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Label-free optical and electrical immunoassays based on lyotropic chromonic liquid crystals: Implications of real-time detection and kinetic analysis. Biosens Bioelectron 2023; 223:115011. [PMID: 36549110 DOI: 10.1016/j.bios.2022.115011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 12/10/2022] [Accepted: 12/12/2022] [Indexed: 12/15/2022]
Abstract
Conventional liquid crystal (LC)-based biosensors utilize predominantly thermotropic LCs as the signal-transducing media, which are less environmentally sustainable compared with lyotropic counterparts. In this study, the nematic phase of the anionic azo dye sunset yellow (SSY), a type of lyotropic chromonic liquid crystals (LCLCs), was employed in the optical and electrical biosensing of bovine serum albumin (BSA) and the cancer biomarker CA125. The optical response observed under a polarizing optical microscope was quantified by image analysis, taking advantage of the specific absorption of SSY. The electrical response derived from the dielectric spectra of SSY provided a new alternative for quantitative bioassay based on nematic LCLCs. The limit of detection (LOD) of the optical and electrical protein assay was ∼10-11- and ∼10-10-g/ml BSA, respectively, whereas that of the optical and electrical immunoassay was 5.97 × 10-11 and 6.02 × 10-12 g/ml for CA125, respectively. Moreover, real-time monitoring and kinetic analysis, which are hardly achievable for the hydrophobic thermotropic LCs, were demonstrated by dispersing CA125 in nematic SSY and subsequently recording the optical response over time during the specific binding between CA125 and the immobilized anti-CA125 antibody. Results from this study further the potential of nematic LCLCs in biosensing, especially in dielectric and real-time detection.
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2
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Revignas D, Ferrarini A. Spontaneous Twisting of Achiral Hard Rod Nematics. PHYSICAL REVIEW LETTERS 2023; 130:028102. [PMID: 36706401 DOI: 10.1103/physrevlett.130.028102] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/25/2022] [Accepted: 12/09/2022] [Indexed: 06/18/2023]
Abstract
Since Onsager's seminal work, hard rods have been taken as a prototype of nematic liquid crystals, characterized by uniaxial order and a uniform director field as a ground state. Here, using Onsager theory to calculate the free energy in the presence of arbitrary deformations, we find that hard rod nematics have an intrinsic tendency to twist around their ordering axis (double twist), driven by a mechanism in which the orientational fluctuations of particles play a key role. The anisotropic hard core potential used here is arguably the simplest form of interaction able to originate spontaneous breaking of mirror symmetry in a 3D fluid. Our results are discussed in relation to the recent discovery of a double twisted ground state in cylindrically confined lyotropic chromonic liquid crystals.
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Affiliation(s)
- Davide Revignas
- Department of Chemical Sciences, University of Padova Via Marzolo 1, 35131 Padova, Italy
| | - Alberta Ferrarini
- Department of Chemical Sciences, University of Padova Via Marzolo 1, 35131 Padova, Italy
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3
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Intercalation or external binding: How to torque chromonic Sunset Yellow. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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4
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Gemini surfactant behavior of conventional surfactant dodecyltrimethylammonium bromide with anionic azo dye Sunset Yellow in aqueous solutions. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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Yu JJ, Chen LF, Li GY, Li YR, Huang Y, Bake M, Tian Z. Rotational viscosity of nematic lyotropic chromonic liquid crystals. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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6
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Bao P, Paterson DA, Peyman SA, Jones JC, Sandoe JAT, Gleeson HF, Evans SD, Bushby RJ. Production of giant unilamellar vesicles and encapsulation of lyotropic nematic liquid crystals. SOFT MATTER 2021; 17:2234-2241. [PMID: 33469638 DOI: 10.1039/d0sm01684e] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We describe a modified microfluidic method for making Giant Unilamellar Vesicles (GUVs) via water/octanol-lipid/water double emulsion droplets. At a high enough lipid concentration we show that the de-wetting of the octanol from these droplets occurs spontaneously (off-chip) without the need to use shear to aid the de-wetting process. The resultant mixture of octanol droplets and GUVs can be separated by making use of the buoyancy of the octanol. A simpler microfluidic device and pump system can be employed and, because of the higher flow-rates and much higher rate of formation of the double emulsion droplets (∼1500 s-1 compared to up to ∼75 s-1), it is easier to make larger numbers of GUVs and larger volumes of solution. Because of the potential for using GUVs that incorporate lyotropic nematic liquid crystals in biosensors we have used this method to make GUVs that incorporate the nematic phases of sunset yellow and disodium chromoglycate. However, the phase behaviour of these lyotropic liquid crystals is quite sensitive to concentration and we found that there is an unexpected spread in the concentration of the contents of the GUVs obtained.
