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  • Photomechanical Detachment and Retrieval of a Single Cell from Microfluidics for Downstream Analyses

    Electronic and Electrical Engineering Prof. BAAC, HYOUNGWON

    Photomechanical Detachment and Retrieval of a Single Cell from Microfluidics for Downstream Analyses

    A new technology to detach a single cell selectively and ‘safely’ from a cell culture substrate has been developed by Hyoung Won BAAC (Assistant professor of electronic and electrical engineering of SKKU, co-first author), Euisik YOON (Professor of electrical engineering and computer science of University of Michigan-Ann Arbor, corresponding author), and a team of researchers at the Univ. of Michigan, whose work has been published in ACS Nano 11, 4660 (2017). They developed a very useful experimental method, using a short pulse laser-based photomechanical effect in a carbon nanotube (CNT)-polymer composite film, and utilized it to study ultimate heterogeneity of cancer cells, i.e. a self-renewal process, in this work, which is a key characteristic to maintain unrestrained growth, metastatic capability, and drug resistance. Cell detachment is being routinely performed every day in biology labs over the world, typically using chemical treatment, called trypsinization. However, this does not provide spatial selectivity when cells are chemically detached from a substrate. This also involves unwanted modification of cell membrane proteins and their properties, although it guarantees high cell viability. Other techniques using laser-induced ablation or tip-based physical removal are available with spatial selectivity and no chemical modification, but cell viability has been extremely low with these approaches so far. The newly developed approach uses a photomechanical effect (laser-generated microbubbles and/or shear-forces) to detach cells placed on a laser focus which can be flushed out through a microfluidic channel for safe harvesting. It was confirmed that the retrieved cells exhibit not just high viability but also intactness of cell membranes. Furthermore, the cells could be analyzed in secondary stages: for example, gene sequencing or continued culture for proliferation of specific cells with heterogeneity. For the first time in a single cell level, the new method allowed to compare two different sister cells from a single mother cell; some genes are activated or deactivated in the sister cells; some cancer cells from an identical origin can be resistant to drugs. “The new technique enables laser-precision selectivity together with cell viability. It is very practical and fundamental, which can be widely utilized for biology labs performing cell culture and analysis research,” said Prof. BAAC.

  • Deep Learning System for Recognition & Detection of Pedestrians & Vehicles in Hostile Environments

    Semiconductor Systems Engineering Prof. JEON, JAE WOOK

    Deep Learning System for Recognition & Detection of Pedestrians & Vehicles in Hostile Environments

    Autonomous vehicles are self-driving vehicles that can recognize their surroundings, understand their risks, and plan their routes. Currently, the sensors that autonomous vehicles use to recognize their surroundings include cameras, radar, and LiDAR. Different from human eyes and cameras, radar and LiDAR do not provide dense information; they only provide sparse information. Therefore, it is difficult to recognize pedestrians and vehicles using radar and LiDAR. It is only possible to calculate the distance between a vehicle and its object by using these sensors. Recent camera-based obstacle detection technology can detect pedestrians and vehicles under good weather conditions, but cannot detect pedestrians and vehicles properly under hostile weather conditions such as heavy snow, heavy rain, or darkness at night. The laboratory led by Prof. Jae Wook JEON developed a new Deep Learning technology that could recognize and detect pedestrians and vehicles in hostile conditions. First, new technologies of stereo matching and local patterns in hostile environments have been developed for obtaining the robust distance and shape information of objects by using two cameras and the robust feature information, respectively. Then, the resultant information from the camera image information has been used to train the Deep Learning system. Unlike existing Deep Learning systems which use only a single camera, a new Deep Learning system has been trained by using two cameras installed in a real vehicle. These two cameras have been used to collect training image information, including hostile conditions. Our lab also developed a Deep Learning technology that can accurately recognize pedestrians, vehicles, traffic lights, and traffic signs on actual roads in real time. With this Deep Learning technology, our lab won 1st prize in the embedded system sector and 2nd prize in the PC sector at the 13th Hyundai Motor Group Future Vehicle Technology Competition: Autonomous Vehicle Competition Image Recognition Area in May 2017. In future autonomous vehicles, it will be necessary to perform the recognition of lanes and their branch merge locations, recognition of traffic lights and traffic signs, autonomous parking, and context understanding of vehicle environments by using several cameras installed in a vehicle. Our lab will continue intelligent image processing research in order to achieve this goal.

