Cell
-
High-resolution Atomic Imaging of Specimens in Liquid Observed by Transmission Electron Microscopes Using Graphene Liquid Cells
Looking into specimens in liquid at the atomic level to understand nanoscale processes so far regarded as impossible to witnessThe Korea Advanced Institute of Science and Technology (KAIST) announced that a research team from the Department of Materials Science and Engineering has developed a technology that enables scientists and engineers to observe processes occurring in liquid media on the smallest possible scale which is less than a nanometer.
Professor Jeong Yong Lee and Researcher Jong Min Yuk, in collaboration with Professors Paul Alivisatos’s and Alex Zettl’s groups at the University of California, Berkeley, succeeded in making a graphene liquid cell or capsule, confining an ultra-thin liquid film between layers of graphene, for real-time and in situ imagining of nanoscale processes in fluids with atomic-level resolution by a transmission electron microscope (TEM). Their research was published in the April 6, 2012 issue of Science. (http://www.sciencemag.org/content/336/6077/61.abstract)
The graphene liquid cell (GLC) is composed of two sheets of graphene sandwiched to create a sealed chamber where a platinum growth solution is encapsulated in the form of a thin slice. Each graphene layer has a thickness of one carbon atom, the thinnest membrane that has ever been used to fabricate a liquid cell required for TEM.
The research team peered inside the GLC to observe the growth and dynamics of platinum nanocrystals in solution as they coalesced into a larger size, during which the graphene membrane with the encapsulated liquid remained intact. The researchers from KAIST and the UC Berkeley identified important features in the ongoing process of the nanocrystals’ coalescence and their expansion through coalescence to form certain shapes by imaging the phenomena with atomic-level resolution.
Professor Lee said,
“It has now become possible for scientists to observe what is happening in liquids on an atomic level under transmission electron microscopes.”
Researcher Yuk, one of the first authors of the paper, explained his research work.
“This research will promote other fields of study related to materials in a fluid stage including physical, chemical, and biological phenomena at the atomic level and promises numerous applications in the future. Pending further studies on liquid microscopy, the full application of a graphene-liquid-cell (GLC) TEM to biological samples is yet to be confirmed. Nonetheless, the GLC is the most effective technique developed today to sustain the natural state of fluid samples or species suspended in the liquid for a TEM imaging.”
The transmission electron microscope (TEM), first introduced in the 1930s, produces images at a significantly higher resolution than light microscopes, allowing users to examine the smallest level of physical, chemical, and biological phenomena. Observations by TEM with atomic resolution, however, have been limited to solid and/or frozen samples, and thus it has previously been impossible to study the real time fluid dynamics of liquid phases.
TEM imaging is performed in a high vacuum chamber in which a thin slice of the imaged sample is situated, and an electron beam passes through the slice to create an image. In this process, a liquid medium, unlike solid or frozen samples, evaporates, making it difficult to observe under TEM.
Attempts to produce a liquid capsule have thus far been made with electron-transparent membranes of such materials as silicon nitride or silicon oxide; such liquid capsules are relatively thick (tens to one hundred nanometers), however, resulting in poor electron transmittance with a reduced resolution of only a few nanometers. Silicon nitride is 25 nanometers thick, whereas graphene is only 0.34 nanometers.
Graphene, most commonly found in bulk graphite, is the thinnest material made out of carbon atoms. It has unique properties such as mechanical tensile strength, high flexibility, impermeability to small molecules, and high electrical conductivity. Graphene is an excellent material to hold micro- and nanoscopic objects for observation in a transmission electron microscope by minimizing scattering of the electron beam that irradiates a liquid sample while reducing charging and heating effects.
###
Figure 1. Schematic illustration of graphene liquid cells. Sandwiched two sheets of graphene encapsulate a platinum growth solution.
Figure 2. In-situ TEM observation of nanocrystal growth and shape evolution. TEM images of platinum nanocrystal coalescence and their faceting in the growth solution.
2012.04.23 View 12209 -
A Step Closer to Ultra Slim Mobile Phone
Professor Baek Kyung Wook (department of Material Science and Engineering) succeeded in developing an ultra-thin conjugation technique that can perfectly replace the modular contact in electronic devices.
