Chem
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Simultaneous Analysis of 21 Chemical Reactions... AI to Transform New Drug Development
< Photo 1. (From left) Professor Hyunwoo Kim and students Donghun Kim and Gyeongseon Choi in the Integrated M.S./Ph.D. program of the Department of Chemistry >
Thalidomide, a drug once used to alleviate morning sickness in pregnant women, exhibits distinct properties due to its optical isomers* in the body: one isomer has a sedative effect, while the other causes severe side effects like birth defects. As this example illustrates, precise organic synthesis techniques, which selectively synthesize only the desired optical isomer, are crucial in new drug development. Overcoming the traditional methods that struggled with simultaneously analyzing multiple reactants, our research team has developed the world's first technology to precisely analyze 21 types of reactants simultaneously. This breakthrough is expected to make a significant contribution to new drug development utilizing AI and robots.
*Optical Isomers: A pair of molecules with the same chemical formula that are mirror images of each other and cannot be superimposed due to their asymmetric structure. This is analogous to a left and right hand, which are similar in form but cannot be perfectly overlaid.
KAIST's Professor Hyunwoo Kim's research team in the Department of Chemistry announced on the 16th that they have developed an innovative optical isomer analysis technology suitable for the era of AI-driven autonomous synthesis*. This research is the world's first technology to precisely analyze asymmetric catalytic reactions involving multiple reactants simultaneously using high-resolution fluorine nuclear magnetic resonance spectroscopy (19F NMR). It is expected to make groundbreaking contributions to various fields, including new drug development and catalyst optimization.
*AI-driven Autonomous Synthesis: An advanced technology that automates and optimizes chemical substance synthesis processes using artificial intelligence (AI). It is gaining attention as a core element for realizing automated and intelligent research environments in future laboratories. AI predicts and adjusts experimental conditions, interprets results, and designs subsequent experiments independently, minimizing human intervention in repetitive experiments and significantly increasing research efficiency and innovativeness.
Currently, while autonomous synthesis systems can automate everything from reaction design to execution, reaction analysis still relies on individual processing using traditional equipment. This leads to slower speeds and bottlenecks, making it unsuitable for high-speed repetitive experiments.
Furthermore, multi-substrate simultaneous screening techniques proposed in the 1990s garnered attention as a strategy to maximize reaction analysis efficiency. However, limitations of existing chromatography-based analysis methods restricted the number of applicable substrates. In asymmetric synthesis reactions, which selectively synthesize only the desired optical isomer, simultaneously analyzing more than 10 types of substrates was nearly impossible.
< Figure 1. Conventional organic reaction evaluation methods follow a process of deriving optimal reaction conditions using a single substrate, then expanding the substrate scope one by one under those conditions, leaving potential reaction areas unexplored. To overcome this, high-throughput screening is introduced to broadly explore catalyst reactivity for various substrates. When combined with multi-substrate screening, this approach allows for a much broader and more systematic understanding of reaction scope and trends. >
To overcome these limitations, the research team developed a 19F NMR-based multi-substrate simultaneous screening technology. This method involves performing asymmetric catalytic reactions with multiple reactants in a single reaction vessel, introducing a fluorine functional group into the products, and then applying their self-developed chiral cobalt reagent to clearly quantify all optical isomers using 19F NMR.
Utilizing the excellent resolution and sensitivity of 19F NMR, the research team successfully performed asymmetric synthesis reactions of 21 substrates simultaneously in a single reaction vessel and quantitatively measured the product yield and optical isomer ratio without any separate purification steps.
Professor Hyunwoo Kim stated, "While anyone can perform asymmetric synthesis reactions with multiple substrates in one reactor, accurately analyzing all the products has been a challenging problem to solve until now. We expect that achieving world-class multi-substrate screening analysis technology will greatly contribute to enhancing the analytical capabilities of AI-driven autonomous synthesis platforms."
< Figure 2. A method for analyzing multi-substrate asymmetric catalytic reactions, where different substrates react simultaneously in a single reactor, using fluorine nuclear magnetic resonance has been implemented. By utilizing the characteristics of fluorine nuclear magnetic resonance, which has a clean background signal and a wide chemical shift range, the reactivity of each substrate can be quantitatively analyzed. It is also shown that the optical activity of all reactants can be simultaneously measured using a cobalt metal complex. >
He further added, "This research provides a technology that can rapidly verify the efficiency and selectivity of asymmetric catalytic reactions essential for new drug development, and it is expected to be utilized as a core analytical tool for AI-driven autonomous research."
< Figure 3. It can be seen that in a multi-substrate reductive amination reaction using a total of 21 substrates, the yield and optical activity of the reactants according to the catalyst system were simultaneously measured using a fluorine nuclear magnetic resonance-based analysis platform. The yield of each reactant is indicated by color saturation, and the optical activity by numbers. >
Donghun Kim (first author, Integrated M.S./Ph.D. program) and Gyeongseon Choi (second author, Integrated M.S./Ph.D. program) from the KAIST Department of Chemistry participated in this research. The study was published online in the Journal of the American Chemical Society on May 27, 2025.※ Paper Title: One-pot Multisubstrate Screening for Asymmetric Catalysis Enabled by 19F NMR-based Simultaneous Chiral Analysis※ DOI: 10.1021/jacs.5c03446
This research was supported by the National Research Foundation of Korea's Mid-Career Researcher Program, the Asymmetric Catalytic Reaction Design Center, and the KAIST KC30 Project.
< Figure 4. Conceptual diagram of performing multi-substrate screening reactions and utilizing fluorine nuclear magnetic resonance spectroscopy. >
2025.06.16 View 124 -
KAIST develops technology for selective RNA modification in living cells and animals
· A team led by Professor Won Do Heo from the Department of Biological Sciences, KAIST, has developed a pioneering technology that selectively acetylates specific RNA molecules in living cells and tissues.
· The platform uses RNA-targeting CRISPR tools in combination with RNA-modifying enzymes to chemically modify only the intended RNA.
· The method opens new possibilities for gene therapy by enabling precise control of disease-related RNA without affecting the rest of the transcriptome.
< Photo 1. (From left) Professor Won Do Heo and Jihwan Yu, a Ph.D. Candidate of the Department of Biological Sciences >
CRISPR-Cas13, a powerful RNA-targeting technology is gaining increasing attention as a next-generation gene therapy platform due to its precision and reduced side effects. Utilizing this system, researchers at KAIST have now developed the world’s first technology capable of selectively acetylating (chemically modifying) specific RNA molecules among countless transcripts within living cells. This breakthrough enables precise, programmable control of RNA function and is expected to open new avenues in RNA-based therapeutic development.
