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Lee S, Bak JH, Lee Y, Jeong DW, Lee J, Lee KK, Cho H, Lee HH, Hyeon C, Choi MC. Water Hydrogen-Bond Mediated Layer by Layer Alignment of Lipid Rafts as a Precursor of Intermembrane Processes. J Am Chem Soc 2024. [PMID: 38652033 DOI: 10.1021/jacs.4c00544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Lipid rafts, which are dynamic nanodomains in the plasma membrane, play a crucial role in intermembrane processes by clustering together and growing in size within the plane of the membrane while also aligning with each other across different membranes. However, the physical origin of layer by layer alignment of lipid rafts remains to be elucidated. Here, by using fluorescence imaging and synchrotron X-ray reflectivity in a phase-separated multilayer system, we find that the alignment of raft-mimicking Lo domains is regulated by the distance between bilayers. Molecular dynamics simulations reveal that the aligned state is energetically preferred when the intermembrane distance is small due to its ability to minimize the volume of surface water, which has fewer water hydrogen bonds (HBs) compared to bulk water. Our results suggest that water HB-driven alignment of lipid rafts plays a role as a precursor of intermembrane processes such as cell-cell fusion, virus entry, and signaling.
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Affiliation(s)
- Suho Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Ji Hyun Bak
- School of Computational Science, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Yuno Lee
- School of Computational Science, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Dae-Woong Jeong
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Jaehee Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - KeunMin Ken Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Hasaeam Cho
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Hyun Hwi Lee
- Pohang Accelerator Lab, POSTECH, Pohang 37673, Korea
| | - Changbong Hyeon
- School of Computational Science, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
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2
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Kohl PA, Song C, Fletcher BJ, Best RL, Tchounwou C, Garcia Arceo X, Chung PJ, Miller HP, Wilson L, Choi MC, Li Y, Feinstein SC, Safinya CR. Complexes of tubulin oligomers and tau form a viscoelastic intervening network cross-bridging microtubules into bundles. Nat Commun 2024; 15:2362. [PMID: 38491006 PMCID: PMC10943092 DOI: 10.1038/s41467-024-46438-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 02/28/2024] [Indexed: 03/18/2024] Open
Abstract
The axon-initial-segment (AIS) of mature neurons contains microtubule (MT) fascicles (linear bundles) implicated as retrograde diffusion barriers in the retention of MT-associated protein (MAP) tau inside axons. Tau dysfunction and leakage outside of the axon is associated with neurodegeneration. We report on the structure of steady-state MT bundles in varying concentrations of Mg2+ or Ca2+ divalent cations in mixtures containing αβ-tubulin, full-length tau, and GTP at 37 °C in a physiological buffer. A concentration-time kinetic phase diagram generated by synchrotron SAXS reveals a wide-spacing MT bundle phase (Bws), a transient intermediate MT bundle phase (Bint), and a tubulin ring phase. SAXS with TEM of plastic-embedded samples provides evidence of a viscoelastic intervening network (IN) of complexes of tubulin oligomers and tau stabilizing MT bundles. In this model, αβ-tubulin oligomers in the IN are crosslinked by tau's MT binding repeats, which also link αβ-tubulin oligomers to αβ-tubulin within the MT lattice. The model challenges whether the cross-bridging of MTs is attributed entirely to MAPs. Tubulin-tau complexes in the IN or bound to isolated MTs are potential sites for enzymatic modification of tau, promoting nucleation and growth of tau fibrils in tauopathies.
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Affiliation(s)
- Phillip A Kohl
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Chaeyeon Song
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Amorepacific R&I Center, Yongin, 17074, Republic of Korea
| | - Bretton J Fletcher
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Rebecca L Best
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Serimmune Inc., 150 Castilian Dr., Goleta, CA, 93117, USA
| | - Christine Tchounwou
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Ximena Garcia Arceo
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Chemistry and Biochemistry, University of California, San Diego, San Diego, CA, 93106, USA
| | - Peter J Chung
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA, 90089, USA
| | - Herbert P Miller
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Leslie Wilson
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Daejeon, 34141, Korea
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Stuart C Feinstein
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Cyrus R Safinya
- Materials Department, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
- Biomolecular Science and Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, USA.
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
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3
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Jang H, Song C, Kim B, Lee C, Lee J, Han Y, An I, Kim JH, Nam J, Choi MC. Regulation of Interfacial Anchoring Orientation of Anisotropic Nanodumbbells. ACS Macro Lett 2023; 12:1298-1305. [PMID: 37696008 PMCID: PMC10586460 DOI: 10.1021/acsmacrolett.3c00339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/09/2023] [Indexed: 09/13/2023]
Abstract
Nanoparticles exhibiting geometrical and chemical anisotropies hold promise for environmentally responsive materials with tunable mechanical properties. However, a comprehensive understanding of their interfacial behaviors remains elusive. In this paper, we control the interfacial anchoring orientation of polystyrene nanodumbbells by adjusting interparticle forces. The film nanostructure is characterized by the orientation angle analysis of individual dumbbells from cross-sectional EM data: dumbbells undergo orientation transitions from a distinctive horizontal bilayer to an isotropic anchoring when electrostatic repulsion is suppressed by either an ionic strength increase or surface amine-modification. This anchoring orientation influences the film's mechanical properties and foam stability, as investigated by a 2D isotherm and dark/bright-field microscopy measurements. Our findings highlight the potential for precise control of supra-colloidal structures by modulating particle alignment, paving the way for smart delivery systems.
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Affiliation(s)
- Hyunwoo Jang
- Department
of Bio and Brain Engineering, Korea Advanced
Institute of Science and Technology, Daejeon 34141, South Korea
| | | | - Byungsoo Kim
- Department
of Bio and Brain Engineering, Korea Advanced
Institute of Science and Technology, Daejeon 34141, South Korea
| | - Chunghyeong Lee
- Department
of Bio and Brain Engineering, Korea Advanced
Institute of Science and Technology, Daejeon 34141, South Korea
| | - Juncheol Lee
- Department
of Bio and Brain Engineering, Korea Advanced
Institute of Science and Technology, Daejeon 34141, South Korea
| | - Youngkyu Han
- AMOREPACIFIC
R&I Center, Yongin 17074, South Korea
| | - Ilsin An
- Department
of Photonics and Nanoelectronics, Hanyang
University, Ansan 15588, South Korea
| | - Joon Heon Kim
- Advanced
Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 61005, South Korea
| | - Jin Nam
- AMOREPACIFIC
R&I Center, Yongin 17074, South Korea
| | - Myung Chul Choi
- Department
of Bio and Brain Engineering, Korea Advanced
Institute of Science and Technology, Daejeon 34141, South Korea
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4
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Cho H, Lee J, Nho H, Lee K, Gim B, Lee J, Lee J, Ewert KK, Li Y, Feinstein SC, Safinya CR, Jin KS, Choi MC. Synchrotron X-ray study of intrinsically disordered and polyampholytic Tau 4RS and 4RL under controlled ionic strength. Eur Phys J E Soft Matter 2023; 46:73. [PMID: 37653246 DOI: 10.1140/epje/s10189-023-00328-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 07/25/2023] [Indexed: 09/02/2023]
Abstract
Aggregated and hyperphosphorylated Tau is one of the pathological hallmarks of Alzheimer's disease. Tau is a polyampholytic and intrinsically disordered protein (IDP). In this paper, we present for the first time experimental results on the ionic strength dependence of the radius of gyration (Rg) of human Tau 4RS and 4RL isoforms. Synchrotron X-ray scattering revealed that 4RS Rg is regulated from 65.4 to 58.5 Å and 4RL Rg is regulated from 70.9 to 57.9 Å by varying ionic strength from 0.01 to 0.592 M. The Rg of 4RL Tau is larger than 4RS at lower ionic strength. This result provides an insight into the ion-responsive nature of intrinsically disordered and polyampholytic Tau, and can be implicated to the further study of Tau-Tau and Tau-tubulin intermolecular structure in ionic environments.
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Affiliation(s)
- Hasaeam Cho
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Jimin Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Hanjoon Nho
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Keunmin Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Bopil Gim
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Juncheol Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Jaehee Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea
| | - Kai K Ewert
- Materials Department, Molecular, Cellular, and Developmental Biology Department, Physics Department, and Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, 93106, USA
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, CA, 93106, USA
| | - Stuart C Feinstein
- Molecular, Cellular, and Developmental Biology Department, College of Creative Studies Biology, Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Cyrus R Safinya
- Materials Department, Molecular, Cellular, and Developmental Biology Department, Physics Department, and Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, 93106, USA
| | - Kyeong Sik Jin
- Pohang Accelerator Laboratory, POSTECH, Pohang, 37673, Korea
- Division of Advanced Nuclear Engineering, POSTECH, Pohang, 37673, Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, KAIST, Daejeon, 305-701, Korea.
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5
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Lee D, Jung WH, Lee S, Yu ES, Lee T, Kim JH, Song HS, Lee KH, Lee S, Han SK, Choi MC, Ahn DJ, Ryu YS, Kim C. Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer. Nat Commun 2021; 12:3741. [PMID: 34145296 PMCID: PMC8213817 DOI: 10.1038/s41467-021-24122-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 06/03/2021] [Indexed: 11/09/2022] Open
Abstract
Despite technological advances in biomolecule detections, evaluation of molecular interactions via potentiometric devices under ion-enriched solutions has remained a long-standing problem. To avoid severe performance degradation of bioelectronics by ionic screening effects, we cover probe surfaces of field effect transistors with a single film of the supported lipid bilayer, and realize respectable potentiometric signals from receptor-ligand bindings irrespective of ionic strength of bulky solutions by placing an ion-free water layer underneath the supported lipid bilayer. High-energy X-ray reflectometry together with the circuit analysis and molecular dynamics simulation discovered biochemical findings that effective electrical signals dominantly originated from the sub-nanoscale conformational change of lipids in the course of receptor-ligand bindings. Beyond thorough analysis on the underlying mechanism at the molecular level, the proposed supported lipid bilayer-field effect transistor platform ensures the world-record level of sensitivity in molecular detection with excellent reproducibility regardless of molecular charges and environmental ionic conditions.