The research team developed a compound material using ultra-fine solder-adhesive film and developed the vertical ultrasonic conjugation process thereby making a reliable utra-thin conjugation.
The developed technique allowed for very thin and reliable conjugation and will be able to replace the socket type connector and is expected to revolutionize the electronic device industry.
In mobile electronic devices like the smartphone, the trend is to incorporate various functional modules like camera, display, touchscreens, etc. in addition to striving for miniaturization of the device.
Recently the problem was the fact that the number of modules within the device was increasing due to the incorporation of various functions, and consequently the volume that these modules took up increased as well, which made miniaturization almost impossible.
Professor Baek‘s team succeeded in improving upon this problem by creating a compound material that has ultra-fine solder particles that can melt to form alloy fusion with the electrode and thermosetting adhesive film that can wrap around the electrode and provide mechanical protection.
The use of this material made it possible to reduce the thickness of the connector by hundredth fold which improved electrical, mechanical properties and highly reliable.
From a processing standpoint the conventional conjugation process involved heating the mechanical block and was therefore hard to manage its production and also consumed 1000W and took up to 15 seconds.
By contrast, Professor Baek’s team’s new process uses only ultrasound to locally heat and melt the conjugation point itself thereby reducing power consumption to 100W and conjugation time to 1~5 seconds.
The technique developed by Professor Baek and Lee Ki Won Doctorate student was awarded Excellent Dissertation Award by world famous journals like the Electronic Components and Technology Conference and is being recognized worldwide.
2012.01.31 View 9811 -
Bio Pharmaceutical Business Center: Now Open
The Signboard Hanging Ceremony for the Bio Pharmaceutical Business Center for the Integrated Research for the field of Bio Pharmaceutics. 150 representatives from various bio pharmaceutics related businesses and institutes were present for this ceremony.
The Ministry of Education, Science and Technology placed the Molecular Process research team, Personalized Drug Delivery Medium research team, and the newly formed Cancer Cell Detection using Blood research team at the Bio Pharmaceutical Business Center at KAIST.
2012.01.31 View 8980
-
New York Times, "First, Catch Your Faculty-A Recipe for Excellence"
The World Bank has recently published a new book entitled “The Road to Academic Excellence: The Making of World Class Research Universities.” The report (book) examined the recent experience of 11 universities in 9 countries (for Korea, it sampled Pohang University of Science and Technology, established in 1986) that have undergone transformations in order to become world-class universities. The book has received a wide coverage from the media all around the world since its publication in late September, among others, the latest article by New York Times (NYT), dated October 16, 2011. The gist of the book, i.e., what elements are required should a research university to become “truly prestigious” in the global scene, is well introduced by the NYT article, and here’s the link:
New York Times, “First, Catch Your Faculty-A Recipe for Excellence”
http://www.nytimes.com/2011/10/17/world/americas/17iht-educLede17.html
2011.10.17 View 11267
-
Artificial Photosynthesis Technology Developed using Solar Cell Material
Humanity is facing global warming and the exhaustion of fossil fuel. In order to remedy these problems, efforts to produce fuel without the production of carbon dioxide using solar energy continues constantly.
KAIST’s Professor Park Chan Beom and Professor Ryu Jeong Ki’s research teams of the department of Material Science and Engineering has developed an artificial photosynthesis system that mimics the photosynthesis in nature using solar cell technology.
The development of the technology is sure to pave the way to ‘Eco-Friendly Green Biological Process’.
Photosynthesis is the process by which a biological entity produces chemical products like carbohydrates using physical and chemical reactions using solar energy as its energy source.
Professor Park’s team was able to develop the artificial photosynthesis technology with a biological catalyst as its basis.
The result of the experiment was published in ‘Advanced Materials’ magazine on the 26th of April edition and has been patented.
2011.05.11 View 11110
-
The 40th Anniversary of the Establishment of KAIST Commemoration Held
KAIST, aspiring to become the best Science and Technology University, has turned 40.
KAIST held the commemoration ceremony for the 40th Anniversary of the Establishment of KAIST in the auditorium.