KAIST (President Kwang Hyung Lee) announced that a research team led by Professor Won Do Heo in the Department of Biological Sciences has recently developed a groundbreaking technology capable of selectively acetylating specific RNA molecules within the human body using the CRISPR-Cas13 system—an RNA-targeting platform gaining increasing attention in the fields of gene regulation and RNA-based therapeutics.
RNA molecules can undergo chemical modifications—the addition of specific chemical groups—which alter their function and behavior without changing the underlying nucleotide sequence. However, some of these modifications, a critical layer of post-transcriptional gene regulation, remain poorly understood. Among them, N4-acetylcytidine (ac4C) has been particularly enigmatic, with ongoing debate about its existence and function in human messenger RNA (mRNA), the RNA that encodes proteins.
To address this gap, the KAIST research team developed a targeted RNA acetylation system, named dCas13-eNAT10. This platform combines a catalytically inactive Cas13 enzyme (dCas13) that guides the system to specific RNA targets, with a hyperactive variant of the NAT10 enzyme (eNAT10), which performs RNA acetylation. This approach enables precise acetylation of only the desired RNA molecules among the vast pool of transcripts within the cell.
< Figure 1. Development of hyperactive variant eNAT10 through NAT10 protein engineering. By engineering the NAT10 protein, which performs RNA acetylation in human cells, based on its domain and structure, eNAT10 was developed, showing approximately a 3-fold increase in RNA acetylation activity compared to the wild-type enzyme. >
Using this system, the researchers demonstrated that guide RNAs could direct the dCas13-eNAT10 complex to acetylate specific RNA targets, and acetylation significantly increased protein expression from the modified mRNA. Moreover, the study revealed, for the first time, that RNA acetylation plays a role in intracellular RNA localization, facilitating the export of RNA from the nucleus to the cytoplasm—a critical step in gene expression regulation.
To validate its therapeutic potential, the team successfully delivered the targeted RNA acetylation system into the livers of live mice using adeno-associated virus (AAV), a commonly used gene therapy vector. This marks the first demonstration of in vivo RNA modification, extending the applicability of RNA chemical modification tools from cell culture models to living organisms.
< Figure 2. Acetylation of various RNA in cells using dCas13-eNAT10 fusion protein. Utilizing the CRISPR-Cas13 system, which can precisely target specific RNA through guide RNA, a dCas13-eNAT10 fusion protein was created, demonstrating its ability to specifically acetylate various endogenous RNA at different locations within cells. >
Professor Won Do Heo, who previously developed COVID-19 treatment technology using RNA gene scissors and technology to activate RNA gene scissors with light, stated, "Existing RNA chemical modification research faced difficulties in controlling specificity, temporality, and spatiality. However, this new technology allows selective acetylation of desired RNA, opening the door for accurate and detailed research into the functions of RNA acetylation." He added, "The RNA chemical modification technology developed in this study can be widely used as an RNA-based therapeutic agent and a tool for regulating RNA functions in living organisms in the future."
< Figure 3. In vivo delivery of targeted RNA acetylation system. The targeted RNA acetylation system was encoded in an AAV vector, commonly used in gene therapy, and delivered intravenously to adult mice, showing that target RNA in liver tissue was specifically acetylated according to the guide RNA. >
This research, with Ph.D. candidate Jihwan Yu from the Department of Biological Sciences at KAIST as the first author, was published in the journal Nature Chemical Biology on June 2, 2025. (Title: Programmable RNA acetylation with CRISPR-Cas13, Impact factor: 12.9, DOI: https://doi.org/10.1038/s41589-025-01922-3)
This research was supported by the Samsung Future Technology Foundation and the Bio & Medical Technology Development Program of the National Research Foundation of Korea.
2025.06.10 View 406 -
KAIST Research Team Develops Electronic Ink for Room-Temperature Printing of High-Resolution, Variable-Stiffness Electronics
A team of researchers from KAIST and Seoul National University has developed a groundbreaking electronic ink that enables room-temperature printing of variable-stiffness circuits capable of switching between rigid and soft modes. This advancement marks a significant leap toward next-generation wearable, implantable, and robotic devices.
< Photo 1. (From left) Professor Jae-Woong Jeong and PhD candidate Simok Lee of the School of Electrical Engineering, (in separate bubbles, from left) Professor Gun-Hee Lee of Pusan National University, Professor Seongjun Park of Seoul National University, Professor Steve Park of the Department of Materials Science and Engineering>
Variable-stiffness electronics are at the forefront of adaptive technology, offering the ability for a single device to transition between rigid and soft modes depending on its use case. Gallium, a metal known for its high rigidity contrast between solid and liquid states, is a promising candidate for such applications. However, its use has been hindered by challenges including high surface tension, low viscosity, and undesirable phase transitions during manufacturing.
On June 4th, a research team led by Professor Jae-Woong Jeong from the School of Electrical Engineering at KAIST, Professor Seongjun Park from the Digital Healthcare Major at Seoul National University, and Professor Steve Park from the Department of Materials Science and Engineering at KAIST introduced a novel liquid metal electronic ink. This ink allows for micro-scale circuit printing – thinner than a human hair – at room temperature, with the ability to reversibly switch between rigid and soft modes depending on temperature.
The new ink combines printable viscosity with excellent electrical conductivity, enabling the creation of complex, high-resolution multilayer circuits comparable to commercial printed circuit boards (PCBs). These circuits can dynamically change stiffness in response to temperature, presenting new opportunities for multifunctional electronics, medical technologies, and robotics.
Conventional electronics typically have fixed form factors – either rigid for durability or soft for wearability. Rigid devices like smartphones and laptops offer robust performance but are uncomfortable when worn, while soft electronics are more comfortable but lack precise handling. As demand grows for devices that can adapt their stiffness to context, variable-stiffness electronics are becoming increasingly important.
< Figure 1. Fabrication process of stable, high-viscosity electronic ink by dispersing micro-sized gallium particles in a polymer matrix (left). High-resolution large-area circuit printing process through pH-controlled chemical sintering (right). >
To address this challenge, the researchers focused on gallium, which melts just below body temperature. Solid gallium is quite stiff, while its liquid form is fluid and soft. Despite its potential, gallium’s use in electronic printing has been limited by its high surface tension and instability when melted.
To overcome these issues, the team developed a pH-controlled liquid metal ink printing process. By dispersing micro-sized gallium particles into a hydrophilic polyurethane matrix using a neutral solvent (dimethyl sulfoxide, or DMSO), they created a stable, high-viscosity ink suitable for precision printing. During post-print heating, the DMSO decomposes to form an acidic environment, which removes the oxide layer on the gallium particles. This triggers the particles to coalesce into electrically conductive networks with tunable mechanical properties.