  • '반도체 위에 성장한 비정질 그래핀' 신기술 개발

    Advanced Materials Science and Engineering Prof. WHANG, DONGMOK

    '반도체 위에 성장한 비정질 그래핀' 신기술 개발

    비정질 그래핀 합성 원천기술 세계 첫 개발, 성균관대-삼성전자 공동 연구결과 국내 연구진이 꿈의 신소재로 불리는 그래핀의 새로운 형태인 비정질 그래핀의 대면적 합성 기술을 개발, 대표적인 차세대 신소재인 2차원 소재의 응용범위 확산에 새로운 전기를 마련한 것으로 알려졌다. 공과대학 신소재공학부의 황동목 교수, 이재현 박사 등 성균관대 연구팀이 삼성전자 종합기술원 황성우 전무, 주원제 박사 등과 공동으로 반도체 웨이퍼 위 “대면적의 단원자층 비정질 그래핀 합성” 원천기술을 세계 최초로 개발했다. 그래핀은 탄소원자들이 육각형의 격자를 이루며 규칙적으로 배열된 구조를 가진 단일원자층 두께의 대표적인 결정성 2차원 물질로, 매우 뛰어난 전기적, 기계적 특성을 가지고 있어 꿈의 신소재로 불리기도 한다. 2004년 그래핀의 우수한 특성이 알려진 이후 다양한 2차원 물질이 세계적으로 매우 활발하게 연구되어 왔으나, 지금까지의 2차원 물질의 연구는 물질내 구성원자들이 규칙적으로 배열되어있는 결정성 물질에 국한되었다. 성대-삼성전자 공동연구팀은 지난 2014년도에 반도체 기판 위에 단결정 그래핀을 대면적으로 합성하는 원천기술을 개발하여 학계 및 산업계에서 큰 주목을 받은 바 있으며, 이번 후속연구를 통해 2차원물질내의 원자간 결함구조를 조절하여 2차원 평면상에서 탄소원자들이 랜덤하게 연결된 비정질 그래핀을 대면적으로 합성하는 데 성공하였다. 이번 성과는 차세대 산업의 핵심소재로 부각되고 있는 2차원 소재의 범위를 대폭 확장한 것이라는 의미를 가지고 있으며, 기존 결정성 2차원 소재와는 다른 비정질 2차원소재의 새로운 특성을 바탕으로 새로운 응용분야를 개척할 수 있을 것이라고 전망한다. 이 연구 논문은 사이언스 어드밴스(Science Advances)지 온라인판에 지난 10일 게재되었으며, 공동제1저자로 참여한 성균관대 이재현 박사는 한국연구재단의 대통령포스닥사업의 지원을 받고 있다.

  • Ultraclean transfer method developed for large-area 2-dimensional semiconductors

    Mechanical Engineering Prof. LEE, CHANG GU

    Ultraclean transfer method developed for large-area 2-dimensional semiconductors

    Graphene, which was discovered in 2005 and awarded the Nobel Prize in 2010, has been so intensely studied due to its high charge carrier mobility, high electric conductivity, superior mechanical strength, excellent chemical stability, and high optical property, and its commercialization has been attempted in various ways and areas. However, despite those strengths, it has been considered hard to be utilized as an electronic material due to the zero bandgap. Overcoming the weakness of graphene, 2-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS2), began to be investigated and are gaining attention and interest among scientists and engineers. Unlike graphene, 2D semiconductors have some bandgaps similar to that of silicon and exhibit reasonable charge carrier mobilities. Hence they are expected to become one of the main semiconducting materials for the next-generation electronics. In addition, it is highly probable that they will become an important material for flexible electronics due to the atomic-level thickness. However, still large-area synthesis or transfer techniques for commercialization of 2D semiconductors are being developed at too slow pace and are at immature stage. Out research team have been developing techniques to grow 2D semiconductors at wafer-scale and to transfer unto flexible substrates and have fabricated high-performance electronic device arrays. At first, a 2D semiconductor is synthesized at 600 degrees on a silicon substrate and the synthesized film is transferred onto a plastic substrate using epoxy glue. (Refer to figure 1) In this process, the liquid-phase glue is poured onto the plastic substrate and the 2D semiconductor film is glued and cured. Then, the glued 2D material film is separated from the silicon substrate in water. The film is easily separated because of its hydrophobicity. Conventionally, when 2D materials are transferred, the substrate had to be etched or they had to be transferred twice to the final target substrate. During the transfer, the film was damaged due to the chemical corrosion or mechanical stress and the quality was degraded. However, the transferred film of ours did not have any sign of damage, and the quality before and after the transfer was almost identical. This is because the atomic-level flatness is maintained and no residues remain even after the transfer. This transfer technique can be applied to various 2D semiconductors at large size, used to the fabrication of flexible displays, sensors, and logic devices, and adopted to the commercial mass-production processes.

