Kinase inhibition profiles of KIST6028, reversible version of L-783277

전성훈 高麗大學校 KU-KIST融合大學院 2015 국내석사

A study on the synthesis of MXenes with controlled surface properties and their thin film applications

Hyerim Kim 고려대학교 KU-KIST융합대학원 2023 국내박사

Two-dimensional materials have a layered structure composed of one atomic layer and can be classified into conductors, semiconductors, and insulators according to their electrical properties. Moreover, due to its optical properties from its thin thickness, active research has been conducted to apply it to various industrial fields such as the Internet of Things, flexible devices, and next-generation batteries. Among them, MXenes, first discovered in 2011, are a family of a two-dimensional planar structure composed of transition metal carbides, carbonitrides, and/or nitrides with an atomic thickness of several nanometers. MXene can be synthesized through selective etching of three-phase crystals called MAX phase with a hydrofluoric acid-based etchant. Due to the layer of transition metal MXene can acquire high electrical conductivity, and stable aqueous solution dispersion property from surface functional groups obtained by the aqueous solution-based synthesis method simultaneously. The surface functional group of MXene acts as an important factor in determining the surface properties of MXene and controlling the surface properties through surface group control is a good strategy to control the physical properties of MXene. First, the quality of MAX and the surface properties of MXene were controlled by controlling the surface properties and impurities of raw materials used in the manufacture of MAX in the synthesis step. In order to lower the unit price of MXene, high-quality titanium carbide was produced using recycled titanium dioxide and graphite, and then MAX was synthesized after sintering MAX. In particular, in order to remove vacancy and oxygen solutes, the size of the particles was made small through high-energy ball-milling, and MAX with minimized oxygen impurities was produced through milling for 20 hours. It was confirmed that the MXene synthesized the improved electrical conductivity and electromagnetic shielding value as the oxygen impurity content of MAX decreased. Second, the surface properties of MXene were controlled by controlling the synthesis method in the MXene synthesis step. The surface group of MXene could be controlled according to the type of etchant and intercalant used in the synthesis of MXene. In particular, as the in-situ hydrofluoric acid used as an etchant and the concentration of hydrofluoric acid increased, it was confirmed that the hydrophilic properties of the surface decreased, and