The resulting printed circuits exhibit fine feature sizes (~50 μm), high conductivity (2.27 × 10⁶ S/m), and a stiffness modulation ratio of up to 1,465 – allowing the material to shift from plastic-like rigidity to rubber-like softness. Furthermore, the ink is compatible with conventional printing techniques such as screen printing and dip coating, supporting large-area and 3D device fabrication.
< Figure 2. Key features of the electronic ink. (i) High-resolution printing and multilayer integration capability. (ii) Batch fabrication capability through large-area screen printing. (iii) Complex three-dimensional structure printing capability through dip coating. (iv) Excellent electrical conductivity and stiffness control capability.>
The team demonstrated this technology by developing a multi-functional device that operates as a rigid portable electronic under normal conditions but transforms into a soft wearable healthcare device when attached to the body. They also created a neural probe that remains stiff during surgical insertion for accurate positioning but softens once inside brain tissue to reduce inflammation – highlighting its potential for biomedical implants.
< Figure 3. Variable stiffness wearable electronics with high-resolution circuits and multilayer structure comparable to commercial printed circuit boards (PCBs). Functions as a rigid portable electronic device at room temperature, then transforms into a wearable healthcare device by softening at body temperature upon skin contact.>
“The core achievement of this research lies in overcoming the longstanding challenges of liquid metal printing through our innovative technology,” said Professor Jeong. “By controlling the ink’s acidity, we were able to electrically and mechanically connect printed gallium particles, enabling the room-temperature fabrication of high-resolution, large-area circuits with tunable stiffness. This opens up new possibilities for future personal electronics, medical devices, and robotics.”
< Figure 4. Body-temperature softening neural probe implemented by coating electronic ink on an optical waveguide structure. (Left) Remains rigid during surgery for precise manipulation and brain insertion, then softens after implantation to minimize mechanical stress on the brain and greatly enhance biocompatibility. (Right) >
This research was published in Science Advances under the title, “Phase-Change Metal Ink with pH-Controlled Chemical Sintering for Versatile and Scalable Fabrication of Variable Stiffness Electronics.” The work was supported by the National Research Foundation of Korea, the Boston-Korea Project, and the BK21 FOUR Program.
2025.06.04 View 850 -
KAIST Develops Novel Catalyst With 100-Fold Platinum Efficiency
Propylene, a key building block used in producing plastics, textiles, automotive components, and electronics, is essential to the petrochemical industry. A KAIST research team has developed a novel catalyst that dramatically enhances the efficiency of propylene production while significantly reducing costs.
< Photo. Professor Minkee Choi (left), and Ph.D. Candidate Susung Lee (right) of the Department of Chemical and Biomolecular Engineering >
KAIST (represented by President Kwang-Hyung Lee) announced on the 12th of May that a research group led by Professor Minkee Choi from the Department of Chemical and Biomolecular Engineering has successfully developed a new catalyst using inexpensive metals—gallium (Ga) and alumina (Al₂O₃)—with only a trace amount of platinum (100 ppm, or 0.01%). Remarkably, this new catalyst outperforms conventional industrial catalysts that use high concentrations of platinum (10,000 ppm).
Propylene is commonly produced through the propane dehydrogenation (PDH) process, which removes hydrogen from propane. Platinum has long been used as a catalyst in PDH due to its high efficiency in breaking carbon-hydrogen bonds and facilitating hydrogen removal. However, platinum is costly and suffers from performance degradation over repeated use.
To address this, the KAIST team engineered a catalyst that incorporates only a minimal amount of platinum, relying on gallium and alumina as the primary components.
< Figure 1. Schematic diagram showing the catalytic cooperation between gallium (Ga) and platinum (Pt) >
The core mechanism of the catalyst involves a cooperative function between the metals: gallium activates the C–H bond in propane to produce propylene, while platinum bonds the residual hydrogen atoms on the surface to form hydrogen gas (H₂), which is then released. This division of roles allows for high catalytic efficiency despite the drastic reduction in platinum content.
The researchers identified an optimal platinum-to-gallium ratio that delivered peak performance and provided a scientific rationale and quantitative metrics to predict this ideal composition.
Additionally, the team addressed a major limitation of traditional platinum catalysts: sintering—the agglomeration of platinum particles during repeated use, which causes performance loss. By adding a small amount of cerium (Ce), the researchers successfully suppressed this aggregation. As a result, the new catalyst maintained stable performance even after more than 20 reaction-regeneration cycles.
< Figure 2. Performance comparison of KAIST's newly developed catalyst (100 ppm platinum) and existing commercial platinum catalyst (10,000 ppm platinum) >
Professor Choi stated, “This research demonstrates the possibility of reducing platinum usage to 1/100th of current levels without compromising, and even enhancing, performance. It presents significant economic and environmental advantages, including lower catalyst costs, extended replacement intervals, and reduced catalyst waste.”
He added, “We are planning to evaluate this technology for large-scale process demonstration and commercialization. If adopted in industry, it could greatly improve the economic viability and efficiency of propylene production.”
The study was led by Professor Minkee Choi as corresponding author, with Ph.D. candidate Susung Lee as the first author. The findings were published in the Journal of the American Chemical Society (JACS), a leading journal in chemistry and chemical engineering, on February 13.※ Paper title: Ideal Bifunctional Catalysis for Propane Dehydrogenation over Pt-Promoted Gallia-Alumina and Minimized Use of Precious Elements※ DOI: https://pubs.acs.org/doi/10.1021/jacs.4c13787
The research was supported by the National Research Foundation of Korea and Hanwha Solutions Corporation.
2025.05.12 View 898 -
KAIST Develops Eco-Friendly, Nylon-Like Plastic Using Microorganisms
Poly(ester amide) amide is a next-generation material that combines the advantages of PET (polyester) and nylon (polyamide), two widely used plastics. However, it could only be produced from fossil fuels, which posed environmental concerns. Using microorganisms, KAIST researchers have successfully developed a new bio-based plastic to replace conventional plastic.
KAIST (represented by President Kwang Hyung Lee) announced on the 20th of March that a research team led by Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering has developed microbial strains through systems metabolic engineering to produce various eco-friendly, bio-based poly(ester amide)s. The team collaborated with researchers from the Korea Research Institute of Chemical Technology (KRICT, President Young-Kook Lee) to analyze and confirm the properties of the resulting plastic.
Professor Sang Yup Lee’s research team designed new metabolic pathways that do not naturally exist in microorganisms, and developed a platform microbial strain capable of producing nine different types of poly(ester amide)s, including poly(3-hydroxybutyrate-ran-3-aminopropionate) and poly(3-hydroxybutyrate-ran-4-aminobutyrate).
