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Choi ES, Kim S, Kim D, Choi E, Ryu JH. Drug-Loaded Nanogel for Efficient Orchestration of Cell Death Pathways by Intramitochondrial Disulfide Polymerization. Small 2024; 20:e2308872. [PMID: 37994300 DOI: 10.1002/smll.202308872] [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] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/08/2023] [Indexed: 11/24/2023]
Abstract
Chemotherapy using a nanoscaled drug delivery system is an effective cancer therapy, but its high drug concentration often causes drug resistance in cancer cells and normal cell damage. Combination therapy involving two or more different cell signaling pathways can be a powerful tool to overcome the limitations of chemotherapy. Herein, this article presents nanogel (NG)-mediated co-delivery of a chemodrug camptothecin (CPT) and mitochondria-targeting monomer (MT monomer) for efficient activation of two modes of the programmed cell death pathway (apoptosis and necroptosis) and synergistic enhancement of cancer therapy. CPT and the monomer are incorporated together into the redox-degradable polymeric NGs for release in response to the intracellular glutathione. The MT monomer is shown to undergo reactive oxygen species (ROS)-triggered disulfide polymerization inside the cancerous mitochondria in cooperation with the chemotherapeutic CPT elevating the intracellular ROS level. The CPT/monomer interconnection in cell death mechanisms for mitochondrial dysfunction and enhanced cell death is evidenced by a series of cell analyses showing ROS generation, mitochondria damage, impacts on (non)cancerous or drug-resistant cells, and cell death modes. The presented work provides beneficial insights for utilizing combination therapy to facilitate a desired cell death mechanism and developing a novel nanosystem for more efficacious cancer treatment.
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Affiliation(s)
- Eun Seong Choi
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Sangpil Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Dohyun Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Eunshil Choi
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Ja-Hyoung Ryu
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
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2
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Rao X, Hussain G, Huang Q, Chu WJ, Li N, Zhao X, Dun Z, Choi ES, Asaba T, Chen L, Li L, Yue XY, Wang NN, Cheng JG, Gao YH, Shen Y, Zhao J, Chen G, Zhou HD, Sun XF. Survival of itinerant excitations and quantum spin state transitions in YbMgGaO 4 with chemical disorder. Nat Commun 2021; 12:4949. [PMID: 34400621 PMCID: PMC8367942 DOI: 10.1038/s41467-021-25247-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 09/02/2020] [Accepted: 07/01/2021] [Indexed: 11/16/2022] Open
Abstract
A recent focus of quantum spin liquid (QSL) studies is how disorder/randomness in a QSL candidate affects its true magnetic ground state. The ultimate question is whether the QSL survives disorder or the disorder leads to a “spin-liquid-like” state, such as the proposed random-singlet (RS) state. Since disorder is a standard feature of most QSL candidates, this question represents a major challenge for QSL candidates. YbMgGaO4, a triangular lattice antiferromagnet with effective spin-1/2 Yb3+ions, is an ideal system to address this question, since it shows no long-range magnetic ordering with Mg/Ga site disorder. Despite the intensive study, it remains unresolved as to whether YbMgGaO4 is a QSL or in the RS state. Here, through ultralow-temperature thermal conductivity and magnetic torque measurements, plus specific heat and DC magnetization data, we observed a residual κ0/T term and series of quantum spin state transitions in the zero temperature limit for YbMgGaO4. These observations strongly suggest that a QSL state with itinerant excitations and quantum spin fluctuations survives disorder in YbMgGaO4. It remains an open question as to whether the quantum spin liquid state survives material disorder, or is replaced by some spin-liquid like state. Here, Rao et al succeed in resolving a resolving a κ0/T residual in the thermal conductivity of YbMgGaO4 strongly suggesting the survival of the quantum spin liquid state.
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Affiliation(s)
- X Rao
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - G Hussain
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
| | - W J Chu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - N Li
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - X Zhao
- School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Z Dun
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - T Asaba
- Department of Physics, University of Michigan, Ann Arbor, MI, USA
| | - L Chen
- Department of Physics, University of Michigan, Ann Arbor, MI, USA
| | - L Li
- Department of Physics, University of Michigan, Ann Arbor, MI, USA
| | - X Y Yue
- Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, People's Republic of China
| | - N N Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Y H Gao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China
| | - Y Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China
| | - J Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China
| | - G Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China. .,Department of Physics and HKU-UCAS Joint Institute for Theoretical and Computational Physics at Hong Kong, The University of Hong Kong, Hong Kong, China.
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA.
| | - X F Sun
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China. .,Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, People's Republic of China.
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Mauws C, Hiebert N, Rutherford ML, Zhou HD, Huang Q, Stone MB, Butch NP, Su Y, Choi ES, Yamani Z, Wiebe CR. Magnetic ordering in the Ising antiferromagnetic pyrochlore Nd 2ScNbO 7. J Phys Condens Matter 2021; 33:245802. [PMID: 33827056 DOI: 10.1088/1361-648x/abf594] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
The question of structural disorder and its effects on magnetism is relevant to a number of spin liquid candidate materials. Although commonly thought of as a route to spin glass behaviour, here we describe a system in which the structural disorder results in long-range antiferromagnetic order due to local symmetry breaking. Nd2ScNbO7is shown to have a dispersionless gapped excitation observed in other neodymium pyrochlores belowTN= 0.37 K through polarized and inelastic neutron scattering. However the dispersing spin waves are not observed. This excited mode is shown to occur in only 14(2)% of the neodymium ions through spectroscopy and is consistent with total scattering measurements as well as the magnitude of the dynamic moment 0.26(2)μB. The remaining magnetic species order completely into the all-in all-out Ising antiferromagnetic structure. This can be seen as a result of local symmetry breaking due disordered Sc+3and Nb+5ions about theA-site. From this work, it has been established thatB-site disorder restores the dipole-like behaviour of the Nd+3ions compared to the Nd2B2O7parent series.
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Affiliation(s)
- C Mauws
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
| | - N Hiebert
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
| | - M L Rutherford
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee-Knoxville, Knoxville 37996-1220, United States of America
- National High Magnetic Field Laboratory, Florida State University, Tallahassee 32306-4005, United States of America
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee-Knoxville, Knoxville 37996-1220, United States of America
| | - M B Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States of America
| | - N P Butch
- Centre for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, MS 6100, Gaithersburg, Maryland 20899, United States of America
| | - Y Su
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich, Lichtenbergstrasse 1, 85747 Garching, Germany
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee 32306-4005, United States of America
| | - Z Yamani
- Canadian Neutron Beam Centre, National Research Council of Canada, Chalk River, K0J 1P0, Canada
| | - C R Wiebe
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
- Department of Chemistry, University of Winnipeg, Winnipeg R3B 2E9, Canada
- Department of Physics and Astronomy, McMaster University, Hamilton L8S 4M1, Canada
- Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
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4
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Li N, Huang Q, Yue XY, Chu WJ, Chen Q, Choi ES, Zhao X, Zhou HD, Sun XF. Possible itinerant excitations and quantum spin state transitions in the effective spin-1/2 triangular-lattice antiferromagnet Na 2BaCo(PO 4) 2. Nat Commun 2020; 11:4216. [PMID: 32839456 PMCID: PMC7445251 DOI: 10.1038/s41467-020-18041-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 12/01/2019] [Accepted: 08/03/2020] [Indexed: 11/09/2022] Open
Abstract
The most fascinating feature of certain two-dimensional (2D) gapless quantum spin liquid (QSL) is that their spinon excitations behave like the fermionic carriers of a paramagnetic metal. The spinon Fermi surface is then expected to produce a linear increase of the thermal conductivity with temperature that should manifest via a residual value (κ0/T) in the zero-temperature limit. However, this linear in T behavior has been reported for very few QSL candidates. Here, we studied the ultralow-temperature thermal conductivity of an effective spin-1/2 triangular QSL candidate Na2BaCo(PO4)2, which has an antiferromagnetic order at very low temperature (TN ~ 148 mK), and observed a finite κ0/T extrapolated from the data above TN. Moreover, while approaching zero temperature, it exhibits series of quantum spin state transitions with applied field along the c axis. These observations indicate that Na2BaCo(PO4)2 possibly behaves as a gapless QSL with itinerant spin excitations above TN and its strong quantum spin fluctuations persist below TN.
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Affiliation(s)
- N Li
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA
| | - X Y Yue
- Institute of Physical Science and Information Technology, Anhui University, 230601, Hefei, Anhui, People's Republic of China
| | - W J Chu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Q Chen
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310-3706, USA
| | - X Zhao
- School of Physical Sciences, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA.
| | - X F Sun
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China. .,Institute of Physical Science and Information Technology, Anhui University, 230601, Hefei, Anhui, People's Republic of China.
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5
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Kim K, Choi H, Choi ES, Park MH, Ryu JH. Hyaluronic Acid-Coated Nanomedicine for Targeted Cancer Therapy. Pharmaceutics 2019; 11:E301. [PMID: 31262049 PMCID: PMC6680416 DOI: 10.3390/pharmaceutics11070301] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/25/2019] [Accepted: 06/26/2019] [Indexed: 11/24/2022] Open
Abstract
Hyaluronic acid (HA) has been widely investigated in cancer therapy due to its excellent characteristics. HA, which is a linear anionic polymer, has biocompatibility, biodegradability, non-immunogenicity, non-inflammatory, and non-toxicity properties. Various HA nanomedicines (i.e., micelles, nanogels, and nanoparticles) can be prepared easily using assembly and modification of its functional groups such as carboxy, hydroxy and N-acetyl groups. Nanometer-sized HA nanomedicines can selectively deliver drugs or other molecules into tumor sites via their enhanced permeability and retention (EPR) effect. In addition, HA can interact with overexpressed receptors in cancer cells such as cluster determinant 44 (CD44) and receptor for HA-mediated motility (RHAMM) and be degraded by a family of enzymes called hyaluronidase (HAdase) to release drugs or molecules. By interaction with receptors or degradation by enzymes inside cancer cells, HA nanomedicines allow enhanced targeting cancer therapy. In this article, recent studies about HA nanomedicines in drug delivery systems, photothermal therapy, photodynamic therapy, diagnostics (because of the high biocompatibility), colloidal stability, and cancer targeting are reviewed for strategies using micelles, nanogels, and inorganic nanoparticles.
