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J. Fraser Stoddart, a Former Visiting Professor at KAIST, Wins the 2016 Nobel Prize in Chemistry
J. Fraser Stoddart, who is Northwestern University’s Board of Trustees Professor of Chemistry and head of the Stoddart Mechanostereochemistry Group, received the 2016 Nobel Prize in Chemistry. He shares it with Professor Jean-Pierre Sauvage of the University of Strasbourg in France and Professor Bernard Feringa of the University of Groningen in the Netherlands.
Professor Stoddart’s relationship with KAIST dates to his term as a visiting professor from 2011 to 2013 at the Environment, Energy, Water and Sustainability (EEWS) Graduate School. The Nobel Committee awarded the prize to Professor Stoddart in recognition of his pioneering work on artificial molecular machines, a.k.a., nanomachines.
A molecular machine is an assembly of a discrete number of molecular components designed to perform machine-like movements as the result of appropriate external stimuli. Like their counterparts in the macroscopic world, molecular machines control mechanical movements and rotations in response to an energy input such as chemical reactions, light, or temperature. The most complex molecular machines, for example, are proteins in cells. Chemists have attempted to imitate these structures for potential applications including smart nanomedicines to track diseases such as cancer cells and deliver drugs to fight them. Other applications include next-generation miniature semiconductor chips, sensors, energy storage, space exploration, and armaments.
In 1991, Professor Stoddart developed artificial molecular machines based on a rotaxane. A rotaxane is a mechanically-interlocked molecular architecture in which a dumbbell-shaped molecule is encircled by a molecular ring called a macrocycle. He presented important research on the production of rotaxanes and demonstrated that a macrocycle could move along or rotate freely around the axle, a dumbbell-shaped molecule.
Professor Stoddart is also an expert in molecular electronics using molecules on the nanoscale as switches in computers and other electronic devices. In 2007, he created a large-scale ultra-dense memory device with reconfigurable molecular switches, the size of white blood cells but capable of storing information. This was a significant achievement towards the development of molecular computers that are much smaller and more powerful compared to today’s silicon-based computers.
KAIST has enjoyed a strong relationship with Professor Stoddart since he served as a visiting professor at the EEWS Graduate School from 2011 to 2013. The graduate school invited him to participate in the Korean government’s science and education program to foster world-class universities in the nation. At KAIST, he taught a course entitled “Nanomachines at the Scale of Molecules.” He also collaborated with Korean researchers on various projects including the publication of a joint research paper, “A Radically Configurable Six-State Compound,” in Science (January 25, 2013) with Professor Jang Wook Choi from the EEWS Graduate School and researchers from the United States, the United Kingdom, and Saudi Arabia.
Two doctors with KAIST ties have links to Professor Stoddart as well. In 2012, Dr. Ali Coskun, who worked with him as a postdoctoral research associate at Northwestern University, became an associate professor at the EEWS Graduate School where he conducts research on secondary batteries and gas storage with artificial molecular machines. Dr. Dong Jun Kim, a KAIST graduate, has been working at the Stoddart Mechanostereochemistry Group as a postdoctoral fellow since 2015.
Picture 1: Synthesis of a Rotaxane Described in the Journal of the American Chemical Society (JACS) in 1991
Picture 2: Professor J. Fraser Stoddart Giving a Presentation at a Workshop Hosted by the EEWS Graduate School at KAIST in 2011
2016.10.13 View 8018 -
Professor Seyun Kim Identifies a Neuron Signal Controlling Molecule
A research team led by Professor Seyun Kim of the Department of Biological Sciences at KAIST has identified inositol pyrophosphates as the molecule that strongly controls neuron signaling via synaptotagmin.
Professors Tae-Young Yoon of Yonsei University’s Y-IBS and Sung-Hyun Kim of Kyung Hee University’s Department of Biomedical Science also joined the team.
The results were published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on June 30, 2016.
This interdisciplinary research project was conducted by six research teams from four different countries and covered a wide scope of academic fields, from neurobiology to super resolution optic imaging.
Inositol pyrophosphates such as 5-diphosphoinositol pentakisphos-phate (5-IP7), which naturally occur in corns and beans, are essential metabolites in the body. In particular, inositol hexakisphosphate (IP6) has anti-cancer properties and is thought to have an important role in cell signaling.