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Affiliation(s)
- Donggeun Lee
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea.,Department of Electrical & Electronic Engineering, Yonsei University, Seoul, Republic of Korea
| | - Woo Hyuk Jung
- Department of Chemical and Biological Engineering, Korea University, Seoul, Republic of Korea
| | - Suho Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Eui-Sang Yu
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Taikjin Lee
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Jae Hun Kim
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Hyun Seok Song
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Kwan Hyi Lee
- Center for Biomaterials, Korea Institute of Science and Technology, Seoul, Republic of Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
| | - Seok Lee
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Sang-Kook Han
- Department of Electrical & Electronic Engineering, Yonsei University, Seoul, Republic of Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dong June Ahn
- Department of Chemical and Biological Engineering, Korea University, Seoul, Republic of Korea. .,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.
| | - Yong-Sang Ryu
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea. .,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.
| | - Chulki Kim
- Sensor System Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea.
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6
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Cera L, Gonzalez GM, Liu Q, Choi S, Chantre CO, Lee J, Gabardi R, Choi MC, Shin K, Parker KK. A bioinspired and hierarchically structured shape-memory material. Nat Mater 2021; 20:242-249. [PMID: 32868876 DOI: 10.1038/s41563-020-0789-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 07/29/2020] [Indexed: 06/11/2023]
Abstract
Shape-memory polymeric materials lack long-range molecular order that enables more controlled and efficient actuation mechanisms. Here, we develop a hierarchical structured keratin-based system that has long-range molecular order and shape-memory properties in response to hydration. We explore the metastable reconfiguration of the keratin secondary structure, the transition from α-helix to β-sheet, as an actuation mechanism to design a high-strength shape-memory material that is biocompatible and processable through fibre spinning and three-dimensional (3D) printing. We extract keratin protofibrils from animal hair and subject them to shear stress to induce their self-organization into a nematic phase, which recapitulates the native hierarchical organization of the protein. This self-assembly process can be tuned to create materials with desired anisotropic structuring and responsiveness. Our combination of bottom-up assembly and top-down manufacturing allows for the scalable fabrication of strong and hierarchically structured shape-memory fibres and 3D-printed scaffolds with potential applications in bioengineering and smart textiles.
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Affiliation(s)
- Luca Cera
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Grant M Gonzalez
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Qihan Liu
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Suji Choi
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Christophe O Chantre
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Juncheol Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Rudy Gabardi
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Kwanwoo Shin
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, Korea
| | - Kevin Kit Parker
- Disease Biophysics Group, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
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7
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Fletcher B, Kohl PA, Song C, Tchounwou C, Chung PJ, Miller HP, Li Y, Chul Choi M, Wilson L, Feinstein SC, Safinya CR. Divalent Cations Induce Non-Equilibrium Phase Transitions in Tau-Mediated Microtubule Bundles Undergoing Dynamic Instability. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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8
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Lee J, Song C, Lee J, Miller HP, Cho H, Gim B, Li Y, Feinstein SC, Wilson L, Safinya CR, Choi MC. Tubulin Double Helix: Lateral and Longitudinal Curvature Changes of Tubulin Protofilament. Small 2020; 16:e2001240. [PMID: 32794304 DOI: 10.1002/smll.202001240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/14/2020] [Indexed: 06/11/2023]
Abstract
By virtue of their native structures, tubulin dimers are protein building blocks that are naturally preprogrammed to assemble into microtubules (MTs), which are cytoskeletal polymers. Here, polycation-directed (i.e., electrostatically tunable) assembly of tubulins is demonstrated by conformational changes to the tubulin protofilament in longitudinal and lateral directions, creating tubulin double helices and various tubular architectures. Synchrotron small-angle X-ray scattering and transmission electron microscopy reveal a remarkable range of nanoscale assembly structures: single- and double-layered double-helix tubulin tubules. The phase transitions from MTs to the new assemblies are dependent on the size and concentration of polycations. Two characteristic scales that determine the number of observed phases are the size of polycation compared to the size of tubulin (≈4 nm) and to MT diameter (≈25 nm). This work suggests the feasibility of using polycations that have scissor- and glue-like properties to achieve "programmable breakdown" of protein nanotubes, tearing MTs into double-stranded tubulins and building up previously undiscovered nanostructures. Importantly, a new role of tubulins is defined as 2D shape-controllable building blocks for supramolecular architectures. These findings provide insight into the design of protein-based functional materials, for example, as metallization templates for nanoscale electronic devices, molecular screws, and drug delivery vehicles.
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Affiliation(s)
- Juncheol Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, South Korea
| | - Chaeyeon Song
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, South Korea
| | - Jimin Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, South Korea
| | - Herbert P Miller
- Molecular, Cellular and Developmental Biology Department and Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Hasaeam Cho
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, South Korea
| | - Bopil Gim
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, South Korea
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, CA, 93106, USA
| | - Stuart C Feinstein
- Molecular, Cellular and Developmental Biology Department and Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Leslie Wilson
- Molecular, Cellular and Developmental Biology Department and Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Cyrus R Safinya
- Materials, Physics, Molecular, Cellular and Developmental Biology Departments, University of California, Santa Barbara, CA, 93106, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, South Korea
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9
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Kim J, Lee J, Lee J, Keum H, Kim Y, Kim Y, Yu B, Lee SY, Tanaka J, Jon S, Choi MC. Tubulin-Based Nanotubes as Delivery Platform for Microtubule-Targeting Agents. Adv Mater 2020; 32:e2002902. [PMID: 32579276 DOI: 10.1002/adma.202002902] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/27/2020] [Indexed: 06/11/2023]
Abstract
Tubulin-based nanotubes (TNTs) to deliver microtubule-targeting agents (MTAs) for clinical oncology are reported. Three MTAs, docetaxel (DTX), laulimalide (LMD), and monomethyl auristatin E (MMAE), which attach to different binding sites in a tubulin, are loaded onto TNTs and cause structural changes in them, including shape anisotropy and tubulin layering. This drug-driven carrier transformation leads to changes in the drug-loading efficiency and stability characteristics of the carrier. TNTs coloaded with DTX and LMD efficiently deliver dual drug cargoes to cellular tubulins by the endolysosomal pathway, and results in synergistic anticancer and antiangiogenic action of the drugs in vitro. In in vivo tests, TNTs loaded with a microtubule-destabilizing agent MMAE suppress the growth of tumors with much higher efficacy than free MMAE did. This work suggests a new concept of using a drug's target protein as a carrier. The findings demonstrate that the TNTs developed here can be used universally as a delivery platform for many MTAs.
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Affiliation(s)
- Jinjoo Kim
- Department of Biological Sciences, Center for Precision Bio-Nanomedicine, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Juncheol Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Jimin Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Hyeongseop Keum
- Department of Biological Sciences, Center for Precision Bio-Nanomedicine, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Yumi Kim
- Department of Biological Sciences, Center for Precision Bio-Nanomedicine, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Yujin Kim
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Byeongjun Yu
- Department of Biological Sciences, Center for Precision Bio-Nanomedicine, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Sang Yeop Lee
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Junichi Tanaka
- Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Nishihara, Okinawa, 903-0213, Japan
| | - Sangyong Jon
- Department of Biological Sciences, Center for Precision Bio-Nanomedicine, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Korea
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10
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Lee S, Choi MC, Al Adem K, Lukman S, Kim TY. Aggregation and Cellular Toxicity of Pathogenic or Non-pathogenic Proteins. Sci Rep 2020; 10:5120. [PMID: 32198463 PMCID: PMC7083973 DOI: 10.1038/s41598-020-62062-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/28/2020] [Indexed: 02/03/2023] Open
Abstract
More than 20 unique diseases such as diabetes, Alzheimer’s disease, Parkinson’s disease are caused by the abnormal aggregations of pathogenic proteins such as amylin, β-amyloid (Aβ), and α-synuclein. All pathogenic proteins differ from each other in biological function, primary sequences, and morphologies; however, the proteins are toxic when aggregated. Here, we investigated the cellular toxicity of pathogenic or non-pathogenic protein aggregates. In this study, six proteins were selected and they were incubated at acid pH and high temperature. The aggregation kinetic and cellular toxicity of protein species with time were characterized. Three non-pathogenic proteins, bovine serum albumin (BSA), catalase, and pepsin at pH 2 and 65 °C were stable in protein structure and non-toxic at a lower concentration of 1 mg/mL. They formed aggregates at a higher concentration of 20 mg/mL with time and they induced the toxicity in short incubation time points, 10 min and 20 min only and they became non-toxic after 30 min. Other three pathogenic proteins, lysozyme, superoxide dismutase (SOD), and insulin, also produced the aggregates with time and they caused cytotoxicity at both 1 mg/mL and 20 mg/mL after 10 min. TEM images and DSC analysis demonstrated that fibrils or aggregates at 1 mg/mL induced cellular toxicity due to low thermal stability. In DSC data, fibrils or aggregates of pathogenic proteins had low thermal transition compared to fresh samples. The results provide useful information to understand the aggregation and cellular toxicity of pathogenic and non-pathogenic proteins.