  • A wet-tolerant adhesive patch inspired by protuberances in suction cups of octopi

    Chemical Engineering Prof. PANG, CHANGHYUN

    A wet-tolerant adhesive patch inspired by protuberances in suction cups of octopi

    A wet-tolerant adhesive patch inspired by protuberances in suction cups of octopi -Nature, Materials science: How to suck like an octopus- Adhesion strategies that rely on mechanical interlocking or molecular attractions between surfaces can suffer when coming into contact with liquids. Thus far, artificial wet and dry adhesives have included hierarchical mushroom-shaped or porous structures that allow suction or capillarity, supramolecular structures comprising nanoparticles, and chemistry-based attractants that use various protein polyelectrolytes. However, it is challenging to develop adhesives that are simple to make and also perform well- and repeatedly- under both wet and dry conditions, while avoiding non-chemical contamination on the adhered surfaces. Here Prof. Chang Hyun PANG and his team present an artificial, biologically inspired, reversible wet/dry adhesion system that is based on the dome-like protuberances found in the suction cups of octopi. To mimic the architecture of these protuberances, they use a simple, solution-based, air-trap technique that involves fabricating a patterned structure as a polymeric master, and using it to produce a reversed architecture, without any sophisticated chemical syntheses or surface modifications. The micrometre-scale domes in our artificial adhesive enhance the suction stress. This octopus-inspired system exhibits strong, reversible, highly repeatable adhesion to silicon wafers, glass, and rough skin surfaces under various conditions (dry, moist, under water and under oil). To demonstrate a potential application, they also used our adhesive to transport a large silicon wafer in air and under water without any resulting surface contamination. Their octopus-inspired adhesives might be useful when applied over skin or a wound and so partially assist with wound healing. They note that our patches promoted wound healing less well than did 3M Tegaderm, but they are investigating stem-cell and drug-loading approaches to improve their practical utility. Please follow the link for the published news. https://www.nature.com/nature/journal/v546/n7658/full/546358a.html http://gizmodo.com/octopus-inspired-materials-could-one-day-save-your-life-1796090566

  • Prof. CHANG discovers a new way to achieve ultra-high resolution images of various tissue samples

    Biomedical Engineering Prof. CHANG, JAE BYUM

    Prof. CHANG discovers a new way to achieve ultra-high resolution images of various tissue samples

    Researchers at Sungkyunkwan University and Massachusetts Institute of Technology (MIT) have developed a new way to achieve ultra-high resolution images of various tissue samples with a low-cost microscopy system. The new technique uses a swellabel hydrogel to physically expand tissue samples. Two years ago, Prof. Ed Boyden's lab at MIT showed that is was possible to expand tissue samples after forming a swellabel hydrogel inside tissue samples and then washing the sample-hydrogel compites in water, resulting in 4.5-fold linear expansion (100-fold volume expansion). Now, the researchers at Sungkyunkwan University and MIT together have shown that it is possible to expand tissue samples multiple times, resulting in 20-fold or even larger linear expansion. Using this technique, the researchers were able to image tissues with a resolution of 22 nanometers, which is similar to or even better than that achieved by state-of-the-art super-resolution imaging techniques, such as stimulated emission depletion (STED) microscopy or Stochastic optical reconstruction microscopy (STORM). However, this technique is much cheaper and simpler than those delicate, complicated, and expensive techniques. Also, this method enables large-scale 3-D volume super-resolution imaging. Left: 100-um thick mouse brain slice. Small piece with a height of 0.17 cm was expanded 20-fold and the height after the expansion was 3.4 cm. Right: Confocal microscopy image of neurons after the 20-fold expansion. The researchers showed that this technique works well with various tissue types, including mouse brain, lung, and liver. Prof. Jae-Byum CHANG, who is the first author of the paper, which apprears in the April 17 issue of Nature Methods, mentioned that this technique would be very useful in mapping neuron circuits of brain and also studying the heterogeneity of cancer or studying the detailed process of animal development. He also added that he would like to combine artificial intelligence (AI) and this technique to enable mass-data acquisition and mass-data analysis.