Using glucose derived from abundant biomass sources such as waste wood and weeds, the team successfully produced poly(ester amide)s in an eco-friendly manner. The researchers also confirmed the potential for industrial-scale production by demonstrating high production efficiency (54.57 g/L) using fed-batch fermentation of the engineered strain.
In collaboration with researchers Haemin Jeong and Jihoon Shin from KRICT, the KAIST team analyzed the properties of the bio-based plastic and found that it exhibited characteristics similar to high-density polyethylene (HDPE). This means the new plastic is not only eco-friendly but also strong and durable enough to replace conventional plastics.
The engineered strains and strategies developed in this study are expected to be useful not only for producing various poly(ester amide)s but also for constructing metabolic pathways for the biosynthesis of other types of polymers.
Professor Sang Yup Lee stated, “This study is the first to demonstrate the possibility of producing poly(ester amide)s (plastics) through a renewable bio-based chemical process rather than relying on the petroleum-based chemical industry. We plan to further enhance the production yield and efficiency through continued research.”
The study was published online on March 17 in the international journal Nature Chemical Biology.
·Title: Biosynthesis of poly(ester amide)s in engineered Escherichia coli
·DOI: 10.1038/s41589-025-01842-2
·Authors: A total of seven authors including Tong Un Chae (KAIST, first author), So Young Choi (KAIST, second author), Da-Hee Ahn (KAIST, third author), Woo Dae Jang (KAIST, fourth author), Haemin Jeong (KRICT, fifth author), Jihoon Shin (KRICT, sixth author), and Sang Yup Lee (KAIST, corresponding author).
This research was supported by the Ministry of Science and ICT (MSIT) under the Eco-Friendly Chemical Technology Development Project as part of the "Next-Generation Biorefinery Technology Development to Lead the Bio-Chemical Industry" initiative (project led by Distinguished Professor Sang Yup Lee at KAIST).
2025.03.24 View 3863 -
KAIST Captures Hot Holes: A Breakthrough in Light-to-Electricity Energy Conversion
When light interacts with metallic nanostructures, it instantaneously generates plasmonic hot carriers, which serve as key intermediates for converting optical energy into high-value energy sources such as electricity and chemical energy. Among these, hot holes play a crucial role in enhancing photoelectrochemical reactions. However, they thermally dissipate within picoseconds (trillionths of a second), making practical applications challenging. Now, a Korean research team has successfully developed a method for sustaining hot holes longer and amplifying their flow, accelerating the commercialization of next-generation, high-efficiency, light-to-energy conversion technologies.
KAIST (represented by President Kwang Hyung Lee) announced on the 12th of March that a research team led by Distinguished Professor Jeong Young Park from the Department of Chemistry, in collaboration with Professor Moonsang Lee from the Department of Materials Science and Engineering at Inha University, has successfully amplified the flow of hot holes and mapped local current distribution in real time, thereby elucidating the mechanism of photocurrent enhancement.
The team designed a nanodiode structure by placing a metallic nanomesh on a specialized semiconductor substrate (p-type gallium nitride) to facilitate hot hole extraction at the surface. As a result, in gallium nitride substrates aligned with the hot hole extraction direction, the flow of hot holes was amplified by approximately two times compared to substrates aligned in other directions.
To fabricate the Au nanomesh, a polystyrene nano-bead monolayer assembly was first placed on a gallium nitride (p-GaN) substrate, and then the polystyrene nano-beads were etched to form a nanomesh template (Figure 1A). Then, a 20 nm thick gold nano-film was deposited, and the etched polystyrene nano-beads were removed to realize the gold nano-mesh structure on the GaN substrate (Figure 1B). The fabricated Au nanomesh exhibited strong light absorption in the visible range due to the plasmonic resonance effect (Figure 1C). >
Furthermore, using a photoconductive atomic force microscopy (pc-AFM)-based photocurrent mapping system, the researchers analyzed the flow of hot holes in real time at the nanometer scale (one hundred-thousandth the thickness of a human hair). They observed that hot hole activation was strongest at "hot spots," where light was locally concentrated on the gold nanomesh. However, by modifying the growth direction of the gallium nitride substrate, hot hole activation extended beyond the hot spots to other areas as well.
Through this research, the team discovered an efficient method for converting light into electrical and chemical energy. This breakthrough is expected to significantly advance next-generation solar cells, photocatalysts, and hydrogen production technologies.
Professor Jeong Young Park stated, "For the first time, we have successfully controlled the flow of hot holes using a nanodiode technique. This innovation holds great potential for various optoelectronic devices and photocatalytic applications. For example, it could lead to groundbreaking advancements in solar energy conversion technologies, such as solar cells and hydrogen production. Additionally, the real-time analysis technology we developed can be applied to the development of ultra-miniaturized optoelectronic devices, including optical sensors and nanoscale semiconductor components."
The study was led by Hyunhwa Lee (PhD., KAIST Department of Chemistry) and Yujin Park (Postdoc Researcher, University of Texas at Austin Department of Chemical Engineering) as co-first authors and Professors Moonsang Lee (Inha University, Department of Materials Science and Engineering) and Jeong Young Park (KAIST, Department of Chemistry) serving as corresponding authors. The research findings were published online in Science Advances on March 7.
(Paper Title: “Reconfiguring hot-hole flux via polarity modulation of p-GaN in plasmonic Schottky architectures”, DOI: https://www.science.org/doi/10.1126/sciadv.adu0086)
This research was supported by the National Research Foundation of Korea (NRF).
2025.03.17 View 3102 -
KAIST Develops Wearable Carbon Dioxide Sensor to Enable Real-time Apnea Diagnosis
- Professor Seunghyup Yoo’s research team of the School of Electrical Engineering developed an ultralow-power carbon dioxide (CO2) sensor using a flexible and thin organic photodiode, and succeeded in real-time breathing monitoring by attaching it to a commercial mask
- Wearable devices with features such as low power, high stability, and flexibility can be utilized for early diagnosis of various diseases such as chronic obstructive pulmonary disease and sleep apnea
< Photo 1. From the left, School of Electrical Engineering, Ph.D. candidate DongHo Choi, Professor Seunghyup Yoo, and Department of Materials Science and Engineering, Bachelor’s candidate MinJae Kim >
Carbon dioxide (CO2) is a major respiratory metabolite, and continuous monitoring of CO2 concentration in exhaled breath is not only an important indicator for early detection and diagnosis of respiratory and circulatory system diseases, but can also be widely used for monitoring personal exercise status. KAIST researchers succeeded in accurately measuring CO2 concentration by attaching it to the inside of a mask.