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Affiliation(s)
- Sungmun Lee
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, United Arab Emirates.
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Kenana Al Adem
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, United Arab Emirates
| | - Suryani Lukman
- Department of Chemistry, College of Arts and Science, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates
| | - Tae-Yeon Kim
- Department of Civil Infrastructure and Environmental Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates
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Fletcher B, Song C, Kohl PA, Miller HP, Li Y, Chul Choi M, Wilson L, Feinstein SC, Safinya CR. The Dependence of Tau-Mediated Microtubule Assembly and Bundle Formation on GTP and Mg2+. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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12
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Cho H, Nho H, Lee J, Yeop Lee S, Sik Jin K, Miller HP, Wilson L, Feinstein SC, Safinya CR, Chul Choi M. Microtubule in vitro Bundle Structures Depends on Tau Projection Domain and Ionic Strength. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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13
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Safinya CR, Chung PJ, Song C, Li Y, Miller HP, Choi MC, Raviv U, Ewert KK, Wilson L, Feinstein SC. Minireview - Microtubules and Tubulin Oligomers: Shape Transitions and Assembly by Intrinsically Disordered Protein Tau and Cationic Biomolecules. Langmuir 2019; 35:15970-15978. [PMID: 31539262 PMCID: PMC6988848 DOI: 10.1021/acs.langmuir.9b02208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this minireview, which is part of a special issue in honor of Jacob N. Israelachvili's remarkable research career on intermolecular forces and interfacial science, we present studies of structures, phase behavior, and forces in reaction mixtures of microtubules (MTs) and tubulin oligomers with either intrinsically disordered protein (IDP) Tau, cationic vesicles, or the polyamine spermine (4+). Bare MTs consist of 13 protofilaments (PFs), on average, where each PF is made of a linear stack of αβ-tubulin dimers (i.e., tubulin oligomers). We begin with a series of experiments which demonstrate the flexibility of PFs toward shape changes in response to local environmental cues. First, studies show that MT-associated protein (MAP) Tau controls the diameter of microtubules upon binding to the outer surface, implying a shape change in the cross-sectional area of PFs forming the MT perimeter. The diameter of a MT may also be controlled by the charge density of a lipid bilayer membrane that coats the outer surface. We further describe an experimental study where it is unexpectedly found that the biologically relevant polyamine spermine (+4e) is able to depolymerize taxol-stabilized microtubules with efficiency that increases with decreasing temperature. This MT destabilization drives a dynamical structural transition where inside-out curving of PFs, during the depolymerization peeling process, is followed by reassembly of ring-like curved PF building blocks into an array of helical inverted tubulin tubules. We finally turn to a very recent study on pressure-distance measurements in bundles of MTs employing the small-angle X-ray scattering (SAXS)-osmotic pressure technique, which complements the surface-forces-apparatus technique developed by Jacob N. Israelachvili. These latter studies are among the very few which are beginning to shed light on the precise nature of the interactions between MTs mediated by MAP Tau in 37 °C reaction mixtures containing GTP and lacking taxol.
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Affiliation(s)
- Cyrus R. Safinya
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Peter J. Chung
- James Franck Institute and Department of Chemistry, University of Chicago, Illinois 60637, USA
| | - Chaeyeon Song
- Amorepacific Corporation R&D Center, Yongin 17074, Republic of Korea
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
| | - Herbert P. Miller
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Uri Raviv
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Kai K. Ewert
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Leslie Wilson
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Stuart C. Feinstein
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
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14
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Lee J, Gim B, Chul Choi M, Park S, Park CY, Kim S, Jang H, Lee S, Daniel OYH, Heon Kim J, Hyeon C, Kwon S. Second Virial Coefficient of Lipid Vesicle Regulated by Surface Charge Density and Electric Double Layer: Optical Confinement Study. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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15
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Lee J, Song C, Lee J, Miller HP, Wilson L, Safinya CR, Chul Choi M. Structural Transformation of Microtubules in the Presence of Cationic Polymers. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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16
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Cho H, Lee J, Lee J, Miller HP, Sik Jin K, Wilson L, Feinstein SC, Safinya CR, Chul Choi M. Higher Order Assembly Structures of Human Tau and Microtubules Regulated by Ionic Strength. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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17
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Fletcher B, Song C, Kohl P, Chung PJ, Miller H, Li Y, Chul Choi M, Wilson L, Feinstein SC, Safinya CR. Condensation of Divalent Metail Ions by Map-Tau Remodels Tau-Microtubule Bundle Architecture. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.1389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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18
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Abstract
More than 30 human degenerative diseases result from protein aggregation such as Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM). Islet amyloid deposits, a hallmark in T2DM, are found in pancreatic islets of more than 90% of T2DM patients. An association between amylin aggregation and reduction in β-cell mass was also established by post-mortem studies. A strategy in preventing protein aggregation-related disorders is to inhibit the protein aggregation and associated toxicity. In this study, we demonstrated that two inhibitors, lipoic acid and ascorbic acid, significantly inhibited amylin aggregation. Compared to amylin (15 μM) as 100%, lipoic acid and ascorbic acid reduced amylin fibril formation to 42.1 ± 17.2% and 42.9 ± 12.8%, respectively, which is confirmed by fluorescence and TEM images. In cell viability tests, both inhibitors protected RIN-m5f β-cells from the toxicity of amylin aggregates. At 10:1 molar ratio of lipoic acid to amylin, lipoic acid with amylin increased the cell viability to 70.3%, whereas only 42.8% RIN-m5f β-cells survived in amylin aggregates. For ascorbic acid, an equimolar ratio achieved the highest cell viability of 63.3% as compared to 42.8% with amylin aggregates only. Docking results showed that lipoic acid and ascorbic acid physically interact with amylin amyloidogenic region (residues Ser20-Ser29) via hydrophobic interactions; hence reducing aggregation levels. Therefore, lipoic acid and ascorbic acid prevented amylin aggregation via hydrophobic interactions, which resulted in the prevention of cell toxicity in vitro.
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Affiliation(s)
- Sarah Kassem Azzam
- Department of Biomedical Engineering , Khalifa University of Science and Technology , P.O. Box 127788, Abu Dhabi , United Arab Emirates
| | - Hyunwoo Jang
- Department of Bio and Brain Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , South Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , South Korea
| | - Habiba Alsafar
- Department of Biomedical Engineering , Khalifa University of Science and Technology , P.O. Box 127788, Abu Dhabi , United Arab Emirates.,Khalifa University's Center for Biotechnology , PO Box 127788, Abu Dhabi , United Arab Emirates
| | - Suryani Lukman
- Department of Chemistry, College of Arts and Science , Khalifa University of Science and Technology , P.O. Box 127788, Abu Dhabi , United Arab Emirates
| | - Sungmun Lee
- Department of Biomedical Engineering , Khalifa University of Science and Technology , P.O. Box 127788, Abu Dhabi , United Arab Emirates
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Chung PJ, Song C, Deek J, Miller HP, Li Y, Choi MC, Wilson L, Feinstein SC, Safinya CR. Comparison between 102k and 20k Poly(ethylene oxide) Depletants in Osmotic Pressure Measurements of Interfilament Forces in Cytoskeletal Systems. ACS Macro Lett 2018; 7:228-232. [PMID: 35610898 DOI: 10.1021/acsmacrolett.7b00937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proliferation of successful, cell-free reconstitutions of cytoskeletal networks have prompted measurements of forces between network elements via induced osmotic pressure by the addition of depletants. Indeed, it was through osmotic pressurization that Tau, an intrinsically disordered protein found in neuronal axons, was recently discovered to mediate two distinct microtubule (MT) bundle states, one widely spaced and a second tightly packed, separated by an energy barrier due to polyelectrolyte repulsions between opposing Tau projection domains on neighboring MT surfaces. Here, we compare interfilament force measurements in Tau coated MT bundles using PEO20k (poly(ethylene oxide), Mw = 20000), a commonly used inert depletant, and recently published measurements with PEO102k. While force measurements with either depletant reveals the transition between the two bundled states, measurements with PEO20k cannot recapitulate the correct critical pressure (Pc) at which widely spaced MT bundles transition to tightly packed MT bundles due to depletant penetration into widely spaced bundles below Pc. Surprisingly, upon transitioning to the tightly packed bundle state data from both depletants are in quantitative agreement indicative of expulsion of the smaller PEO20k depletant, but only at distances comparable or less than the PEO20k radius of gyration, significantly smaller than the effective diameter of PEO20k. While PEO102k (with size larger than the wall-to-wall distance between MTs in bundles) can more accurately capture the force response behavior at low to intermediate pressures (<104 Pa), measurements with PEO20k, beyond the overlap regime with PEO102k, extend the achievable osmotic pressure range into the higher-pressure regime (∼5 × 104 Pa). The data underscores the importance of the use of polymeric depletants of different sizes to elucidate force response behavior of cytoskeletal filamentous networks over a more complete extended pressure range.