  • Photonic neuromorphic devices: For the light speed cognitive computing

    Advanced Materials Science and Engineering Prof. KIM, YONGHOON

    Photonic neuromorphic devices: For the light speed cognitive computing

    The Von Neumann computer only can do well-structured mathematical calculation. The brain, However, can make proper decision under unfamiliar situations based on the past experience and memory consuming 20 Watt so that the brain have been attracting as a biological model to make the energy-efficient cognitive computing system. Neural cell, which is the building block of the brain transmit the electrical and chemical information through the synapse and its connecting strength is modulated according to the neural activities. This operating principle contributes to a significant role in learning and memory so that the key issue for making brain-like electronics is to emulate behaviors of neurons and synapses. Recently, a team of researchers from the Sungkyunkwan University in Suwon, Korea, led by Prof. S. K. PARK and Prof. Y. H. KIM successfully mimic short-term memory/long-term memory, spike-timing dependent plasticity and neural facilitation, which is a major synaptic function for learning and memory, in Advanced Materials. These synaptic functions were emulated by using the inherent persistent photoconductivity characteristics of amorphous oxide semiconductors (AOSs). Prof. KIM et al. not only emulate synaptic functions of the brain, but also explore the dynamics of photo-generated carriers for various AOSs systematically to reveal the underlying mechanisms of the photo-induced carrier generation and relaxation behaviors. They found that the activation energy for the neutralization of ionized oxygen vacancies had a significant influence on the photo-carrier dynamics. Given that photonic neuromorphic devices opens the door of opportunities for the mimicry of learning and memory function with the ultrafast operating speed and broad bandwidth for applications in cognitive computing system.

  • SKKU Research Team Successfully Demonstrated The Structure of Grain Boundary

    Energy Science Prof. JEONG, MUNSEOK

    SKKU Research Team Successfully Demonstrated The Structure of Grain Boundary

    A research team led by Prof. Mun Seok JEONG from the Department of Energy Science of SKKU and the researcher Kyung Duk PARK from Colorado State University, successfully demonstrated the structure of grain boundary which is one of the main defects that cause a decrease in the quality of graphene. Though structural, chemical, and optical analysis, the team claimed that they confirmed that the structure of graphene is composed of two layers. Besides the grain boundary, they also succeeded with Nano Raman Imaging of nano wrinkle and seed later, which is expected to increase the understanding of the growth mechanism of graphene.

  • Enhanced electrocatalytic activity via phase transitions in strongly correlated SrRuO3 thin films

    Physics Prof. CHOI, WOOSEOK

    Enhanced electrocatalytic activity via phase transitions in strongly correlated SrRuO3 thin films

    Recent demand for sustainable energy sources have led to active research on advanced materials/devices. Electrochemical catalytic activity is one of the key mechanisms for fuel cell and hydrogen storage operation. Yet, the fundamental understanding of the oxygen evolution reaction (OER) is rather limited so far. The research team led by Prof. CHOI focused on fabrication of high quality single crystalline transition metal oxide thin film samples to unveil the fundamental physical/chemical mechanism for the OER activity. Introducing atomic-level control of elemental defects during pulsed laser epitaxy (PLE), a strong correlation between the lattice/electronic structure and electrocatalytic activity could be deduced. In particular, the structural phase transition from an orthorhombic to a tetragonal perovskite SrRuO3 resulted in substantial modification in the electronic structure, which led to a 30% reduction in the overpotential for the OER activity. Such change was explained systematically, in terms of hybridization within the Ru-O network, as well as the adsorption probability of oxygen or hydroxyl molecules. Based on this study, the strong correlation within the perovskite oxides which is the key ingredient for many intriguing emergent phenomena, is also considered as an essential part for the energy conversion mechanism. In addition, the study provides microscopic approach in studying the energy-related behavior. This research was published in April issue of Energy & Environmental Science.