KAIST (President Kwang-Hyung Lee) announced on February 10th that Professor Seunghyup Yoo's research team in the Department of Electrical and Electronic Engineering developed a low-power, high-speed wearable CO2 sensor capable of stable breathing monitoring in real time.
Existing non-invasive CO2 sensors had limitations in that they were large in size and consumed high power. In particular, optochemical CO2 sensors using fluorescent molecules have the advantage of being miniaturized and lightweight, but due to the photodegradation phenomenon of dye molecules, they are difficult to use stably for a long time, which limits their use as wearable healthcare sensors.
Optochemical CO2 sensors utilize the fact that the intensity of fluorescence emitted from fluorescent molecules decreases depending on the concentration of CO2, and it is important to effectively detect changes in fluorescence light.
To this end, the research team developed a low-power CO2 sensor consisting of an LED and an organic photodiode surrounding it. Based on high light collection efficiency, the sensor, which minimizes the amount of excitation light irradiated on fluorescent molecules, achieved a device power consumption of 171 μW, which is tens of times lower than existing sensors that consume several mW.
< Figure 1. Structure and operating principle of the developed optochemical carbon dioxide (CO2) sensor. Light emitted from the LED is converted into fluorescence through the fluorescent film, reflected from the light scattering layer, and incident on the organic photodiode. CO2 reacts with a small amount of water inside the fluorescent film to form carbonic acid (H2CO3), which increases the concentration of hydrogen ions (H+), and the fluorescence intensity due to 470 nm excitation light decreases. The circular organic photodiode with high light collection efficiency effectively detects changes in fluorescence intensity, lowers the power required light up the LED, and reduces light-induced deterioration. >
The research team also elucidated the photodegradation path of fluorescent molecules used in CO2 sensors, revealed the cause of the increase in error over time in photochemical sensors, and suggested an optical design method to suppress the occurrence of errors.
Based on this, the research team developed a sensor that effectively reduces errors caused by photodegradation, which was a chronic problem of existing photochemical sensors, and can be used continuously for up to 9 hours while existing technologies based on the same material can be used for less than 20 minutes, and can be used multiple times when replacing the CO2 detection fluorescent film.
< Figure 2. Wearable smart mask and real-time breathing monitoring. The fabricated sensor module consists of four elements (①: gas-permeable light-scattering layer, ②: color filter and organic photodiode, ③: light-emitting diode, ④: CO2-detecting fluorescent film). The thin and light sensor (D1: 400 nm, D2: 470 nm) is attached to the inside of the mask to monitor the wearer's breathing in real time. >
The developed sensor accurately measured CO2 concentration by being attached to the inside of a mask based on the advantages of being light (0.12 g), thin (0.7 mm), and flexible. In addition, it showed fast speed and high resolution that can monitor respiratory rate by distinguishing between inhalation and exhalation in real time.
< Photo 2. The developed sensor attached to the inside of the mask >
Professor Seunghyup Yoo said, "The developed sensor has excellent characteristics such as low power, high stability, and flexibility, so it can be widely applied to wearable devices, and can be used for the early diagnosis of various diseases such as hypercapnia, chronic obstructive pulmonary disease, and sleep apnea." He added, "In particular, it is expected to be used to improve side effects caused by rebreathing in environments where dust is generated or where masks are worn for long periods of time, such as during seasonal changes."
This study, in which KAIST's Department of Materials Science and Engineering's undergraduate student Minjae Kim and School of Electrical Engineering's doctoral student Dongho Choi participated as joint first authors, was published in the online version of Cell's sister journal, Device, on the 22nd of last month. (Paper title: Ultralow-power carbon dioxide sensor for real-time breath monitoring) DOI: https://doi.org/10.1016/j.device.2024.100681
< Photo 3. From the left, Professor Seunghyup Yoo of the School of Electrical Engineering, MinJae Kim, an undergraduate student in the Department of Materials Science and Engineering, and Dongho Choi, a doctoral student in the School of Electrical Engineering >
This study was supported by the Ministry of Trade, Industry and Energy's Materials and Components Technology Development Project, the National Research Foundation of Korea's Original Technology Development Project, and the KAIST Undergraduate Research Participation Project. This work was supported by the (URP) program.
2025.02.13 View 5308 -
“Cross-Generation Collaborative Labs” for Semiconductor, Chemistry, and Computer Science Opened
< Photo of Professor Hoi-Jun Yoo (center) of the School of Electrical Engineering at the signboard unveiling ceremony >
KAIST held a ceremony to mark the opening of three additional ‘Cross-Generation Collaborative Labs’ on the morning of January 7th, 2025.
The “Next-Generation AI Semiconductor System Lab” by Professor Hoi-Jun Yoo of the School of Electrical Engineering, the “Molecular Spectroscopy and Chemical Dynamics Lab” by Professor Sang Kyu Kim of the Department of Chemistry, and the “Advanced Data Computing Lab” by Professor Sue Bok Moon of the School of Computer Science are the three new labs given the honored titled of the “Cross-Generation Collaborative Lab”.
The Cross-Generation Collaborative Lab is KAIST’s unique system that was set up to facilitate the collaboration between retiring professors and junior professors to continue the achievements and know-how the elders have accumulated over their academic career. Since its introduction in 2018, nine labs have been named to be the Cross-Generation Labs, and this year’s new addition brings the total up to twelve.
The ‘Next-Generation AI Semiconductor System Lab’ led by Professor Hoi-Jun Yoo will be operated by Professor Joo-Young Kim of the same school.
Professor Hoi-Jun Yoo is a world-renowned scholar with outstanding research achievements in the field of on-device AI semiconductor design. Professor Joo-Young Kim is an up-and-coming researcher studying large language models and design of AI semiconductors for server computers, and is currently researching technologies to design PIM (Processing-in-Memory), a core technology in the field of AI semiconductors.
Their research goal is to systematically collaborate and transfer next-generation AI semiconductor design technology, including brain-mimicking AI algorithms such as deep neural networks and generative AI, to integrate core technologies, and to maximize the usability of R&D outputs, thereby further solidifying the position of Korean AI semiconductor companies in the global market.
Professor Hoi-Jun Yoo said, “I believe that, we will be able to present a development direction of for the next-generation AI semiconductors industries at home and abroad through collaborative research and play a key role in transferring and expanding global leadership.”
< Professor Sang Kyu Kim of the Department of Chemistry (middle), at the signboard unveiling ceremony for his laboratory >
The “Molecular Spectroscopy and Chemical Dynamics Laboratory”, where Professor Sang Kyu Kim of the Department of Chemistry is in charge, will be operated by Professor Tae Kyu Kim of the same department, and another professor in the field of spectroscopy and dynamics will join in the future.