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Affiliation(s)
- Peng Bao
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Daniel A Paterson
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK and School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
| | - Sally A Peyman
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK and Leeds Institute of Medical Research, University of Leeds, Leeds, LS2 9JT, UK
| | - J Cliff Jones
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Jonathan A T Sandoe
- Leeds Institute of Medical Research, University of Leeds, Leeds, LS2 9JT, UK
| | - Helen F Gleeson
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Stephen D Evans
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
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7
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Akpinar E, Topcu G, Reis D, Neto AMF. Effect of the anionic azo dye Sunset Yellow in lyotropic mixtures with uniaxial and biaxial nematic phases. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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8
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Potter TD, Walker M, Wilson MR. Self-assembly and mesophase formation in a non-ionic chromonic liquid crystal: insights from bottom-up and top-down coarse-grained simulation models. SOFT MATTER 2020; 16:9488-9498. [PMID: 32955531 DOI: 10.1039/d0sm01157f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
New coarse-grained models are introduced for a non-ionic chromonic molecule, TP6EO2M, in aqueous solution. The multiscale coarse-graining (MS-CG) approach is used, in the form of hybrid force matching (HFM), to produce a bottom-up CG model that demonstrates self-assembly in water and the formation of a chromonic stack. However, the high strength of binding in stacks is found to limit the transferability of the HFM model at higher concentrations. The MARTINI 3 framework is also tested. Here, a top-down CG model is produced which shows self-assembly in solution in good agreement with atomistic studies and transfers well to higher concentrations, allowing the full phase diagram of TP6EO2M to be studied. At high concentration, both self-assembly of molecules into chromonic stacks and self-organisation of stacks into mesophases occurs, with the formation of nematic (N) and hexagonal (M) chromonic phases. This CG-framework is suggested as a suitable way of studying a range of chromonic-type drug and dye molecules that exhibit complex self-assembly and solubility behaviour in solution.
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Affiliation(s)
- Thomas D Potter
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, DH1 3LE, UK.
| | - Martin Walker
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, DH1 3LE, UK.
| | - Mark R Wilson
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, DH1 3LE, UK.
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9
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Rodríguez-Abreu C, Kolen'ko YV, Kovnir K, Sanchez-Dominguez M, Shrestha RG, Bairi P, Ariga K, Shrestha LK. 1D materials from ionic self-assembly in mixtures containing chromonic liquid crystal mesogens. Phys Chem Chem Phys 2020; 22:23276-23285. [PMID: 33030486 DOI: 10.1039/d0cp04348f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ionic self-assembly is a simple yet powerful method to obtain robust nanostructures. Herewith, we use mixtures of oppositely-charged porphyrins that can act as mesogens to form chromonic liquid crystals in water, i.e., molecular stacks with orientational (nematic) or positional (hexagonal) order. Electrostatic locking coupled with π-π interactions between aromatic groups within the stacks, together with inter-stack hydrogen bonding induce formation of all-organic crystalline nanofibers with high aspect ratio (a few tenths of nanometers in width but several tenths of micrometers in length) and that display branching. The nanofibers prepared from metal-free porphyrin units feature interesting optical properties, including an absorption spectrum that is different from the simple sum of the individual spectra of the components, which is attributed to a striking aggregation-induced chromism. When in contact with some polar organic solvents the materials become fluorescent, as a result of disaggregation. In a proof-of-concept, the obtained self-assembled one-dimensional (1D) materials were carbonized (yield ca. 60%) to produce nitrogen-doped carbon nanofibers that can be used as active electrode materials for energy storage applications.
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Affiliation(s)
- Carlos Rodríguez-Abreu
- Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain. and CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Yury V Kolen'ko
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, Braga, 4715-330, Portugal
| | - Kirill Kovnir
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA and Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA
| | - Margarita Sanchez-Dominguez
- Centro de Investigación en Materiales Avanzados (CIMAV, S.C.), Unidad Monterrey, Apodaca, Nuevo León 66628, Mexico
| | - Rekha Goswami Shrestha
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Ibaraki, Japan.
| | - Partha Bairi
- Department of Physics, Jadavpur University, Kolkata 700032, India
| | - Katsuhiko Ariga
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Ibaraki, Japan. and Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Lok Kumar Shrestha
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Ibaraki, Japan.