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Affiliation(s)
- Kibeom Kim
- Department of Chemistry, School of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Huyeon Choi
- Department of Chemistry, School of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Eun Seong Choi
- Department of Chemistry, School of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
| | - Myoung-Hwan Park
- Department of Chemistry and Life Science, Sahmyook University, Seoul 01795, Korea.
| | - Ja-Hyoung Ryu
- Department of Chemistry, School of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea.
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6
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Lu Y, Palanikumar L, Choi ES, Huskens J, Ryu JH, Wang Y, Pang W, Duan X. Hypersound-Enhanced Intracellular Delivery of Drug-Loaded Mesoporous Silica Nanoparticles in a Non-Endosomal Pathway. ACS Appl Mater Interfaces 2019; 11:19734-19742. [PMID: 31090387 DOI: 10.1021/acsami.9b02447] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The intracellular delivery efficiency of drug-loaded nanocarriers is often limited by biological barriers arising from the plasma membrane and the cell interior. In this work, the entering of doxorubicin (Dox)-loaded mesoporous silica nanoparticles (MSNs) into the cytoplasm was acoustically enhanced through direct penetration with the assistance of hypersound of gigahertz (GHz) frequency. Both fluorescence and cell viability measurements revealed that the therapeutic efficacy of Dox-loaded MSNs was significantly improved by tuning the power and duration of hypersound on demand with a nanoelectromechanical resonator. Mechanism studies with inhibitors illustrated that the membrane defects induced by the hypersound-triggered GHz acoustic streaming facilitated the Dox-loaded MSNs of 100-200 nm to directly penetrate through the cell membrane instead of via the traditional endocytosis, which highly increased the delivery efficiency by avoiding the formation of endosomes. This acoustic method enables the drug carriers to overcome biological barriers of the cell membrane and the endosomes without the limitation of carrier materials, which provides a versatile way of enhanced drug delivery for biomedical applications.
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Affiliation(s)
- Yao Lu
- State Key Laboratory of Precision Measuring Technology & Instruments , Tianjin University , Tianjin 300072 , China
- Molecular Nanofabrication Group, MESA+ Institute for Nanotechnology , University of Twente , Enschede 7500 AE , The Netherlands
| | - Loganathan Palanikumar
- Department of Chemistry, School of Natural Science , Ulsan National Institutes of Science and Technology (UNIST) , Ulsan 44919 , Korea
| | - Eun Seong Choi
- Department of Chemistry, School of Natural Science , Ulsan National Institutes of Science and Technology (UNIST) , Ulsan 44919 , Korea
| | - Jurriaan Huskens
- Molecular Nanofabrication Group, MESA+ Institute for Nanotechnology , University of Twente , Enschede 7500 AE , The Netherlands
| | - Ja-Hyoung Ryu
- Department of Chemistry, School of Natural Science , Ulsan National Institutes of Science and Technology (UNIST) , Ulsan 44919 , Korea
| | - Yanyan Wang
- State Key Laboratory of Precision Measuring Technology & Instruments , Tianjin University , Tianjin 300072 , China
| | - Wei Pang
- State Key Laboratory of Precision Measuring Technology & Instruments , Tianjin University , Tianjin 300072 , China
| | - Xuexin Duan
- State Key Laboratory of Precision Measuring Technology & Instruments , Tianjin University , Tianjin 300072 , China
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7
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Kamiya Y, Ge L, Hong T, Qiu Y, Quintero-Castro DL, Lu Z, Cao HB, Matsuda M, Choi ES, Batista CD, Mourigal M, Zhou HD, Ma J. Author Correction: The nature of spin excitations in the one-third magnetization plateau phase of Ba 3CoSb 2O 9. Nat Commun 2018; 9:3110. [PMID: 30068947 PMCID: PMC6070534 DOI: 10.1038/s41467-018-05679-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Y Kamiya
- Condensed Matter Theory Laboratory, RIKEN, Wako, 351-0198, Saitama, Japan.
| | - L Ge
- School of Physics, Georgia Institute of Technology, 30332, Atlanta, GA, USA
| | - Tao Hong
- Neutron Scattering Division, Oak Ridge National Laboratory, 37831, Oak Ridge, TN, USA
| | - Y Qiu
- NIST Centre for Neutron Research, National Institute of Standards and Technology, 20899, Gaithersburg, MD, USA
| | - D L Quintero-Castro
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany
| | - Z Lu
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany
| | - H B Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, 37831, Oak Ridge, TN, USA
| | - M Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, 37831, Oak Ridge, TN, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, 32310, Tallahassee, FL, USA
| | - C D Batista
- Department of Physics and Astronomy, University of Tennessee, 37996, Knoxville, TN, USA.,Neutron Scattering Division and Shull-Wollan Center, Oak Ridge National Laboratory, 37831, Oak Ridge, TN, USA
| | - M Mourigal
- School of Physics, Georgia Institute of Technology, 30332, Atlanta, GA, USA
| | - H D Zhou
- National High Magnetic Field Laboratory, Florida State University, 32310, Tallahassee, FL, USA.,Department of Physics and Astronomy, University of Tennessee, 37996, Knoxville, TN, USA
| | - J Ma
- Department of Physics and Astronomy, University of Tennessee, 37996, Knoxville, TN, USA. .,Key Laboratory of Artificial Structures and Quantum Control, Department of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, Jiangsu, China.
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8
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Kamiya Y, Ge L, Hong T, Qiu Y, Quintero-Castro DL, Lu Z, Cao HB, Matsuda M, Choi ES, Batista CD, Mourigal M, Zhou HD, Ma J. The nature of spin excitations in the one-third magnetization plateau phase of Ba 3CoSb 2O 9. Nat Commun 2018; 9:2666. [PMID: 29991805 PMCID: PMC6039502 DOI: 10.1038/s41467-018-04914-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [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: 11/08/2017] [Accepted: 05/21/2018] [Indexed: 11/25/2022] Open
Abstract
Magnetization plateaus in quantum magnets—where bosonic quasiparticles crystallize into emergent spin superlattices—are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet Ba3CoSb2O9 in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of Ba3CoSb2O9 exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin. Frustrated magnetic materials attract significant interest because their properties can become dominated by quantum fluctuations. Here the authors show that excitations in the plateau phase of a quantum magnet can be understood semiclassically even though the ground state involves strong quantum effects.
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Affiliation(s)
- Y Kamiya
- Condensed Matter Theory Laboratory, RIKEN, Wako, Saitama, 351-0198, Japan.
| | - L Ge
- School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Tao Hong
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Y Qiu
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - D L Quintero-Castro
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany
| | - Z Lu
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany
| | - H B Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - M Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - C D Batista
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.,Neutron Scattering Division and Shull-Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - M Mourigal
- School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - H D Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.,Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA
| | - J Ma
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA. .,Key Laboratory of Artificial Structures and Quantum Control, Department of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, Jiangsu, China.
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9
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Palanikumar L, Choi ES, Oh JY, Park SA, Choi H, Kim K, Kim C, Ryu JH. Importance of Encapsulation Stability of Nanocarriers with High Drug Loading Capacity for Increasing in Vivo Therapeutic Efficacy. Biomacromolecules 2018; 19:3030-3039. [PMID: 29883544 DOI: 10.1021/acs.biomac.8b00589] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Current drug delivery systems are hampered by poor delivery to tumors, in part reflecting poor encapsulation stability of nanocarriers. Although nanocarriers such as polymeric micelles have high colloidal stability and do not aggregate or precipitate in bulk solution, nanocarriers with low encapsulation stability can lose their cargo during circulation in blood due to interactions with blood cells, cellular membranes, serum proteins, and other biomacromolecules. The resulting premature drug release from carriers limits the therapeutic efficacy at target sites. Herein, we report a simple and robust technique to improve encapsulation stability of drug delivery systems. Specifically, we show that installation of disulfide cross-linked noncovalent polymer gatekeepers onto mesoporous silica nanoparticles with a high loading capacity for hydrophobic drugs enhances in vivo therapeutic efficacy by preventing premature release of cargo. Subsequent release of drug cargos was triggered by cleavage of disulfide cross-linking by glutathione, leading to improved antitumor activity of doxoroubicin in mice. These findings provide novel insights into the development of nanocarriers with high encapsulation stability and improved in vivo therapeutic efficacy.
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10
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Gu CC, Zhao ZY, Chen XL, Lee M, Choi ES, Han YY, Ling LS, Pi L, Zhang YH, Chen G, Yang ZR, Zhou HD, Sun XF. Field-Driven Quantum Criticality in the Spinel Magnet ZnCr_{2}Se_{4}. Phys Rev Lett 2018; 120:147204. [PMID: 29694140 DOI: 10.1103/physrevlett.120.147204] [Citation(s) in RCA: 1] [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: 09/19/2017] [Revised: 03/08/2018] [Indexed: 06/08/2023]
Abstract
We report detailed dc and ac magnetic susceptibilities, specific heat, and thermal conductivity measurements on the frustrated magnet ZnCr_{2}Se_{4}. At low temperatures, with an increasing magnetic field, this spinel material goes through a series of spin state transitions from the helix spin state to the spiral spin state and then to the fully polarized state. Our results indicate a direct quantum phase transition from the spiral spin state to the fully polarized state. As the system approaches the quantum criticality, we find strong quantum fluctuations of the spins with behaviors such as an unconventional T^{2}-dependent specific heat and temperature-independent mean free path for the thermal transport. We complete the full phase diagram of ZnCr_{2}Se_{4} under the external magnetic field and propose the possibility of frustrated quantum criticality with extended densities of critical modes to account for the unusual low-energy excitations in the vicinity of the criticality. Our results reveal that ZnCr_{2}Se_{4} is a rare example of a 3D magnet exhibiting a field-driven quantum criticality with unconventional properties.
