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Researchers Control Multiple Wavelengths of Light from a Single Source
KAIST researchers have synthesized a collection of nanoparticles, known as carbon dots, capable of emitting multiple wavelengths of light from a single particle. Additionally, the team discovered that the dispersion of the carbon dots, or the interparticle distance between each dot, influences the properties of the light the carbon dots emit. The discovery will allow researchers to understand how to control these carbon dots and create new, environmentally responsible displays, lighting, and sensing technology.
Research into nanoparticles capable of emitting light, such as quantum dots, has been an active area of interest for the last decade and a half. These particles, or phosphors, are nanoparticles made out of various materials that are capable of emitting light at specific wavelengths by leveraging quantum mechanical properties of the materials. This provides new ways to develop lighting and display solutions as well as more precise detection and sensing in instruments.
As technology becomes smaller and more sophisticated, the usage of fluorescent nanoparticles has seen a dramatic increase in many applications due to the purity of the colors emitting from the dots as well as their tunability to meet desired optical properties.
Carbon dots, a type of fluorescent nanoparticles, have seen an increase in interest from researchers as a candidate to replace non-carbon dots, the construction of which requires heavy metals that are toxic to the environment. Since they are made up of mostly carbon, the low toxicity is an extremely attractive quality when coupled with the tunability of their inherent optical properties.
Another striking feature of carbon dots is their capability to emit multiple wavelengths of light from a single nanoparticle. This multi-wavelength emission can be stimulated under a single excitation source, enabling the simple and robust generation of white light from a single particle by emitting multiple wavelengths simultaneously.
Carbon dots also exhibit a concentration-dependent photoluminescence. In other words, the distance between individual carbon dots affects the light that the carbon dots subsequently emit under an excitation source. These combined properties make carbon dots a unique source that will result in extremely accurate detection and sensing.
This concentration-dependency, however, had not been fully understood. In order to fully utilize the capabilities of carbon dots, the mechanisms that govern the seemingly variable optical properties must first be uncovered. It was previously theorized that the concentration-dependency of carbon dots was due to a hydrogen bonding effect.
Now, a KAIST research team, led by Professor Do Hyun Kim of the Department of Chemical and Biomolecular Engineering has posited and demonstrated that the dual-color-emissiveness is instead due to the interparticle distances between each carbon dot. This study was made available online in June 2020 ahead of final publication in the 36th Issue of Physical Chemistry Chemical Physics on September 28, 2020.
First author of the paper, PhD candidate Hyo Jeong Yoo, along with Professor Kim and researcher Byeong Eun Kwak, examined how the relative light intensity of the red and blue colors changed when varying the interparticle distances, or concentration, of the carbon dots. They found that as the concentration was adjusted, the light emitted from the carbon dots would transform. By varying the concentration, the team was able to control the relative intensity of the colors, as well as emit them simultaneously to generate a white light from a single source (See Figure).
“The concentration-dependence of the photoluminescence of carbon dots on the change of the emissive origins for different interparticle distances has been overlooked in previous research. With the analysis of the dual-color-emission phenomenon of carbon dots, we believe that this result may provide a new perspective to investigate their photoluminescence mechanism,” Yoo explained.
The newly analyzed ability to control the photoluminescence of carbon dots will likely be heavily utilized in the continued development of solid-state lighting applications and sensing.
Publication:
Yoo, H. J., Kwak, B. E., and Kim. D. H. (2020) Interparticle distance as a key factor for controlling the dual-emission properties of carbon dots. Physical Chemistry Chemical Physics, Issue 36, Pages 20227-20237. Available online at https://doi.org/10.1039/d0cp02120b
Profile:
Do Hyun Kim, Sc.D.
Professor
dokim@kaist.ac.kr
http://procal.kaist.ac.kr/
Process Analysis Laboratory
Department of Chemical and Biomolecular Engineering
https://www.kaist.ac.kr
Korea Advanced Institute of Science and Technology (KAIST)Daejeon, Republic of Korea
(END)
2020.11.23 View 9281 -
What Fuels a “Domino Effect” in Cancer Drug Resistance?
KAIST researchers have identified mechanisms that relay prior acquired resistance to the first-line chemotherapy to the second-line targeted therapy, fueling a “domino effect” in cancer drug resistance. Their study featured in the February 7 edition of Science Advances suggests a new strategy for improving the second-line setting of cancer treatment for patients who showed resistance to anti-cancer drugs.