Inositol pentakisphosphate (IP7) differs from IP6 by having an additional phosphate group, which was first discovered 20 years ago. IP7 has recently been identified as playing a key role in diabetes and obesity.
Psychopathy and neurodegenerative diseases are known to result from the disrupted balance of inositol pyrophosphates. However, the role and the mechanism of action of IP7 in brain neurons and nerve transmission remained unknown.
Professor Kim’s team has worked on inositol pyrophosphates for several years and discovered that very small quantities of IP7 control cell-signaling transduction. Professor Yoon of Yonsei University identified IP7 as a much stronger inhibitor of neuron signaling compared to IP6. In particular, IP7 directly suppresses synaptotagmin, one of the key proteins in neuron signaling. Moreover, Professor Kim of Kyung Hee University observed IP7 inhibition in sea horse neurons.
Together, the joint research team identified inositol pyrophosphates as the key switch metabolite of brain-signaling transduction.
The researchers hope that future research on synaptotagmin and IP7 will reveal the mechanism of neuron-signal transduction and thus enable the treatment of neurological disorders.
These research findings were the result of cooperation of various science and technology institutes: KAIST, Yonsei-IBS (Institute for Basic Science), Kyung Hee University, Sungkyunkwan University, KIST, University of Zurich in Switzerland, and Albert-Ludwigs-University Freiburg in Germany.
Schematic Image of Controlling the Synaptic Exocytotic Pathway by 5-IP7 , Helping the Understanding of the Signaling Mechanisms of Inositol Pyrophosphates
2016.07.21 View 10543 -
ICISTS Hosts the International Interdisciplinary Conference
A KAIST student organization, The International Conference for the Integration of Science, Technology and Society (ICISTS), will host ICISTS 2016 at the Hotel ICC in Daejeon from 3 to 7 August with the participation of around 300 Korean and international students.
ICISTS was first established in 2005 to provide an annual platform for delegates and speakers to discuss the integration and the convergence of science, technology, and society regardless of their academic backgrounds.
This year’s conference, with the theme of “Beyond the Center,” emphasizes the ways in which technological advancements can change central organizations in areas such as financial technology, healthcare, and global governance.
The keynote speakers include Dennis Hong, a developer of the first automobile for the blind and a professor of the Mechanical and Aerospace Engineering Department at UCLA, Dor Konforty, a founder and a CEO of SNS platform Synereo, and Marzena Rostek, a professor of Economics at the University of Wisconsin-Madison.
Other notable speakers include: Gi-Jung Jung, Head of the National Fusion Research Institute; Janos Barberis, Founder of FinTech HK; Tae-Hoon Kim, CEO and Founder of Rainist; Gulrez Shah Azhar, Assistant Policy Analyst at RAND Corporation; Thomas Concannon, Senior Policy Researcher at RAND Corporation; Leah Vriesman, Professor at the School of Public Health, UCLA; and Bjorn Cumps, Professor of Management Practice at Vlerick Business School in Belgium.
The conference consists of keynote speeches, panel discussions, open talks, experience sessions, team project presentations, a culture night, and a beer party, at which all participants will be encouraged to interact with speakers and delegates and to discuss the topics of their interest.
Han-Kyul Jung, ICISTS’s Head of Public Relations, said, “This conference will not only allow the delegates to understand the trends of future technology, but also be an opportunity for KAIST students to form valuable contacts with students from around the world.”
For more information, please go to www.icists.org.
2016.07.20 View 7406 -
Unveiling the Distinctive Features of Industrial Microorganism
KAIST researchers have sequenced the whole genome of Clostridium tyrobutyricum, which has a higher tolerance to toxic chemicals, such as 1-butanol, compared to other clostridial bacterial strains.
Clostridium tyrobutyricum, a Gram-positive, anaerobic spore-forming bacterium, is considered a promising industrial host strain for the production of various chemicals including butyric acid which has many applications in different industries such as a precursor to biofuels. Despite such potential, C. tyrobutyricum has received little attention, mainly due to a limited understanding of its genotypic and metabolic characteristics at the genome level.
A Korean research team headed by Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department at the Korea Advanced Institute of Science and Technology (KAIST) deciphered the genome sequence of C. tyrobutyricum and its proteome profiles during the course of batch fermentation. As a result, the research team learned that the bacterium is not only capable of producing a large amount of butyric acid but also can tolerate toxic compounds such as 1-butanol. The research results were published in mBio on June 14, 2016.