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Affiliation(s)
- C C Gu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
| | - Z Y Zhao
- Department of Physics, Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People's Republic of China
| | - X L Chen
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
| | - M Lee
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
- Department of Physics, Florida State University, Tallahassee, Florida 32306-3016, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
| | - Y Y Han
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
| | - L S Ling
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
| | - L Pi
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
- Department of Physics, Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, Jiangsu 210093, People's Republic of China
| | - Y H Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, Jiangsu 210093, People's Republic of China
| | - G Chen
- State Key Laboratory of Surface Physics and Department of Physics, Center for Field Theory and Particle Physics, Fudan University, Shanghai, 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, Jiangsu 210093, People's Republic of China
| | - Z R Yang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, Jiangsu 210093, People's Republic of China
- Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, People's Republic of China
| | - H D Zhou
- Key laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai JiaoTong University, Shanghai 200240, China
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | - X F Sun
- Department of Physics, Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, Jiangsu 210093, People's Republic of China
- Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, People's Republic of China
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11
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Sinclair R, Cao HB, Garlea VO, Lee M, Choi ES, Dun ZL, Dong S, Dagotto E, Zhou HD. Canted magnetic ground state of quarter-doped manganites R 0.75Ca 0.25MnO 3 (R = Y, Tb, Dy, Ho, and Er). J Phys Condens Matter 2017; 29:065802. [PMID: 28002058 DOI: 10.1088/1361-648x/aa4de1] [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: 06/06/2023]
Abstract
Polycrystalline samples of the quarter-doped manganites R 0.75Ca0.25MnO3 (R = Y, Tb, Dy, Ho, and Er) were studied by x-ray diffraction and AC/DC susceptibility measurements. All five samples are orthorhombic and exhibit similar magnetic properties: enhanced ferromagnetism below T 1 (∼80 K) and a spin glass (SG) state below T SG (∼30 K). With increasing R 3+ ionic size, both T 1 and T SG generally increase. The single crystal neutron diffraction results on Tb0.75Ca0.25MnO3 revealed that the SG state is mainly composed of a short-range ordered version of a novel canted (i.e. noncollinear) antiferromagnetic spin state. Furthermore, calculations based on the double exchange model for quarter-doped manganites reveal that this new magnetic phase provides a transition state between the ferromagnetic state and the theoretically predicted spin-orthogonal stripe phase.
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Affiliation(s)
- R Sinclair
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200, USA
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12
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Lee M, Choi ES, Ma J, Sinclair R, Dela Cruz CR, Zhou HD. Magnetism and multiferroicity of an isosceles triangular lattice antiferromagnet Sr3NiNb2O9. J Phys Condens Matter 2016; 28:476004. [PMID: 27661860 DOI: 10.1088/0953-8984/28/47/476004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Various experimental measurements were performed to complete the phase diagram of a weakly distorted triangular lattice system, Sr3NiNb2O9 with Ni(2+) , spin-1 magnetic ions. This compound possesses an isosceles triangular lattice with two shorter bonds and one longer bond. It shows a two-step magnetic phase transition at [Formula: see text] K and [Formula: see text] K at zero magnetic field, characteristic of an easy-axis anisotropy. In the magnetization curves, a series of magnetic phase transitions was observed such as an up-up-down phase at [Formula: see text] T with 1/3 of the saturation magnetization (M sat) and an oblique phase at [Formula: see text] T with [Formula: see text]/3 M sat. Intriguingly, the magnetic phase transition below T N2 is in tandem with the ferroelectricity, which demonstrates multiferroic behaviors. Moreover, the multiferroic phase persists in all magnetically ordered phases regardless of the spin structure. The comparison between the phase diagrams of Sr3NiNb2O9 and its sister compound with an equilateral triangular lattice antiferromagnet Ba3NiNb2O9 (Hwang et al 2012 Phys. Rev. Lett. 109 257205), illustrates how a small imbalance among exchange interactions change the magnetic ground states of the TLAFs.
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Affiliation(s)
- M Lee
- Department of Physics, Florida State University, Tallahassee, FL 32306-3016, USA. National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-3706, USA
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13
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Dun ZL, Trinh J, Li K, Lee M, Chen KW, Baumbach R, Hu YF, Wang YX, Choi ES, Shastry BS, Ramirez AP, Zhou HD. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er). Phys Rev Lett 2016; 116:157201. [PMID: 27127982 DOI: 10.1103/physrevlett.116.157201] [Citation(s) in RCA: 10] [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] [Received: 01/08/2016] [Indexed: 06/05/2023]
Abstract
We present the structural and magnetic properties of a new compound family, Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system.
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Affiliation(s)
- Z L Dun
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | - J Trinh
- Department of Physics, University of California, Santa Cruz, California 95064, USA
| | - K Li
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, People's Republic of China
| | - M Lee
- Department of Physics, Florida State University, Tallahassee, Florida 32306-3016, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-3706, USA
| | - K W Chen
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-3706, USA
| | - R Baumbach
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-3706, USA
| | - Y F Hu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Y X Wang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-3706, USA
| | - B S Shastry
- Department of Physics, University of California, Santa Cruz, California 95064, USA
| | - A P Ramirez
- Department of Physics, University of California, Santa Cruz, California 95064, USA
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-3706, USA
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14
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Palanikumar L, Kim HY, Oh JY, Thomas AP, Choi ES, Jeena MT, Joo SH, Ryu JH. Noncovalent Surface Locking of Mesoporous Silica Nanoparticles for Exceptionally High Hydrophobic Drug Loading and Enhanced Colloidal Stability. Biomacromolecules 2015. [DOI: 10.1021/acs.biomac.5b00589] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- L. Palanikumar
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Ho Young Kim
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Joon Yong Oh
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Ajesh P. Thomas
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Eun Seong Choi
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - M. T. Jeena
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Sang Hoon Joo
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
| | - Ja-Hyoung Ryu
- Department of Chemistry,
School of Natural Science,
and ‡Department of Chemical
Engineering, School of Energy and Chemical Engineering, Ulsan National Institutes of Science and Technology (UNIST), Ulsan 689-798, Korea
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15
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Yang SH, Choi J, Palanikumar L, Choi ES, Lee J, Kim J, Choi IS, Ryu JH. Cytocompatible in situ cross-linking of degradable LbL films based on thiol-exchange reaction. Chem Sci 2015; 6:4698-4703. [PMID: 28717481 PMCID: PMC5500856 DOI: 10.1039/c5sc01225b] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [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: 04/06/2015] [Accepted: 05/18/2015] [Indexed: 12/26/2022] Open
Abstract
Formation of both mechanically durable and programmably degradable layer-by-layer (LbL) films in a biocompatible fashion has potential applications in cell therapy, tissue engineering, and drug-delivery systems, where the films are interfaced with living cells. In this work, we developed a simple but versatile method for generating in situ cross-linked and responsively degradable LbL films, based on the thiol-exchange reaction, under highly cytocompatible conditions (aqueous solution at pH 7.4 and room temperature). The cytocompatibility of the processes was confirmed by coating individual yeast cells with the cross-linked LbL films and breaking the films on demand, while maintaining the cell viability. In addition, the processes were applied to the controlled release of an anticancer drug in the HeLa cells.
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Affiliation(s)
- Sung Ho Yang
- Department of Chemistry Education , Korea National University of Education , Chungbuk 363-791 , Korea .
| | - Jinsu Choi
- Department of Chemistry Education , Korea National University of Education , Chungbuk 363-791 , Korea .
| | - L Palanikumar
- Center for Cell-Encapsulation Research , Department of Chemistry , KAIST , Daejeon 305-701 , Korea .
| | - Eun Seong Choi
- Center for Cell-Encapsulation Research , Department of Chemistry , KAIST , Daejeon 305-701 , Korea .
| | - Juno Lee
- Department of Chemistry , Ulsan National Institute of Science and Technology , Ulsan 689-798 , Korea .
| | - Juan Kim
- Department of Chemistry Education , Korea National University of Education , Chungbuk 363-791 , Korea .
| | - Insung S Choi
- Department of Chemistry , Ulsan National Institute of Science and Technology , Ulsan 689-798 , Korea .
| | - Ja-Hyoung Ryu
- Center for Cell-Encapsulation Research , Department of Chemistry , KAIST , Daejeon 305-701 , Korea .
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16
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Eom MJ, Kim K, Jo YJ, Yang JJ, Choi ES, Min BI, Park JH, Cheong SW, Kim JS. Dimerization-induced Fermi-surface reconstruction in IrTe2. Phys Rev Lett 2014; 113:266406. [PMID: 25615364 DOI: 10.1103/physrevlett.113.266406] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Indexed: 06/04/2023]
Abstract
We report a de Haas-van Alphen (dHvA) oscillation study on IrTe2 single crystals showing complex dimer formations. By comparing the angle dependence of dHvA oscillations with band structure calculations, we show distinct Fermi surface reconstruction induced by a 1/5-type and a 1/8-type dimerizations. This verifies that an intriguing quasi-two-dimensional conducting plane across the layers is induced by dimerization in both cases. A phase transition to the 1/8 phase with higher dimer density reveals that local instabilities associated with intra- and interdimer couplings are the main driving force for complex dimer formations in IrTe2.