the work function was improved. In addition, in the case of MXene using lithium fluoride as an intercalant, the concentration of fluorine could be adjusted complexly. In particular, it was confirmed that the MXene film had the higher hydrophobicity and the higher electrical conductivity value when the larger amount of fluorine functional groups on the surface exists. Finally, MXene thin films were fabricated using interfacial self-assembly. In particular, the surface was controlled through heat treatment of the layered MXene thin film, which the electrical conductivity was improved by increasing the charge mobility and carrier density of the surface as the water and hydroxyl groups on the surface of the MXene was reduced, and the hydrophobic property of the surface was improved. In addition, in the case of MXene thin films whose surface characteristics were controlled through annealing, it was found that the electromagnetic interference shielding performance had higher values than that of two-dimensional material thin films of a few nanometer thicknesses. Especially, absolute electromagnetic interference shielding performance showed the highest value so far. 2차원 소재는 하나의 원자 층으로 이루어진 층상 구조로, 전기적 특성에 따라 도체, 반도체, 부도체로 분류될 수 있으며 이러한 다양한 전기적 특성과 얇은 두께로 인한 광학적 특성 때문에, 사물 인터넷, 유연 소자, 차세대 배터리 등 다양한 산업분야에 적용하기 위한 활발한 연구가 진행되고 있다. 그 중에서도 2011년 처음 발견된 맥신 소재는 전이금속 탄화물, 탄화질화물, 질화물로 구성된 수나노미터의 원자 두께로 구성된 2차원 평면 구조를 갖는 물질이다. 맥스로 불리는 삼상계 결정질을 불화수소 기반의 에천트로 선택적 식각을 통하여 맥신을 합성할 수 있으며, 전이금속의 금속 층으로 인한 고 전기 전도성과 수용액 기반의 합성법으로 인해 얻은 표면 관능기의 친수성으로 수용액 분산 안정성을 동시에 갖는 신물질이다. 맥신의 표면 관능기는 맥신의 표면 특성을 결정짓는 중요한 요인으로 작용하는데, 표면기 제어를 통해 표면 특성을 조절하는 것은 맥신의 물성을 제어할 수 있는 좋은 전략이라 할 수 있다. 먼저, 맥스의 합성 단계에서 맥스 제조 시 사용되는 원료의 표면 특성과 불순물을 제어함으로써 맥스의 품질 및 맥신의 표면 특성을 제어하였다. 맥신의 단가를 낮추기 위해 재활용 이산화 타이타늄과 흑연을 이용하여 결점이 제어된 고품질의 탄화 티탄을 제작 후 맥스를 제작한 뒤 맥신을 합성하였다. 특히, 결정질의 정공과 산소 불순물을 제거하기 위하여 고에너지 밀링을 통하여 입자의 크기를 작게 만들고 20시간 밀링을 통하여 산소 불순물이 최소화된 맥스를 제작하였고, 이렇게 이산화 타이타늄과 흑연 표면 특성을 제어하여 제작한 맥스로 합성한 맥신은 맥스의 산소 불순물 함량이 적어질 수록 전기전도성과 전자파 차폐 값이 향상됨을 확인하였다. 두번째로, 맥신의 합성 단계에서 합성 방법을 제어함으로써 맥신의 표면 특성을 제어하였다. 맥신의 합성에 사용되는 에천트의 종류와 박리제에 따라서 맥신의 표면기를 제어할 수 있었다. 특히, 에천트로 사용된 불산의 직접도가 낮고 불산의 농도가 높아짐에 따라 표면의 친수 특성이 감소하는 것을 확인할 수 있었고, 일함수를 향상시킬 수 있었다. 또한, 단순히 불산의 직접도와 농도뿐만 아니라, 박리제인 플루오린화 리튬을 이용한 맥신의 경우, 에천트의 농도와 복합적으로 불소 농도를 조절할 수 있었다. 특히, 표면의 불소 기능기가 가장 많은 경우 맥신 필름의 소수 특성이 가장 높았으며, 가장 높은 전기전도도 값을 갖는 것을 확인하였다. 마지막으로, 계면 자가 조립을 이용하여 맥신 박막을 제조하였다. 특히, 층층이 쌓아 올린 맥신 박막의 열처리를 통하여 표면을 제어하였는데, 맥신 표면의 수분 및 수산화 기를 감소시키면서 표면의 전하 이동도 및 캐리어 밀도를 높여 전기 전도성을 향상시켰으며, 표면의 소수성 특성을 높였다. 또한, 열처리를 통해 표면 특성을 제어한 맥신 박막의 경우 전자파 차폐 성능이 향상된 것을 알 수 있었고, 다양한 나노미터 두께의 2차원 소재 박막의 전자파 차폐 성능보다 높은 값을 지니며, 특히 단위 두께 및 중량에서 현재까지 보고된 절대 차폐 효과 중 가장 높은 값을 보여줬다.