  • Biomimetic Organocatalysis : Towards “Ideal” Catalysis

    Chemistry Prof. SONG, CHOONGEUI

    Biomimetic Organocatalysis : Towards “Ideal” Catalysis

    Through millions of years of evolution, nature has accomplished the development of the ideal catalysts called enzymes that catalyze the biological chemical reactions necessary to sustain all life on Earth. Thus, lessons from how natural enzymatic systems operate can therefore be very important for the design of the more efficient and environmentally benign catalytic systems. Prof. Choong Eui SONG and his students (Department of Chemistry) successfully developed biomimetic catalytic transformation of toxic α-oxoaldehydes to high-value chiral α-hydroxythioesters using artificial glyoxalase I. This reaction is exceptionally enantioselective and the α-hydroxythioester products are of high value for multiple synthetic applications. The synthetic applicability was highlighted by the coupling reagent-free synthesis of several optically pure α-hydroxyamides, highly important drug candidates in the pharmaceutical industry. Moreover, his group made the important scientific discovery that water enables new catalytic reactions for otherwise unreactive substrate systems. Enantioselective Michael addition of extremely unreactive α,α-disubstituted β-nitroalkenes with malonate derivatives using hydrophobic catalysts, affording both enantiomers of highly enantio-enriched Michael adducts with all-carbon-substituted chiral quaternary centers, has been achieved for the first time. The reaction was made possible by the “on water condition,” which enables enforced hydrophobic interactions between catalysts and substrates due to hydrophobic hydration effects. Developed water protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogues bearing all-carbon quaternary stereogenic centers at the β-position that might show highly interesting pharmaceutical properties. These results were recently published in the world top journals Nature Communications and Angewandte Chemie International Edition. * Related papers: 1) “Biomimetic catalytic transformation of toxic-oxoaldehydes to high-value chiral α-hydroxythioesters using artificial glyoxalase I” – Nat. Commun. 2017, 8, 14877. 2) “Water-enabled catalytic asymmetric Michael reactions of unreactive nitroalkenes: One-pot synthesis of chiral GABA-analogs with all-carbon quaternary stereogenic centers” – Angew. Chem. Int. Ed. 2017, 56, 1835 (as a Hot Paper).

  • Discovery of Rare Damaging Mutations Associated with Coronary Artery Disease

    Samsung Advanced Institute for Health Sciences and Technology, SKKU Prof. WON, HONG HEE

    Discovery of Rare Damaging Mutations Associated with Coronary Artery Disease

    Rare damaging mutations that are highly associated with increased triglyceride levels and presence of coronary artery disease (CAD) were identified by an SKKU and Harvard Medical School joint research team. Together with Drs. Amit KHERA and Sekar KATHIRESAN (Massachusetts General Hospital, Harvard Medical School and Broad Institute), Prof. Hong Hee WON in Samsung Advanced Institute for Health Sciences and Technology (SAIHST) at SKKU and Samsung Medical Center analyzed DNA sequences of the lipoprotein lipase (LPL) gene of 46,891 individuals. In this cross-sectional study of CAD casecontrol studies, gene sequencing identified a damaging mutation in the LPL gene in 188 of 46,891 individuals (0.4%). These mutations were associated with an increase of 19.6mg/dL in plasma triglycerides. In particular, these mutations were associated with increased odds of early-onset CAD with an odds ratio of 1.84. This research team previously published that rare mutations in the APOC3 (NEJM 2014), APOA5 (Nature 2015), ANGPTL4 (NEJM 2016) genes associated with plasma triglycerides and risk for CAD. These genes are known to be involved in hydrolyzing triglycerides in lipoproteins in the LPL pathway. “We, as a team, pursue successful combinations of advanced informatics skills and biomedical technologies to understand the genetic bases of human disease and improve healthcare,” Prof. WON mentioned. “In order to prevent cardiovascular disease, it is very important to control plasma triglyceride levels as well as LDL cholesterol. I hope this finding leads to the development of drugs for targeting LPL and related proteins and controlling triglycerides so that it can help maintain people’s health by preventing cardiovascular disease.” This research was published in the Journal of American Medical Association (JAMA) in 2017, with the title of “Association of Rare and Common Variation in the Lipoprotein Lipase Gene with Coronary Artery Disease.”

