SUNGKYUNKWAN UNIVERSITY (SKKU), SEOUL, KOREA
- Prof. Jeong Mun-Seok's Research Team Develops a Semiconductor-insulator-
semiconductor (SIS) Heterojunction Diode - Pathological Mechanism Involved in High Mortality in Sepsis Solved for the First Time
- An 'Artificial Cell Nucleus' Appliable to Genetic Disorder Treatment
- Prof. Ahn Jong-real's Research Team Creates Seamless lamination of a Concave-convex
Architecture with Single-layer Graphene - SKKU Researchers Develop Biomimetic Self-Templated Hierarchical Structures of
Collagen-Like Peptide Amphiphiles - Prof. Kim Kyeong-Kyu Finds a New Way to Convert Pluripotent Cells into Functional Neurons
Sungkyunkwan University announced on November 5th that a research team headed by Prof. Jeong Mun-Seok from the Department of Energy Science has developed a SIS heterojunction diode consisting of monolayer (1-L) MoS2 hexagonal boron nitride (h-BN) and epitaxial p-GaN that can be applied to high-performance nanoscale optoelectronics.
The layered materials of 1-L MoS2 and h-BN are grown by chemical vapor deposition and vertically stacked by a wet-transfer method on a p-GaN layer. The final structure was verified by confocal photoluminescence and Raman spectroscopy. Current-voltage (I-V) measurements were conducted to compare the device performance with that of a more classical p-n structure. In both structures (the p-n and SIS heterojunction diode), clear current-rectifying characteristics were observed. In particular, a current and threshold voltage was obtained for the SIS structure that was higher than the p-n structure. This indicated that tunneling is the predominant carrier transport mechanism. In addition, the photo response of the SIS structure induced by the illumination of visible light was observed by photocurrent measurements.
Prof. Jeong said, "This SIS heterojunction structure consisting of layered 1-L MoS2, h-BN, and epitaxial p-GaN is expected to be a promising device for nanoscale electronics, optoelectronics, and integrated circuits."
The results of this research were published in the online edition of 'ACS Nano' on October 4, 2015.
Find more information at:
http://pubs.acs.org/doi/abs/10.1021/acsnano.5b04233
The Ministry of Health & Welfare announced that the research team headed by Prof. Bae Yoe-Sik from the Department of Biological Sciences revealed for the first time that the cause of high level of septicemia related vital organ damage and subsequent fatality is due to the cell signal molecule 'phospholipase D2 (PLD2)'.
Prof. Bae's research team revealed the cause behind the high level of vital organ damage and fatality related to septicemia (blood poisoning), and discovered a new potential drug that will help in the treatment for the disease. The researchers explained that when septicemia occurs the PLD2 expressed in neutrophils restricts the generation of neutrophil extracellular traps, which are in charge of removing infectious germs, and also hinders the movement of neutrophils which leads to decreased bactericidal activity and a higher rate of fatality.
With experimental sepsis models the researchers were able to confirm the new potential drug, CAY10594 (PLD2 inhibitor), to show astonishing remedial results in septicemia treatment. After administering CAY10594 to a septicemic mouse, the researchers observed that neutrophil extracellular trap generation was enhanced and inflammatory cytokine generation and immune cell apoptosis were contained, resulting in the impressive remedial effects in septicemia treatment. Out of the group of septicemic mice treated by administering CAY10594, 90% survived, while only 25% survived out of the group that had no administration. Septicemia is a severe acute infectious disease where an excessive influx of microbes in the blood to the organs causes an infection which, in serious cases, can lead to death.
"Using a drug targeting PLD2 we are expecting to develop an effective septicemia cure," asserted Prof. Bae, who added, "the patent for the research results has been applied for domestically and an international patent is being prepared."
This research was published in the 'Journal of Experimental Medicine' online edition on August 17, 2015.
Find more information at:
http://jem.rupress.org/content/212/9/1381.abstract?sid=9f679749-68aa-4893-911d-0d1c69e9c355
On September 3rd, a Sungkyunkwan University research team headed by Prof. Um Soong-Ho of the Department of Chemical Engineering announced that they have developed an artificial cell nucleus system which may be able to replace defected cell nucleuses. The system is simply manufactured by cross-linking protein-encoding genes with four-armed junctional DNA nanostructure as a histone-like bio-polymer which is enveloped by lipid membranes to be easily transported into the target cell. As engaged with coupled transcription and a translation system, the synthetic cell nucleus is also able to produce messenger RNA, eventually leading to massive protein production inside the cytosol of a cell.
