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Fast, Accurate 3D Imaging to Track Optically-Trapped Particles
KAIST researchers published an article on the development of a novel technique to precisely track the 3-D positions of optically-trapped particles having complicated geometry in high speed in the April 2015 issue of Optica.
Optical tweezers have been used as an invaluable tool for exerting micro-scale force on microscopic particles and manipulating three-dimensional (3-D) positions of particles. Optical tweezers employ a tightly-focused laser whose beam diameter is smaller than one micrometer (1/100 of hair thickness), which generates attractive force on neighboring microscopic particles moving toward the beam focus. Controlling the positions of the beam focus enabled researchers to hold the particles and move them freely to other locations so they coined the name “optical tweezers.”
To locate the optically-trapped particles by a laser beam, optical microscopes have usually been employed. Optical microscopes measure light signals scattered by the optically-trapped microscopic particles and the positions of the particles in two dimensions. However, it was difficult to quantify the particles’ precise positions along the optic axis, the direction of the beam, from a single image, which is analogous to the difficulty of determining the front and rear positions of objects when closing an eye due to a lack of depth perception. Furthermore, it became more difficult to measure precisely 3-D positions of particles when scattered light signals were distorted by optically-trapped particles having complicated shapes or other particles occlude the target object along the optic axis.
Professor YongKeun Park and his research team in the Department of Physics at the Korea Advanced Institute of Science and Technology (KAIST) employed an optical diffraction tomography (ODT) technique to measure 3-D positions of optically-trapped particles in high speed. The principle of ODT is similar to X-ray CT imaging commonly used in hospitals for visualizing the internal organs of patients. Like X-ray CT imaging, which takes several images from various illumination angles, ODT measures 3-D images of optically-trapped particles by illuminating them with a laser beam in various incidence angles.
The KAIST team used optical tweezers to trap a glass bead with a diameter of 2 micrometers, and moved the bead toward a white blood cell having complicated internal structures. The team measured the 3-D dynamics of the white blood cell as it responded to an approaching glass bead via ODT in the high acquisition rate of 60 images per second. Since the white blood cell screens the glass bead along an optic axis, a conventionally-used optical microscope could not determine the 3-D positions of the glass bead. In contrast, the present method employing ODT localized the 3-D positions of the bead precisely as well as measured the composition of the internal materials of the bead and the white blood cell simultaneously.
Professor Park said, “Our technique has the advantage of measuring the 3-D positions and internal structures of optically-trapped particles in high speed without labelling exogenous fluorescent agents and can be applied in various fields including physics, optics, nanotechnology, and medical science.”
Kyoohyun Kim, the lead author of this paper (“Simultaneous 3D Visualization and Position Tracking of Optically Trapped Particles Using Optical Diffraction Tomography”), added, “This ODT technique can also apply to cellular-level surgeries where optical tweezers are used to manipulate intracellular organelles and to display in real time and in 3-D the images of the reaction of the cell membrane and nucleus during the operation or monitoring the recovery process of the cells from the surgery.”
The research results were published as the cover article in the April 2014 issue of Optica, the newest journal launched last year by the Optical Society of America (OSA) for rapid dissemination of high-impact results related to optics.
Figure 1: This picture shows the concept image of tweezing an optically-trapped glass bead on the cellular membrane of a white blood cell.
Figure 2: High-speed 3-D images produced from optical diffraction tomography technique
2015.04.24 View 11377 -
KAIST and the Naver Corporation Agree to Cooperate in Computer Science
KAIST and Naver, a Korean Internet corporation, concluded a memorandum of understanding (MOU) on April 17, 2015, to cooperate in advancing research and education in computer science.
Doo-Hwan Bae (pictured on the right below), the Dean of School of Computing at KAIST and Jong-Mok Park (pictured on left), the Director of Technical Cooperation at Naver, signed the MOU.
Under this agreement, the two organizations will foster computer scientists and engineers, conduct joint research projects, and develop training programs for entrepreneurs.
KAIST and Naver will organize a steering committee to lay out further details on the agreement.
2015.04.17 View 7302 -
Anti-Cancer Therapy Delivering Drug to an Entire Tumor Developed
KAIST’s Department of Bio and Brain Engineering Professor Ji-Ho Park and his team successfully developed a new highly efficacious anti-cancer nanotechnology by delivering anti-cancer drugs uniformly to an entire tumor. Their research results were published in Nano Letters online on March 31, 2015.
To treat inoperable tumors, anti-cancer medicine is commonly used. However, efficient drug delivery to tumor cells is often difficult, treating an entire tumor with drugs even more so.