The team adopted a genoproteomic approach, combining genomics and proteomics, to investigate the metabolic features of C. tyrobutyricum. Unlike Clostridium acetobutylicum, the most widely used organism for 1-butanol production, C. tyrobutyricum has a novel butyrate-producing pathway and various mechanisms for energy conservation under anaerobic conditions. The expression of various metabolic genes, including those involved in butyrate formation, was analyzed using the “shotgun” proteome approach.
To date, the bio-based production of 1-butanol, a next-generation biofuel, has relied on several clostridial hosts including C. acetobutylicum and C. beijerinckii. However, these organisms have a low tolerance against 1-butanol even though they are naturally capable of producing it. C. tyrobutyricum cannot produce 1-butanol itself, but has a higher 1-butanol-tolerance and rapid uptake of monosaccharides, compared to those two species.
The team identified most of the genes involved in the central metabolism of C. tyrobutyricum from the whole-genome and shotgun proteome data, and this study will accelerate the bacterium’s engineering to produce useful chemicals including butyric acid and 1-butanol, replacing traditional bacterial hosts.
Professor Lee said,
“The unique metabolic features and energy conservation mechanisms of C. tyrobutyricum can be employed in the various microbial hosts we have previously developed to further improve their productivity and yield. Moreover, findings on C. tyrobutyricum revealed by this study will be the first step to directly engineer this bacterium.”
Director Jin-Woo Kim at the Platform Technology Division of the Ministry of Science, ICT and Future Planning of Korea, who oversees the Technology Development Program to Solve Climate Change, said,
“Over the years, Professor Lee’s team has researched the development of a bio-refinery system to produce natural and non-natural chemicals with the systems metabolic engineering of microorganisms. They were able to design strategies for the development of diverse industrial microbial strains to produce useful chemicals from inedible biomass-based carbon dioxide fixation. We believe the efficient production of butyric acid using a metabolic engineering approach will play an important role in the establishment of a bioprocess for chemical production.”
The title of the research paper is “Deciphering Clostridium tyrobutyricum Metabolism Based on the Who-Genome Sequence and Proteome Analyses.” (DOI: 10.1128/mBio.00743-16)
The lead authors are Joungmin Lee, a post-doctoral fellow in the BioProcess Research Center at KAIST, currently working in CJ CheilJedang Research Institute; Yu-Sin Jang, a research fellow in the BioProcess Research Center at KAIST, currently working at Gyeongsang National University as an assistant professor; and Mee-Jung Han, an assistant professor in the Environmental Engineering and Energy Department at Dongyang University. Jin Young Kim, a senior researcher at the Korea Basic Science Institute, also participated in the research.
This research was supported by the Technology Development Program to Solve Climate Change’s research project entitled “Systems Metabolic Engineering for Biorefineries” from the Ministry of Science, ICT and Future Planning through the National Research Foundation of Korea (NRF-2012M1A2A2026556).
Schematic Diagram of C. tyrobutyricum’s Genome Sequence and Its Proteome Profiles
The picture below shows the complete genome sequence, global protein expression profiles, and the genome-based metabolic characteristics during batch fermentation of C. tyrobutyricum.
2016.06.20 View 9533 -
Graphene-Based Transparent Electrodes for Highly Efficient Flexible OLEDs
A Korean research team developed an ideal electrode structure composed of graphene and layers of titanium dioxide and conducting polymers, resulting in highly flexible and efficient OLEDs.
The arrival of a thin and lightweight computer that even rolls up like a piece of paper will not be in the far distant future. Flexible organic light-emitting diodes (OLEDs), built upon a plastic substrate, have received greater attention lately for their use in next-generation displays that can be bent or rolled while still operating.
A Korean research team led by Professor Seunghyup Yoo from the School of Electrical Engineering, KAIST and Professor Tae-Woo Lee from the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) has developed highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE) which is placed in between titanium dioxide (TiO2) and conducting polymer layers. The research results were published online on June 2, 2016 in Nature Communications.