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Affiliation(s)
| | | | | | | | | | - Myung Chul Choi
- Department
of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
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20
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Lee S, Lee Y, Hyun Bak J, Jeong DW, Lee JH, Hwi Lee H, Hyeon C, Chul Choi M. Electrostatically Controlled Domain Size and Alignment in Phase Separated Lipid Multilayers. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.1575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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21
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Jo Y, Park S, Jung J, Yoon J, Joo H, Kim MH, Kang SJ, Choi MC, Lee SY, Park Y. Holographic deep learning for rapid optical screening of anthrax spores. Sci Adv 2017; 3:e1700606. [PMID: 28798957 DOI: 10.1101/109108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/29/2017] [Indexed: 05/19/2023]
Abstract
Establishing early warning systems for anthrax attacks is crucial in biodefense. Despite numerous studies for decades, the limited sensitivity of conventional biochemical methods essentially requires preprocessing steps and thus has limitations to be used in realistic settings of biological warfare. We present an optical method for rapid and label-free screening of Bacillus anthracis spores through the synergistic application of holographic microscopy and deep learning. A deep convolutional neural network is designed to classify holographic images of unlabeled living cells. After training, the network outperforms previous techniques in all accuracy measures, achieving single-spore sensitivity and subgenus specificity. The unique "representation learning" capability of deep learning enables direct training from raw images instead of manually extracted features. The method automatically recognizes key biological traits encoded in the images and exploits them as fingerprints. This remarkable learning ability makes the proposed method readily applicable to classifying various single cells in addition to B. anthracis, as demonstrated for the diagnosis of Listeria monocytogenes, without any modification. We believe that our strategy will make holographic microscopy more accessible to medical doctors and biomedical scientists for easy, rapid, and accurate point-of-care diagnosis of pathogens.
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Affiliation(s)
- YoungJu Jo
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Sangjin Park
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), KAIST, Daejeon 34141, Republic of Korea
- Agency for Defense Development (ADD), Daejeon 34186, Republic of Korea
| | - JaeHwang Jung
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Jonghee Yoon
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hosung Joo
- School of Electrical Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Min-Hyeok Kim
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Suk-Jo Kang
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Sang Yup Lee
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), KAIST, Daejeon 34141, Republic of Korea
| | - YongKeun Park
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Tomocube Inc., Daejeon 34051, Republic of Korea
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22
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Jo Y, Park S, Jung J, Yoon J, Joo H, Kim MH, Kang SJ, Choi MC, Lee SY, Park Y. Holographic deep learning for rapid optical screening of anthrax spores. Sci Adv 2017; 3:e1700606. [PMID: 28798957 PMCID: PMC5544395 DOI: 10.1126/sciadv.1700606] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/29/2017] [Indexed: 05/19/2023]
Abstract
Establishing early warning systems for anthrax attacks is crucial in biodefense. Despite numerous studies for decades, the limited sensitivity of conventional biochemical methods essentially requires preprocessing steps and thus has limitations to be used in realistic settings of biological warfare. We present an optical method for rapid and label-free screening of Bacillus anthracis spores through the synergistic application of holographic microscopy and deep learning. A deep convolutional neural network is designed to classify holographic images of unlabeled living cells. After training, the network outperforms previous techniques in all accuracy measures, achieving single-spore sensitivity and subgenus specificity. The unique "representation learning" capability of deep learning enables direct training from raw images instead of manually extracted features. The method automatically recognizes key biological traits encoded in the images and exploits them as fingerprints. This remarkable learning ability makes the proposed method readily applicable to classifying various single cells in addition to B. anthracis, as demonstrated for the diagnosis of Listeria monocytogenes, without any modification. We believe that our strategy will make holographic microscopy more accessible to medical doctors and biomedical scientists for easy, rapid, and accurate point-of-care diagnosis of pathogens.
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Affiliation(s)
- YoungJu Jo
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Sangjin Park
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), KAIST, Daejeon 34141, Republic of Korea
- Agency for Defense Development (ADD), Daejeon 34186, Republic of Korea
| | - JaeHwang Jung
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Jonghee Yoon
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hosung Joo
- School of Electrical Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Min-hyeok Kim
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Suk-Jo Kang
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Sang Yup Lee
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), KAIST, Daejeon 34141, Republic of Korea
- Corresponding author. (S.Y.L.); (Y.P.)
| | - YongKeun Park
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Tomocube Inc., Daejeon 34051, Republic of Korea
- Corresponding author. (S.Y.L.); (Y.P.)
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Chung PJ, Song C, Deek J, Miller HP, Li Y, Chul Choi M, Wilson L, Feinstein SC, Safinya CR. Cell-Free Reconstituions of Tau and Tubulin Mediate Complex Microtubule Architectures Found in the Axon. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.3038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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24
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Jeong DW, Jang H, Choi SQ, Choi MC. Enhanced stability of freestanding lipid bilayer and its stability criteria. Sci Rep 2016; 6:38158. [PMID: 27982049 PMCID: PMC5159868 DOI: 10.1038/srep38158] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 11/04/2016] [Indexed: 11/08/2022] Open
Abstract
We present a new strategy to dramatically enhance the stability of freestanding lipid bilayers. We found that an addition of a water in oil emulsion stabilizer, SPAN 80 to a solvent phase guarantees nearly millimeter-scale stable freestanding lipid bilayers. The water permeability, bilayer area, contact angle, and interfacial tension were measured as a function of time and SPAN 80-to-lipid weight ratio (ΦSPAN 80) with several different solvents. Surprisingly, the SPAN 80, instead of remaining in the bilayer, was moved out of the bilayer during the bilayer formation. Also we studied the effect of solvent on freestanding bilayer formation, and found that squalene was the only solvent that was not incorporated into the bilayer. The regime of stable bilayer formation was experimentally determined to be 3/1 < ΦSPAN 80 < 15/1, and we suggest general stability criteria for bilayer formation. This technique and the suggested stability criteria can be potentially helpful to many model membrane-based researches in life sciences, physical sciences and biomedical engineering fields.
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Affiliation(s)
- Dae-Woong Jeong
- KAIST, Department of Bio and Brain Engineering, Daejeon, 34141, Korea
| | - Hyunwoo Jang
- KAIST, Department of Bio and Brain Engineering, Daejeon, 34141, Korea
| | - Siyoung Q. Choi
- KAIST, Department of Chemical and Biomolecular Engineering, Daejeon, 34141, Korea
| | - Myung Chul Choi
- KAIST, Department of Bio and Brain Engineering, Daejeon, 34141, Korea
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25
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Choi MC, Chung PJ, Song C, Miller HP, Kiris E, Li Y, Wilson L, Feinstein SC, Safinya CR. Paclitaxel suppresses Tau-mediated microtubule bundling in a concentration-dependent manner. Biochim Biophys Acta Gen Subj 2016; 1861:3456-3463. [PMID: 27632200 DOI: 10.1016/j.bbagen.2016.09.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 08/31/2016] [Accepted: 09/09/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Microtubules (MTs) are protein nanotubes comprised of straight protofilaments (PFs), head to tail assemblies of αβ-tubulin heterodimers. Previously, it was shown that Tau, a microtubule-associated protein (MAP) localized to neuronal axons, regulates the average number of PFs in microtubules with increasing inner radius <RinMT> observed for increasing Tau/tubulin-dimer molar ratio ΦTau at paclitaxel/tubulin-dimer molar ratio ΛPtxl=1/1. METHODS We report a synchrotron SAXS and TEM study of the phase behavior of microtubules as a function of varying concentrations of paclitaxel (1/32≤ΛPtxl≤1/4) and Tau (human isoform 3RS, 0≤Φ3RS≤1/2) at room temperature. RESULTS Tau and paclitaxel have opposing regulatory effects on microtubule bundling architectures and microtubule diameter. Surprisingly and in contrast to previous results at ΛPtxl=1/1 where microtubule bundles are absent, in the lower paclitaxel concentration regime (ΛPtxl≤1/4), we observe both microtubule doublets and triplets with increasing Tau. Furthermore, increasing paclitaxel concentration (up to ΛPtxl=1/1) slightly decreased the average microtubule diameter (by ~1 PF) while increasing Tau concentration (up to Φ3RS=1/2) significantly increased the diameter (by ~2-3 PFs). CONCLUSIONS The suppression of Tau-mediated microtubule bundling with increasing paclitaxel is consistent with paclitaxel seeding more, but shorter, microtubules by rapidly exhausting tubulin available for polymerization. Microtubule bundles require the aggregate Tau-Tau attractions along the microtubule length to overcome individual microtubule thermal energies disrupting bundles. GENERAL SIGNIFICANCE Investigating MAP-mediated interactions between microtubules (as it relates to in vivo behavior) requires the elimination or minimization of paclitaxel.
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Affiliation(s)
- Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Peter J Chung
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Chaeyeon Song
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Herbert P Miller
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - E Kiris
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA
| | - Leslie Wilson
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Stuart C Feinstein
- Neuroscience Research Institute and Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA
| | - Cyrus R Safinya
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, California 93106, USA.
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26
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Chung PJ, Choi MC, Miller HP, Feinstein HE, Raviv U, Li Y, Wilson L, Feinstein SC, Safinya CR. Direct force measurements reveal that protein Tau confers short-range attractions and isoform-dependent steric stabilization to microtubules. Proc Natl Acad Sci U S A 2015; 112:E6416-25. [PMID: 26542680 PMCID: PMC4664379 DOI: 10.1073/pnas.1513172112] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Microtubules (MTs) are hollow cytoskeletal filaments assembled from αβ-tubulin heterodimers. Tau, an unstructured protein found in neuronal axons, binds to MTs and regulates their dynamics. Aberrant Tau behavior is associated with neurodegenerative dementias, including Alzheimer's. Here, we report on a direct force measurement between paclitaxel-stabilized MTs coated with distinct Tau isoforms by synchrotron small-angle X-ray scattering (SAXS) of MT-Tau mixtures under osmotic pressure (P). In going from bare MTs to MTs with Tau coverage near the physiological submonolayer regime (Tau/tubulin-dimer molar ratio; ΦTau = 1/10), isoforms with longer N-terminal tails (NTTs) sterically stabilized MTs, preventing bundling up to PB ∼ 10,000-20,000 Pa, an order of magnitude larger than bare MTs. Tau with short NTTs showed little additional effect in suppressing the bundling pressure (PB ∼ 1,000-2,000 Pa) over the same range. Remarkably, the abrupt increase in PB observed for longer isoforms suggests a mushroom to brush transition occurring at 1/13 < ΦTau < 1/10, which corresponds to MT-bound Tau with NTTs that are considerably more extended than SAXS data for Tau in solution indicate. Modeling of Tau-mediated MT-MT interactions supports the hypothesis that longer NTTs transition to a polyelectrolyte brush at higher coverages. Higher pressures resulted in isoform-independent irreversible bundling because the polyampholytic nature of Tau leads to short-range attractions. These findings suggest an isoform-dependent biological role for regulation by Tau, with longer isoforms conferring MT steric stabilization against aggregation either with other biomacromolecules or into tight bundles, preventing loss of function in the crowded axon environment.