Resistance to cancer drugs is often managed in the clinic by chemotherapy and targeted therapy. Unlike chemotherapy that works by repressing fast-proliferating cells, targeted therapy blocks a single oncogenic pathway to halt tumor growth. In many cases, targeted therapy is engaged as a maintenance therapy or employed in the second-line after front-line chemotherapy.
A team of researchers led by Professor Yoosik Kim from the Department of Chemical and Biomolecular Engineering and the KAIST Institute for Health Science and Technology (KIHST) has discovered an unexpected resistance signature that occurs between chemotherapy and targeted therapy. The team further identified a set of integrated mechanisms that promotes this kind of sequential therapy resistance.
“There have been multiple clinical accounts reflecting that targeted therapies tend to be least successful in patients who have exhausted all standard treatments,” said the first author of the paper Mark Borris D. Aldonza. He continued, “These accounts ignited our hypothesis that failed responses to some chemotherapies might speed up the evolution of resistance to other drugs, particularly those with specific targets.”
Aldonza and his colleagues extracted large amounts of drug-resistance information from the open-source database the Genomics of Drug Sensitivity in Cancer (GDSC), which contains thousands of drug response data entries from various human cancer cell lines. Their big data analysis revealed that cancer cell lines resistant to chemotherapies classified as anti-mitotic drugs (AMDs), toxins that inhibit overacting cell division, are also resistant to a class of targeted therapies called epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs).
In all of the cancer types analyzed, more than 84 percent of those resistant to AMDs, representatively ‘paclitaxel’, were also resistant to at least nine EGFR-TKIs. In lung, pancreatic, and breast cancers where paclitaxel is often used as a first-line, standard-of-care regimen, greater than 92 percent showed resistance to EGFR-TKIs. Professor Kim said, “It is surprising to see that such collateral resistance can occur specifically between two chemically different classes of drugs.”
To figure out how failed responses to paclitaxel leads to resistance to EGFR-TKIs, the team validated co-resistance signatures that they found in the database by generating and analyzing a subset of slow-doubling, paclitaxel-resistant cancer models called ‘persisters’.
The results demonstrated that paclitaxel-resistant cancers remodel their stress response by first becoming more stem cell-like, evolving the ability to self-renew to adapt to more stressful conditions like drug exposures. More surprisingly, when the researchers characterized the metabolic state of the cells, EGFR-TKI persisters derived from paclitaxel-resistant cancer cells showed high dependencies to energy-producing processes such as glycolysis and glutaminolysis.
“We found that, without an energy stimulus like glucose, these cells transform to becoming more senescent, a characteristic of cells that have arrested cell division. However, this senescence is controlled by stem cell factors, which the paclitaxel-resistant cancers use to escape from this arrested state given a favorable condition to re-grow,” said Aldonza.
Professor Kim explained, “Before this research, there was no reason to expect that acquiring the cancer stem cell phenotype that dramatically leads to a cascade of changes in cellular states affecting metabolism and cell death is linked with drug-specific sequential resistance between two classes of therapies.”
He added, “The expansion of our work to other working models of drug resistance in a much more clinically-relevant setting, perhaps in clinical trials, will take on increasing importance, as sequential treatment strategies will continue to be adapted to various forms of anti-cancer therapy regimens.”
This study was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF-2016R1C1B2009886), and the KAIST Future Systems Healthcare Project (KAISTHEALTHCARE42) funded by the Korean Ministry of Science and ICT (MSIT). Undergraduate student Aldonza participated in this research project and presented the findings as the lead author as part of the Undergraduate Research Participation (URP) Program at KAIST.
< Figure 1. Schematic overview of the study. >
< Figure 2. Big data analysis revealing co-resistance signatures between classes of anti-cancer drugs. >
Publication:
Aldonza et al. (2020) Prior acquired resistance to paclitaxel relays diverse EGFR-targeted therapy persistence mechanisms. Science Advances, Vol. 6, No. 6, eaav7416. Available online at http://dx.doi.org/10.1126/sciadv.aav7416
Profile: Prof. Yoosik Kim, MA, PhD
ysyoosik@kaist.ac.kr
https://qcbio.kaist.ac.kr/
Assistant Professor
Bio Network Analysis Laboratory
Department of Chemical and Biomolecular Engineering
Korea Advanced Institute of Science and Technology (KAIST)
http://kaist.ac.kr
Daejeon, Republic of Korea
Profile: Mark Borris D. Aldonza
borris@kaist.ac.kr
Undergraduate Student
Department of Biological Sciences
Korea Advanced Institute of Science and Technology (KAIST)
http://kaist.ac.kr
Daejeon, Republic of Korea
(END)
2020.02.10 View 11671 -
Students from Science Academies Shed a Light on KAIST
Recent KAIST statistics show that graduates from science academies distinguish themselves not only by their academic performance at KAIST but also in various professional careers after graduation.