Professor Sang Kyu Kim has secured technologies for developing unique experimental equipment based on ultrashort lasers and supersonic molecular beams, and is a world leader who has been creatively pioneering new fields of experimental physical chemistry.
The research goal is to describe chemical reactions and verify from a quantum mechanical perspective and introduce new theories and technologies to pursue a complete understanding of the principles of chemical reactions. In addition, the accompanying basic scientific knowledge will be applied to the design of new materials.
Professor Sang Kyu Kim said, “I am very happy to be able to pass on the research infrastructure to the next generation through this system, and I will continue to nurture it to grow into a world-class research lab through trans-generational collaborative research.”
< Photo of Professor Sue Bok Moon (center) at the signboard unveiling ceremony by the School of Computing >
Lastly, the “Advanced Data Computing Lab” led by Professor Sue Bok Moon is joined by Professor Mee Young Cha of the same school and Professor Wonjae Lee of the Graduate School of Culture Technology.
Professor Sue Bok Moon showed the infinite possibilities of large-scale data-based social network research through Cyworld, YouTube, and Twitter, and had a great influence on related fields beyond the field of computer science.
Professor Mee Young Cha is a data scientist who analyzes difficult social issues such as misinformation, poverty, and disaster detection using big data-based AI. She is the first Korean to be recognized for her achievements as the director of the Max Planck Institute in Germany, a world-class basic science research institute. Therefore, there is high expectation for synergy effects from overseas collaborative research and technology transfer and sharing among the participating professors of the collaborative research lab. Professor Wonjae Lee is researching dynamic interaction analysis between science and technology using structural topic models.
They plan to conduct research aimed at improving the analysis and understanding of negative influences occurring online, and in particular, developing a hateful precursor detection model using emotions and morality to preemptively block hateful expressions.
Professor Sue Bok Moon said, “Through this collaborative research lab, we will play a key role in conducting in-depth collaborative research on unexpected negative influences in the AI era so that we can have a high level of competitiveness worldwide.”
The ceremonies for the unveiling of the new Cross-Generation Collaborative Lab signboard were held in front of each lab from 10:00 AM on the 7th, in the attendance of President Kwang Hyung Lee, Senior Vice President for Research Sang Yup Lee, and other key officials of KAIST and the new staff members to join the laboratories.
2025.01.07 View 3903 -
KAIST Researchers Introduce New and Improved, Next-Generation Perovskite Solar Cell
- KAIST-Yonsei university researchers developed innovative dipole technology to maximize near-infrared photon harvesting efficiency
- Overcoming the shortcoming of existing perovskite solar cells that cannot utilize approximately 52% of total solar energy
- Development of next-generation solar cell technology with high efficiency and high stability that can absorb near-infrared light beyond the existing visible light range with a perovskite-dipole-organic semiconductor hybrid structure
< Photo. (From left) Professor Jung-Yong Lee, Ph.D. candidate Min-Ho Lee, and Master’s candidate Min Seok Kim of the School of Electrical Engineering >
Existing perovskite solar cells, which have the problem of not being able to utilize approximately 52% of total solar energy, have been developed by a Korean research team as an innovative technology that maximizes near-infrared light capture performance while greatly improving power conversion efficiency. This greatly increases the possibility of commercializing next-generation solar cells and is expected to contribute to important technological advancements in the global solar cell market.
The research team of Professor Jung-Yong Lee of the School of Electrical Engineering at KAIST (President Kwang-Hyung Lee) and Professor Woojae Kim of the Department of Chemistry at Yonsei University announced on October 31st that they have developed a high-efficiency and high-stability organic-inorganic hybrid solar cell production technology that maximizes near-infrared light capture beyond the existing visible light range.
The research team suggested and advanced a hybrid next-generation device structure with organic photo-semiconductors that complements perovskite materials limited to visible light absorption and expands the absorption range to near-infrared.
In addition, they revealed the electronic structure problem that mainly occurs in the structure and announced a high-performance solar cell device that dramatically solved this problem by introducing a dipole layer*.
*Dipole layer: A thin material layer that controls the energy level within the device to facilitate charge transport and forms an interface potential difference to improve device performance.
Existing lead-based perovskite solar cells have a problem in that their absorption spectrum is limited to the visible light region with a wavelength of 850 nanometers (nm) or less, which prevents them from utilizing approximately 52% of the total solar energy.
To solve this problem, the research team designed a hybrid device that combined an organic bulk heterojunction (BHJ) with perovskite and implemented a solar cell that can absorb up to the near-infrared region.
In particular, by introducing a sub-nanometer dipole interface layer, they succeeded in alleviating the energy barrier between the perovskite and the organic bulk heterojunction (BHJ), suppressing charge accumulation, maximizing the contribution to the near-infrared, and improving the current density (JSC) to 4.9 mA/cm².
The key achievement of this study is that the power conversion efficiency (PCE) of the hybrid device has been significantly increased from 20.4% to 24.0%. In particular, this study achieved a high internal quantum efficiency (IQE) compared to previous studies, reaching 78% in the near-infrared region.
< Figure. The illustration of the mechanism of improving the electronic structure and charge transfer capability through Perovskite/organic hybrid device structure and dipole interfacial layers (DILs). The proposed dipole interfacial layer forms a strong interfacial dipole, effectively reducing the energy barrier between the perovskite and organic bulk heterojunction (BHJ), and suppressing hole accumulation. This technology improves near-infrared photon harvesting and charge transfer, and as a result, the power conversion efficiency of the solar cell increases to 24.0%. In addition, it achieves excellent stability by maintaining performance for 1,200 hours even in an extremely humid environment. >
In addition, this device showed high stability, showing excellent results of maintaining more than 80% of the initial efficiency in the maximum output tracking for more than 800 hours even under extreme humidity conditions.
Professor Jung-Yong Lee said, “Through this study, we have effectively solved the charge accumulation and energy band mismatch problems faced by existing perovskite/organic hybrid solar cells, and we will be able to significantly improve the power conversion efficiency while maximizing the near-infrared light capture performance, which will be a new breakthrough that can solve the mechanical-chemical stability problems of existing perovskites and overcome the optical limitations.”
This study, in which KAIST School of Electrical Engineering Ph.D. candidate Min-Ho Lee and Master's candidate Min Seok Kim participated as co-first authors, was published in the September 30th online edition of the international academic journal Advanced Materials. (Paper title: Suppressing Hole Accumulation Through Sub-Nanometer Dipole Interfaces in Hybrid Perovskite/Organic Solar Cells for Boosting Near-Infrared Photon Harvesting).
This study was conducted with the support of the National Research Foundation of Korea.