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Affiliation(s)
- Man Jin Eom
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyoo Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Y J Jo
- Department of Physics, Kyungpook National University, Daegu 702-701, Korea
| | - J J Yang
- Laboratory for Pohang Emergent Materials, Pohang University of Science and Technology, Pohang 790-784, Korea and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - B I Min
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - J-H Park
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - S-W Cheong
- Laboratory for Pohang Emergent Materials, Pohang University of Science and Technology, Pohang 790-784, Korea and Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Piscataway, New Jersey 08854, USA
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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17
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Hallas AM, Cheng JG, Arevalo-Lopez AM, Silverstein HJ, Su Y, Sarte PM, Zhou HD, Choi ES, Attfield JP, Luke GM, Wiebe CR. Incipient ferromagnetism in Tb2Ge2O7: application of chemical pressure to the enigmatic spin-liquid compound Tb2Ti2O7. Phys Rev Lett 2014; 113:267205. [PMID: 25615381 DOI: 10.1103/physrevlett.113.267205] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Indexed: 06/04/2023]
Abstract
After nearly 20 years of study, the origin of the spin-liquid state in Tb2Ti2O7 remains a challenge for experimentalists and theorists alike. To improve our understanding of the exotic magnetism in Tb2Ti2O7, we synthesize a chemical pressure analog: Tb2Ge2O7. Substitution of titanium by germanium results in a lattice contraction and enhanced exchange interactions. We characterize the magnetic ground state of Tb2Ge2O7 with specific heat, ac and dc magnetic susceptibility, and polarized neutron scattering measurements. Akin to Tb2Ti2O7, there is no long-range order in Tb2Ge2O7 down to 20 mK. The Weiss temperature of -19.2(1) K, which is more negative than that of Tb2Ti2O7, supports the picture of stronger antiferromagnetic exchange. Polarized neutron scattering of Tb2Ge2O7 reveals that liquidlike correlations dominate in this system at 3.5 K. However, below 1 K, the liquidlike correlations give way to intense short-range ferromagnetic correlations with a length scale similar to the Tb-Tb nearest neighbor distance. Despite stronger antiferromagnetic exchange, the ground state of Tb2Ge2O7 has ferromagnetic character, in stark contrast to the pressure-induced antiferromagnetic order observed in Tb2Ti2O7.
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Affiliation(s)
- A M Hallas
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - J G Cheng
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - A M Arevalo-Lopez
- Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
| | - H J Silverstein
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Y Su
- Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ, Lichtenbergstrasse 1, 85747 Garching, Germany
| | - P M Sarte
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
| | - J P Attfield
- Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom
| | - G M Luke
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada and Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z7, Canada
| | - C R Wiebe
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada and Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada and Department of Chemistry, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada
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18
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Jo YJ, Park J, Lee G, Eom MJ, Choi ES, Shim JH, Kang W, Kim JS. Valley-polarized interlayer conduction of anisotropic Dirac fermions in SrMnBi2. Phys Rev Lett 2014; 113:156602. [PMID: 25375728 DOI: 10.1103/physrevlett.113.156602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Indexed: 06/04/2023]
Abstract
We report the valley-selective interlayer conduction of SrMnBi(2) under in-plane magnetic fields. The c-axis resistivity of SrMnBi(2) shows clear angular magnetoresistance oscillations indicating coherent interlayer conduction. Strong fourfold variation of the coherent peak in the c-axis resistivity reveals that the contribution of each Dirac valley is significantly modulated by the in-plane field orientation. This originates from anisotropic Dirac Fermi surfaces with strong disparity in the momentum-dependent interlayer coupling. Furthermore, we found a signature of broken valley symmetry at high magnetic fields. These findings demonstrate that a quasi-two-dimensional anisotropic Dirac system can host a valley-polarized interlayer current through magnetic valley control.
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Affiliation(s)
- Y J Jo
- Department of Physics, Kyungpook National University, Daegu 702-710, Korea
| | - Joonbum Park
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - G Lee
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Man Jin Eom
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - E S Choi
- National High Magnetic field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Ji Hoon Shim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - W Kang
- Department of Physics, Ewha Womans University, Seoul 120-750, Korea
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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19
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Ok JM, Jo YJ, Kim K, Shishidou T, Choi ES, Noh HJ, Oguchi T, Min BI, Kim JS. Quantum oscillations of the metallic triangular-lattice antiferromagnet PdCrO2. Phys Rev Lett 2013; 111:176405. [PMID: 24206508 DOI: 10.1103/physrevlett.111.176405] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 07/15/2013] [Indexed: 06/02/2023]
Abstract
We report the electronic and transport properties of the triangular antiferromagnet PdCrO(2) at high magnetic fields up to 33 T, using measurements of the de Haas-van Alphen oscillations and the Hall resistivity. The de Haas-van Alphen oscillations below the magnetic ordering temperature T(N) reveal several two-dimensional Fermi surfaces of smaller size than those found in nonmagnetic PdCoO(2), consistent with the band structure calculations. This evidences Fermi surface reconstruction due to the 120° helical ordering of the localized Cr spins, suggesting significant coupling of the itinerant electrons to the underlying spin texture. This induces the nonlinear Hall resistivity at low temperatures via the magnetic breakdown in the reconstructed Fermi surface. Furthermore, such a coupling leads to the unconventional anomalous Hall effects near T(N) due to the field-induced spin chirality at high magnetic fields.
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Affiliation(s)
- Jong Mok Ok
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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20
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Park JA, Koh KN, Choi ES, Jang S, Kwon SW, Park CJ, Seo JJ, Im HJ. Successful rescue of early graft failure in pediatric patients using T-cell-depleted haploidentical hematopoietic SCT. Bone Marrow Transplant 2013; 49:270-5. [PMID: 24141651 DOI: 10.1038/bmt.2013.163] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 08/21/2013] [Accepted: 08/30/2013] [Indexed: 11/09/2022]
Abstract
Graft failure (GF) is a significant complication after allogeneic hematopoietic stem cell transplantation (HCT) and is associated with a high mortality rate. We performed re-transplantation using haploidentical-related donors to rescue children with early GF. Between 2008 and 2013, 10 patients received re-transplantation from haploidentical family donors. The median age at HCT was 13.5 years and the median time between transplantations was 52.5 days. Conditioning regimen with fludarabine and CY was used in seven patients, and TBI was added in three patients. All 10 patients received T-cell-depleted grafts using CD3 or CD3/CD19 MoAb. The median numbers of CD34(+) and CD3(+) cells were 5.52 × 10(6)/kg and 1.08 × 10(6)/kg, respectively. For GVHD prophylaxis, mycophenolate mofetil (MMF) and tacrolimus or MMF and CYA were used. All 10 patients achieved a sustained neutrophil engraftment and maintained a complete donor chimerism at the time of analysis (median 23 months, range 6-62 months). Nine of 10 patients were alive, and one patient with moyamoya disease with AML died of encephalopathy 7 months post transplant. This study suggests that fludarabine- and CY-based conditioning with T-cell-depleted haploidentical HCT is a feasible option to rescue pediatric patients with primary GF.
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Affiliation(s)
- J A Park
- Department of Pediatrics, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - K N Koh
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
| | - E S Choi
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
| | - S Jang
- Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
| | - S W Kwon
- Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
| | - C-J Park
- Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
| | - J J Seo
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
| | - H J Im
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, University of Ulsan College of Medicine, Asan Medical Center Children's Hospital, Seoul, Korea
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21
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Hu R, Wang K, Ryu H, Lei H, Choi ES, Uhlarz M, Wosnitza J, Petrovic C. Electronic Griffiths phase in the Te-doped semiconductor FeSb2. Phys Rev Lett 2012; 109:256401. [PMID: 23368482 DOI: 10.1103/physrevlett.109.256401] [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] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Indexed: 06/01/2023]
Abstract
We report on the emergence of an electronic Griffiths phase in the doped semiconductor FeSb(2), predicted for disordered insulators with random localized moments in the vicinity of a metal-insulator transition. Magnetic, transport, and thermodynamic measurements of Fe(Sb(1-x)Te(x))(2) single crystals show signatures of disorder-induced non-Fermi liquid behavior and a Wilson ratio expected for strong electronic correlations. The electronic Griffiths phase states are found on the metallic boundary between the insulating state (x = 0) and a long-range albeit weak magnetic order (x ≥ 0.075).
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Affiliation(s)
- Rongwei Hu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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Hwang J, Choi ES, Ye F, Dela Cruz CR, Xin Y, Zhou HD, Schlottmann P. Successive magnetic phase transitions and multiferroicity in the spin-one triangular-lattice antiferromagnet Ba3NiNb2O9. Phys Rev Lett 2012; 109:257205. [PMID: 23368494 DOI: 10.1103/physrevlett.109.257205] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/12/2012] [Indexed: 06/01/2023]
Abstract
We report the magnetic and electric properties of Ba3NiNb2O9, which is a quasi-two-dimensional spin-one triangular-lattice antiferromagnet with trigonal structure. At low T and with increasing magnetic field, the system evolves from a 120 degree magnetic ordering phase (A phase) to an up-up-down (uud) phase (B phase) with a change of slope at 1/3 of the saturation magnetization, and then to an "oblique" phase (C phase). Accordingly, the ferroelectricity switches on at each phase boundary with appearance of spontaneous polarization. Therefore, Ba3NiNb2O9 is a unique triangular-lattice antiferromagnet exhibiting both uud phase and multiferroicity.
