which converts the chemical ornithine into putrescine. Finally the putrescine exporter, which allows excretion of intracellularly made putrescine, was engineered while a global regulator was engineered to further increase the concentration of putrescine. The final result of this process was an engineered E.coli strain which produced 24.2 g of putrescine per litre.
However, as it was believed that putrescine is toxic to microorganisms the team had to study putrescine tolerance in E.coli before it could be engineered to overproduce the chemical to the levels needed for industrial production.
The results revealed that E. coli can tolerate at least 0.5 M of putrescine, which is tenfold higher than the usual concentration in the cell. This level of tolerance was an important surprise as it means that E. coli can be engineered to overproduce putrescine to industrially competitive levels.
"The previously expected toxicity of putrescine may explain why its microbial production has been overlooked," said Lee. "Now a metabolically engineered E. coli strain has been developed which is capable of efficiently producing putrescine using renewable methods to an industrial level. This metabolic engineering framework should be useful for developing metabolically engineered microorganisms for the efficient production of other chemicals from renewable resources," he added.
2009.09.01 View 12945 -
Prof. Sang-Ouk Kim Featured on the Cover of Emerging Investigator Special Issue
KAIST Prof. Sang-Ouk Kim of the Department of Materials Science and Engineering was featured on the cover of the Emerging Investigator Special Issue published by Britain"s Royal Society of Chemistry on June 21, university authorities said on Monday (June 22).
The special issue shed spotlight on 18 up-and-coming scientists who have been selected through the recommendation and rigorous screening process of the editorial and advisory boards of the Royal Society of Chemistry. The 18 scientists consist of six from the American continent, 10 from Europe, one from Japan and one from Korea.
The journal introduced Prof. Kim"s paper, titled "Highly entangled carbon nanotube (CNT) scaffolds by self-organized aqueous droplets." Kim explained in the paper that the cellular CNT demonstrated high electrical conductivity and field-emission properties, which is potentially useful for various applications in electronics and energy storage devices.
2009.06.24 View 12048 -
Method to Synthesize New Lithium Ion Battery Cathode Material Identified
A KAIST research team headed by Prof. Do-Kyung Kim at the Department of Materials Science and Engineering developed a technology to synthesize a new lithium ion battery spinel cathode which is regarded as a core part of hybrid and lithium battery cars.
The research was conducted in collaboration with a research team of Prof. Yi Cui at Stanford University"s Department of Chemistry. Their findings were introduced in the November issue of Nano Letters, one of the leading academic journals in nano-science.
The newly synthesized lithium ion battery spinel cathode known as spinel LiMn2O4 nanorods is attracting interests as an alternative cathode material since it is a low-cost, environmentally friendly substance for Li-ion battery cathodes. Its raw material is also highly available.
Lithium ion batteries with high energy and power density are important for consumer electronic devices, portable power tools, and vehicle electrification. LixCoO2 is a commonly used cathode material in commercial lithium iron batteries. However, the high cost, toxicity, and limited abundance of cobalt have been recognized to be disadvantageous.
2008.11.20 View 11835 -
Prof. Sang-Yup Lee Receives Merck Award for Metabolic Engineering
Prof. Sang-Yup Lee of KAIST"s Department of Chemical and Biomolecular Engineering has been chosen as the winner of the 2008 Merck Award for Metabol;ic Engineering established by the world"s leading pharmaceutical and chemical company Merck, KAIST officials said Tuesday, Sept. 16.
The Distinguished Professor of KAIST and LG Chem Chair Professor will receive the award on Sept. 18 during the 7th Metabolic Engineering convention now underway at Puerto Vallarta, Mexico. Prof. Lee will give a commemorative lecture, titled "Systems Metabolic Engineering for Chemicals," at the biannual academic conference. Prof. Lee is the fourth to win the coveted award which is given to the world"s top expert in metabolic engineering with outstanding achievements in the field.
Prof. Lee, 44, who graduated from Seoul National University and earned his master"s and doctoral degrees in chemical engineering from Northwestern University of the United States, is now the dean of the College of Life Science and Bioengineering, KAIST. Since 1994, he has served as the head of the Metabolic and Biomolecular Engineering National Research Laboratory, director of the BioProcess Engineering Center, Director of the Bioinformatics Research Center and Co-Director of the Institute for the BioCentury in KAIST.