2024.10.31 View 5901 -
KAIST Develops Technology for the Precise Diagnosis of Electric Vehicle Batteries Using Small Currents
Accurately diagnosing the state of electric vehicle (EV) batteries is essential for their efficient management and safe use. KAIST researchers have developed a new technology that can diagnose and monitor the state of batteries with high precision using only small amounts of current, which is expected to maximize the batteries’ long-term stability and efficiency.
KAIST (represented by President Kwang Hyung Lee) announced on the 17th of October that a research team led by Professors Kyeongha Kwon and Sang-Gug Lee from the School of Electrical Engineering had developed electrochemical impedance spectroscopy (EIS) technology that can be used to improve the stability and performance of high-capacity batteries in electric vehicles.
EIS is a powerful tool that measures the impedance* magnitude and changes in a battery, allowing the evaluation of battery efficiency and loss. It is considered an important tool for assessing the state of charge (SOC) and state of health (SOH) of batteries. Additionally, it can be used to identify thermal characteristics, chemical/physical changes, predict battery life, and determine the causes of failures. *Battery Impedance: A measure of the resistance to current flow within the battery that is used to assess battery performance and condition.
However, traditional EIS equipment is expensive and complex, making it difficult to install, operate, and maintain. Moreover, due to sensitivity and precision limitations, applying current disturbances of several amperes (A) to a battery can cause significant electrical stress, increasing the risk of battery failure or fire and making it difficult to use in practice.
< Figure 1. Flow chart for diagnosis and prevention of unexpected combustion via the use of the electrochemical impedance spectroscopy (EIS) for the batteries for electric vehicles. >
To address this, the KAIST research team developed and validated a low-current EIS system for diagnosing the condition and health of high-capacity EV batteries. This EIS system can precisely measure battery impedance with low current disturbances (10mA), minimizing thermal effects and safety issues during the measurement process.
In addition, the system minimizes bulky and costly components, making it easy to integrate into vehicles. The system was proven effective in identifying the electrochemical properties of batteries under various operating conditions, including different temperatures and SOC levels.
Professor Kyeongha Kwon (the corresponding author) explained, “This system can be easily integrated into the battery management system (BMS) of electric vehicles and has demonstrated high measurement accuracy while significantly reducing the cost and complexity compared to traditional high-current EIS methods. It can contribute to battery diagnosis and performance improvements not only for electric vehicles but also for energy storage systems (ESS).”
This research, in which Young-Nam Lee, a doctoral student in the School of Electrical Engineering at KAIST participated as the first author, was published in the prestigious international journal IEEE Transactions on Industrial Electronics (top 2% in the field; IF 7.5) on September 5th. (Paper Title: Small-Perturbation Electrochemical Impedance Spectroscopy System With High Accuracy for High-Capacity Batteries in Electric Vehicles, Link: https://ieeexplore.ieee.org/document/10666864)
< Figure 2. Impedance measurement results of large-capacity batteries for electric vehicles. ZEW (commercial EW; MP10, Wonatech) versus ZMEAS (proposed system) >
This research was supported by the Basic Research Program of the National Research Foundation of Korea, the Next-Generation Intelligent Semiconductor Technology Development Program of the Korea Evaluation Institute of Industrial Technology, and the AI Semiconductor Graduate Program of the Institute of Information & Communications Technology Planning & Evaluation.
2024.10.17 View 5375 -
Novel High-performance and Sustainable Paper Coating Material created by KAIST-Yonsei University Research Team to reduce microplastic pollution
What if there is a biodegradable packaging material with high performance without leaving microplastics?
Plastic pollution presents a global challenge that must be solved. In particular, packaging accounts for 30-50% of the total plastic consumption. While paper packaging is eco-friendly, it lacks crucial functionalities like moisture resistance and strength. Traditional coating materials exacerbate plastic pollution, prompting the need for sustainable alternatives.
Polyethylene (PE) and ethylene vinyl alcohol (EVOH) are typically used as coating materials to improve the low barrier properties of paper packaging, but these substances do not decompose and worsen microplastic pollution when disposed of in the natural environment. In response to this problem, packaging materials made from bio-based substances and biodegradable plastics have been developed, but in most cases, as the packaging performance improves, the biodegradability diminishes rapidly.
KAIST announced that a joint research team led by Professor Jaewook Myung of the Department of Civil and Environmental Engineering, Professor Hanseul Yang of the Department of Life Sciences, and Professor Jongcheol Seo of the Department of Packaging and Logistics <Figure 4. Back cover art of Green Chemistry journal of the latest volume, describing the boric acid cross-linked poly(vinyl alcohol) coated paper featuring marine biodegradability, biocompatibility, high barrier properties, and robustness developed through this study.>
at Yonsei University tackled the challenge of balancing packaging performance and sustainability. They successfully developed a sustainable, marine biodegradable, high-performance paper coating material.
* Biodegradable plastic: A plastic that can be decomposed by microorganisms in natural environments such as soil and ocean or artificial conditions such as industrial composting and anaerobic digestion by microorganisms.
*Microplastics: Tiny pieces of plastic less than 5 mm, produced during the decomposition of bulk plastic materials. Microplastics can persist in the sea for more than decades, causing severe marine pollution.
The team utilized boric acid-crosslinked poly(vinyl alcohol) (PVA), a biodegradable plastic, to coat the paper, thereby enhancing its biodegradability, barrier properties, and strength. The resulting coated paper exhibited superior performance compared to conventional plastics, with excellent barrier properties and physical strength, even in humid conditions.
<Figure 1. (a) Chemical structure of boric acid-crosslinked poly(vinyl alcohol) coating on paper, (b-c) Oxygen and water vapor barrier properties, (d-f) Tensile strength in dry and moist conditions. OTR: Oxygen transmission rate, WVTR: Water vapor transmission rate.>
The team also conducted an in-depth examination of biodegradation and biocompatibility to systematically evaluate the sustainability of the newly developed coated paper. Biodegradation was assessed by simulating the marine environment, known for its challenging biodegradability conditions. The team employed a respiratory system-based bioreactor to measure the degree of carbon mineralization into carbon dioxide. After 111 days of biodegradation, it was found that the coated papers achieved 59-82% biodegradation depending on the coating component. The phenomenon in which marine bacteria are decomposing the coating material was captured through a scanning electron microscope. In addition, in vitro biocompatibility was confirmed through human embryonic kidney and mouse embryonic fibroblast cells, as well as high in-vivo biocompatibility of the coated paper was verified through mouse experiments.