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Eun J, Cheon J, Kim SJ, Shin TJ, Jeong J. Lyotropic Chromonic Liquid Crystals and Their Impurities Reveal the Importance of the Position of Functional Groups in Self-Assembly. J Phys Chem B 2020; 124:9246-9254. [PMID: 32960600 DOI: 10.1021/acs.jpcb.0c07163] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We study the effect of purification and impurities on the self-assembly and phase behavior of lyotropic chromonic liquid crystals (LCLCs). LCLC molecules in water stack to form aggregates; then, the elongated nanoaggregates align to make liquid crystalline phases. Utilizing multiple experimental techniques, we unveil impurities in commercial Sunset Yellow FCF (SSY), a representative LCLC, and how the precipitation-based purification promotes the formation of the aggregates and mesophase. We further explore the roles of intrinsic impurities, i.e., byproducts of the SSY synthesis, whose molecular structures are almost identical to that of SSY but differ only in the number and position of sulfonate groups. Combining quantum chemical calculations of molecular structures and experimental investigation of aggregate structures and phase behavior, we propose that the impurities of the planar shapes behave as planar SSY, i.e., participating in aggregate formation, whereas the nonplanar one disrupts the nematic phase. These results highlight the critical roles of the impurities and deepen our understanding of self-assembled aggregates and their aligned mesophases.
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Affiliation(s)
- Jonghee Eun
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Jiyong Cheon
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Sung-Jo Kim
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Tae Joo Shin
- UNIST Central Research Facilities & School of Natural Science, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Joonwoo Jeong
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
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11
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Kim HW, Won SH, Kuzmin V, Kim BS, Shin ST. Molecular Ordering Behavior of Lyotropic Chromonic Liquid Crystals on a Polyimide Alignment Layer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5778-5786. [PMID: 32388988 DOI: 10.1021/acs.langmuir.0c00486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Coating-type polarizing films with a high dichroic ratio (DR) and polarization efficiency in the visible region were fabricated using a solution of ternary lyotropic chromonic liquid crystals (LCLCs). Optical characteristics of these anisotropic LCLC polarizing films were then determined. DR increased with increasing LCLC concentrations. Molecular ordering of these LCLCs on a rubbed polyimide (PI) layer increased because LCLC molecules' orientation was enhanced by the dielectric anisotropy effect from rubbing the surface of the PI. In addition, this study demonstrated how the interaction between liquid crystal aggregates and the PI surface with different LCLC solutions correlated with LCLC molecular orientations on the PI which is significantly dependent on whether the coating direction of the LCLC solution was parallel or perpendicular to the PI rubbing direction. It was found that the ordering direction at high LCLC concentrations was determined by shearing direction of the LCLC solution coating, whereas the ordering direction at low LCLC concentrations was governed by the dielectric anisotropy effect from the PI rubbing direction.
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Affiliation(s)
- Hyeong Wook Kim
- Department of Applied Physics, Korea University, 2511, Sejong-ro, Sejong 30019, Republic of Korea
| | - Sang Hee Won
- Department of Applied Physics, Korea University, 2511, Sejong-ro, Sejong 30019, Republic of Korea
| | - Valery Kuzmin
- Light Polymers Inc., 298 Lawrence Avenue, South San Francisco, California 94080, United States
| | - Bo Sung Kim
- Department of Applied Physics, Korea University, 2511, Sejong-ro, Sejong 30019, Republic of Korea
- Light Polymers Inc., 298 Lawrence Avenue, South San Francisco, California 94080, United States
| | - Sung Tae Shin
- Department of Applied Physics, Korea University, 2511, Sejong-ro, Sejong 30019, Republic of Korea
- Light Polymers Inc., 298 Lawrence Avenue, South San Francisco, California 94080, United States
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12
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Katz JR, Day IJ. Using Small-Molecule Probes to Investigate Aggregation of Sunset Yellow FCF: What are the Concentration Limits? J Phys Chem B 2019; 123:8987-8994. [PMID: 31560194 DOI: 10.1021/acs.jpcb.9b07997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The assembly of small molecules into larger structures, often driven by noncovalent interactions such as hydrogen bonding, aromatic stacking interactions, and burial of hydrophobic surface, is of widespread interest. The interaction of small molecules with aggregates also has a large range of applications from fluorescence aggregation assays to gas storage in framework materials. Here, we utilize nuclear magnetic resonance spectroscopy to investigate the interaction of a small-molecule probe on the assembly state of sunset yellow across a wide range of relative concentrations. Information from both macroscopic (diffusion) and microscopic (chemical shifts) measurements allows the interaction to be studied and the binding mode to be interrogated. Using fluorophenol as the small-molecule probe, we show that the aggregation behavior of sunset yellow is broadly unaffected by the relative amount of fluorophenol added.