Every year, approximately 20% of newly-enrolled students of KAIST are from science academies. In the case of the class of 2017, 170 students from science academies accounted for 22% of the newly-enrolled students. Moreover, they are forming a top-tier student group on campus. As shown in the table below, the ratio of students graduating early for either enrolling in graduate programs or landing a job indicates their excellent performance at KAIST.
There are eight science academies in Korea: Korea Science Academy of KAIST located in Busan, Seoul Science High School, Gyeonggi Science High School, Gwangju Science High School, Daejeon Science High School, Sejong Academy of Science and Arts, and Incheon Arts and Sciences Academy.
Recently, KAIST analyzed 532 university graduates from the class of 2012. It was found that 23 out of 63 graduates with the alma mater of science academies finished their degree early; as a result, the early graduation ratio of the class of 2012 stood at 36.5%. This percentage was significantly higher than that of students from other high schools.
Among the notable graduates, there was a student who made headlines with donation of 30 million KRW to KAIST. His donation was the largest donation from an enrolled student on record. His story goes back when Android smartphones were about to be distributed. Seung-Gyu Oh, then a student in the School of Electrical Engineering felt that existing subway apps were inconvenient, so he invented his own subway app that navigated the nearest subway lines in 2015. His app hit the market and ranked second in the subway app category. It had approximately five million users, which led to it generating advertising revenue. After the successful launch of the app, Oh accepted the takeover offered by Daum Kakao. He then donated 30 million KRW to his alma mater. “Since high school, I’ve always been thinking that I have received many benefits from my country and felt heavily responsible for it,” the alumnus of Korea Science of Academy and KAIST said. “I decided to make a donation to my alma mater, KAIST because I wanted to return what I had received from my country.” After graduation, Oh is now working for the web firm, Daum Kakao.
In May 24, 2017, the 41st International Collegiate Programming Contest, hosted by Association for Computing Machinery (ACM) and sponsored by IBM, was held in Rapid City, South Dakota in the US. It is a prestigious contest that has been held annually since 1977. College students from around the world participate in this contest; and in 2017, a total of 50,000 students from 2,900 universities in 104 countries participated in regional competitions, and approximately 400 students made it to the final round, entering into a fierce competition. KAIST students also participated in this contest. The team was comprised of Ji-Hoon Ko, Jong-Won Lee, and Han-Pil Kang from the School of Computing. They are also alumni of Gyeonggi Science High School. They received the ‘First Problem Solver’ award and a bronze medal which came with a 3,000 USD cash prize.
Sung-Jin Oh, who also graduated from Korea Science Academy of KAIST, is a research professor at the Korea Institute of Advanced Study (KIAS). He is the youngest recipient of the ‘Young Scientist Award’, which he received by proving a hypothesis from Einstein’s Theory of General Relativity mathematically at the age of 27. After graduating from KAIST, Oh earned his master’s and doctorate degrees from Princeton University, completed his post-doctoral fellow at UC Berkeley, and is now immersing himself in research at KIAS.
Heui-Kwang Noh from the Department of Chemistry and Kang-Min Ahn from the School of Computing, who were selected to receive the presidential scholarship for science in 2014, both graduated from Gyeonggi Science High School. Noh was recognized for his outstanding academic capacity and was also chosen for the ‘GE Foundation Scholar-Leaders Program’ in 2015. The ‘GE Foundation Scholar-Leaders Program’, established in 1992 by the GE Foundation, aims at fostering talented students. This program is for post-secondary students who have both creativity and leadership. It selects five outstanding students and provides 3 million KRW per annum for a maximum of three years.
The grantees of this program have become influential people in various fields, including professors, executives, staff members of national/international firms, and researchers. And they are making a huge contribution to the development of engineering and science. Noh continues doing various activities, including the completion of his internship at ‘Harvard-MIT Biomedical Optics’ and the publication of a paper (3rd author) for the ACS Omega of American Chemical Society (ACS).