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Affiliation(s)
- J Hwang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-3706, USA
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Krstovska D, Choi ES, Steven E, Brooks JS. The angular magnetothermoelectric power of a charge density wave system. J Phys Condens Matter 2012; 24:265502. [PMID: 22691452 DOI: 10.1088/0953-8984/24/26/265502] [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: 06/01/2023]
Abstract
The angular dependence of the magnetothermopower of a charge transfer organic salt α-(ET)(2)KHg(SCN)(4) below (4 K) and above (9 K) the phase transition temperature, T(p) = 8 K, and under fields of 15 T and 25 T, below and above the 'kinkfield', has been studied. We find that for a longitudinal thermoelectric measurement both an interlayer thermopower (the Seebeck effect), S(zz), and a transverse thermopower (the Nernst effect), S(yz), exist in all three different B-T phases (the CDW (0), CDW (x) and metallic states) with large amplitude. Both thermoelectric effects display a resonant-like behavior without a sign reversal at the angles corresponding to angular magnetoresistance oscillation minima and maxima in this compound. The resonant behavior is most evident in the CDW(0) state, indicating a mechanism involving the Fermi surface nesting. Angular dependences reveal different behaviors of the thermopower and Nernst effect in the high magnetic field (CDW(x)) state.
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Affiliation(s)
- D Krstovska
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
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24
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Zhou HD, Cheng JG, Hallas AM, Wiebe CR, Li G, Balicas L, Zhou JS, Goodenough JB, Gardner JS, Choi ES. Chemical pressure effects on pyrochlore spin ice. Phys Rev Lett 2012; 108:207206. [PMID: 23003185 DOI: 10.1103/physrevlett.108.207206] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Indexed: 06/01/2023]
Abstract
A comparison among the two sets of studied pyrochlore spin ices, Ho2Sn2O7, Ho2Ti2O7, and Ho2Ge2O7 with Ho3+ spins and Dy2Sn2O7, Dy2Ti2O7, and Dy2Ge2O7 with Dy3+ spins, shows that the application of chemical pressure through each set drives the system toward the antiferromagnetic phase boundary from the spin ice region, which agrees with the prediction of the "dipolar spin ice" model of den Hertog and Gingras. Among all the studied pyrochlore spin ices, Dy2Ge2O7 has the smallest ratio of Jnn/Dnn=-0.73.
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Affiliation(s)
- H D Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA
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Raičević I, Popović D, Panagopoulos C, Benfatto L, Silva Neto MB, Choi ES, Sasagawa T. Skyrmions in a doped antiferromagnet. Phys Rev Lett 2011; 106:227206. [PMID: 21702631 DOI: 10.1103/physrevlett.106.227206] [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: 06/04/2010] [Indexed: 05/31/2023]
Abstract
Magnetization and magnetoresistance have been measured in insulating antiferromagnetic La2Cu0.97Li0.03O4 over a wide range of temperatures, magnetic fields, and field orientations. The magnetoresistance step associated with a weak ferromagnetic transition exhibits a striking nonmonotonic temperature dependence, consistent with the presence of Skyrmions.
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Affiliation(s)
- I Raičević
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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26
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Zhou HD, Choi ES, Li G, Balicas L, Wiebe CR, Qiu Y, Copley JRD, Gardner JS. Spin liquid state in the S = 1/2 triangular lattice Ba3CuSb2O9. Phys Rev Lett 2011; 106:147204. [PMID: 21561219 DOI: 10.1103/physrevlett.106.147204] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Indexed: 05/30/2023]
Abstract
The synthesis and characterization of Ba3CuSb2O9, which has a layered array of Cu2+ spins in a triangular lattice, are reported. The magnetic susceptibility and neutron scattering experiments of this material show no magnetic ordering down to 0.2 K with a θ(CW) = -55 K. The magnetic specific heat reveals a T-linear dependence with a γ = 43.4 mJ K(-2) mol(-1) below 1.4 K. These observations suggest that Ba3CuSb2O9 is a new quantum spin liquid candidate with a S = 1/2 triangular lattice.
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Affiliation(s)
- H D Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306-4005, USA.
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Lim JS, Kim DH, Jung IO, Woo CH, Choi ES, Gim JH, Kim J. Synthesis and electrochemical properties of LiMPO4 (M = Fe, Mn, Co) nanocrystals in polyol medium. J Nanosci Nanotechnol 2010; 10:3357-3361. [PMID: 20358956 DOI: 10.1166/jnn.2010.2311] [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] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Olivine structured LiMPO4 (M = Fe, Mn, Co) was synthesized by the solvothermal process using a polyol medium of diethylene glycol (DEG) without any further heating as a post procedure. The synthesized LiMPO4 nanoparticles exhibited an average length of 200 approximately 400 nm, width of 200 approximately 300 nm, and thickness of 20 approximately 50 nm, and with well dispersed plate and rod morphologies. The Rietveld-refined X-ray diffraction (XRD) pattern of LiFePO4 exhibited a good fit with an olivine structure (space group: Pnma) and no undesirable impurity phases. The LiFePO4 nanocrystals showed a reversible capacity of 167 mAh/g, equating to a utilization efficiency of 98% of its theoretical capacity, with a good cyclability over an extended range up to 40 cycles.
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Affiliation(s)
- J S Lim
- Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Buk-Gu, Gwangju 500-757, Korea
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Choi ES, Kim DH, Woo CH, Choi CH, Kim J. Synthesis and electrochemical properties of LiFePO4/carbon nanocomposites in polyol medium. J Nanosci Nanotechnol 2010; 10:3416-3419. [PMID: 20358969 DOI: 10.1166/jnn.2010.2310] [Citation(s) in RCA: 3] [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] [Indexed: 05/29/2023]
Abstract
LiFePO4/Carbon nanocomposites with varying amounts of carbon were synthesized using polyol process without any further heating as a post step. The X-ray diffraction patterns of all samples were indexed on the basis of orthorhombic olivine-type structure. The field emission-TEM images of composites with the amount of 3 approximately 15 wt% carbon showed the average sizes of 45 approximately 80 nm with nanorod shape surrounded by carbon. The initial discharge curves of LiFePO4/Carbon show 166, 157, 142, and 119 mAh/g capacities at a current density of 0.1 mA/cm2 in the voltage range of 2.5-4.2 V, respectively, without capacity fading and excellent cycle retentions during the 20 cycles. Especially, the sample of amount of 3 wt% carbon shows the excellent high rate performances at 15 and 30 C rates with high capacity retention compared with previously reported results of high temperature processed results, due to the existence of conductive agents such as carbon which suppresses particle growth and exhibits improved electronic conductivity and lithium ion diffusivity, simultaneously.
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Affiliation(s)
- E S Choi
- Department of Materials Science and Engineering, Chonnam National University, 300 Yongbongdong, Buk-Gu, Gwangju 500-757, Korea
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Song YM, Choi ES, Yu JS, Lee YT. Light-extraction enhancement of red AlGaInP light-emitting diodes with antireflective subwavelength structures. Opt Express 2009; 17:20991-20997. [PMID: 19997337 DOI: 10.1364/oe.17.020991] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate the enhancement of light extraction in 633 nm AlGaInP light-emitting diodes (LEDs) with antireflective subwavelength structures (SWS). From the contour plots by the rigorous coupled wave analysis method, it is found that the reduction of the internal reflection strongly depends on the period of SWS. The Ag nanoparticles formed by thermal dewetting were used as an etch mask for dry etch process to fabricate antireflective SWS on the LED surface. The tapered pillars on the GaP were fabricated, on average, with distances below 200 nm, satisfying the required antireflection condition at the emission wavelength. The improvement in light output power by approximately 26.4% was achieved for the fabricated AlGaInP LEDs with SWS compared to the conventional LEDs due to a strongly reduced Fresnel internal reflection at the GaP/air interface. The improved directionality in the far-field pattern was also obtained due to the directional light extraction enhancement.
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Affiliation(s)
- Y M Song
- Department of Information and Communications, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea
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Lee YS, Choi ES, Song CJ. Symptomatic nerve root changes on contrast-enhanced MR imaging after surgery for lumbar disk herniation. AJNR Am J Neuroradiol 2009; 30:1062-7. [PMID: 19213822 DOI: 10.3174/ajnr.a1497] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The significance of postoperative nerve root changes (enhancement, thickening, and displacement) is still a topic of debate. The purpose of this study was to evaluate the association between nerve root changes and residual or recurrent symptoms after lumbar surgery with contrast-enhanced MR imaging. MATERIALS AND METHODS A total of 120 patients with 140 postoperative lumbar disk lesions causing residual or recurrent pain underwent contrast-enhanced MR imaging. The levels at which diskectomies had been performed were retrospectively evaluated for nerve root enhancement (NRE), thickening, and displacement. Association between nerve root changes and corresponding clinical presentations were statistically assessed. Nerve root changes in recurrent disk herniation (RDH) and postoperative epidural fibrosis (PEF) were also evaluated with clinical symptoms. RESULTS Ninety-two (65.7%) of the 140 disks demonstrated NRE. Regarding the association with clinical symptoms, the sensitivity was 91.7%, the specificity was 73.2%, the positive predictive value (PPV) was 83.7%, and the negative predictive value was 85.4% (P = .000). Nerve root thickening and displacement were significantly associated with the clinical symptoms, especially when NRE was combined (PPV, 87.7% and 87.2%, respectively). When RDH was combined with all 3 nerve root changes, the PPV was increased up to 94.1%. However, in PEF, the association between nerve root changes and clinical symptoms was not significant unless all 3 nerve root changes were combined. CONCLUSIONS In patients with residual or recurrent pain after surgery for lumbar disk herniation, nerve root changes on contrast-enhanced MR imaging were well associated with clinical symptoms, of which NRE was the most significant finding.