Through this study, the joint research team proposed a coating strategy that can improve packaging performance while upholding sustainability to address the drawbacks of paper packaging. The boric acid-crosslinked PVA-coated paper eliminates the need for artificial composting conditions or sewage treatment facilities. Being biodegradable in natural environments and characterized by low toxicity, this newly coated paper does not exacerbate environmental pollution when accidentally discarded. Thus, it presents a sustainable substitute for plastic packaging materials.
<Figure 2. (a) Normal paper and boric acid-crosslinked poly(vinyl alcohol) coated paper, (b) Biodegradation of the coated paper by marine bacteria, (c) Result of cytotoxicity test using human embryonic kidney and mouse embryonic fibroblast cells. (d) Vital organs after one-month exposure of the coated papers to mice.>
Professor Jaewook Myung at KAIST, who led the sustainability study of coated paper, said, "The development of a marine biodegradable high-performance paper coating is the result of combining the innovative technologies of three leading research teams in each field." He said, “We will continue to develop sustainable materials with excellent performance.” Meanwhile, Professor Jongchul Seo of Yonsei University, who led the research on the development of high-performance paper coating, mentioned, “Through this research, we have developed a sustainable paper packaging technology that can replace non-degradable plastic packaging, and we expect the research outcome will be applied in industry,”.
<Figure 3. End-of-life scenario of papers coated by BA-crosslinked PVA in the marine environment. The coated papers potentially be disintegrated by marine microorganisms and ocean waves and tides. The depolymerization of PVA coating and paper is then mediated by extracellular depolymerases such as oxidases and cellulases, after which the small subunits (oligomers and monomers) are assimilated by microbial cells. The carbon components in the coated papers are ultimately mineralized into CO2, posing no harm in the ocean.>
The work was published in Green Chemistry and Food Chemistry journals. This study was conducted with the support of the Korea Research Foundation and the Korea Institute for Agriculture, Food and Rural Affairs Technology Planning and Evaluation, etc.
*Title of paper published in Green Chemistry: Boric acid-crosslinked poly(vinyl alcohol): biodegradable, biocompatible, robust, and high-barrier paper coating
※ Selected as the article for the back cover of the journal .
- Authors: Shinhyeong Choe, Seulki You, Kitae Park, Youngju Kim, Jehee Park, Yongjun Cho, Jongchul Seo, Hanseul Yang, and Jaewook Myung)
- Date: April 17, 2024
- DOI: 10.1039/D4GC00618F
*Title of paper published in Food Chemistry: Effect of epichlorohydrin treatment on the coating process and performance of high-barrier paper packaging
- Authors: Kitae Park, Shinhyeong Choe, Kambiz Sadeghi, Pradeep Kumar Panda, Jaewook Myung, Dowan Kim, and Jongchul Seo
- Date: February 19, 2024
- DOI: 10.1016/j.foodchem.2024.138772
<Figure 4. Back cover art of Green Chemistry journal of the latest volume, describing the boric acid cross-linked poly(vinyl alcohol) coated paper featuring marine biodegradability, biocompatibility, high barrier properties, and robustness developed through this study.>
2024.05.22 View 7449 -
KAIST Research Team Creates the Scent of Jasmine from Microorganisms
The fragrance of jasmine and ylang-ylang, used widely in the manufacturing of cosmetics, foods, and beverages, can be produced by direct extraction from their respective flowers. In reality, this makes it difficult for production to meet demand, so companies use benzyl acetate, a major aromatic component of the two fragrances that is chemically synthesized from raw materials derived from petroleum.
On February 26, a KAIST research team led by Research Professor Kyeong Rok Choi from the BioProcess Engineering Research Center and Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering revealed the development of the first microbial process to effectively produce benzyl acetate, an industrially useful compound, from renewable carbon sources such as glucose. The results were published in their paper titled “A microbial process for the production of benzyl acetate”.
< Figure 1. Production of benzyl acetate through co-culture of upstream and downstream strains harboring the benzoic acid-dependent pathway. >
The team, led by Distinguished Professor Lee, aimed to produce benzyl acetate through an environmentally friendly and sustainable method, and developed an Escherichia coli strand to convert glucose into benzyl acetate through system metabolic engineering*.
*System metabolic engineering: a field of research founded by Distinguished Professor Lee to effectively develop microbial cell plants, a core component of the bio-industry that will replace the existing chemical industry, which is highly dependent on petroleum.
The research team developed a metabolic pathway that biosynthesizes benzyl acetate from benzoic acid derived from glucose, and successfully produced benzyl acetate by co-culturing** the strain.
**co-culture: simultaneously synthesizing two or more types of microorganisms in a mixture
However, it has been confirmed that the enzyme used to convert benzoic acid into benzyl acetate in this co-culturing technique acts non-specifically on an intermediate product during benzoic acid biosynthesis, producing a by-product called cinnamyl acetate. This process consumes the intermediate product needed for benzoic acid biosynthesis, thereby reducing the production efficiency of the target compound, benzyl acetate.
To overcome this problem, Distinguished Professor Lee and his team devised a delayed co-culture method, where they first produced benzoic acid in the earlier stages of fermentation by only culturing the top strain that produces benzoic acid from glucose, and later inoculated the bottom strain to convert the accumulated benzoic acid in the culture medium into benzyl acetate.
By applying this co-culture technique, the team suppressed the formation of by-products without further strain improvement or applying additional enzymes, and multiplied the concentration of the target compound by 10 times, producing 2.2 g/L of benzyl acetate. In addition, the team confirmed its potential for the commercial production of benzyl acetate through a technical economic analysis on this microbial process.
< Figure 2. Delayed co-culture of the Bn1 and Bn-BnAc3 strains for improved production of benzyl acetate through the benzoic acid-independent pathway.>
Research Professor Keyong Rok Choi, who was the first author of this paper, said, “This work is significant in that we have developed an effective microbial process to produce the industrially useful compound benzyl acetate, and also in that we have suggested a new approach to overcome the target chemical efficiency diminution and by-product formation issues caused commonly through non-specific enzyme activities during metabolic engineering.”
Distinguished Professor Lee said, “If we can increase the variety and number of microbial processes that produce useful chemicals through sustainable methods and at the same time develop effective strategies to solve chronic and inevitable problems that arise during microbial strain development, we will be able to accelerate the transition from the petrochemical industry into the eco-friendly and sustainable bio-industry.
This work was published online in Nature Chemical Engineering, issued by Nature.
This research was supported by the ‘Implementation of Intelligent Cell Factory Technology (PI: Distinguished Professor Sang Yup Lee) Project by the Ministry of Science and ICT, and the ‘Development of Protein Production Technology from Inorganic Substances through Microbiological Metabolic System Control’ (PI: Research Professor Kyeong Rok Choi) by the Agricultural Microbiological Project Group at the Rural Development Administration.
2024.03.05 View 6550