To visualize the concept, a green-light emitting protein-encoding gene was used as a test model and positioned in the system matrix. It resulted in strong green fluorescent emissions in a breast cancer cell line. Traditional gene transfer methodologies for the genomic correction of serious genetic disorders have suffered from more limitations including low transfection efficiency and safety. By utilizing artificial cell nuclei, protein productivity can be increased up to 2.5 folds. Prof. Um explained, "Instead of the light-emitting protein-encoding gene it will be possible to insert actual healthy genes that can cure genetic disorders in the synthetic nucleus system."
This research was published in the authoritative journal of Nano-material sciences, 'Small' online edition on October 27, 2015.
Find more information at:
http://onlinelibrary.wiley.com/doi/10.1002/smll.201501334/full
A research team headed by Prof. Ahn Jong-real from the Department of Physics at Sungkyunkwan University has developed seamless lamination of a concave-convex architecture with single-layer graphene. Prof. Ahn's research team successfully demonstrated that chemical-vapor-deposited single-layer graphene can be transferred onto a silicon dioxide substrate with 3D geometry, such as a concave-convex architecture. A variety of silicon dioxide concave-convex architectures were uniformly and seamlessly laminated with graphene using a thermal treatment. The planar graphene was stretched to cover the concave-convex architecture, and the resulting strain on the curved graphene was spatially resolved by confocal Raman spectroscopy; molecular dynamic simulations were also conducted which supported the observations. Changes in electrical resistivity caused by the spatially varying strain induced as the graphene-silicon dioxide laminate varies dimensionally from 2D to 3D were measured by using a four-point probe.
The resistivity measurements suggest that the electrical resistivity can be systematically controlled by the 3D geometry of the graphene-silicon dioxide laminate. This 3D graphene-insulator laminate will broaden the range of graphene applications beyond planar structures to 3D materials.
The results were published online by 'Nanoscale', an international nanoscience and nanotechnology journal, on October 5, 2015.
Find more information at:
http://pubs.rsc.org/en/content/articlelanding/2015/nr/c5nr04004c
A research team headed by Prof. Chung Woo-Jae from the Department of Genetic Engineering at Sungkyunkwan University has developed biomimetic self-templated hierarchical structures of collagen-like peptide amphiphiles. Developing hierarchically structured biomaterials with tunable chemical and physical properties like those found in nature is critically important to regenerative medicine and studies on tissue morphogenesis.
Despite advances in materials synthesis and assembly processes, our ability to control hierarchical assembly using fibrillar biomolecules remains limited. Prof. Chung's research team developed a bio-inspired approach to create collagen-like materials through directed evolutionary screening and directed self-assembly. They first synthesized peptide amphiphiles by coupling phage display-identified collagen-like peptides to long-chain fatty acids. Then, researchers assembled the amphiphiles into diverse, hierarchically organized, nanofibrous structures using directed self-assembly based on liquid crystal flow and its controlled deposition.
The resulting structures sustained and directed the growth of bone cells and hydroxyapatite biominerals. We believe these self-assembling collagen-like amphiphiles could prove useful in the structural design of tissue regenerating materials. "Our combined strategy of directed evolutionary screening and self-templating assembly provides opportunities for developing multifunctional biomimetic peptide-based materials and represents a means to study the dynamics of biomolecule-based supramolecular assemblies, areas that will play essential roles in tissue engineering and regenerative medicine," said Prof. Chung.
The results were published online by 'ACS Nano', an international chemical and nanomaterial journal, on September 22, 2015.
Find more information at:
http://pubs.acs.org/doi/full/10.1021/acs.nanolett.5b03313
Sungkyunkwan University announced that Prof. Kim Kyeong-Kyu from the Department of Medicine has developed a method to combine suppression of stemness with lineage-specific induction leading to the conversion of pluripotent cells into functional neurons. Sox2 is a key player in the maintenance of pluripotency and stemness and thus inhibition of its function would abrogate the stemness of pluripotent cells and induce differentiation into several types of cells. Herein we describe a strategy that relies on a combination of Sox2 inhibition with lineage-specific induction to promote efficient and selective differentiation of pluripotent P19 cells into neurons.
When P19 cells transduced with Skp protein, an inhibitor of Sox2, are incubated with a neurogenesis inducer, the cells are selectively converted into neurons that generate depolarization-induced sodium currents and action potentials. This finding indicates that the differentiated neurons are electrophysiologically active. Signaling pathway studies have lead Prof. Kim to conclude that a combination of Skp with the neurogenesis inducer enhances neurogenesis in P19 cells by activating Wnt and Notch pathways. The present differentiation protocol could be valuable to selectively generate functionally active neurons from pluripotent cells.
The results were published online by 'Chemistry & Biology', an international chemical and biological journal, on November 19, 2015.
Find more information at:
http://www.cell.com/chemistry-biology/abstract/S1074-5521(15)00411-1