Ahn, a member of the Young Engineers Honor Society (YEHS) of the National Academy of Engineering of Korea, had an interest in startup businesses. In 2015, he founded DataStorm, a firm specializing in developing data solution, and merged with a cloud back-office, Jobis & Villains, in 2016. Ahn is continuing his business activities and this year he founded, and is successfully running, cocKorea.
“KAIST students whose alma mater are science academies form a top-tier group on campus and produce excellent performance,” said Associate Vice President for Admissions, Hayong Shin. “KAIST is making every effort to assist these students so that they can perform to the best of their ability.”
(Clockwise from top left: Seung-Gyu Oh, Sung-Jin Oh, Heui-Kwang Noh and Kang-Min Ahn)
2017.08.09 View 8017 -
Professor Lee Recognized by the KMS as Best Paper Awardee
Professor Ji Oon Lee of the Department of Mathematical Sciences was selected as the 2017 Best Paper Awardee by the Korean Mathematical Society. The award will be presented during the KMS spring meeting on April 29. Dr. Lee is being honored for proving a necessary and sufficient condition for the Tracy-Wisdom law of Wigner matrices. In a paper titled ‘A Necessary and Sufficient Condition for Edge Universality of Wigner Matrices,’ he proposed a solution for one of the many unanswered problems in the field of random matrix theory that have existed for decades. The paper, co-authored with Professor Jun Yin at the University of Wisconsin – Madison, was published in the Duke Mathematical Journal in 2014. Professor Lee joined KAIST in 2010 after finishing his Ph.D. at Harvard University. He was named a ‘POSCI Science Fellow’ and received the ‘Young Scientist Award’ from the KMS in 2014.
2017.04.27 View 7664 -
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 12206 -
Professor Haeng-Ki Lee appointed as "ICCES Distinguished Fellow"
Professor Haeng-Ki Lee
Professor Haeng-Ki Lee from the Department of Civil and Environmental Engineering at KAIST has been appointed as “Distinguished Fellow” and has also received the “Outstanding Research Award” at the International Conference on Computational & Experimental Engineering and Sciences (ICCES).
Founded in 1986, ICCES is regarded as one of the most prestigious international conferences in the field of computational mechanics and experimental engineering.
The Nominating Committee at ICCES recommends the appointment of a distinguished member who has made significant contributions to the development of computational mechanics and experimental engineering. Professor Lee was the first Korean who received such title. Furthermore, he was the recipient of the “Outstanding Research Award” presented by ICCES for his academic research on damage mechanics of complex systems.
Professor Lee is currently serving as the Head of the Department of Civil and Environmental Engineering at KAIST and the Director of BK Plus Agency, a Korean government’s research program. He received an award from the Minister of Science, ICT and Future Planning in 2013 for the promotion of science and technology.
2014.07.02 View 10304 -
KAIST-Saudi Nuclear Workforce Training
Nuclear Engineering Intensive Course Program Held in Saudi Arabia from January 5th to 23rd
KUSTAR (The Khalifa University of Science and Technology Studies)-KAIST Institute of Education began its Nuclear Engineering Intensive Course Program on 5th January with researchers from K.A.CARE (King Abdullah City for Atomic and Renewable Energy) of Riyadh, Saudi Arabia.
This program, which was lasted until 23rd January, provided education to students on the basic technologies in the field of nuclear power.
The course involves a wide range of lectures, such as basic nuclear physics, applications using radiation, nuclear reactor design and safety, as well as nuclear power engineering.
In order to utilize the nuclear power and renewable energy, K.A.CARE was established in April 2010. The institution is also involved in the construction of nuclear infrastructure, including the site investigations, the establishment of regulatory bodies and state-owned nuclear companies, along with the newly launched workforce-training program.
The Director of the KUSTAR-KAIST Education Research Institute, Professor Soong-Heung Jang said, “This program is the beginning of long-term cooperation with Saudi Arabia. Our experience can be the basis for the construction of an extensive training program that involves many areas of nuclear engineering field.”
KAIST has been working in close cooperation with various institutions around the world, which also includes the establishment of KUSTAR-KAIST Institute of Education and Research in July 2010. KAIST is also actively cooperating with UAE Khalifa University in Middle East, sharing faculty, holding joint research programs and exchanging students.
2014.02.03 View 9809