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Affiliation(s)
- Peter J Chung
- Materials Department, University of California, Santa Barbara, CA 93106; Physics Department, University of California, Santa Barbara, CA 93106; Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Herbert P Miller
- Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106; Neuroscience Research Institute, University of California, Santa Barbara, CA 93106
| | - H Eric Feinstein
- Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106; Neuroscience Research Institute, University of California, Santa Barbara, CA 93106
| | - Uri Raviv
- Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, CA 93106
| | - Leslie Wilson
- Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106; Neuroscience Research Institute, University of California, Santa Barbara, CA 93106
| | - Stuart C Feinstein
- Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106; Neuroscience Research Institute, University of California, Santa Barbara, CA 93106
| | - Cyrus R Safinya
- Materials Department, University of California, Santa Barbara, CA 93106; Physics Department, University of California, Santa Barbara, CA 93106; Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106;
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Jeong DW, Kim K, Choi MC, Choi SQ. Fluorescence Recovery after Merging a Droplet to Measure the Two-dimensional Diffusion of a Phospholipid Monolayer. J Vis Exp 2015:e53376. [PMID: 26556128 PMCID: PMC4692663 DOI: 10.3791/53376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We introduce a new method to measure the lateral diffusivity of a surfactant monolayer at the fluid-fluid interface, called fluorescence recovery after merging (FRAM). FRAM adopts the same principles as the fluorescence recovery after photobleaching (FRAP) technique, especially for measuring fluorescence recovery after bleaching a specific area, but FRAM uses a drop coalescence instead of photobleaching dye molecules to induce a chemical potential gradient of dye molecules. Our technique has several advantages over FRAP: it only requires a fluorescence microscope rather than a confocal microscope equipped with high power lasers; it is essentially free from the selection of fluorescence dyes; and it has far more freedom to define the measured diffusion area. Furthermore, FRAM potentially provides a route for studying the mixing or inter-diffusion of two different surfactants, when the monolayers at a surface of droplet and at a flat air/water interface are prepared with different species, independently.
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Affiliation(s)
| | - KyuHan Kim
- Information and Electrical Research Institute, KAIST
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Jeong DW, Kim K, Lee S, Choi MC, Choi SQ. Fluorescence recovery after merging a surfactant-covered droplet: a novel technique to measure the diffusion of phospholipid monolayers at fluid/fluid interfaces. Langmuir 2014; 30:14369-14374. [PMID: 25422050 DOI: 10.1021/la503219n] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a novel technique to measure diffusion coefficients of insoluble surfactant monolayers. We merge a surfactant-coated droplet with a fluorescently labeled planar monolayer. During the merging process, a monolayer on a droplet displaces the existing planar monolayer, leaving a dark area when viewed under a fluorescence microscope. We measure fractional intensities as the dyes recover, which allows diffusion coefficients to be computed. We validate this technique with the two most common phospholipid monolayers (DPPC and DOPC) and study the diffusion of their mixtures. The proposed technique has several advantages over the FRAP technique and is potentially capable of measuring the diffusion of any soluble/insoluble surfactant monolayers.
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Affiliation(s)
- Dae-Woong Jeong
- Department of Bio and Brain Engineering and ‡Information Electrical Research Institute, KAIST , Daejeon 305-701, Korea
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Park S, Choi SQ, Song C, Kim MW, Choi MC. Surface charge effects on optical trapping of nanometer-sized lipid vesicles. Soft Matter 2014; 10:8406-8412. [PMID: 25130878 DOI: 10.1039/c4sm01007h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Optical trapping of nanometer-sized lipid vesicles has been challenging due to the low refractive index contrast of the thin lipid bilayer to the aqueous medium. Using an "optical bottle", a recently developed technique to measure interactions of nanoparticles trapped by an infrared laser, we report, for the first time, quantitative measurements of the trapping energy of charged lipid vesicles. We found that the trapping energy increases with the relative amount of anionic lipids (DOPG) to neutral lipids (DOPC) in vesicles. Moreover, as monovalent salt is added into the exterior solution of vesicles, the trapping energy rapidly approaches zero, and this decrease in trapping energy strongly depends on the amount of anionic lipids in vesicles. A simple model with our experimental observations explains that the trapping energy of charged lipid vesicles is highly correlated with the surface charge density and electric double layer. In addition, we demonstrated selective trapping of a binary mixture of vesicles in different mole fractions of charged lipids, a strategy that has potential implications on charge selective vesicle sorting for engineering applications.
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Affiliation(s)
- Seongmin Park
- Department of Physics, KAIST, Daejeon, 305-701, Korea.
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Kim K, Park K, Kim G, Kim H, Choi MC, Choi SQ. Surface charge regulation of carboxyl terminated polystyrene latex particles and their interactions at the oil/water interface. Langmuir 2014; 30:12164-12170. [PMID: 25226338 DOI: 10.1021/la502863f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We study electrostatic interactions of polystyrene particles at an oil/water interface controlled by a chemical reaction of carboxylate surface functional groups. By replacing the carboxyl functional groups with hydrocarbon chains using the well-known EDC (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide) coupling reaction, the surface charge density decreases while the hydrophobicity of the colloid surface increases. Direct visualization of the particle-laden interface reveals that, depending on the extent of hydrocarbon coupling, the strength of the electrostatic repulsion can be regulated: the repulsive interaction increases with the reaction, removing aggregates, but rapidly decreases if the reaction proceeds too much, forming a large aggregation. This simple reaction, thus, dramatically changes the structures of the colloidal monolayers at the oil/water interface. We conclude that such structural change is the result of change of the repulsive interactions from the oil phase, although interactions in the water phase are also changed slightly.
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Affiliation(s)
- KyuHan Kim
- Information Electrical Research Institute, KAIST , Daejeon, 305-701, Korea
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Ojeda-Lopez MA, Needleman DJ, Song C, Ginsburg A, Kohl PA, Li Y, Miller HP, Wilson L, Raviv U, Choi MC, Safinya CR. Transformation of taxol-stabilized microtubules into inverted tubulin tubules triggered by a tubulin conformation switch. Nat Mater 2014; 13:195-203. [PMID: 24441880 PMCID: PMC3946914 DOI: 10.1038/nmat3858] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 11/29/2013] [Indexed: 05/30/2023]
Abstract
Bundles of taxol-stabilized microtubules (MTs)--hollow tubules comprised of assembled αβ-tubulin heterodimers--spontaneously assemble above a critical concentration of tetravalent spermine and are stable over long times at room temperature. Here we report that at concentrations of spermine several-fold higher the MT bundles (B(MT)) quickly become unstable and undergo a shape transformation to bundles of inverted tubulin tubules (B(ITT)), the outside surface of which corresponds to the inner surface of the B(MT) tubules. Using transmission electron microscopy and synchrotron small-angle X-ray scattering, we quantitatively determined both the nature of the B(MT)-to-B(ITT) transformation pathway, which results from a spermine-triggered conformation switch from straight to curved in the constituent taxol-stabilized tubulin oligomers, and the structure of the B(ITT) phase, which is formed of tubules of helical tubulin oligomers. Inverted tubulin tubules provide a platform for studies requiring exposure and availability of the inside, luminal surface of MTs to MT-targeted drugs and MT-associated proteins.
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Affiliation(s)
- Miguel A. Ojeda-Lopez
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106, USA
| | - Daniel J. Needleman
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106, USA
| | - Chaeyeon Song
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Avi Ginsburg
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 91904 Jerusalem, Israel
| | - Phillip A. Kohl
- Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA
| | - Herbert P. Miller
- Molecular, Cellular, & Developmental Biology Department & Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Leslie Wilson
- Molecular, Cellular, & Developmental Biology Department & Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Uri Raviv
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 91904 Jerusalem, Israel
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Cyrus R. Safinya
- Materials Department, Physics Department, Molecular, Cellular, and Developmental Biology Department, University of California, Santa Barbara, CA 93106, USA
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Abstract
A unilamellar polymeric vesicle is a self-assembled structure of a block copolymer that forms a spherical single bilayer structure with a hydrophobic interlayer and a hydrophilic surface. Due to their enhanced colloidal stability and mechanical property, controllable surface functionality, or tunable membrane thickness, polymeric vesicles are useful in nano and bio-science, providing potential applications as nanosized carriers for catalysts, drugs, and enzymes. For fabrication of a unilamellar vesicle, however, preparative procedures with a few steps are inherently required. Herein, without complicated preparative procedures, we report spontaneous unilamellar polymeric vesicles with nanometer sizes (<100 nm), which are prepared by simply mixing a triblock copolymer, Pluronic P85 (PEO26PPO40PEO26), and an organic derivative, 5-methyl salicylic acid (5mS), in aqueous solution. Depending on the 5mS concentration and the temperature, the P85-5mS mixtures presented various self-assembled nanostructures such as spherical and cylindrical micelles or vesicles, which were characterized by small angle neutron scattering and cryo-TEM, resulting in a phase diagram drawn as a function of temperature and the 5mS concentration. Interestingly the critical temperature for the micelle-to-vesicle phase transition was easily controlled by varying the 5mS concentration, i.e. it was decreased with increasing the 5mS concentration.