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Affiliation(s)
- Y S Lee
- Department of Radiology, Daejeon St. Mary's Hospital, The Catholic University of Korea, Daejeon, Korea.
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Meneghin A, Choi ES, Evanoff HL, Kunkel SL, Martinez FJ, Flaherty KR, Toews GB, Hogaboam CM. TLR9 is expressed in idiopathic interstitial pneumonia and its activation promotes in vitro myofibroblast differentiation. Histochem Cell Biol 2008; 130:979-92. [PMID: 18633634 DOI: 10.1007/s00418-008-0466-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2008] [Indexed: 12/28/2022]
Abstract
Infectious diseases can be cofactors in idiopathic interstitial pneumonias (IIP) pathogenesis; recent data suggests that toll-like receptors 9 (TLR9) ligands contribute to experimental chronic tissue remodeling. Real-time TAQMAN and immunohistochemical analysis of IIP normal surgical lung biopsies (SLBs), primary fibroblast lines grown from both IIP and normal SLBs indicate that TLR9 is prominently and differentially expressed in a disease-specific manner. TLR9 expression was increased in biopsies from patients with IIP compared with normal lung biopsies and its expression is localized to areas of marked interstitial fibrosis. TLR9 in fibroblasts appeared to be increased by profibrotic Th2 cytokines (IL-4 and IL-13) and this was true in fibroblasts cultured from the most severe form of IIP, idiopathic pulmonary fibrosis (IPF) SLBs, in non-specific interstitial pneumonia fibroblast lines, and in normal fibroblasts. Finally, confocal microscopy studies have shown that TLR9 activation by its synthetic agonist CpG-ODN significantly increased the expression of alpha smooth muscle actin, the main marker of myofibroblast differentiation. These data indicate that TLR9 expression may drive the abnormal tissue healing response in severe forms of IIP and its activation can have a key role in myofibroblast differentiation promoting the progression of disease during the terminal phase of IPF.
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Affiliation(s)
- A Meneghin
- Department of Pathology, University of Michigan Medical School, Room 4710, BSRB, 109 Zina Pitcher Pl, Ann Arbor, MI 48109-2200, USA.
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Tokumoto T, Brooks JS, Oshima Y, Choi ES, Brunel LC, Akutsu H, Kaihatsu T, Yamada J, van Tol J. Antiferromagnetic d-electron exchange via a spin-singlet pi-electron ground state in an organic conductor. Phys Rev Lett 2008; 100:147602. [PMID: 18518072 DOI: 10.1103/physrevlett.100.147602] [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] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Indexed: 05/26/2023]
Abstract
Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.
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Affiliation(s)
- T Tokumoto
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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Uji S, Terashima T, Nishimura M, Takahide Y, Konoike T, Enomoto K, Cui H, Kobayashi H, Kobayashi A, Tanaka H, Tokumoto M, Choi ES, Tokumoto T, Graf D, Brooks JS. Vortex dynamics and the Fulde-Ferrell-Larkin-Ovchinnikov state in a magnetic-field-induced organic superconductor. Phys Rev Lett 2006; 97:157001. [PMID: 17155350 DOI: 10.1103/physrevlett.97.157001] [Citation(s) in RCA: 9] [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: 03/13/2006] [Indexed: 05/12/2023]
Abstract
Under special conditions, a superconducting state where the order parameter oscillates in real space, the so-called FFLO state, is theoretically predicted to exist near the upper critical field, as first proposed by Fulde and Ferrell, and Larkin and Ovchinnikov. We report systematic measurements of the interlayer resistance in high magnetic fields to 45 T in the two-dimensional magnetic-field-induced organic superconductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The resistance is found to show characteristic dip structures in the superconducting state. The results are consistent with pinning interactions between the vortices penetrating the insulating layers and the order parameter of the FFLO state. This gives strong evidence for an oscillating order parameter in real space.
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Affiliation(s)
- S Uji
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
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Choi ES, Pierce EM, Jakubzick C, Carpenter KJ, Kunkel SL, Evanoff H, Martinez FJ, Flaherty KR, Moore BB, Toews GB, Colby TV, Kazerooni EA, Gross BH, Travis WD, Hogaboam CM. Focal interstitial CC chemokine receptor 7 (CCR7) expression in idiopathic interstitial pneumonia. J Clin Pathol 2006; 59:28-39. [PMID: 16394278 PMCID: PMC1860265 DOI: 10.1136/jcp.2005.026872] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [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: 01/23/2023]
Abstract
BACKGROUND/AIMS Idiopathic interstitial pneumonias (IIPs) are a diverse grouping of chronic pulmonary diseases characterised by varying degrees of pulmonary fibrosis. The triggers of the fibroproliferative process in IIP remain enigmatic but recent attention has been directed towards chemokine involvement in this process. METHODS The expression of two chemokine receptors, CCR7 and CXCR4, and their respective ligands, CCL19, CCL21, and CXCL12, were examined in surgical lung biopsies (SLBs) from patients with IIP. Transcript and protein expression of these receptors and their ligands was compared with that detected in histologically normal margin SLBs. RESULTS CCR7 and CXCR4 were detected by gene array and real time polymerase chain reaction analysis and CCR7, but not CXCR4, expression was significantly raised in usual interstitial pneumonia (UIP) relative to biopsies from patients diagnosed with non-specific interstitial pneumonia (NSIP) or respiratory bronchiolitis/interstitial lung disease (RBILD). CCR7 protein was expressed in interstitial areas of all upper and lower lobe UIP SLBs analysed. CCR7 expression was present in 50% of NSIP SLBs, and CCR7 was restricted to blood vessels and mononuclear cells in 75% of RBILD SLBs. Immune cell specific CXCR4 expression was seen in IIP and normal margin biopsies. CCR7 positive areas in UIP biopsies were concomitantly positive for CD45 (the leucocyte common antigen) but CCR7 positive areas in all IIP SLBs lacked the haemopoietic stem cell antigen CD34, collagen 1, and alpha smooth muscle actin. CONCLUSION This molecular and immunohistochemical analysis showed that IIPs are associated with abnormal CCR7 transcript and protein expression.
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Affiliation(s)
- E S Choi
- Department of Pathology, University of Michigan Medical School, Room 5214, Medical Science I, 1301 Catherine Road, Ann Arbor, MI 48109-0602, USA
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Choi ES, Brooks JS, Kang H, Jo YJ, Kang W. Resonant nernst effect in the metallic and field-induced spin density wave States of (TMTSF)2ClO4. Phys Rev Lett 2005; 95:187001. [PMID: 16383935 DOI: 10.1103/physrevlett.95.187001] [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] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Indexed: 05/05/2023]
Abstract
We examine an unusual phenomenon where, in tilted magnetic fields near magic angles parallel to crystallographic planes, a "giant" resonant Nernst signal has been observed by Wu et al. [Phys. Rev. Lett. 91, 056601 (2003)] in the metallic state of an organic conducting Bechgaard salt. We show that this effect appears to be a general feature of these materials and is also present in the field-induced spin density wave phase with even larger amplitude. Our results place conditions on any model that treats the metallic state as a state with finite Cooper pairing.
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Affiliation(s)
- E S Choi
- NHMFL/Physics, Florida State University, Tallahassee, Florida 32310, USA
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Uji S, Yasuzuka S, Konoike T, Enomoto K, Yamada J, Choi ES, Graf D, Brooks JS. Quantum oscillation of Hall resistance in the extreme quantum limit of an organic conductor (TMTSF)2ClO4. Phys Rev Lett 2005; 94:077206. [PMID: 15783852 DOI: 10.1103/physrevlett.94.077206] [Citation(s) in RCA: 3] [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: 08/10/2004] [Indexed: 05/24/2023]
Abstract
We report resistance and magnetic torque experiments under a high magnetic field up to 45 T in a three dimensional quantum Hall (QH) system (TMTSF)(2)ClO(4), where TMTSF = tetramethyltetraselenafulvalene. The Hall resistance shows huge oscillations accompanied with sign reversal after the final QH state, where the Landau level filling factor is unity, is removed above 26 T. The magnetic torque also oscillates with the field. The results suggest that a novel quantum state, where the character of the carriers periodically changes with the field, is stabilized in the extreme quantum limit.
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Affiliation(s)
- S Uji
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
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Graf D, Choi ES, Brooks JS, Matos M, Henriques RT, Almeida M. High magnetic field induced charge density wave state in a quasi-one-dimensional organic conductor. Phys Rev Lett 2004; 93:076406. [PMID: 15324259 DOI: 10.1103/physrevlett.93.076406] [Citation(s) in RCA: 10] [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: 12/31/2003] [Indexed: 05/24/2023]
Abstract
The quasi-one-dimensional organic conductor (Per)2Pt(mnt)2 exhibits a charge density wave ground state below 8 K. Magnetoresistance and magnetization measurements show that the charge density wave is suppressed with magnetic fields of order 20 T, above which a high resistance state, with a cascade of subphases, appears. This new state, tentatively identified as a field induced charge density wave, reenters a low resistance state above 40 T. The results are presented in light of theoretical work [D. Zanchi et al. Phys. Rev. B 53, 1240 (1996)]] involving field induced charge density wave ground states in high magnetic fields.