OLEDs are stacked in several ultra-thin layers on glass, foil, or plastic substrates, in which multi-layers of organic compounds are sandwiched between two electrodes (cathode and anode). When voltage is applied across the electrodes, electrons from the cathode and holes (positive charges) from the anode draw toward each other and meet in the emissive layer. OLEDs emit light as an electron recombines with a positive hole, releasing energy in the form of a photon. One of the electrodes in OLEDs is usually transparent, and depending on which electrode is transparent, OLEDs can either emit from the top or bottom.
In conventional bottom-emission OLEDs, an anode is transparent in order for the emitted photons to exit the device through its substrate. Indium-tin-oxide (ITO) is commonly used as a transparent anode because of its high transparency, low sheet resistance, and well-established manufacturing process. However, ITO can potentially be expensive, and moreover, is brittle, being susceptible to bending-induced formation of cracks.
Graphene, a two-dimensional thin layer of carbon atoms tightly bonded together in a hexagonal honeycomb lattice, has recently emerged as an alternative to ITO. With outstanding electrical, physical, and chemical properties, its atomic thinness leading to a high degree of flexibility and transparency makes it an ideal candidate for TEs. Nonetheless, the efficiency of graphene-based OLEDs reported to date has been, at best, about the same level of ITO-based OLEDs.
As a solution, the Korean research team, which further includes Professors Sung-Yool Choi (Electrical Engineering) and Taek-Soo Kim (Mechanical Engineering) of KAIST and their students, proposed a new device architecture that can maximize the efficiency of graphene-based OLEDs. They fabricated a transparent anode in a composite structure in which a TiO2 layer with a high refractive index (high-n) and a hole-injection layer (HIL) of conducting polymers with a low refractive index (low-n) sandwich graphene electrodes. This is an optical design that induces a synergistic collaboration between the high-n and low-n layers to increase the effective reflectance of TEs. As a result, the enhancement of the optical cavity resonance is maximized. The optical cavity resonance is related to the improvement of efficiency and color gamut in OLEDs. At the same time, the loss from surface plasmon polariton (SPP), a major cause for weak photon emissions in OLEDs, is also reduced due to the presence of the low-n conducting polymers.
Under this approach, graphene-based OLEDs exhibit 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency, which is unprecedented in those using graphene as a TE. Furthermore, these devices remain intact and operate well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm. This is a remarkable result for OLEDs containing oxide layers such as TiO2 because oxides are typically brittle and prone to bending-induced fractures even at a relatively low strain. The research team discovered that TiO2 has a crack-deflection toughening mechanism that tends to prevent bending-induced cracks from being formed easily.
Professor Yoo said, “What’s unique and advanced about this technology, compared with previous graphene-based OLEDs, is the synergistic collaboration of high- and low-index layers that enables optical management of both resonance effect and SPP loss, leading to significant enhancement in efficiency, all with little compromise in flexibility.” He added, “Our work was the achievement of collaborative research, transcending the boundaries of different fields, through which we have often found meaningful breakthroughs.”
Professor Lee said, “We expect that our technology will pave the way to develop an OLED light source for highly flexible and wearable displays, or flexible sensors that can be attached to the human body for health monitoring, for instance.”
The research paper is entitled “Synergistic Electrode Architecture for Efficient Graphene-based Flexible Organic Light-emitting Diodes” (DOI. 10.1038/NCOMMS11791). The lead authors are Jae-Ho Lee, a Ph.D. candidate at KAIST; Tae-Hee Han, a Ph.D. researcher at POSTECH; and Min-Ho Park, a Ph.D. candidate at POSTECH.
This study was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF) through the Center for Advanced Flexible Display (CAFDC) funded by the Ministry of Science, ICT and Future Planning (MSIP); by the Center for Advanced Soft-Electronics funded by the MSIP as a Global Frontier Project; by the Graphene Research Center Program of KAIST; and by grants from the IT R&D Program of the Ministry of Trade, Industry and Energy of Korea (MOTIE).
Figure 1: Application of Graphene-based OLEDs
This picture shows an OLED with the composite structure of TiO2/graphene/conducting polymer electrode in operation. The OLED exhibits 40.8% of ultrahigh external quantum efficiency (EQE) and 160.3 lm/W of power efficiency. The device prepared on a plastic substrate shown in the right remains intact and operates well even after 1,000 bending cycles at a radius of curvature as small as 2.3 mm.