  • Photothermal Therapy for Brain Tumors Using a Rabies Virus-Mimetic Gold Nanorods Platform

    Pharmacy Prof. YOUN, YU SEOK

    Photothermal Therapy for Brain Tumors Using a Rabies Virus-Mimetic Gold Nanorods Platform

    Professor Yu Seok YOUN (School of Pharmacy) has developed a brain tumor-targeting treatment and photothermal therapy using gold nanorods that mimic the actual body of the rabies virus. A brain tumor (glioblastoma) is one of the most fatal types of cancer because patients with it have a very short average survival rate of 14.6 months. Many researchers have had great difficulty developing an effective therapeutic because of the dense brain capillary endothelial structure, so-called, blood-brain barrier (BBB), which is considered to be a crucial hurdle for the treatment of brain tumors. To solve this problem, the research team suggested a unique platform of rabies virus-mimetic gold nanorods (AuNRs) that have the ability to reach the brain tumors by bypassing the BBB. These AuNRs emitted heat (~50°C) in response to the irradiation of near infrared (NIR) light and thus suppressed tumor growth. In detail, the research team has designed and fabricated a unique gold nanorod structure that closely mimics many features of the rabies virus, such as its size, shape, and surface morphologies, for the purpose of enhancing the ability to target brain tumors. The rabies virus causes deadly symptoms such as hydrophobia and encephalomyelitis when humans are infected by it. However, the rabies virus has special ability to enter the central nervous system (CNS) and eventually bypass the BBB and reach the brain tumor site because rabies virus glycoprotein (RVG) specifically binds to the nicotinic acetylcholine receptors present in the human body (Figure 1). In particular, the unique shape of the rabies virus, which is like a bullet or rod, is advantageous for neuronal pathway migration and it is characterized by its ability to penetrate into the CNS. To achieve this strategy, the team fabricated gold nanorods of 80 nm / 20 nm in size (length and width, respectively), to maintain an aspect ratio (AR = length/width: ~4.0) that reacts efficiently to NIR (808 nm). The resulting AuNRs was serially coated by silica and RVG to form a 120 nm / 50 nm nanostructure (AR: 2.34) with very similar size, shape, and surface characteristics to the rabies virus (AR: 2.4) (Figure 1). The prepared gold nanorods displayed remarkable penetration into the brain tumor cells (N2a) when comparing spherical gold nanoparticles with RVG or gold nanorods without RVG, and reached the brains of mice through the CNS as if it was an actual rabies virus. Consequently, the NIR irradiation (808 nm) resulted in increasing tumor temperature (~50°C) and effectively suppressed tumor growth in the N2a cell-inoculated mice (Figure 2). A brain tumor target therapeutic agent has been proposed by a paradoxical strategy of creating gold nanorods mimicking the biological characteristics of the rabies virus known to be very dangerous to humans. However, there are many steps that need to be overcome for FDA approval of clinically applicable anti-brain tumor nanodrugs. Therefore, interest and research of scientists in related fields are urgently needed, and the importance and value of the development of nanodrugs should be highly evaluated. The results of this study were published in the world's leading authoritative journal Advanced Materials Online (January 30, 2017) and shown in an article in Science/AAAS Magazine Online (February 10, 2017) entitled "How to Stop Brain Cancer with Rabies”. ※Information about the research paper - Title: Rabies Virus-Inspired Silica-Coated Gold Nanorods as a Photothermal Therapeutic Platform for Treating Brain Tumors - Authors: Changkyu LEE (first author, Ph.D. candidate), Ha Shin HWANG, Sungin LEE, Bomi KIM (co-authors, master course), Yu Seok YOUN (corresponding author, professor)

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