Theoretical Study on Spin and Orbital Transport in Magnetic Systems

Hyeon-Jong Park 고려대학교 KU-KIST융합대학원 2023 국내박사

This thesis deals with spin and orbital transport in magnetic systems and magnetic properties originating from the spin-orbit coupling. Since the spin and orbital transport have unique features depending on the magnetic systems, there are arising interest in field of spintronics such as the anomalous and spin Hall effects in various magnetic materials, i.e., ferromagnets [1-3], antiferromagnets [4-7], nonmagnets [8-10], and the orbital Hall effect which is the orbital analogue of spin Hall effect [11-13]. Moreover, the spin transport and related spin-transfer torque in magnetic textures such as domain walls [14-15] and magnetic skyrmions [16] also have been studied. At the interface of magnetic heterostructures, there is Rashba spin-orbit coupled transport such as interfacial spin current [18, 19], spin and orbital Rashba-Edelstein effects [19,20], and intrinsic spin swapping effect [21]. In this thesis, we focus on the spin transport, orbital transport, and interfacial magnetic properties in magnetic systems. In chapter 1, we introduce the generation of spin and orbital currents such as spin Hall, orbital Hall, and spin swapping effects (section 1.2). In addition, we briefly introduce the spin-transfer torque and the spin-orbit torque (section 1.3). Finally, we show the numerical methods to calculate the spin and orbital related quantities (section 1.4). In chapter 2, we theoretically demonstrate the spin swapping effect of band structure origin in centrosymmetric ferromagnets. We show that the magnitude of intrinsic spin swapping conductivity is large at the band anticrossing which is a crossing point of different spin and orbital character bands. Also, we confirm that the intrinsic spin swapping conductivity is comparable to spin Hall conductivity in transition metal ferromagnets using density functional theory. In chapter 3, we numerically compute the spin-transfer torques for antiferromagnetic domain walls (DWs). We show that the spin-mistracking phenomenon, which results in a nonadiabatic torque, is remarkable for antiferromagnetic DWs. Furthermore, unlike for ferromagnetic DWs, we theoretically and numerically confirm that the dynamics of antiferromagnetic DWs is determined by the nondiabetic torque only. In chapter 4, we study the Rashba spin-orbit coupled spin properties. These properties include the both equilibrium and nonequilibrium properties such as surface anisotropy, Dzyaloshinskii-Moriya interaction (DMI), and Rashba-Edelstein effect. We confirm that the equilibrium spin properties can be manipulated by the electron populations, whereas nonequilibrium spin density can be induced by the lateral inversion symmetry breaking. We note that the most of results in this thesis, including the figures and schematics, have already been published in scientific journals. Results of chapter 2 and chapter 3 are reproduced from the [22, 23] with the permission of American Physical Society. Chapter 4 is reproduced from the [24, 25] with the permission of American Physical Society and [26] which are open access articles.

Two-dimensional Pyrene conjugated Peptide Assembly via Donor-Acceptor Interaction