Figure 2: Schematic Device Structure of Graphene-based OLEDs
This picture shows the new architecture to develop highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE).
2016.06.07 View 12533 -
Special Lecture by Professor Sung-Hou Kim of UC Berkeley
As part of its special lecture series, the Department of Biological Sciences at KAIST has invited Professor Sung-Hou Kim of the Department of Chemistry at the University of California, Berkeley, to lecture on his research in structural biology. He will speak twice on May 23 and 30, respectively, on the topics “Origin of Universe and Earth—A Narrative” and “Origin of Life and Human Species—A Narrative.”
Professor Kim's research addresses the structural basis of molecules to reveal how they communicate with each other to activate or inhibit particular processes in cell growth, cell differentiation, and cancer. Using the single-crystal X-ray diffraction technology, he discovered, for the first time in the world, the three-dimensional (3-D) structure of a transfer RNA (t-RNA) and received much praise for this work from the scientific community. Since then, he has been cited as a candidate for a Nobel Prize in Chemistry for many years.
He also examined the 3-D structures of a RAS protein in normal and cancer cells and identified the mutations of the RAS protein as a cause for cancer. His work has assisted in the development of target drugs for cancer treatment. In recent years, he has adopted a computational biology approach to study the structure and function of biological genomics, with which he has tried to predict disease-sensitive genes.
Professor Kim graduated from Seoul National University in 1962 and received his Ph.D. degree in chemistry from the University of Pittsburgh in the United States in 1966. He worked at the Massachusetts Institute of Technology (MIT) as a senior research scientist, and has taught at UC Berkeley since 1978.
2016.05.23 View 6192 -
KAIST Researchers Receive the 2016 IEEE William R. Bennett Prize
A research team led by Professors Yung Yi and Song Chong from the Electrical Engineering Department at KAIST has been awarded the 2016 William R. Bennett Prize of the Institute of Electrical and Electronics Engineers (IEEE), which is the most prestigious award in the field of communications network. The IEEE bestows the honor annually and selects winning papers from among those published in the past three years for its quality, originality, scientific citation index, and peer reviews.
The IEEE award ceremony will take place on May 24, 2016 at the IEEE International Conference on Communications in Kuala Lumpur, Malaysia.
The team members include Dr. Kyoung-Han Lee, a KAIST graduate, who is currently a professor at Ulsan National Institute of Science and Technology (UNIST) in Korea, Dr. Joo-Hyun Lee, a postdoctoral researcher at Ohio State University in the United States, and In-Jong Rhee, a vice president of the Mobile Division at Samsung Electronics. The same KAIST team previously received the award back in 2013, making them the second recipient ever to win the IEEE William R. Bennett Prize twice.
Past winners include Professors Robert Gallager of the Massachusetts Institute of Technology (MIT), Sachin Katti of Stanford University, and Ion Stoica of the University of California at Berkeley.
The research team received the Bennett award for their work on “Mobile Data Offloading: How Much Can WiFi Deliver?” Their research paper has been cited more than 500 times since its publication in 2013. They proposed an original method to effectively offload the cellular network and maximize the Wi-Fi network usage by analyzing the pattern of individual human mobility in daily life.
2016.05.02 View 12215 -
KAIST, NTU, and Technion Collaborate for Research in Emerging Fields
KAIST, Nanyang Technological University (NTU) of Singapore, and Technion of Israel signed an agreement on April 11, 2016 in Seoul to create a five-year joint research program for some of the most innovative and entrepreneurial areas: robotics, medical technologies, satellites, materials science and engineering, and entrepreneurship. Under the agreement, the universities will also offer dual degree opportunities, exchange visits, and internships.
In the picture from the left, Bertil Andersson of NTU, Sung-Mo Kang of KAIST, and Peretz Lavie of Technion hold the signed memorandum of understanding.
2016.04.14 View 9717 -
Efficient Methane C-H Bond Activated by KAIST and UPenn Teams
Professor Mu-Hyun Baik of the Chemistry Department at KAIST and his team collaborated with an international team to discover a novel chemical reaction, carbon-hydrogen borylation using methane, and their research results were published in the March 25th issue of Science.
For details, please refer to the following press release from the Institute for Basic Sciences (IBS) in Korea and the University of Pennsylvania in the United States.