Prof. Lee said he was receiving the Merck award "as a representative of KAIST graduates, students and researchers" who have worked with him at the Metabolic Engineering Lab. He added he was happy to see the outcome of bioengineering development projects supported by the Ministry of Education, Science and Technology over the past years was now being recognized by the world"s leading scientific society with the Merck Award.
Metabolic engineering, the art of optimizing genetic and regulatory processes within cells to increase the cell"s production of a certain substance, develops technologies that hold the key to the resolution of the world"s energy, food and environmental problems. The indispensible technology in bioengineering can be applied to the production of biomass to obtain alternative fuel.
Prof. Lee has actively participated in publishing such academic periodicals as Biotechnology Journal (as chief editor), Biotechnology and Bioengineering (deputy editor) and Metabolic Engineering (a member of the editorial committee).
2008.09.17 View 14484 -
Home-Grown Transparent Thin Film Transistor Developed
KAIST, Aug. 6, 2008 -- A KAIST research team led by Profs. Jae-Woo Park and Seung-Hyup Yoo of the Electrical Engineering Division has developed a home-grown technology to create transparent thin film transistor using titanium dioxide., university authorities said.The KAIST team made the technological advance in collaboration with the LCD Division of Samsung Electronics and the Techno Semichem Co., a local LCD equipment maker. Transparent thin film transistor continues to enjoy a wealth of popularity and intensive research interest since it is used in producing operating circuits including transparent display, active-matrix OLED (AMOLED) display and flexible display.
The new technology is significant in that it is based on a titanium dioxide, the first such attempt in the world, while the technologies patented by the United States and Japan are based on ZnO.
Researchers will continue to work on securing technological reliability and developing a technology to mass-produce in a large-scale chemical vapor deposition equipment for the next couple of years.
"The development of technology to produce transparent thin film transistor will help Korean LCD makers reduce its dependence on foreign technologies, as well as maintain Korea"s status as a leader of the world"s display industry," said Prof. Park.
KAIST has applied for local patent registration of the technology and the process is expected to complete by this October or November. International patents have been also applied for in the U.S., Japan and Europe.
The new technology was introduced in the latest edition of the Electron Device Letters, a journal published by the Institute of Electrical and Electronics Engineers or IEEE, a New York-based international non-profit, professional organization for the advancement of technology related to electricity. It will be presented at the International Display Workshop 2008 on Dec. 5 in Niigata, Japan.
2008.08.07 View 14256 -
Storing Stably Hydrogen Atoms in Icy Materials Discovered
KAIST, Aug. 8, 2008 -- A KAIST research team led by Prof. Huen Lee of the Department of Chemical & Biomolecular Engineering has discovered that icy organic hydrates, which contain small cages that can trap guest molecules, can be used to create and trap hydrogen atoms at higher temperatures.
The properties and reactions of single hydrogen atoms are of great scientific interest because of their inherent quantum mechanical behavior; experimentally, they can be generated and stabilized at very low temperatures (4 K) by high-energy irradiation of solid molecular hydrogen.
The finding was reported in the journal of American Chemical Society and featured in the "Editor"s Choice" in the July 11 issue of Science as a recent research highlight.
Hydrogen is a clean and sustainable form of energy that can be used in mobile and stationary applications. Hydrogen has the potential to solve several major challenges today: depletion of fossil fuels, poor air quality, and green house gas emissions.
However, the trapping of hydrogen atoms in crystalline solid matrix has never been attempted mainly because of experimental difficulties in identifying the generated hydrogen atoms with either spectroscopic or microscopic technique.
"To overcome the barriers and limitations of the existing storage approaches, we have continuously attempted to find the new hydrogen storage media such as icy powders and other related inclusion compounds," said Prof. Lee
The discovery follows the breakthrough concept Prof. Lee"s research team proposed in Nature in 2005 to use pure ice to capture and store hydrogen molecules. At moderate temperature and pressure conditions small guest molecules are entrapped in pure ice powders to form the mixed icy hydrate materials.
"Stable existence of single hydrogen molecule/radical in icy crystalline matrices may offer significant advantages in exploring hydrogen as a quantum medium because icy hydrogen hydrates can be formed at milder conditions when compared with pure solid hydrogen, which requires the ultra low temperature of 4.2 K," said Prof. Lee.