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Affiliation(s)
- Tae-Hwan Kim
- Neutron Science Division, Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon, 305-353, Republic of Korea.
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Han Y, Lee J, Choi SQ, Choi MC, Kim MW. Shape-induced chiral ordering in two-dimensional packing of snowmanlike dimeric particles. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:042202. [PMID: 24229162 DOI: 10.1103/physreve.88.042202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Indexed: 06/02/2023]
Abstract
Understanding the distinctive phase behaviors in random packing due to particle shapes is an important issue in condensed matter physics. In this paper, we investigate the random packing structure of two-dimensional (2D) snowmen via wax-snowman packing experiments and Brownian dynamics simulations. Both experiments and simulations reveal that neighboring snowmen have a strong short-range orientational correlation and consequently locally form particular conformations. A chiral conformation is dominant for high area fractions near the jamming condition (φ>0.8), and the proportion of the chiral conformation increases with γ. We also found that the attractive interaction does not have a significant impact on the results. The geometry of chirally ordered snowmen causes a mismatch with 2D crystalline symmetries and thus inhibits the development of long-range spatial order, despite the strong orientational correlation between neighbors.
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Affiliation(s)
- Youngkyu Han
- Department of Physics, KAIST, Daejeon 305-701, Korea
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Lee J, Lee MG, Jung C, Park YH, Song C, Choi MC, Park HG, Park JK. High-throughput nanoscale lipid vesicle synthesis in a semicircular contraction-expansion array microchannel. BioChip J 2013. [DOI: 10.1007/s13206-013-7303-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Lee JKT, Tsui KL, Cheung CY, Chau CH, Chan HL, Wu KL, Cheung GSH, Choi MC, Chan KK, Li SK. Aspirin desensitisation for Chinese patients with coronary artery disease. Hong Kong Med J 2013; 19:207-13. [PMID: 23650199 DOI: 10.12809/hkmj133914] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE. To assess the efficacy and safety of aspirin desensitisation in Chinese patients with coronary artery disease. DESIGN. Case series. SETTING. A regional hospital in Hong Kong. PATIENTS. Chinese patients with coronary artery disease and a history of a hypersensitivity reaction to aspirin or non-steroidal anti-inflammatory drug, who underwent aspirin desensitisation between February 2008 and July 2012. RESULTS. There were 24 Chinese patients with coronary artery disease who were admitted to our unit for aspirin desensitisation during this period. The majority (79%) were clinical admissions for desensitisation; eight (33%) of them developed a hypersensitivity reaction during desensitisation. Half of the latter had only limited cutaneous reactions and were able to complete the desensitisation protocol and developed aspirin tolerance. Overall, 20 (83%) of the patients were successfully desensitised at the initial attempt. No serious adverse reactions occurred in the cohort. Twelve of the patients had significant coronary artery disease revealed by coronary angiography and received a percutaneous coronary intervention, nine of whom received drug-eluting stents while three received bare metal stents due to financial constraints. All 11 successfully desensitised patients received aspirin and clopidogrel as double antiplatelet therapy after percutaneous coronary intervention. The remaining patient had a bare metal stent implant due to failed aspirin desensitisation. CONCLUSION. Given the potentially different genetic basis of aspirin hypersensitivity in different ethnicities, recourse to desensitisation in the Chinese population has not previously been addressed. This study demonstrated that aspirin desensitisation using a rapid protocol can be performed effectively and safely in Chinese patients. Our results were comparable to those in other reported studies involving other ethnicities. Successful aspirin desensitisation permits patients to pursue long-term double antiplatelet therapy that includes aspirin after percutaneous coronary intervention, and thus allows the use of drug-eluting stents as a feasible option.
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Affiliation(s)
- Joe K T Lee
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong
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Ahmed A, Ghosh MK, Choi MC, Choi CH, Kim S. Which hydrogen atom of toluene protonates PAH molecules in (+)-mode APPI MS analysis? J Am Soc Mass Spectrom 2013; 24:316-319. [PMID: 23354472 DOI: 10.1007/s13361-012-0520-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 10/09/2012] [Accepted: 10/09/2012] [Indexed: 06/01/2023]
Abstract
A previous study (Ahmed, A. et al., Anal. Chem. 84, 1146-1151( 2012) reported that toluene used as a solvent was the proton source for polyaromatic hydrocarbon compounds (PAHs) that were subjected to (+)-mode atmospheric-pressure photoionization. In the current study, the exact position of the hydrogen atom in the toluene molecule (either a methyl hydrogen or an aromatic ring hydrogen) involved in the formation of protonated PAH ions was investigated. Experimental analyses of benzene and anisole demonstrated that although the aromatic hydrogen atom of toluene did not contribute to the formation of protonated anthracene, it did contribute to the formation of protonated acridine. Thermochemical data and quantum mechanical calculations showed that the protonation of anthracene by an aromatic ring hydrogen atom of toluene is endothermic, while protonation by a methyl hydrogen atom is exothermic. However, protonation of acridine by either an aromatic ring hydrogen or a methyl hydrogen atom of toluene is exothermic. The different behavior of acridine and anthracene was attributed to differences in gas-phase basicity. It was concluded that both types of hydrogen in toluene can be used for protonation of PAH compounds, but a methyl hydrogen atom is preferred, especially for non-basic compounds.
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Affiliation(s)
- Arif Ahmed
- Department of Chemistry, Kyungpook National University, Daegu, Republic of Korea
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Cho S, Jang J, Song C, Lee H, Ganesan P, Yoon TY, Kim MW, Choi MC, Ihee H, Heo WD, Park Y. Simple super-resolution live-cell imaging based on diffusion-assisted Förster resonance energy transfer. Sci Rep 2013; 3:1208. [PMID: 23383376 PMCID: PMC3563037 DOI: 10.1038/srep01208] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 01/04/2013] [Indexed: 12/31/2022] Open
Abstract
Despite the recent development of several super-resolution fluorescence microscopic techniques, there are still few techniques that can be readily employed in conventional imaging systems. We present a very simple, rapid, general and cost-efficient super-resolution imaging method, which can be directly employed in a simple fluorescent imaging system with general fluorophores. Based on diffusion-assisted Förster resonance energy transfer (FRET), fluorescent donor molecules that label specific target structures can be stochastically quenched by diffusing acceptor molecules, thereby temporally separating otherwise spatially overlapped fluorescence signals and allowing super-resolution imaging. The proposed method provides two- to three-fold-enhancement in spatial resolution, a significant optical sectioning property, and favorable temporal resolution in live-cell imaging. We demonstrate super-resolution live-cell dynamic imaging using general fluorophores in a standard epi-fluorescence microscope with light-emitting diode (LED) illumination. Due to the simplicity of this approach, we expect that the proposed method will prove an attractive option for super-resolution imaging.
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Affiliation(s)
- Sangyeon Cho
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
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Needleman DJ, Ojeda-Lopez MA, Raviv U, Miller HP, Li Y, Song C, Feinstein SC, Wilson L, Choi MC, Safinya CR. Ion specific effects in bundling and depolymerization of taxol-stabilized microtubules. Faraday Discuss 2013; 166:31-45. [PMID: 24611267 PMCID: PMC3955895 DOI: 10.1039/c3fd00063j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Microtubules (MTs) are nanometer scale hollow cylindrical biological polyelectrolytes. They are assembled from alpha/beta-tubulin dimers, which stack to form protofilaments (PFs) with lateral interactions between PFs resulting in the curved MT. In cells, MTs and their assemblies are critical components in a range of functions from providing tracks for the transport of cargo to forming the spindle structure during mitosis. Previous studies have, shown that while cations with valence equal to or larger than 3+ tend to assemble tight 3D bundles of taxol-stabilized MTs, certain divalent cations induce relatively loose 2D bundles of different symmetry (D. J. Needleman et al., Proc. Natl. Acad. Sci. U. S. A., 2004, 101, 16099). Similarly, divalent cations form 2D bundles of DNA adsorbed on cationic membranes (I. Koltover et al., Proc. Natl. Acad. Sci. U. S. A., 2000, 97, 14046). The bundling behavior for these biological polyelectrolyte systems is qualitatively in agreement with current theory. Here, we present results which show that, unlike the case for DNA adsorbed on cationic membranes, bundling of taxol-stabilized MTs occurs only for certain divalent cations above a critical ion concentration (e.g. Ca2+, Sr2+, Ba2+). Instead, many divalent cations pre-empt the bundling transition and depolymerize taxol-stabilized MTs at a lower counterion concentration. Although previous cryogenic TEM has shown that, in the absence of taxol, Ca2+ depolymerizes MTs assembling in buffers containing GTP (guanosine triphosphate), our finding is surprising given the know stabilizing effects of taxol on GDP (guanosine diphosphate)-MTs. The ion concentration required for MT depolymerization decreases with increasing atomic number for the divalents Mg2+, Mn2+, Co2+, and Zn2+. GdCl3 (3+) is found to be extremely efficient at MT depolymerization requiring ion concentrations of about 1 mM, while oligolysine(2+), is observed not to depolymerize MTs at concentrations as high as 144 mM. The surprising MT depolymerization results are discussed in the context of divalents either disrupting lateral interactions between PFs (which are strengthened for taxol containing beta-tubulin) or interfering with taxol's ability to induce flexibility at the interface between two tubulin dimers in the same PF (which has been recently suggested as a mechanism by which taxol stabilizes MTs post-hydrolysis with the induced flexibility counteracting the kink between GDP-tublin dimers in a PF).