Efficient Methane C-H Bond Activation Achieved for the First Time
The Institute for Basic Science, March 24, 2016
Penn Chemists Lay Groundwork for Countless New, Cleaner Uses of Methane
University of Pennsylvania, March 24, 2016
2016.03.25 View 8806 -
Public Lectures on the Korean Language and Alphabet
The School of Humanities and Social Sciences at KAIST will offer public lectures on the Korean language and alphabet, Hangul, from March 22, 2016 to April 26, 2016.
The lectures, which are entitled “The Riddle of Hangul,” will take place on campus in Daejeon.
A total of six lectures will be held on such topics as the origin of Korean, the grammar of ancient Korean in the Chosun Dynasty (1392-1897), and subsequent developments in contemporary Korean.
Professor Jung-Hoon Kim, who is responsible for organizing the public lecture program, said, “The audience will have an interesting opportunity to understand the history of Korean and its mechanism, while reviewing the unique spelling system of Hangul. I hope many people will show up for these wonderful classes.”
For further information and registration, please visit: http://hss.kaist.ac.kr. All lectures, available only in Korean, are free and open to the public.
2016.03.15 View 7448 -
Non-Natural Biomedical Polymers Produced from Microorganisms
KAIST researchers have developed metabolically engineered Escherichia coli strains to synthesize non-natural, biomedically important polymers including poly(lactate-co-glycolate) (PLGA), previously considered impossible to obtain from biobased materials.
Renewable non-food biomass could potentially replace petrochemical raw materials to produce energy sources, useful chemicals, or a vast array of petroleum-based end products such as plastics, lubricants, paints, fertilizers, and vitamin capsules. In recent years, biorefineries which transform non-edible biomass into fuel, heat, power, chemicals, and materials have received a great deal of attention as a sustainable alternative to decreasing the reliance on fossil fuels.
A research team headed by Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department at KAIST has established a biorefinery system to create non-natural polymers from natural sources, allowing various plastics to be made in an environmentally-friendly and sustainable manner. The research results were published online in Nature Biotechnology on March 7, 2016. The print version will be issued in April 2016.
The research team adopted a systems metabolic engineering approach to develop a microorganism that can produce diverse non-natural, biomedically important polymers and succeeded in synthesizing poly(lactate-co-glycolate) (PLGA), a copolymer of two different polymer monomers, lactic and glycolic acid. PLGA is biodegradable, biocompatible, and non-toxic, and has been widely used in biomedical and therapeutic applications such as surgical sutures, prosthetic devices, drug delivery, and tissue engineering.
Inspired by the biosynthesis process for polyhydroxyalkanoates (PHAs), biologically-derived polyesters produced in nature by the bacterial fermentation of sugar or lipids, the research team designed a metabolic pathway for the biosynthesis of PLGA through microbial fermentation directly from carbohydrates in Escherichia coli (E. coli) strains.
The team had previously reported a recombinant E. coli producing PLGA by using the glyoxylate shunt pathway for the generation of glycolate from glucose, which was disclosed in their patents KR10-1575585-0000 (filing date of March 11, 2011), US08883463 and JP5820363. However, they discovered that the polymer content and glycolate fraction of PLGA could not be significantly enhanced via further engineering techniques. Thus, in this research, the team introduced a heterologous pathway to produce glycolate from xylose and succeeded in developing the recombinant E. coli producing PLGA and various novel copolymers much more efficiently.
In order to produce PLGA by microbial fermentation directly from carbohydrates, the team incorporated external and engineered enzymes as catalysts to co-polymerize PLGA while establishing a few additional metabolic pathways for the biosynthesis to produce a range of different non-natural polymers, some for the first time. This bio-based synthetic process for PLGA and other polymers could substitute for the existing complicated chemical production that involves the preparation and purification of precursors, chemical polymerization processes, and the elimination of metal catalysts.
Professor Lee and his team performed in silico genome-scale metabolic simulations of the E. coli cell to predict and analyze changes in the metabolic fluxes of cells which were caused by the introduction of external metabolic pathways. Based on these results, genes are manipulated to optimize metabolic fluxes by eliminating the genes responsible for byproducts formation and enhancing the expression levels of certain genes, thereby achieving the effective production of target polymers as well as stimulating cell growth.