Taeyeon Kim 고려대학교 KU-KIST융합대학원 2023 국내박사

Supramolecular assemblies based on weak non-covalent intermolecular interactions are attractive tools for the sophisticated fabrication of various nanostructures and stimuli-responsive materials. Furthermore, supramolecular materials can be reassembled into dynamic architectures in response to external stimuli, including ions, temperature, pH, and light. Among the various self-assembling building blocks, aromatic amphiphiles, consisting of hydrophobic aromatic segments and hydrophilic flexible segments, are good candidates for well-defined supramolecular structures. Such structures include micelles, nanofibers, vesicles, and two-dimensional (2D) sheets with a hydrophobic aromatic core surrounded by hydrophilic flexible segments in an aqueous solution. The physical and chemical properties of 2D assemblies can be attributed to their large surface area, flexibility, low cytotoxicity, enhanced molecular loading, and high bioconjugation efficiency in biological applications. This study reports supramolecular 2D materials based on a pyrene-grafted amphiphilic peptide, which contains a peptide sequence (Asp-Gly-Glu-Ala; DGEA) reported to bind to the integrin α2β1 receptor in cell membranes. The addition of acceptor molecules to the pyrene-grafted peptide can induce a well-ordered 2D assembly by face-centered donor-acceptor interactions. In Chapter 1, the pyrene-grafted peptide as the addition of octafluoronaphthalene (OFN) with a flat structure, structural stability against enzymatic degradation, and a larger size can enhance the proliferation and differentiation of muscle cells via continuous interactions with cell membrane receptors integrin α2β1. The DGEA–peptide 2D assembly exhibits low intracellular uptake (15 %) compared with vesicular peptide assembly (62 %). Peptide assembly via a supramolecular approach can overcome the inherent limitations of bioactive peptides, such as proteolytic degradation and rapid internalization into the cytosol. In Chapter 2, we observed that pyrene-grafted peptide with acceptor molecules demonstrated two-dimensional materials via D-A interaction. Furthermore, amphiphilic pyrene showed novel light-responsive systems via co-assemblies of acceptor molecules with octafluoronaphthalene (OFN), Nile red, and N,N,N',N'-tetrakis(4- dibutylaminophenyl)-1,4-benzoquinone diiminium bis (NIR dye) that could be excited on the multi-wavelength. As the replacement of each acceptor molecule that absorbs longer wavelengths, 2D materials based on amphiphilic pyrene caused light-responsive performances from the visible region to the NIR region, leading to rapid structural aggregation according to the direction of light irradiation. In addition, the aromatic rings of the D-A complex weakened by light irradiation demonstrated exposure of inner aromatic molecules to the outside surface, which eventually induced irregular aggregation due to exposed hydrophobicity. The weakened D-A complex with a lower band gap and distant intermolecular interaction by the photo-excitation was transformed into micelles (OFN complex), nanosheets (Nile red complex), and nanofibers (NIR complex) under continuous light irradiation. This research is expected to bring considerable interests to a range of interest to both supramolecular chemistry and biology, as follows. These supramolecular approaches via the D-A interaction provide a strategy to fabricate well-defined 2D peptide materials with an understanding of assembly at the molecular level. Bioactive peptide-based supramolecular 2D assemblies could overcome the limitations of having the instability of conventional peptide materials and will provide detailed insights into the peptide-based drug field. Furthermore, through continuous light irradiation, the photoexcited D-A complex with two-dimensional structures eventually demonstrated the transformation of micelles (OFN complexes), nanosheets (NIR complexes), and nanofibers (NIR complexes) as the inner aromatic molecules reverse outward. In this study, the novel light-responsive system can be deployed as a next-generation material in various light-mediated fields because the one assembly constructed between two molecules can respond to most of the wavelengths from the short visible regions to the NIR region.

Efficient RAGE siRNA delivery via bioreducible polyethylenimine for myocardial infarction therapy

양민정 고려대학교 KU-KIST융합대학원 2015 국내석사

All-solution Synthesized High-performance 2D Bi2O2Se Thin-film Transistor

Kim, Jin Seok 고려대학교 KU-KIST융합대학원 2023 국내석사

Two-dimensional (2D) semiconductors have emerged as a next-generation electronic material because of their excellent electrical and mechanical properties in the atomically thin regime. These materials with a van der Waals layered structure are particularly promising for emerging electronics capable of heterogeneous integration and flexibility. For this purpose, low-temperature, and high-quality synthesis of 2D semiconductors are essential, wet chemical synthesis has remarkable advantages in low process temperature, scalability, and cost-effectiveness compared to conventional chemical vapor deposition processes. However, it remains a considerable challenge to achieve high quality and device performance. Here, we report the wet chemical synthesis via a bottom-up process of 2D Bi2O2Se semiconductors showing a high mobility characteristic. The all-solution-based processes are carried out at a low temperature below 200 ℃ producing free-standing 2D flakes with a lateral size of over 10 μm and thickness down to 8 nm. In addition, the single-crystalline Bi2O2Se channel in a back-gated field-effect transistor geometry exhibited high mobility up to 132 cm2V-1s-1 at room temperature. Notably, this solution can be assembled into a thin film for large-area device fabrication through a simple method such as liquid/air interface self-assembly. Our demonstration provides an innovative bottom-up synthesis approach to preparing high-quality semiconductors cost- and energy-effectively.

Biological Evaluation of Novel Targeted Inhibitors Against SbnE, RAF1, and BRAF Class I/II/III Mutants to Overcome Drug Resistance

Kim, Nam Kyoung 고려대학교 KU-KIST융합대학원 2023 국내박사

Cathepsin B-Specific Prodrug Nanoparticles to Overcome Tumor Heterogeneity

Kim, Jin Seong 고려대학교 KU-KIST융합대학원 2023 국내박사

Design and Fabrication of Stretchable and Transient Electronics for Wearable, Implantable Medical Devices.