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Affiliation(s)
- D Graf
- NHMFL/Physics, Florida State University, Tallahassee, Florida 32310, USA
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Jakubzick C, Choi ES, Kunkel SL, Evanoff H, Martinez FJ, Puri RK, Flaherty KR, Toews GB, Colby TV, Kazerooni EA, Gross BH, Travis WD, Hogaboam CM. Augmented pulmonary IL-4 and IL-13 receptor subunit expression in idiopathic interstitial pneumonia. J Clin Pathol 2004; 57:477-86. [PMID: 15113854 PMCID: PMC1770295 DOI: 10.1136/jcp.2003.012799] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [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: 11/03/2022]
Abstract
BACKGROUND Some idiopathic interstitial pneumonias (IIPs) are characterised by fibroproliferation and deposition of extracellular matrix. Because efficacious treatment options are limited, research has been directed towards understanding the cytokine networks that may affect fibroblast activation and, hence, the progression of certain IIPs. AIMS To examine the expression of interleukin 4 (IL-4), IL-13, and their corresponding receptor subunits in the various forms of IIP and normal patient groups. METHODS Molecular and immunohistochemical analysis of IL-4, interferon gamma (IFNgamma), IL-13, IL-4 receptor (IL-R), and IL-13 receptor subunits in surgical lung biopsies (SLBs) from 39 patients (21 usual interstitial pneumonia (UIP), six non-specific interstitial pneumonia (NSIP), eight respiratory bronchiolitic interstitial lung disease (RBILD), and five normal controls). RESULTS Molecular analysis demonstrated that IL-13Ralpha2, IL-13Ralpha1, and IL-4Ralpha were present in a greater proportion of upper and lower lobe biopsies from patients with UIP than patients with NSIP and RBILD. Immunohistochemical analysis of patients with UIP, NSIP, and RBILD revealed interstitial staining for all three receptor subunits, whereas such staining was only seen in mononuclear cells present in normal SLBs. Fibroblastic foci in patients with UIP strongly stained for IL-4Ralpha and IL-13Ralpha2. Localised expression of IL-4Ralpha was also seen in SLBs from patients with NSIP but not in other groups. CONCLUSION Some histological subtypes of IIP are associated with increased pulmonary expression of receptor subunits responsive to IL-4 and IL-13. These findings may be of particular importance in understanding the pathogenesis of IIP and, more importantly, may provide important novel therapeutic targets.
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Affiliation(s)
- C Jakubzick
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-0602, USA
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Ahn JO, Choi ES, Lee HW, Hwang SH, Kim CS, Jang HW, Haam SJ, Jung JK. Enhanced secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae by translational fusion to cellulose-binding domain. Appl Microbiol Biotechnol 2004; 64:833-9. [PMID: 14740195 DOI: 10.1007/s00253-003-1547-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Revised: 12/02/2003] [Accepted: 12/12/2003] [Indexed: 10/26/2022]
Abstract
The secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae was investigated by employing a fusion partner, a cellulose-binding domain (CBD) from Trichoderma harzianum endoglucanase II (THEG). The CBD was connected to the N-terminal of L1 lipase through an endogenous linker peptide from THEG. The expression cassette for the fusion protein in S. cerevisiae was constructed using the alpha-amylase signal peptide and the galactose-inducible GAL10 promoter. Secretion of CBD-linker-L1 lipase by this fusion construct was dramatically 7-fold enhanced, compared with that of the mature L1 lipase without CBD-fusion. The fusion protein was secreted into the culture medium, reaching levels of approximately 1.3 g/l in high-cell-density fed-batch cultures. Insertion of a KEX2 cleavage site into the junction between CBD-linker and L1 lipase resulted in the same level of enhanced secretion, indicating that the CBD-linker fusion probably plays a critical role in secretion from endoplasmic reticulum to Golgi apparatus. Therefore, the CBD from THEG can be used both as an affinity tag and as a secretion enhancer for the secretory production of heterologous proteins in S. cerevisiae, since in vivo breakage at the linker was almost negligible.
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Affiliation(s)
- J O Ahn
- Bio-Pilot Plant, Korea Research Institute of Bioscience and Biotechnology, Yusong, 305-600 Taejon, Korea
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Moon H, Kim SW, Lee J, Rhee SK, Choi ES, Kang HA, Kim IH, Hong SI. Independent Exponential Feeding of Glycerol and Methanol for Fed-Batch Culture of Recombinant Hansenula polymorpha DL-1. Appl Biochem Biotechnol 2003; 111:65-80. [PMID: 14645999 DOI: 10.1385/abab:111:2:65] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2002] [Revised: 04/01/2003] [Accepted: 05/01/2003] [Indexed: 11/11/2022]
Abstract
As a novel feeding strategy for optimizing human epidermal growth factor (hEGF) production with a recombinant Hansenula polymorpha DL-1 using the methanol oxidase (MOX) promoter in H. polymorpha DL-1, independent exponential feeding of two substrates was used. A simple kinetic model considering the cell growth on two substrates was established and used to calculate the respective feeding rates of glycerol and methanol. In the fedbatch culture with methanol-only feeding, the optimal set point of specific growth rate on methanol was found to be 0.10 h-1. When the fed-batch cultures were conducted by the independent feeding of glycerol and methanol, the actual specific growth rate on glycerol and methanol was slightly lower than the set point of specific growth rate. By the uncoupled feeding of glycerol and methanol the volumetric productivity of hEGF increased from 6.4 to 8.0 mg/(L.h), compared with methanol-only feeding.
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Affiliation(s)
- H Moon
- Graduate School of Biotechnology, Korea University, Seoul 136-701, Korea
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41
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Agafonov MO, Deev AV, Kim SY, Sohn JH, Choi ES, Ter-Avanesian MD. [A novel approach to isolation and functional characterization of genomic DNA from the methylotrophic yeast Hansenula polymorpha]. Mol Biol (Mosk) 2003; 37:81-7. [PMID: 12624950] [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: 03/01/2023]
Abstract
A novel approach to isolation and functional characterization of the Hansenula polymorpha genes basing on the use of two strains of different origin is described. One of these strains is better suited for the isolation of genomic DNA fragments, while the other is preferable for their functional analysis. Thirty three genomic sequences governing expression of a reporter protein have been isolated. Analysis of the sequence encoding a homolog of the Saccharomyces cerevisiae cofilin revealed two introns. Another isolated DNA fragment encoded a homolog of the S. cerevisiae V ps10p. Disruption of the corresponding gene resulted in secretion of a vacuolar protein, carboxypeptidase Y, into the culture medium.
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Affiliation(s)
- M O Agafonov
- Institute of Experimental Cardiology, Cardiology Research Center, Moscow, 121552 Russia.
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Sohn JH, Kang HA, Rao KJ, Kim CH, Choi ES, Chung BH, Rhee SK. Current status of the anticoagulant hirudin: its biotechnological production and clinical practice. Appl Microbiol Biotechnol 2001; 57:606-13. [PMID: 11778867 DOI: 10.1007/s00253-001-0856-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hirudin is a potent thrombin inhibitor originally derived from the medicinal leech, Hirudo medicinalis. Owing to its high affinity and specificity for thrombin, hirudin has been intensively investigated for research and therapeutic purposes. The investigation of hirudin has contributed greatly to the understanding of the mode of action of thrombin and the clotting system. Hirudin and several hirudin analogues have also been demonstrated to have several advantages as a highly specific anticoagulant over the most widely used drug, heparin. Due to the great demand for hirudin in physicochemical and clinical studies, various recombinant systems have been developed, using bacteria, yeasts, and higher eukaryotes, to obtain the biologically active hirudin in significant quantities. After 10 years of clinical applications, two recombinant hirudins and a hirudin analogue have gained marketing approval from the United States Food and Drug Administration, for several applications. Clinical trials are currently ongoing for other treatments for thrombotic disease. As a consequence, it is conceivable that hirudin may expand its therapeutic utility over heparin in the near future.
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Affiliation(s)
- J H Sohn
- Korea Research Institute of Bioscience and Biotechnology, Yusong, Taejon
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Park IK, Kim TH, Park YH, Shin BA, Choi ES, Chowdhury EH, Akaike T, Cho CS. Galactosylated chitosan-graft-poly(ethylene glycol) as hepatocyte-targeting DNA carrier. J Control Release 2001; 76:349-62. [PMID: 11578748 DOI: 10.1016/s0168-3659(01)00448-5] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lactobionic acid bearing galactose group was coupled with chitosan for liver specificity, and poly(ethylene glycol) (PEG) was grafted to galactosylated chitosan (GC) for stability in water and enhanced cell permeability. Complex formation of galactosylated chitosan-graft-PEG (GCP)/DNA complexes was confirmed by agarose gel electrophoresis. Compared to GC/DNA complex, the stability of GCP/DNA complex could be enhanced. Particle sizes of GCP/DNA complexes decreased as the charge ratio of GCP to DNA increased and had a minimum value around 27 nm at the charge ratio of 5. Conformational change of DNA did not occur after complex formation with GCP compared to conformation of DNA itself. GCP/DNA complexes were only transfected into Hep G2 having asialoglycoprotein receptors (ASGR), indicative of specific interaction of ASGR on cells and galactose ligands on GCP.