Using the existing drug delivery systems, including nanotechnology, a drug can be delivered only to tumor cells near blood vessels, leaving cells at the heart of a tumor intact. Since most drugs are injected into the bloodstream, tumor recurrence post medication is frequent.
Therefore, the team used liposomes that can fuse to the cell membrane and enter the cell. Once inside liposomes the drug can travel into the bloodstream, enter tumor cells near blood vessels, where they are loaded to exosomes, which are naturally occurring nanoparticles in the body. Since exosomes can travel between cells, the drug can be delivered efficiently into inner cells of the tumor.
Exosomes, which are secreted by cells that exist in the tumor microenvironment, is known to have an important role in tumor progression and metastasis since they transfer biological materials between cells. The research team started the investigation recognizing the possibility of delivering the anti-cancer drug to the entire tumor using exosomes.
The team injected the light-sensitive anti-cancer drug using their new delivery technique into experimental mice. The researchers applied light to the tumor site to activate the anti-cancer treatment and analyzed a tissue sample. They observed the effects of the anti-cancer drug in the entire tumor tissue.
The team’s results establish a ground-breaking foothold in drug delivery technology development that can be tailored to specific diseases by understanding its microenvironment. The work paves the way to more effective drug delivery systems for many chronic diseases, including cancer tumors that were difficult to treat due to the inability to penetrate deep into the tissue.
The team is currently conducting experiments with other anti-cancer drugs, which are being developed by pharmaceutical companies, using their tumor-penetrating drug delivery nanotechnology, to identify its effects on malignant tumors.
Professor Park said, “This research is the first to apply biological nanoparticles, exosomes that are continuously secreted and can transfer materials to neighboring cells, to deliver drugs directly to the heart of tumor.”
Picture: Incorporation of hydrophilic and hydrophobic compounds into membrane vesicles by engineering the parental cells via synthetic liposomes.
2015.04.07 View 11106 -
Light Driven Drug-Enzyme Reaction Catalytic Platform Developed
Low Cost Dye Used, Hope for Future Development of High Value Medicinal Products to Treat Cardiovascular Disease and Gastric Ulcers
A KAIST research team from the Departments of Materials Science and Engineering and of Chemical and Biomolecular Engineering, led respectively by Professors Chan Beum Park and Ki Jun Jeong, has developed a new reaction platform to induce drug-enzyme reaction using light.
The research results were published in the journal Angewandte Chemie, International Edition, as the back cover on 12 January 2015.
Applications of this technology may enable production of high value products such as medicine for cardiovascular disease and gastric ulcers, for example Omeprazole, using an inexpensive dye.
Cytochrome P450 is an enzyme involved in oxidative response which has an important role in drug and hormone metabolism in organisms. It is known to be responsible for metabolism of 75% of drugs in humans and is considered a fundamental factor in new drug development.
To activate cytochrome P450, the enzyme must receive an electron by reducing the enzyme. In addition, NADPH (a coenzyme) needs to be present. However, since NADPH is expensive, the use of cytochrome P450 was limited to the laboratory and has not yet been commercialized.
The research team used photosensitizer eosin Y instead of NADPH to develop “Whole Cell Photo-Biocatalysis” in bacteria E. coli. By exposing inexpensive eosin Y to light, cytochrome P450 reaction was catalyzed to produce the expensive metabolic material.
Professor Park said, “This research enabled industrial application of cytochrome P450 enzyme, which was previous limited.” He continued, “This technology will help greatly in producing high value medical products using cytochrome P450 enzyme.”
The research was funded by the National Research Foundation of Korea and KAIST's High Risk High Return Project (HRHRP).
Figure 1: Mimetic Diagram of Electron Transfer from Light to Cytochrome P450 Enzyme via Eosin Y, EY
Figure 2: The back cover of Angewandte Chemie published on 12 January 2015, showing the research results
2015.01.26 View 9597 -
Professor Sunyoung Park Receives an Award from the Minister of Strategy and Finance of Korea
Professor Sunyoung Park, the Department of Industrial and Systems Engineering at KAIST, received an award from the Deputy Prime Minister and the Minister of Strategy and Finance of the Republic of Korea on December 31, 2014 in recognition of her contribution to the Korean economy. Known as an expert in macroeconomics and finance in Korea, Professor Park has conducted research in macroeconomic policies and capital flows.
Recently, Professor Park attended the 18th ASEAN+3 (Korea, Japan, and China) Finance and Central Bank Deputies’ Meeting held in Tokyo, Japan, on December 3-5, 2014 and presented a paper on the economic policies of Asian and G20 nations, receiving positive responses from the participants.