The novel design and synthesis of ionic and radicalized icy hydrates are expected to open a new field for inclusion chemistry and ice-based science and technology. Specifically, the fact that hydrogen atoms can be stably stored in icy materials might provide versatile and practical applications to energy devices including fuel cells, ice-induced reactions, and novel energy storage process, according to the KAIST professor.
2008.08.07 View 12684 -
KAIST Holds Symposium on Metabolic Engineering
The KAIST Institute for Bio-Century held a symposium on metabolic engineering at the auditorium of the KAIST"s Applied Engineering Bldg. on Thursday, Feb. 14, in cooperation with the BK21 Chemical Engineering Research Team.
The symposium focused on researches on bio-refinery program and bio-energy production in connection with steep hikes in oil prices and worsening environmental problems, including global warming.
Seven Korean experts presented their views on metabolic engineering strategies to effectively produce bio-energy and biofuel and the latest research trends.
Among the speakers, Prof. Lee Sang-yup, co-head of the KAIST Institute for Bio-Century, spoke on the theme of "Metabolic Engineering for Bio-refinery and Bio-energy.
The symposium provided an opportunity to take a glimpse into the latest research trends of metabolic engineering technology. Metabolic engineering technology is crucial to producing chemicals, energy and other substances from renewable biomass materials in a departure from heavy reliance on crude oil.
2008.02.14 View 12684 -
Research Outputs over Carbon Nanotube by Prof. Choi Selected as Research Highlight by ACS
Research Outputs over Carbon Nanotube by Prof. Choi Selected as Research Highlight by ACS
Research Outputs over Carbon Nanotube by Prof. Choi Selected as Research Highlight by ACS
A research team headed by Seong-Min Choi, a professor of Nuclear and Quantum Engineering, KAIST, has developed technologies to stably disperse carbon nanotube particles in aqueous solutions and organic solvents, essential for industrial applications of carbon nanotube, and discovered the dispersion characteristics of carbon nanotube. The research outputs have been published by ‘Advanced materials’ (19, 929, 2007), the most distinguished journal in Material Science field, and introduced as Research Highlight at the May 7th edition of ‘Heart Cut’ by the American Chemical Society (ACS).
A number of processes for industrial applications of carbon nanotube require the dispersion of carbon nanotube in aqueous solutions or organic solvents, and thus far, surfactant particles or DNAs have been used to disperse carbon nanotube particles. However, they have shortcomings of easy destruction of dispersion. In order to overcome such shortcomings, Prof. Choi’s team produced carbon nanotube particle-dispersed aqueous solutions by using surfactant particles and then polymerized surfactant particles absorbed to the surfaces of carbon nanotube in situ to develop carbon nanotube with hydrophile and safe surfaces. The functional carbon nanotube so obtained shows features of easy dispersion in aqueous solutions and organic solvents even after being processed, such as freeze drying, therefore, is expected to significantly contribute to the development of application technologies of carbon nanotubes. Tae-Hwan Kim and Chang-Woo Doh, both doctoral students, played key roles in the researches carried out under the auspices of the Ministry of Science and Technology (MOST) as a nuclear power R&D project, and the relevant technologies were filed for patent applications.
Figures: Carbon nanotube before polymerization (left), carbon nanotube polymerized with surfactant particles (right)
2007.05.14 View 13135 -
Professor Yang Named Recipient of Dupont Science & Technology Award
Professor Yang Named Recipient of Dupont Science & Technology Award
- Named as the recipient of Dupont Science & Technology Award of 2007- In recognition of his development of optical?bio-functional photonic crystal structures through Self-assembly of nanoparticles
Seung-Man Yang, a professor of Chemical and Biomolecular Engineering of KAIST (President Nam Pyo Suh) and the president of the National Creative Research Initiatives Center for Photon and Fluid Integrated Circuit by the Ministry of Science and Technology, has been named as the recipient of Dupont Science & Technology Award.
Dupont Korea, associate of Dupont, a world-class science firm, has established and conferred ‘Dupont Science & Technology Award’ since 2002 to promote basic sciences and industrial development of Korea. Dupont Science & Technology Awards are awarded to scientists of universities or state-run institutes who have made outstanding R&D achievements in the fields of Chemistry, Chemical Engineering, Material Science and Material Engineering within five years. Dupont Korea announced on May 2, 2007 that Professor Yang is the recipient of the award this year, following the strict examination by the Koran Academy of Science and Technology (KAST).