Five awards (Scholar, Creative Lecture, Excellence in Lecture, International Cooperation, Experiment) were given to Professors Kim Eun Jun and Walton Jones (department of Biology), Professor Abigail Shin (department of Humanities and Social Sciences), Professor Shin Seong Chul (department of Physics), and Professor Lee Sang Yeop (department of Biological Chemical Engineering). Each recipient received a prize of five million won.
Professor Song Joon Hwa (department of Computer Sciences) received the ‘New Knowledge Award’ in recognition of his development of the Orchestrator Mobile platform. The new platform is different from Android or the IOS platform in that it allows a fluid relationship to be formed between the smartphone and the user.
KAIST also showed off its new emblem.
The emblem consists of a star which represents the KAIST’s goals of becoming the world leader, of training leaders, the center point, and hope. The main keywords are: ‘Leadership’, ‘Premium’, ‘Scientific’, and ‘Humanity’.
KAIST plans on having various events from May 9th when there will be the Vision Declaration.
2011.02.21 View 14590
-
Success in differentiating Functional Vascular Progenitor Cells (VPC)
KAIST’s Professor Han Yong Man successfully differentiated vascular progenitor cells from human embryonic stem cells and reversed differentiated stem cells.
The research went beyond the current method of synthesis of embryonic body or mice cell ball culture and used the careful alteration of signal transmission system of the human embryonic stem cells to differentiate the formation of vascular progenitor cells.
The team controlled the MEK/ERK and BMP signal transmission system that serves an important role in the self replication of human embryonic stem cells and successfully differentiated 20% of the cells experimented on to vascular progenitor cells.
The vascular progenitor cells produced with such a method successfully differentiated into cells forming the endodermis of the blood vessel, vascular smooth muscle cells and hematopoietic cells in an environment outside of the human body and also successfully differentiated into blood vessels in nude mice.
In addition, the vascular progenitor cell derived from human embryonic cells successfully formed blood vessels or secreted vascular growth factors and increased the blood flow and the necrosis of blood vessels when injected into an animal with limb ischemic illness.
The research was funded by the Ministry of Education, Science and Technology, 21st Century Frontier Research and Development Institution’s Cell Application Research Department and Professor Ko Kyu Young (KAIST), Professor Choi Chul Hee (KAIST), Professor Jeong Hyung Min (Cha Medical School) and Doctor Jo Lee Sook (Researcher in Korea Bio Engineering Institute) participated in it.
The results of the research was published as the cover paper of the September edition of “Blood (IF:10.55)”, the American Blood Journal and has been patented domestically and has finished registration of foreign PCT.
The results of the experiment opened the possibility of providing a patient specific cure using stem cells in the field of blood vessel illness.
2011.01.18 View 14188 -
KAIST developed a plastic film board less sensitive to heat.
The research result was made the cover of magazine, Advanced Materials and is accredited to paving the way to commercialize flexible display screens and solar power cells.
Transparent plastic and glass cloths, which have a limited thermal expansion needed for the production of flexible display screens and solar power cells, were developed by Korean researchers.
The research, led by KAIST’s Professor Byoung-Soo Bae, was funded by the Engineering Research Center under the initiative of the Ministry of Education, Science and Technology and the National Research Foundation. The research result was printed as the cover paper of ‘Advanced Materials’ which is the leading magazine in the field of materials science.
Professor Bae’s team developed a hybrid material with the same properties as fiber glass. With the material, they created a transparent, plastic film sheet resistant to heat. Transparent plastic film sheets were used by researchers all over the world to develop devices such as flexible displays or solar power cells that can be fit into various living spaces. However, plastic films are heat sensitive and tend to expand as temperature increases, thereby making it difficult to produce displays or solar power cells.
The new transparent, plastic film screen shows that heat expansion index (13ppm/oC) similar to that of glass fiber (9ppm/oC) due to the presence of glass fibers; its heat resistance allows to be used for displays and solar power cells over 250oC.
Professor Bae’s team succeeded in producing a flexible thin plastic film available for use in LCD or AMOLED screens and thin solar power cells.