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Affiliation(s)
- Jonathan R Katz
- School of Life Sciences , University of Sussex , Falmer , Brighton BN1 9QJ , U.K
| | - Iain J Day
- School of Life Sciences , University of Sussex , Falmer , Brighton BN1 9QJ , U.K
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13
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Matus Rivas OM, Rey AD. Molecular Dynamics Study of the Effect of l-Alanine Chiral Dopants on Diluted Chromonic Solutions. J Phys Chem B 2019; 123:8995-9010. [PMID: 31525883 DOI: 10.1021/acs.jpcb.9b06111] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atomistic molecular dynamics simulations have been performed for disodium cromoglycate (DSCG) chromonic solutions mixed with l-alanine chiral dopants. We study the fundamental molecular mechanisms induced by low concentrations of l-alanine on diluted DSCG solutions, including their effect on the chromonic aggregates, the solvent, and sodium counterions. Simulations reveal that l-alanine molecules primarily interact with DSCG stacks establishing salt bridges between their respective ammonium and carboxylate groups. Our results demonstrate that l-alanine and sodium counterions jointly establish an intricate network of noncovalent interactions around DSCG aggregates that decreases the global electrostatic repulsion of the chromonic system. Two possible structural effects in DSCG aggregates arise from this electronic stabilization: the increment of the total number of consecutively stacked aromatic planes per DSCG aggregate (intracolumnar effect) or the partial separation reduction between neighboring DSCG columnar sections due to the simultaneous bridging of intercolumnar DSCG carboxylate sites by sodium counterions, forming sodium bridges (intercolumnar effect). Sodium bridges may be responsible for the formation of stacking faults in DSCG aggregates in the form of lateral overlap junctions. This mechanism would explain the difference between lower X-ray correlation lengths with the expected persistence length in chromonics.
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Affiliation(s)
- Oscar M Matus Rivas
- Department of Chemical Engineering , McGill University , Montreal , Quebec H3A 0C5 , Canada
| | - Alejandro D Rey
- Department of Chemical Engineering , McGill University , Montreal , Quebec H3A 0C5 , Canada
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14
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Effect of Crowding Agent Polyethylene Glycol on Lyotropic Chromonic Liquid Crystal Phases of Disodium Cromoglycate. CRYSTALS 2019. [DOI: 10.3390/cryst9030160] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Adding crowding agents such as polyethylene glycol (PEG) to lyotropic chromonic liquid crystals (LCLCs) formed by water dispersions of materials such as disodium cromoglicate (DSCG) leads to a phase separation of the isotropic phase and the ordered phase. This behavior resembles nanoscale condensation of DNAs but occurs at the microscale. The structure of condensed chromonic regions in crowded dispersions is not yet fully understood, in particular, it is not clear whether the condensed domains are in the nematic (N) or the columnar (C) state. In this study, we report on small angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements of mixtures of aqueous solutions of DSCG with PEG and compare results to measurements of aqueous solutions of pure DSCG. X-ray measurements demonstrate that addition of PEG to DSCG in the N phase triggers appearance of the C phase that coexists with the isotropic (I) phase. Within the coexisting region, the lateral distance between the columns of the chromonic aggregates decreases as the temperature is increased.
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15
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Matus Rivas OM, Rey AD. Effects of Sodium and Magnesium Cations on the Aggregation of Chromonic Solutions Using Molecular Dynamics. J Phys Chem B 2019; 123:1718-1732. [PMID: 30672292 DOI: 10.1021/acs.jpcb.8b12130] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lyotropic chromonic liquid crystals (LCLCs) constitute a unique variety of water-soluble mesogens that spontaneously assemble into elongated aggregates, thereby resulting in the formation of liquid crystal phases depending on the temperature and concentration. The influence of ionic additives on the aggregation of LCLC has been extensively studied, but the molecular mechanisms governing these effects remain unclear. In this investigation, we perform atomistic molecular dynamics simulations of dilute sunset yellow (SSY) LCLC solutions doped with NaCl and MgCl2 salts. Structural and dynamical properties of SSY hydration shells are considerably modified by the partial substitution of their H bonds with sodium/magnesium-sulfonate ion pairs. Although the intermolecular distance of ∼3.4 Å between SSY mesogens is preserved regardless of the ionic content, the growing number of ion pairs favors the reduction of the electrostatic repulsion between mesogens, increasing the length of SSY stacks. Moreover, magnesium cations exert the strongest electrostatic effects due to their higher hydration capabilities and acute electrostatic binding to SSY. For these reasons, experimental observations of dilute SSY solutions doped with Mg2+ exhibit higher nematic-to-isotropic transition temperatures than Na+. This work provides a fundamental understanding of the influence of ionic additives on the self-assembly of diluted LCLC solutions derived from the synergistic molecular mechanisms between mesogens, the solvent, and cations.