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Affiliation(s)
- I K Park
- School of Agricultural Biotechnology, Seoul National University, 441-744, Suwon, South Korea
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Kang HA, Kang W, Hong WK, Kim MW, Kim JY, Sohn JH, Choi ES, Choe KB, Rhee SK. Development of expression systems for the production of recombinant human serum albumin using the MOX promoter in Hansenula polymorpha DL-1. Biotechnol Bioeng 2001; 76:175-85. [PMID: 11505387 DOI: 10.1002/bit.1157] [Citation(s) in RCA: 37] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
To optimize the secretory expression of recombinant human serum albumin (HSA) under the control of methanol oxidase (MOX) promoter in the methylotrophic yeast Hansenula polymorpha DL-1, we analyzed several parameters affecting the expression of HSA from the MOX promoter. Removal of the 5'-untranslated region derived from HSA cDNA in the expression cassette led to at least a fivefold improvement of HSA expression efficiency at the translational level. With the optimized expression cassette, the gene dosage effect on HSA expression was abolished and thus, a single copy of the expression vector integrated into the MOX locus became sufficient for the maximal expression of HSA. Northern blot analysis revealed that the levels of HSA transcript did not increase any further upon increasing copy number. The mox-disrupted (mox Delta) transformant was constructed, in which the genomic MOX gene was transplaced with the HSA expression cassette, to examine the effect of the methanol oxidase-deficient phenotype of the host on HSA expression. The mox Delta transformant showed higher levels of HSA production in shake-flask cultures than the MOX wild-type transformant, especially at low concentrations of methanol and a twofold higher specific HSA production rate in fed-batch fermentation with an abrupt induction mode. The native prepro signal sequence of HSA secreted in H. polymorpha was correctly processed and the mature recombinant protein had a pI value identical to that of the authentic HSA. Our results suggest that the H. polymorpha expression systems developed in this study are suitable for large-scale production of recombinant albumin.
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Affiliation(s)
- H A Kang
- Korea Research Institute of Bioscience and Biotechnology, Yusong P.O. Box 115, Taejon 305-600, Korea
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Kang HA, Hong WK, Sohn JH, Choi ES, Rhee SK. Molecular characterization of the actin-encoding gene and the use of its promoter for a dominant selection system in the methylotrophic yeast Hansenula polymorpha. Appl Microbiol Biotechnol 2001; 55:734-41. [PMID: 11525622 DOI: 10.1007/s002530100605] [Citation(s) in RCA: 14] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The actin gene (ACT) from the methylotrophic yeast Hansenula polymorpha was cloned and its structural feature was characterized. In contrast to the actin genes of other ascomycetous yeasts, which have only one large intron, the H. polymorpha ACT gene was found to be split by two introns. The H. polymorpha ACT introns were correctly processed in the heterologous host Saccharomyces cerevisiae despite appreciable differences in the splice site sequences. The promoter region of H. polymorpha ACT displayed two CCAAT motifs and two TATA-like sequences in a configuration similar to that observed in the S. cerevisiae actin promoter. A set of deleted H. polymorpha ACT promoters was exploited to direct expression of the bacterial hygromycin B resistance (hph) gene as a dominant selectable marker in the transformation of H. polymorpha. The resistance level of H. polymorpha transformants to the antibiotic was shown to be dependent on the integration copy number of the hph cassette. The selectivity of the hygromycin B resistance marker for transformants of higher copy number was remarkably increased with the deletion of the upstream TATA-like sequence, but not with the removal of either CCAAT motif, from the H. polymorpha promoter. The dosage-dependent selection system developed in this study should be useful for genetic manipulation of H. polymorpha as an industrial strain to produce recombinant proteins.
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Affiliation(s)
- H A Kang
- Microbial and Bioprocess Engineering Laboratory, Korea Research Institute of Bioscience and Biotechnology, Taejon
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Kim SY, Sohn JH, Kang HA, Yoo SK, Pyun YR, Choi ES. Cloning and characterization of the Hansenula polymorpha homologue of the Saccharomyces cerevisiae MNN9 gene. Yeast 2001; 18:455-61. [PMID: 11255253 DOI: 10.1002/yea.699] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A gene homologous to Saccharomyces cerevisiae MNN9 has been cloned and characterized in the methylotrophic yeast Hansenula polymorpha. This gene was cloned from a H. polymorpha genomic DNA library using the S. cerevisiae MNN9 gene as a probe. The H. polymorpha MNN9 homologue (HpMNN9) contained a 1062 bp open reading frame encoding a predicted protein of 354 amino acids. The deduced amino acid sequence showed 58% and 51% identity, respectively, with the S. cerevisiae and Candida albicans Mnn9 proteins. Disruption of HpMNN9 leads to phenotypic effects suggestive of cell wall defects, including detergent sensitivity and hygromycin B sensitivity. The hygromycin B sensitivity of S. cerevisiae mnn9 null mutant was complemented in the presence of the HpMNN9 gene. The DNA sequence of the H. polymorpha homologue has been submitted to GenBank with the Accession No. AF264786.
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Affiliation(s)
- S Y Kim
- Division of Life Sciences, Korea Research Institute of Bioscience and Biotechnology, Taejon 305-333, Korea
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Agaphonov MO, Packeiser AN, Chechenova MB, Choi ES, Ter-Avanesyan MD. Mutation of the homologue of GDP-mannose pyrophosphorylase alters cell wall structure, protein glycosylation and secretion in Hansenula polymorpha. Yeast 2001; 18:391-402. [PMID: 11255248 DOI: 10.1002/yea.678] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A Hansenula polymorpha mutant with enhanced ability to secrete a heterologous protein has been isolated. The mutation defines a gene, designated OPU24, which encodes a protein highly homologous to GDP-mannose pyrophosphorylase Psa1p/Srb1p/Vig9p of Saccharomyces cerevisiae and CaSrb1p of Candida albicans. The opu24 mutant manifests phenotypes similar to those of S. cerevisiae mutants depleted for GDP-mannose, such as cell wall fragility and defects in N- and O-glycosylation of secreted proteins. The influence of the opu24 mutation on endoplasmic reticulum-associated protein degradation is discussed. The GenBank Accession No. for the OPU24 sequence is AF234177.
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Affiliation(s)
- M O Agaphonov
- Institute of Experimental Cardiology, Cardiology Research Centre, 3rd Cherepkovskaya Street 15A, Moscow 121552, Russia.
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Park SJ, Nam SL, Choi ES. Removal of odor emitted from composting facilities using a porous ceramic biofilter. Water Sci Technol 2001; 44:301-308. [PMID: 11762477] [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] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A field experiment was conducted using a full-scale ceramic biofilter (approximately 150 m3/min) in order to determine the potential for biofiltration to remove malodorous gases from composting facilities. The main compounds found in malodorous gases were NH3 and H2S. These compounds were analyzed by a UV-spectrophotometer and gas chromatograph. The microbial carrier was a porous ceramic consisting of diatomite and fly ash. About 12 m3 of ceramic media inoculated with waste activated sludge were filled in the biofilter. The experimental conditions were space velocity of 500 hr(-1), empty bed residence time of 7.2 s, and linear velocity of 0.2 m/s. About 90 L/d of water were sprayed for the operation. The NH3 concentration in inlet gases ranged from 8 to 90 ppmv. The concentration of H2S ranged from 3.2-5.5 ppmv. The acclimation of the biofilter was slow, but more than 95% of removal efficiency was achieved after one month of operation. No nutrients were supplied to the biofilter. The pressure drop in the biofilter varied from 20-40 mmAq during the operation. The energy consumption of this biofilter was about 200 kW/d. It was estimated that the deodorization using this ceramic biofilter was successfully carried out to remove the odor emitted from composting facilities.
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Affiliation(s)
- S J Park
- Department of Civil and Environmental Engineering, Woo-Song University, 12-7 Jayang-Dong, Dong-Gu, Dae-Jeon, Korea
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Park IK, Park YH, Shin BA, Choi ES, Kim YR, Akaike T, Cho CS, Park YK, Park YR. Galactosylated chitosan-graft-dextran as hepatocyte-targeting DNA carrier. J Control Release 2000; 69:97-108. [PMID: 11018549 DOI: 10.1016/s0168-3659(00)00298-4] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lactobionic acid bearing galactose group was coupled with chitosan for liver specificity, and dextran was grafted to galactosylated chitosan (GC) for stability in water. Compared to the GC/DNA complex, the stability of the galactosylated chitosan-graft-dextran (GCD)/DNA complex could be enhanced. The particle size of the GCD/DNA complexes decreased as the charge ratio of GCD to DNA increased. Conformational change of DNA did not occur after complex formation with GCD compared with the conformation of DNA itself. The GCD/DNA complexes were only transfected into Chang liver cells and that of Hep G2 having asialoglycoprotein receptors (ASGR), indicative of specific interaction of ASGRs on cells and galactose ligands on chitosan.
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Affiliation(s)
- I K Park
- School of Agricultural Biotechnology, Seoul National University, Suwon 441-744, South Korea
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50
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Kang HA, Choi ES, Hong WK, Kim JY, Ko SM, Sohn JH, Rhee SK. Proteolytic stability of recombinant human serum albumin secreted in the yeast Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2000; 53:575-82. [PMID: 10855718 DOI: 10.1007/s002530051659] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In order to direct the persistent expression of recombinant human serum albumin (HSA) from the GAL10 promoter in the yeast Saccharomyces cerevisiae, we carried out periodic feeding of galactose during shake-flask cultures. Unexpectedly, the recombinant protein secreted was observed to undergo rapid degradation, which was apparently accelerated by carbon-source feeding. The extracellular degradation of HSA occurred even in the strain deficient in the major vacuolar proteases PrA and PrB, and in the strain lacking the acidic protease Yap3p (involved in the generation of HSA-truncated fragments). Interestingly, the degradation correlated closely with the acidification of extracellular pH and thus was significantly overcome either by buffering the culture medium above pH 5.0 or by adding amino acid-rich supplements to the culture medium, which could prevent the acidification of medium pH during cultivation. Addition of arginine or ammonium salt also substantially minimized the degradation of HSA, even without buffering. The extracellular degradation activity was not detected in the cell-free culture supernatant but was found to be associated with intact cells. The results of the present study strongly suggest that the HSA secreted in S. cerevisiae is highly susceptible to the pH-dependent proteolysis mediated by cell-bound protease(s) whose activity and expression are greatly affected by the composition of the medium.
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Affiliation(s)
- H A Kang
- Korea Research Institute of Bioscience and Biotechnology, Yusong, Taejon
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