Ko, Gwan Jin 고려대학교 KU-KIST융합대학원 2023 국내박사

Hierarchically Interpenetrated and Reentrant Micro-Cellular Frameworks for Stretchable Lithium Metal Batteries

An, Yoo Joo 고려대학교 KU-KIST융합대학원 2023 국내석사

Human-friendly wearable devices have been rapidly developed these days and there are strong demands for skin-like stretchability to fit the human body more closely and comfortably. In addition, it is crucial to integrate a stretchable energy storage component with high energy density and a high voltage window into wearable devices with small dimensions for long-term usage. In this study, we introduce a hierarchically interpenetrated reentrant microcellular structure combined with two-dimensional microcellular structure of graphene-MXene-carbon nanotubes (CNTs) and three-dimensional cellular melamine foam serving as a stretchable structure for lithium metal composite electrodes to provide stretchability for lithium metal electrodes, which hold great promise as advanced energy storage systems of the future. The non-conductive and deformable melamine foam, provide stable structural deformability, while the graphene/CNT/MXene network ensures high electrical conductivity, lithiophilicity, and mechanical stability, facilitating the deposition of lithium during electrodeposition. The reentrant structure was fabricated by radially compressing the hierarchical cellular structures, leveraging the structural stretchability of the accordion-like reentrant frameworks. The resulting composite electrodes with lithium deposition exhibit significantly lower overpotential during Li stripping and plating compared to conventional lithium metal foil anodes, and they demonstrate stable electrochemical performance even under a mechanical strain of 30%. The reentrant micro-cellular electrodes exhibit significant potential in the advancement of lithium metal electrodes with a high energy density for stretchable batteries. 최근 스마트 워치, 스마트 글래스 등 인간 친화적인 웨어러블 기기가 급속도로 발전하면서 인체에 보다 편안하게 밀착이 가능한 높은 신축성을 가진 디바이스에 대한 수요가 증가하고 있다. 또한 웨어러블 디바이스의 편의성을 높이기 위해 배터리가 차지하는 공간은 줄이되 충전 후 방전까지의 시간은 늘릴 수 있는 높은 에너지 밀도를 가지는 배터리가 요구된다. 따라서 본 연구는 높은 전도성 및 비표면적을 가지는 그래핀-맥신-탄소나노튜브의 안쪽으로 구부러진 재진입 구조를 리튬 증착을 위한 뼈대로 사용하여 신축 가능한 고성능의 복합 리튬 메탈 배터리 음극을 구현하고자 한다. 그러나 그래핀/탄소나노튜브로만 이루어진 뼈대에 리튬을 증착하여 복합 음극을 형성할 경우 그래핀과 탄소나노튜브에 금속 리튬이 둘러싸여 리튬 금속이 전극의 기계적 물성을 지배하게 되어 신축 시 쉽게 파손된다. 이를 보완하기 위해 전도성이 없어 리튬이 증착되지 않으면서도 유연성을 가져 형태 변형이 가능하며, 적은 부피에도 높은 기계적 안정성을 유지하는 삼차원 구조의 멜라민 폼을 이용한다. 이러한 구조를 통해 안정적인 구조적 변형성을 성공적으로 얻었으며 동시에 전기도금법으로 그래핀-맥신-탄소나노튜브 네트워크에 리튬을 안정적으로 전착하였다. 재진입 구조는 그래핀-맥신-탄소나노튜브/멜라민 폼을 방사형으로 압축하여 아코디언과 같은 프레임워크의 구조적 신축성을 가질 수 있도록 하였다. 제작된 복합 리튬 메탈 배터리 음극은 충방전 테스트에서 낮은 과전위를 가지며 30% 신축시에도 안정적인 전기화학적 성능을 보였다. 이를 통해 높은 에너지 밀도의 신축성 배터리용 복합 리튬 메탈 배터리 음극으로의 활용 가능성 및 잠재력을 확인하였다.