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Affiliation(s)
- Oscar M Matus Rivas
- Department of Chemical Engineering , McGill University , Montreal , Quebec H3A OC5 , Canada
| | - Alejandro D Rey
- Department of Chemical Engineering , McGill University , Montreal , Quebec H3A OC5 , Canada
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16
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Magana JR, Solans C, Salonen LM, Carbó-Argibay E, Gallo J, Tiddy GJ, Rodríguez-Abreu C. Chromonic self-assemblies in a series of dialkyl-thiacarbocyanine dyes and generalization of a facile route for the synthesis of fluorescent nanostructured silica fibers. J Taiwan Inst Chem Eng 2018. [DOI: 10.1016/j.jtice.2018.03.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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17
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Affiliation(s)
- Emanuele Romani
- Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma, Italy
| | - Alberta Ferrarini
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Cristiano De Michele
- Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma, Italy
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18
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Orellana AG, Romani E, De Michele C. Speeding up Monte Carlo simulation of patchy hard cylinders. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2018; 41:51. [PMID: 29651630 DOI: 10.1140/epje/i2018-11657-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 03/29/2018] [Indexed: 06/08/2023]
Abstract
The hard cylinder model decorated with attractive patches proved to be very useful recently in studying physical properties of several colloidal systems. Phase diagram, elastic constants and cholesteric properties obtained from computer simulations based on a simple hard cylinder model have been all successfully and quantitatively compared to experimental results. Key to these simulations is an efficient algorithm to check the overlap between hard cylinders. Here, we propose two algorithms to check the hard cylinder overlap and we assess their efficiency through a comparison with an existing method available in the literature and with the well-established algorithm for simulating hard spherocylinders. In addition, we discuss a couple of optimizations for performing computer simulations of patchy anisotropic particles and we estimate the speed-up which they can provide in the case of patchy hard cylinders.
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Affiliation(s)
| | - Emanuele Romani
- Dipartimento di Fisica, "Sapienza" Università di Roma, P.le A. Moro 2, 00185, Roma, Italy
| | - Cristiano De Michele
- Dipartimento di Fisica, "Sapienza" Università di Roma, P.le A. Moro 2, 00185, Roma, Italy.
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Kristinaitytė K, Maršalka A, Dagys L, Aidas K, Doroshenko I, Vaskivskyi Y, Chernolevska Y, Pogorelov V, Valevičienė NR, Balevicius V. NMR, Raman, and DFT Study of Lyotropic Chromonic Liquid Crystals of Biomedical Interest: Tautomeric Equilibrium and Slow Self-Assembling in Sunset Yellow Aqueous Solutions. J Phys Chem B 2018; 122:3047-3055. [DOI: 10.1021/acs.jpcb.8b00350] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Aru̅nas Maršalka
- Faculty of Physics, Vilnius University, Sauletekio al. 3, LT-10257 Vilnius, Lithuania
| | - Laurynas Dagys
- Faculty of Physics, Vilnius University, Sauletekio al. 3, LT-10257 Vilnius, Lithuania
| | - Kęstutis Aidas
- Faculty of Physics, Vilnius University, Sauletekio al. 3, LT-10257 Vilnius, Lithuania
| | - Iryna Doroshenko
- Faculty of Physics, Taras Shevchenko National University of Kyiv, Glushkova Avenue 4, 03022 Kyiv, Ukraine
| | - Yevhenii Vaskivskyi
- Faculty of Physics, Taras Shevchenko National University of Kyiv, Glushkova Avenue 4, 03022 Kyiv, Ukraine
| | - Yelyzaveta Chernolevska
- Faculty of Physics, Taras Shevchenko National University of Kyiv, Glushkova Avenue 4, 03022 Kyiv, Ukraine
| | - Valeriy Pogorelov
- Faculty of Physics, Taras Shevchenko National University of Kyiv, Glushkova Avenue 4, 03022 Kyiv, Ukraine
| | | | - Vytautas Balevicius
- Faculty of Physics, Vilnius University, Sauletekio al. 3, LT-10257 Vilnius, Lithuania
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20