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Affiliation(s)
- Daniel J. Needleman
- Materials, Physics, and Molecular, Cellular, and Developmental Biology Departments, University of California, Santa Barbara, CA 93106, USA. ; Fax +1 805 893 8797; Tel +1 805 893 8635
| | - Miguel A. Ojeda-Lopez
- Materials, Physics, and Molecular, Cellular, and Developmental Biology Departments, University of California, Santa Barbara, CA 93106, USA. ; Fax +1 805 893 8797; Tel +1 805 893 8635
| | - Uri Raviv
- Materials, Physics, and Molecular, Cellular, and Developmental Biology Departments, University of California, Santa Barbara, CA 93106, USA. ; Fax +1 805 893 8797; Tel +1 805 893 8635
| | - Herbert P. Miller
- Molecular, Cellular, & Developmental Biology Department & Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Youli Li
- Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA
| | - Chaeyeon Song
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Stuart C. Feinstein
- Molecular, Cellular, & Developmental Biology Department & Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Leslie Wilson
- Molecular, Cellular, & Developmental Biology Department & Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Cyrus R. Safinya
- Materials, Physics, and Molecular, Cellular, and Developmental Biology Departments, University of California, Santa Barbara, CA 93106, USA. ; Fax +1 805 893 8797; Tel +1 805 893 8635
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Wu KL, Tsui KL, Lee KT, Chau CH, Chan HL, Cheung SH, Cheung CY, Choi MC, Chan KK, Li SK. Reperfusion strategy for ST-segment elevation myocardial infarction: trend over a 10-year period. Hong Kong Med J 2012; 18:276-283. [PMID: 22865170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Abstract
OBJECTIVES. To review the 10-year trend of reperfusion strategies in patients with ST-segment elevation myocardial infarction, and the adoption rate of percutaneous coronary interventions as opposed to thrombolytic therapy. Also to explore why some patients did not receive reperfusion therapy, and document changes in reperfusion strategies after the introduction of primary percutaneous coronary intervention programmes. DESIGN. Case series. SETTING. A regional hospital, Hong Kong. PATIENTS. All patients with ST-segment elevation myocardial infarction from January 2000 to December 2009. RESULTS. There were 1835 patients with ST-segment elevation myocardial infarction in that period, of which 1179 (64.3%) received reperfusion therapy (thrombolytic therapy, 46.0%; primary percutaneous coronary intervention, 17.5%; emergency coronary artery bypass graft, 0.7%). After introduction of the primary percutaneous coronary intervention programme, significantly more ST-segment elevation myocardial infarction cases underwent that particular intervention (1.6% in 2000 increasing to 30.6% in 2009), while the proportion receiving thrombolytic therapy declined (57.4% in 2000 decreasing to 35.0% in 2009). Seven reasons for no reperfusion therapy were identified. The commonest ones were delayed presentation (45.1%), succumbed before reperfusion (16.0%), multiple medical co-morbidities (15.2%), and contra-indication to thrombolytic therapy (14.8%). The proportion without reperfusion therapy due to a contra-indication to thrombolytic therapy declined (22.7% in 2000 decreasing to 4.9% to 2009), whilst an increasing proportion received primary percutaneous coronary interventions. CONCLUSIONS. Primary percutaneous coronary intervention is increasingly used as the reperfusion therapy in ST-segment elevation myocardial infarction and is replacing thrombolytic therapy, though the latter still remains a mainstay of therapy. A significant proportion of ST-segment elevation myocardial infarction cases received no reperfusion due to various reasons.
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Affiliation(s)
- K L Wu
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Chai Wan, Hong Kong.
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Chung PJ, Deek J, Feinstein HE, Miller H, Chul Choi M, Wilson L, Feinstein SC, Safinya CR. A Structure-Function Study of Map Tau: Analyzing Distinct Map Tau Domains in Mediating Microtubule Assembly and Bundling using Synchrotron SAXS. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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Safinya CR, Raviv U, Needleman DJ, Zidovska A, Choi MC, Ojeda-Lopez MA, Ewert KK, Li Y, Miller HP, Quispe J, Carragher B, Potter CS, Kim MW, Feinstein SC, Wilson L. Nanoscale assembly in biological systems: from neuronal cytoskeletal proteins to curvature stabilizing lipids. Adv Mater 2011; 23:2260-70. [PMID: 21506171 PMCID: PMC3864889 DOI: 10.1002/adma.201004647] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Indexed: 05/30/2023]
Abstract
The review will describe experiments inspired by the rich variety of bundles and networks of interacting microtubules (MT), neurofilaments, and filamentous-actin in neurons where the nature of the interactions, structures, and structure-function correlations remain poorly understood. We describe how three-dimensional (3D) MT bundles and 2D MT bundles may assemble, in cell free systems in the presence of counter-ions, revealing structures not predicted by polyelectrolyte theories. Interestingly, experiments reveal that the neuronal protein tau, an abundant MT-associated-protein in axons, modulates the MT diameter providing insight for the control of geometric parameters in bio- nanotechnology. In another set of experiments we describe lipid-protein-nanotubes, and lipid nano-tubes and rods, resulting from membrane shape evolution processes involving protein templates and curvature stabilizing lipids. Similar membrane shape changes, occurring in cells for the purpose of specific functions, are induced by interactions between membranes and proteins. The biological materials systems described have applications in bio-nanotechnology.
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Affiliation(s)
- Cyrus R Safinya
- Materials, Physics, and Molecular, Cellular, and Developmental Biology Departments, University of California-Santa Barbara, CA 93106, USA.
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Beck R, Deek J, Choi MC, Ikawa T, Watanabe O, Frey E, Pincus P, Safinya CR. Unconventional salt trend from soft to stiff in single neurofilament biopolymers. Langmuir 2010; 26:18595-18599. [PMID: 21082794 DOI: 10.1021/la103655x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present persistence length measurements on neurofilaments (NFs), an intermediate filament with protruding side arms, of the neuronal cytoskeleton. Tapping mode atomic force microscopy enabled us to visualize and trace at subpixel resolution photoimmobilized NFs, assembled at various subunit protein ratios, thereby modifying the side-arm length and chain density charge distribution. We show that specific polyampholyte sequences of the side arms can form salt-switchable intrafilament attractions that compete with the net electrostatic and steric repulsion and can reduce the total persistence length by half. The results are in agreement with present X-ray and microscopy data yet present a theoretical challenge for polyampholyte interchain interactions.
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Affiliation(s)
- Roy Beck
- Departments of Materials and Physics, University of California—Santa Barbara, Santa Barbara, California 93106, United States.
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Chung J, Lee KD, Seo DC, Nam YU, Choi MC. Characterization of a linear device developed for research on advanced plasma imaging and dynamics. Rev Sci Instrum 2010; 81:10E107. [PMID: 21033972 DOI: 10.1063/1.3478671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Within the scope of long term research on imaging diagnostics for steady-state plasmas and understanding of edge plasma physics through diagnostics with conventional spectroscopic methods, we have constructed a linear electron cyclotron resonance (ECR) plasma device named Research on Advanced Plasma Imaging and Dynamics (RAPID). It has a variety of axial magnetic field profiles provided by eight water-cooled magnetic coils and two dc power supplies. The positions of the magnetic coils are freely adjustable along the axial direction and the power supplies can be operated with many combinations of electrical wiring to the coils. Here, a 6 kW 2.45 GHz magnetron is used to produce steady-state hydrogen, helium, and argon plasmas with central magnetic fields of 875 and/or 437.5 G (second harmonic). In order to achieve the highest possible plasma performance within the limited input parameters, wall conditioning experiments were carried out. Chamber bake-out was achieved with heating coils that were wound covering the vessel, and long-pulse electron cyclotron heating discharge cleaning was also followed after 4 days of bake-out. A uniform bake-out temperature (150 °C) was achieved by wrapping the vessel in high temperature thermal insulation textile and by controlling the heating coil current using a digital control system. The partial pressure changes were observed using a residual gas analyzer, and a total system pressure of 5×10(-8) Torr was finally reached. Diagnostic systems including a millimeter-wave interferometer, a high resolution survey spectrometer, a Langmuir probe, and an ultrasoft x-ray detector were used to provide the evidence that the plasma performance was improved as we desired. In this work, we present characterization of the RAPID device for various system conditions and configurations.
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Affiliation(s)
- J Chung
- National Fusion Research Institute, Gwahangno 113, Daejeon 305-333, Korea.
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Yoon DK, Yoon J, Kim YH, Choi MC, Kim J, Sakata O, Kimura S, Kim MW, Smalyukh II, Clark NA, Ree M, Jung HT. Liquid-crystal periodic zigzags from geometrical and surface-anchoring-induced confinement: origin and internal structure from mesoscopic scale to molecular level. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 82:041705. [PMID: 21230293 DOI: 10.1103/physreve.82.041705] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Indexed: 05/30/2023]
Abstract
We figured out periodic undulations of lamellae "zigzags" in liquid crystals under confinement by glass and patterned silicon hybrid cell, but in the absence of applied fields. The optical and internal structures of zigzags have been investigated from mesoscopic scale to molecular level by convoluting real and reciprocal space probes, such as polarized light microscopy, scanning electron microscopy, and microbeam x-ray diffraction. The homeotropic anchoring happens at air/liquid crystal, while planar one appears at glass or patterned silicon surfaces. The wetting and displacement of lamellae near the glass surface give rise to tilting and bending in the stacking of lamellae. This can provide a solution for the origin of periodic zigzags: asymmetric strain exerted to lamellae at two-dimensional glass surface and one-dimensional-like pattern. This can give a hint for potential photonic applications such as optical gratings and modulators due to its high periodicity.