At the award ceremony, she said, “With continuous support from the government and collaborations with regional partners, I hope that my research will help Korea and the Asian economies grow further.”
2015.01.06 View 7376 -
Professor Joong-Keun Park Receives SeAH Heam Academic Award
Professor Joong-Keun Park of the Department of Materials Science and Engineering at KAIST received an award from SeAH Steel Corp. in recognition of his academic achievements in the field of metallic and materials engineering.
The award was presented at the 2014 Fall Conference of the Korean Institute of Metals and Materials which took place on October 22-24 at the Kangwon Land Convention Hotel.
The award, called “SeAH Heam Academic Award,” is given annually to a scholar who has contributed to the development of new metal and polymer composite materials and its related field in Korea. Following the award ceremony, Professor Park gave a keynote speech on ferrous metals for automotive materials.
2014.11.04 View 7446 -
KAIST's graduate, the first Ph.D. holder in games, is appointed professor at Michigan State University in East Lansing
Dr. Tae-Woo Park
The academic community recognizes the study in games as a field for research
Dr. Tae-Woo Park, a graduate of KAIST, has been appointed a professor at Michigan State University (MSU) in East Lansing. He will start working in August at the Department of Telecommunications, Information Studies, and Media, the College of Communications Arts, MSU.
Dr. Park received a doctoral degree in games, the first of its kind in KAIST. His research focus is game design, research, and development.
Dr. Park has strived to enhance user experience by incorporating various aspects of everyday life into games and made efforts to introduce measures limiting or preventing game addiction, a major concern among young people in South Korea. Professor Joon-Hwa Song of Computer Science at KAIST, Dr. Park's advisor, commented that "KAIST graduates have been the main actors in the development of Korea's gaming industry. Our efforts to systemize the field of games into an academic discipline have been recognized through Dr. Park's appointment."
Dr. Park said that he plans "to apply mobile device and ubiquitous technology and develop games that will not only entertain users but also help them have a better life.”
2014.05.29 View 10320 -
Yong-Joon Park, doctoral student, receives the Korea Dow Chemical Award 2014
Yong-Joon Park, a Ph.D. candidate of Materials Science and Engineering at KAIST, received the Korea Dow Chemical Award 2014, a prestigious recognition of the year’s best paper produced by students in the field of chemistry and materials science.
The award ceremony took place on April 18, 2014 at Ilsan Kintex, Republic of Korea.
The Korea Dow Chemical Award is annually given by Korea Dow Chemical and the Korean Chemical Society to outstanding papers produced by graduate and postdoc students. This year, a total of nine papers were selected out of 148 papers submitted.
The title of Park’s paper is “The Development of 3D Nano-structure-based New Concept Super-elastic Materials.” This material could be used in flexible electronic devices such as displays and wearable computers.
2014.05.03 View 8107 -
A game enthusiast received a Ph.D. at the 2014 commencement
A high school student, who was addicted to video gaming and had barely managed to gain entrance to KAIST, became a star of its 2014 commencement ceremony.
The student was Tae-Woo Park who received his Ph.D. in games at 32 years of age.
Park entered KAIST in 2002 as an undergraduate student. However, owning to bad grades, he was not accepted to the graduate school of KAIST until 2006. He began playing games at the age of 7, which distracted him from his studies at an early age. Nevertheless, he was able to complete master’s degree after two and a half years, which normally takes two years for average students.
Professor Joon-Hwa Song saw a possibility from his student’s experience of producing and commercializing a mobile puzzle game while Park was working as a president of the game club, HAJE, at KAIST. Professor Song advised him to take the advantage of his interests and try developing game platforms and contents. Park decided to develop a game that could help others and would change people’s negative views of games. He created a whole new generation of games.
In order to find ideas for games that can be easily enjoyed in daily lives, Park went to numerous gyms, swimming pools, daycare centers, and parks to analyze people’s behaviors and discussed with his colleagues who were also interested in games. During this process, the experience of organizing creative ideas through cooperation and discussions became a great foundation for his future research.
He observed some people quitting midway during a workout on treadmills because they were bored with working out alone. From this, Park embarked on developing a new style of game that allowed people to exercise together.
Park used the system on a treadmill, which recognizes the speed of the person running to automatically adjust the machine’s speed, to develop an interactive game platform for Swan Boat. The Swan Boat game is a race exercise game that adjusts the direction according to speed difference between two players. The game utilizes the difference of running speed between two people on treadmills to change the direction of the boat.
With the Swan Boat game, people can now play games and exercise at the same time. The technology also allows online access anywhere in the world, which means checking friends’ rankings at nearby gyms or homes, or even a World Gym Running Contest.