Professor Bae commented, “Not only the newly developed plastic film has superior qualities, compared to the old models, but also it is cheap to produce, potentially bringing forward the day when flexible displays and solar panels become commonplace. With the cooperation of various industries, research institutes and universities, we will strive to improve the existing design and develop it further.”
2011.01.05 View 14674 -
International Workshop on EEWS 2010 was held.
On October 7 and 8th at Fusion Hall of KI Building, KAIST, the 2010 International Workshop on EEWS (Energy, Environment, Water, and Sustainability) was held.
The third to be held, forty national and international academic professionals including Mark Shannon, professor at University of Illinois at Urbana-Champaign, Domen Kazunari, Tokyo University professor, Dong Sub Kim, CTO of SK Energy and Doyoung Seung, Senior Vice President of GS Caltex, participated at this year’s workshop.
In twelve sessions, themes including Artificial Photosynthesis, Wireless Power Transfer, Green Aviation, Safe Nuclear Fuel Reuse, Fuel Cells in Action, LED 2.0, Foundation of Energy-Water Nexus, and Flexible Battery & Solar Cell were presented and discussed.
“Through this workshop, current EEWS policy and research progress from different countries and the future of related technologies will be foreseen,” said Jae Kyu Lee, Dean of KAIST EEWS Initiative. “I hope it became an opportunity to create cooperative relationships with leading researchers.”
EEWS is a research project conducted by KAIST to solve global issues that mankind faces today such as depletion of energy, environmental pollution, water shortage, and sustainability.
2010.10.15 View 16769
-
An internationally renowned academic journal published the research result produced by a KAST research team on its cover.
Fc DAAP VEGF-Trap
Photograph showing the gross features of tumor growth along the mesentery-intestinal border. T: tumor. Scale bars represent 5 mm.
Professor Gou-Young Koh of the Biological Sciences Department, KAIST, and his research team published their research result in Cancer Cell, a peer-review scientific journal, as a cover article dated August 17, 2010. It is the first time for the journal to pick up a paper written by a Korean research team and publish it as the cover.
It has been known that a vascular growth factor (VEGF) is closely related to the growth of a tumor. The research team recently discovered that in addition to VEGF, another growth factor, angiopoietin-2 (Ang2), is also engaged with the increase of tumors.
Professor Koh said, “VEGF and the angiopoietins play critical roles in tumor progression and metastasis, and a single inhibitor targeting both factors have not been available.”
The team led by Professor Koh has developed a double anti-angiogenic protein (DAAP) that can simultaneously bind VEGF-A and the angiopoietins and block their actions.
Professor Koh said in his paper, “DAAP is a highly effective molecule for regressing tumor angiogenesis and metastasis in implanted and spontaneous solid tumor; it can also effectively reduce ascites formation and vascular leakage in an ovarian carcinoma model. Thus, simultaneous blockade of VEGF-A and angiopoietins with DAAP is an effective therapeutic strategy for blocking tumor angiogenesis, metastasis, and vascular leakage.”
So far, cancer patients have received Avastin, anticancer drug, to inhibit VEGF, but the drug has not successfully restrained the growth of cancer tumors and brought to some of the patients with serious side effects instead.
Professor Koh said, “DAAP will be very effective to control the expansion of tumor growth factors, which will open up a new possibility for the development of more helpful cancer medicine with low side effects.”
2010.08.20 View 12510 -
Bioengineers develop a new strategy for accurate prediction of cellular metabolic fluxes
A team of pioneering South Korean scientists has developed a new strategy for accurately predicting cellular metabolic fluxes under various genotypic and environmental conditions. This groundbreaking research is published in the journal Proceedings of the National Academy of Sciences of the USA (PNAS) on August 2, 2010.
To understand cellular metabolism and predict its metabolic capability at systems-level, systems biological analysis by modeling and simulation of metabolic network plays an important role. The team from the Korea Advanced Institute of Science and Technology (KAIST), led by Distinguished Professor Sang Yup Lee, focused their research on the development of a new strategy for more accurate prediction of cellular metabolism.