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Affiliation(s)
- Dong Ki Yoon
- Department of Chemical and Biomolecular Engineering (BK-21), Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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Cheung GSH, Tsui KL, Lau CC, Chan HL, Chau CH, Wu KL, Cheung CY, Choi MC, Tse TS, Chan KK, Li SK. Primary percutaneous coronary intervention for ST elevation myocardial infarction: performance with focus on timeliness of treatment. Hong Kong Med J 2010; 16:347-353. [PMID: 20889998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023] Open
Abstract
OBJECTIVE To review primary percutaneous coronary interventions performed for patients with ST elevation myocardial infarction with a focus on door-to-treatment time, especially after introduction of a new management programme in November 2003. DESIGN Retrospective study. SETTING Regional hospital, Hong Kong. PATIENTS All patients with ST elevation myocardial infarction who underwent primary percutaneous coronary intervention in our hospital from January 2002 to December 2007. RESULTS In all, 209 patients with ST elevation myocardial infarction had primary percutaneous coronary interventions between January 2002 and December 2007; 140 of them were admitted within office hours, 125 of whom came directly from Accident and Emergency Department. The mean door-to-balloon time of these patients was 115 minutes, and in 41% the time was less than 90 minutes (as recommended by the American College of Cardiology/American Heart Association guidelines). Since introduction of the new programme, the mean door-to-balloon time has diminished significantly, from 146 to 116 minutes (P=0.047). Delay in diagnosis (28%) and Cardiac Catheterization Laboratory being occupied (20%) were the two most common reasons for prolonged door-to-balloon times. CONCLUSION We achieved satisfactory performance in our primary percutaneous coronary intervention programme, providing timely reperfusion therapy for patients with ST elevation myocardial infarction. A well-organised and systematic clinical pathway is a prerequisite for a centre that provides a timely and effective primary percutaneous coronary intervention service for patients with ST elevation myocardial infarction. Better public education and greater awareness on the part of medical service providers are needed, so as to facilitate urgent revascularisation and improve outcomes in patients with ST elevation myocardial infarction.
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Affiliation(s)
- Gary S H Cheung
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong.
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Chung J, Lee KD, Seo DC, Nam YU, Ko WH, Lee JH, Choi MC. Descriptions of a linear device developed for research on advanced plasma imaging and dynamics. Rev Sci Instrum 2009; 80:103503. [PMID: 19895060 DOI: 10.1063/1.3239405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The research on advanced plasma imaging and dynamics (RAPID) device is a newly developed linear electron cyclotron resonance (ECR) plasma device. It has a variety of axial magnetic field profiles provided by eight water-cooled magnetic coils and two dc power supplies. The positions of the magnetic coils are freely adjustable along the axial direction and the power supplies can be operated with many combinations of electrical wiring to the coils. A 6 kW 2.45 GHz magnetron is used to produce steady-state ECR plasmas with central magnetic fields of 875 and/or 437.5 G (second harmonic). The cylindrical stainless steel vacuum chamber is 300 mm in diameter and 750 mm in length and has eight radial and ten axial ports including 6-in. and 8-in. viewing windows for heating and diagnostics. Experimental observation of ECR plasma heating has been recently carried out during the initial plasma operation. The main diagnostic systems including a 94 GHz heterodyne interferometer, a high-resolution 25 channel one-dimensional array spectrometer, a single channel survey spectrometer, and an electric probe have been also prepared. The RAPID device is a flexible simulator for the understanding of tokamak edge plasma physics and new diagnostic system development. In this work, we describe the RAPID device and initial operation results.
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Affiliation(s)
- J Chung
- National Fusion Research Institute, Gwahangno 113, Daejeon 305-333, Korea.
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Kim YH, Yoon DK, Choi MC, Jeong HS, Kim MW, Lavrentovich OD, Jung HT. Confined self-assembly of toric focal conic domains (the effects of confined geometry on the feature size of toric focal conic domains). Langmuir 2009; 25:1685-1691. [PMID: 19133728 DOI: 10.1021/la802870z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A smectic liquid crystal (LC) containing a rigid biphenyl group and semifluorinated chains exhibits a high density of toric focal conic domains (TFCDs) arranged in an ordered array when confined within a microchannel. The formation of the TFCDs is strongly influenced by the width (W) and depth (h) of the confined microchannels, most importantly, by the channel depth. We studied a broad variety of microchannels, with varying width in the range of 3-200 mum and depth in the range of 2-10 mum. The radius of the TFCDs increases with increases in the width until the saturated radius is achieved, which is determined by the depth of the channel. We used the elastic-anchoring model of TFCD formation to explain the experimental observations. The model allows one to trace the dependence of the TFCD radius on the channel depth h, to explain why the TFCDs do not form in channels that are too shallow or too narrow.
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Affiliation(s)
- Yun Ho Kim
- Department of Chemical and Biomolecular Engineering (BK-21), Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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Li Y, Beck R, Huang T, Choi MC, Divinagracia M. Scatterless hybrid metal–single-crystal slit for small-angle X-ray scattering and high-resolution X-ray diffraction. J Appl Crystallogr 2008. [DOI: 10.1107/s0021889808031129] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A simple hybrid design has been developed to produce practically scatterless aperture slits for small-angle X-ray scattering and high-resolution X-ray diffraction. The hybrid slit consists of a rectangular single-crystal substrate (e.g.Si or Ge) bonded to a high-density metal base with a large taper angle (> 10°). The beam-defining single-crystal tip is oriented far from any Bragg peak position with respect to the incident beam and hence produces none of the slit scattering commonly associated with conventional metal slits. It has been demonstrated that the incorporation of the scatterless slits leads to a much simplified design in small-angle X-ray scattering instruments employing only one or two apertures, with dramatically increased intensity (a threefold increase observed in the test setup) and improved low-angle resolution.
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Yoon DK, Choi MC, Kim YH, Kim MW, Lavrentovich OD, Jung HT. Internal structure visualization and lithographic use of periodic toroidal holes in liquid crystals. Nat Mater 2007; 6:866-870. [PMID: 17934466 DOI: 10.1038/nmat2029] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 08/28/2007] [Indexed: 05/25/2023]
Abstract
The formation of a large-area ordered structure by organic molecular soft building blocks is one of the most exciting interdisciplinary research areas in current materials science and nanotechnology. So far, several distinct organic building blocks--including colloids, block copolymers and surfactants--have been examined as potential materials for the creation of lithographic templates. Here, we report that perfect ordered arrays of toric focal conic domains (TFCDs) covering large areas can be formed by semi-fluorinated smectic liquid crystals. Combined with controlled geometry, that is, a microchannel, our smectic liquid-crystal system exhibits a high density of TFCDs that are arranged with remarkably high regularity. Direct visualization of the internal structure of the TFCDs clearly verified that the smectic layers were aligned normal to the side walls and parallel to the top surface, and merge with the circular profile on the bottom wall surface. Moreover, we demonstrate a new concept: smectic liquid-crystal lithography. Grown in microchannels from a mixture of liquid-crystal molecules and fluorescent particles, TFCDs of the smectic liquid crystals acted as a template, trapping particles in an ordered array. Our findings pose new theoretical challenges and potentially enable lithographic applications based on smectic liquid-crystalline materials.
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Affiliation(s)
- Dong Ki Yoon
- Organic Opto-Electronic Materials Lab, Department of Chemical and Biomolecular Engineering (BK-21), Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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Tse TS, Lam KKH, Tsui KL, Chan CK, Leung GTC, Choi MC, Ko WC, Chan KK, Li SK. Feasibility of transradial coronary angiography and angioplasty in Chinese patients. Hong Kong Med J 2006; 12:108-14. [PMID: 16603777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023] Open
Abstract
OBJECTIVE To assess the clinical applicability, efficacy, and safety of coronary angiography and angioplasty via a transradial approach in local Chinese patients. DESIGN Prospective case series. SETTING Regional hospital, Hong Kong. PATIENTS All patients undergoing coronary angiography and coronary angioplasty between 1 January and 30 June 2004. INTERVENTIONS Transradial coronary angiography and coronary angioplasty. MAIN OUTCOME MEASURES Feasibility, success rate, and complications. RESULTS A total of 268 coronary angiographies (62% of all coronary angiographies) and 118 coronary angioplasties (48% of all coronary angioplasties) were performed via a transradial approach. The procedural success rate for coronary angiography was 93.7% with a mean duration of 21.8 (standard deviation, 13.5) minutes compared with 17.9 (10.0) minutes for angiography via a femoral approach. Most (99%) patients were free from any complications. Of those patients who underwent elective transradial coronary angiography in the morning, 64% were discharged on the same day. Comparison of data in the first half of the study period with those in the second half revealed a significant increase in the percentage of coronary angiographies performed via a transradial approach (from 52% to 73%, P<0.0001), and an improved procedural success rate (from 91.5% to 95.3%, P=0.1). For transradial coronary angioplasty, the procedural success rate was 98%. A total of 246 lesions (2.08 lesions per patient) were treated with no procedure-related complications. CONCLUSIONS Transradial coronary angiography and angioplasty are feasible in a significant proportion of local Chinese patients and achieve a high success rate and low complication rate. It tends to prolong procedural duration, but improves patients' comfort and permits earlier ambulation and discharge. The procedural success rate improves with accumulating experience.
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Affiliation(s)
- T S Tse
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong.
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