The reason for the award is Professor Yang’s development of prototype optical?bio-functional photonic crystal structures that can process a huge amount of data, resulting from a study that has discovered the principle of Self-assembly where multifunctional nanoparticles are manufactured and assembled for themselves.
Professor Yang’s recent research result about photon structures and nano patterns was published by Nature (February 2, 2006 edition); posted on Heart-Cut, the portal site of the American Chemistry Society (ACS), as highlight paper two times (November 4, 2002 and May 1, 2006); and introduced at Research/Researcher of MRS Bulletin by the U.S. Material Research Society (MRS) as main paper in December 2003. Professor Yang is very famous in Korea and abroad for the excellences of his research achievements and has made request seminars at Harvard University, University of Wisconsin, Caltech, University of California, etc. He is also invited speaker and session organizer of the MRS and the SPIE.
2007.05.08 View 17146 -
Professor Seong-Ihl Woo Develops New High-Speed Research Method
Professor Seong-Ihl Woo Develops New High-Speed Research Method
Reduce research periods and expenses for thin film materials several ten times
Posted on the online version of Proceedings of National Academy of Sciences of the United States of America (PNAS) on January 9
A team led by Seong-Ihl Woo, a professor of KAIST Department of Chemical & Biomolecular Engineering and the director of the Center for Ultramicrochemical Process Systems, has developed a high-speed research method that can maximize research performances and posted the relevant contents on the online version of Proceedings of National Academy of Sciences of the United States of America (PNAS), a distinguished scientific journal, on January 9, 2007.
Professor Woo’s team has developed a high-speed research method that can fabricate several tens or several thousands of thin films with different compositions (mixing ratio) at the same time and carry out structural analysis and performance evaluation more than ten times faster and accurately, which leads to the shortening of the research processes of thin film materials. This is an epoch-making method that can reduce research periods and expenses several ten times or more, compared to the previous methods.
The qualities of final products of electronic materials, displays, and semi-conductors depend on the features of thin film materials. Averagely, it takes about two weeks or longer to fabricate a functional thin film and analyze and evaluate its performances. In order to fabricate thin film materials in need successfully, more than several thousand times of tests are required.
The existing thin film-fabricating equipment is expensive one demanding high-degree vacuum, such as chemical vapor deposition, sputtering, physical vapor deposition, laser evaporation, and so on. In order to fabricate thin films of various compositions with this equipment, a several million won-worth target (solid-state raw material) and precursors (volatile organic metal compound) pricing several hundreds won per gram are required. Therefore, huge amount of experiment expense is demanded for fabrication of several ten thousands of thin films with various compositions.
Professor Woo’s team has developed ‘combinatorial droplet chemical deposition’ equipment, which does not demand high-degree vacuum and is automated by computers and robots, by using a new high-speed research measure. The equipment is priced at about 1/5 of the existing equipment and easy for maintenance.
This equipment uses cheap reagents, instead of expensive raw materials. Reagents necessary to form required compositions are dissolved in water or proper solvents, and then applied by high frequencies to make several micrometer-scaled droplets (fine liquid droplet). Theses droplets are moved by nitrogen and dropped onto a substrate, which is to be fabricated into a thin film, and then subsequent thermal treatment is applied to the substrate to fabricate a thin film of required composition. At this moment, several tens or several hundreds of thin films with various compositions can be fabricated at the same time by reducing the size of thin film specimens into millimeter scale with the use of shade mask and adjusting vaporization time with masks, the moving speed of which can be adjusted. The expenses for materials necessary for the fabrication of thin films with this equipment amount to several ten thousands won per 100 grams, which is in the range of 1/100 and 1/10 of the previous methods, and the research period can be shortened into one of several tenth.
“If this new method is applied to the development of elements in the fields of core energy, material and health, which have not been discovered by the existing research methods so far, as well as researches in thin film material field, substantial effects will be brought,” said Professor Woo.
‘Combinatorial droplet chemical vaporization’ equipment is pending a domestic patent application and international patent applications at Japan and Germany. This equipment will be produced by order and provided to general researchers.
2007.02.02 View 15726