“For strain improvement, biologists have made every effort to understand the global picture of biological systems and investigate the changes of all metabolic fluxes of the system under changing genotypic and environmental conditions,” said Lee. The accumulation of omics data, including genome, transcriptome, proteome, metabolome, and fluxome, provides an opportunity to understand the cellular physiology and metabolic characteristics at systems-level. With the availability of the fully annotated genome sequence, the genome-scale in silico (means “performed on computer or via computer simulation.”) metabolic models for a number of organisms have been successfully developed to improve our understanding on these biological systems. With these advances, the development of new simulation methods to analyze and integrate systematically large amounts of biological data and predict cellular metabolic capability for systems biological analysis is important.
Information used to reconstruct the genome-scale in silico cell is not yet complete, which can make the simulation results different from the physiological performances of the real cell. Thus, additional information and procedures, such as providing additional constraints (constraint: a term to exclude incorrect metabolic fluxes by restricting the solution space of in silico cell) to the model, are often incorporated to improve the accuracy of the in silico cell.
By employing information generated from the genome sequence and annotation, the KAIST team developed a new set of constraints, called Grouping Reaction (GR) constraints, to accurately predict metabolic fluxes. Based on the genomic information, functionally related reactions were organized into different groups. These groups were considered for the generation of GR constraints, as condition- and objective function- independent constraints. Since the method developed in this study does not require complex information but only the genome sequence and annotation, this strategy can be applied to any organism with a completely annotated genome sequence.
“As we become increasingly concerned with environmental problems and the limits of fossil resources, bio-based production of chemicals from renewable biomass has been receiving great attention. Systems biological analysis by modeling and simulation of biological systems, to understand cellular metabolism and identify the targets for the strain improvement, has provided a new paradigm for developing successful bioprocesses,” concluded Lee. This new strategy for predicting cellular metabolism is expected to contribute to more accurate determination of cellular metabolic characteristics, and consequently to the development of metabolic engineering strategies for the efficient production of important industrial products and identification of new drug targets in pathogens.”
2010.08.05 View 14048 -
The thermal fluctuation and elasticity of cell membranes, lipid vesicles, interacting with pore-forming peptides were reported by a research team at KAIST.
A research team from KAIST, consisted of Sung-Min Choi, Professor of Nuclear and Quantum Engineering Department, and Ji-Hwan Lee, a doctoral student in the Department, published a paper on the “thermal fluctuation and elasticity of lipid vesicles interacting with pore-forming peptides.” The paper was carried by Physical Review Letters, an internationally renowned peer-review journal on physics on July 16, 2010.
Cell membranes, which consist of lipid bilayers, play important roles in cells as barriers to maintain concentrations and matrices to host membrane proteins. During cellular processes such as cell fission and fusion, the cell membranes undergo various morphological changes governed by the interplay between protein and lipid membranes. There have been many theoretical and experimental approaches to understand cellular processes driven by protein-lipid membrane interactions. However, it is not fully established how the membrane elastic properties, which play an important role in membrane deformation, are affected by the protein-membrane interactions.
Antimicrobial peptides are one of the most common examples of proteins that modify membrane morphology. While the pore-forming mechanisms of antimicrobial peptides in lipid bilayers have been widely investigated, there have been only a few attempts to understand the mechanisms in terms of membrane elastic properties. In particular, the effects of pore formation on the membrane fluctuation and elastic properties, which provide key information to understand the mechanism of antimicrobial peptide activity, have not been reported yet. The research team reports the thermal fluctuation and elasticity of lipid vesicles interacting with pore-forming peptides, which were measured by neutron spin-echo spectroscopy.
The results of this study are expected to pay an important role in understanding the elastic behavior and morphological changes of cell membranes induced by protein-membrane interactions, and may provide new insights for developing new theoretical models for membrane fluctuations which include the membrane mediated interaction between protein patches.
(a) (b)
Figure
(a) Schematics for bound melittin and pores in lipid bilayers
(b) P NMR signal ratio (with/without Mn2+) of DOPC LUV-melittin vs P/L at 30˚C. The dashed line is a guide for eyes.
2010.07.23 View 12474