In addition, Park helped develop various next generation exercise games and life-based services, including the sparrow chirp application, which finds children that go astray, or an avatar game that utilizes the user’s daily life patterns. These results and papers attracted attention from international societies and have also won a number of awards.
Professor Song said, “There has been no precedent of receiving a Ph.D. at KAIST for developing games, however, Park’s case has given courage to many people that if you can create what is really required in everyday life, you can indeed receive a doctor’s degree.”
Park remarked, “I’d like to express my gratitude to my advisor, Professor Song, for giving me courage. I want to continue to make games that can help people’s lives in the future.”
Park will continue his work at the NASA Ames Research Center this June.
2014.02.27 View 9647 -
Nanoparticle based Super Lens selected as 2013 Science and Technology News
Professor Yong-keun Park
"Nanoparticle-based Super Lens", an article by KAIST Physics Department’s Professor Yong-keun Park and Professor Yong-hoon Cho’s joint research team, has been selected as one of the ten representative 2013 Science and Technology News, by the Korea Federation of Science and Technology Societies.
This new concept super lens uses the scattering of light, which can yield over three times more superior resolution of previous optical lenses.
Unlike the conventional optical lens that utilizes refraction of the light, the super lens can give the image of viruses and structure within the cell at 100㎚. This lens is also applicable to state-of-the-art optical and semiconductor processes.
In addition, this year's research achievements also include the successful launch of Naro, a new technology to remove the brain cell membrane which gives a more transparent view of the brain, a new drug to inhibit cancer metastasis, as well as the development of ultra-wide-angle insect eye camera technology.
Articles for 2013 Science and Technology News are chosen in three trial reviews by committee and online voting by 5,437 people over the course of [two weeks]14 days, from November 21st to December 4th.
2013.12.14 View 9478 -
Ph.D. students Hyowon Park and Won Ma receive Grand Prizes in Mathematics and Biology respectively.
Researchers in KAIST received best paper awards in two out of three fields at this year’s award ceremony for the “Second Annual Best Thesis Paper Award” held collectively by the Korea University Presidents’ Federation (with Chairman DaeSoon Lee) and the Korean Academy of Science and Technology (with Director GilSang Jung).
Two researchers from KAIST, Hyowon Park (Department of Mathematics) and Won Ma (Department of Biology) received best paper awards.
This prize, given by the both the Korea University Presidents’ Federation and the Korean Academy of Science and Technology since last year, is awarded to researchers and assistant professors who write the most outstanding thesis papers in the field of basic sciences.
Park, who received the best paper award this year, did research on graph braid groups. He was supervised by Professor Kihyung Ko, who received the best supervisor reward.
Ma, who received the best paper award in the field of biological science, researched about the Attention Deficit/Hyperactivity Disorder due to deficiency of the GIT1 synapse protein. His supervising professor also received the supervisor award.
The award ceremony was held in the auditorium of the S-OIL headquarters in Seoul on November 30.
Meanwhile, NASA researcher Jaehwa Lee received the best paper award in the field of earth science, and his supervising professor, Professor Jun Kim from Yonsei University who studies atmospheric science, received the best supervisor award.
2012.12.21 View 9558 -
Biomimetic Carbon Nanotube Fiber Synthesis Technology Developed
The byssus of the mussel allows it to live in harsh conditions where it is constantly battered by crashing waves by allowing the mussel to latch onto the seaside rocks. This particular characteristic of the mussel is due to the unique structure and high adhesiveness of the mussel’s byssus.
KAIST’s Professor Hong Soon Hyung (Department of Material Science and Engineering) and Professor Lee Hae Shin (Department of Chemistry) and the late Professor Park Tae Kwan (Department of Bio Engineering) were able to reproduce the mussel’s byssus using carbon nanotubes.
The carbon nanotube, since its discovery in 1991, was regarded as the next generation material due to its electrical, thermal, and mechanical properties. However due to its short length of several nanometers, its industrial use was limited.
The KAIST research team referred to the structure of the byssus of the mussel to solve this problem.
The byssus is composed of collagen fibers and Mefp-1 protein which are in a cross-linking structure. The Mefp-1 protein has catecholamine that allows it to bind strongly with the collagen fiber.
In the artificial structure, the carbon nanotube took on the role of the collagen fibers and the macromolecular adhesive took on the role of the catecholamine. The result was a fiber that was ultra-light and ultra-strong.
The results of the experiment were published in the Advanced Materials magazine and is patent registered both domestically and internationally.
2011.06.20 View 11814