The team utilized the structural basis of broad substrate specificity of the key synthesizing enzyme, PHA synthase, to incorporate various co-monomers with main and side chains of different lengths. These monomers were produced inside the cell by metabolic engineering, and then copolymerized to improve the material properties of PLGA. As a result, a variety of PLGA copolymers with different monomer compositions such as the US Food and Drug Administration (FDA)-approved monomers, 3-hydroxyburate, 4-hydroxyburate, and 6-hydroxyhexanoate, were produced. Newly applied bioplastics such as 5-hydroxyvalerate and 2-hydroxyisovalerate were also made.
The team employed a systems metabolic engineering application which, according to the researchers, is the first successful example of biological production of PGLA and several novel copolymers from renewable biomass by one-step direct fermentation of metabolically engineered E.coli.
Professor Lee said, “We presented important findings that non-natural polymers, such as PLGA which is commonly used for drug delivery or biomedical devices, were produced by a metabolically engineered gut bacterium. Our research is meaningful in that it proposes a platform strategy in metabolic engineering, which can be further utilized in the development of numerous non-natural, useful polymers.”
Director Ilsub Baek at the Platform Technology Division of the Ministry of Science, ICT and Future Planning of Korea, who oversees the Technology Development Program to Solve Climate Change, said, “Professor Lee has led one of our research projects, the Systems Metabolic Engineering for Biorefineries, which began as part of the Ministry’s Technology Development Program to Solve Climate Change. He and his team have continuously achieved promising results and been attracting greater interest from the global scientific community. As climate change technology grows more important, this research on the biological production of non-natural, high value polymers will have a great impact on science and industry.”
The title of the research paper is “One-step Fermentative Production of Poly(lactate-co-glycolate) from Carbohydrates in Escherichia coli (DOI: 10.1038/nbt.3485).” The lead authors are So Young Choi, a Ph.D. candidate in the Department of Chemical and Biomolecular Engineering at KAIST, and Si Jae Park, Assistant Professor of the Environmental Engineering and Energy Department at Myongji University. Won Jun Kim and Jung Eun Yang, both doctoral students in the Department of Chemical and Biomolecular Engineering at KAIST, also participated in the research.
This research was supported by the Technology Development Program to Solve Climate Change’s research project titled “Systems Metabolic Engineering for Biorefineries” from the Ministry of Science, ICT and Future Planning through the National Research Foundation of Korea (NRF-2012M1A2A2026556).
Figure: Production of PLGA and Other Non-Natural Copolymers
This schematic diagram shows the overall conceptualization of how metabolically engineered E. coli produced a variety of PLGAs with different monomer compositions, proposing the chemosynthetic process of non-natural polymers from biomass. The non-natural polymer PLGA and its other copolymers, which were produced by engineered bacteria developed by taking a systems metabolic engineering approach, accumulate in granule forms within a cell.
2016.03.08 View 10913 -
KAIST Commencement 2016
KAIST hosted its 2016 commencement ceremony on February 19, 2016 at the Sports Complex on campus.
KAIST celebrated the event with five thousand participants including graduating students, faculty, guests, Vice Minister Nam-Ki Hong of Science, ICT and Future Planning of Korea, Chairman Jang-Moo Lee of KAIST's Board of Trustees, and President Jeong-Sik Ko of the KAIST Alumni Association.
President Patrick Aebischer of the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland, and the former Speaker of the National Assembly of Korea Chang-Hee Kang received honorary doctorates in science and technology for their contributions to the advancement of science and engineering in education and research.
KAIST granted 570 doctoral degrees, 1,329 master’s degrees, and 867 bachelor degrees on this day.
Yoon-Bum Lee of the Chemistry Department graduated with honors; Woo-Young Jin of the Mathematical Sciences Department received the Chairman’s Award of the KAIST Board and Eun-Hee Yoo of the Biological Sciences Department for the KAIST Presidential Award. Min-Hyun Cho and Yoon-Seok Chang were recipients of the President’s Award of the KAIST Alumni Association and the President’s Award of the University Supporting Association, respectively.
President Steve Kang addressed the ceremony and congratulated the graduates, saying,
“Now, your task is to make significant contributions to your communities: be leaders in your fields and remain active members of society. Given your academic knowledge and vision for the future, I encourage you to dream big.”
2016.02.23 View 40886