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Cha YJ, Gim MJ, Ahn H, Shin TJ, Jeong J, Yoon DK. Orthogonal Liquid Crystal Alignment Layer: Templating Speed-Dependent Orientation of Chromonic Liquid Crystals. ACS APPLIED MATERIALS & INTERFACES 2017; 9:18355-18361. [PMID: 28489345 DOI: 10.1021/acsami.7b04188] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Lyotropic chromonic liquid crystals (LCLCs) have been extensively studied because of the interesting structural characteristics of the linear aggregation of their plank-shaped molecules in aqueous solvents. We report a simple method to control the orientation of LCLCs such as Sunset Yellow (SSY), disodium cromoglycate (DSCG), and DNA by varying pulling speed of the top substrate and temperatures during shear flow induced experiment. Crystallized columns of LCLCs are aligned parallel and perpendicular to the shear direction, at fast and slow pulling speeds of the top substrate, respectively. On the basis of this result, we fabricated an orthogonally patterned film that can be used as an alignment layer for guiding rodlike liquid crystals (LCs) to generate both twisted and planar alignments simultaneously. Our resulting platform can provide a facile method to form multidirectional orientation of soft materials and biomaterials in a process of simple shearing and evaporation, which gives rise to potential patterning applications using LCLCs due to their unique structural characteristics.
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Affiliation(s)
- Yun Jeong Cha
- Graduate School of Nanoscience and Technology and KINC, Korea Advanced Institute of Science and Technology , Daejeon 34141, Republic of Korea
| | - Min-Jun Gim
- Graduate School of Nanoscience and Technology and KINC, Korea Advanced Institute of Science and Technology , Daejeon 34141, Republic of Korea
| | - Hyungju Ahn
- Pohang Accelerator Laboratory, POSTECH , Pohang 37673, Republic of Korea
| | - Tae Joo Shin
- UNIST Central Research Facilities & School of Natural Science, UNIST , Ulsan 44919, Republic of Korea
| | - Joonwoo Jeong
- School of Natural Science, UNIST , Ulsan 44919, Republic of Korea
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology and KINC, Korea Advanced Institute of Science and Technology , Daejeon 34141, Republic of Korea
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Using chiral tactoids as optical probes to study the aggregation behavior of chromonics. Proc Natl Acad Sci U S A 2017; 114:3826-3831. [PMID: 28336530 DOI: 10.1073/pnas.1614620114] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tactoids are nuclei of an orientationally ordered nematic phase that emerge upon cooling the isotropic phase. In addition to providing a natural setting for exploring chromonics under confinement, we show that tactoids can also serve as optical probes to delineate the role of temperature and concentration in the aggregation behavior of chromonics. For high concentrations, we observe the commonly reported elongated bipolar tactoids. As the concentration is lowered, breaking of achiral symmetry in the director configuration is observed with a predominance of twisted bipolar tactoids. On further reduction of concentration, a remarkable transformation of the director configuration occurs, wherein it conforms to a unique splay-minimizing configuration. Based on a simple model, we arrive at an interesting result that lower concentrations have longer aggregates at the same reduced temperature. Hence, the splay deformation that scales linearly with the aggregate length becomes prohibitive for lower concentrations and is relieved via twist and bend deformations in this unique configuration. Raman scattering measurements of the order parameters independently verify the trend in aggregate lengths and provide a physical picture of the nematic-biphasic transition.
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Affiliation(s)
- Valentina Domenici
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa, Italy
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van der Asdonk P, Kouwer PHJ. Liquid crystal templating as an approach to spatially and temporally organise soft matter. Chem Soc Rev 2017; 46:5935-5949. [DOI: 10.1039/c7cs00029d] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Liquid crystal templating: an emerging technique to organise and control soft matter at multiple length scales.
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Affiliation(s)
- Pim van der Asdonk
- Radboud University
- Institute for Molecules and Materials
- 6525 AJ Nijmegen
- The Netherlands
| | - Paul H. J. Kouwer
- Radboud University
- Institute for Molecules and Materials
- 6525 AJ Nijmegen
- The Netherlands
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Walker M, Wilson MR. Formation of complex self-assembled aggregates in non-ionic chromonics: dimer and trimer columns, layer structures and spontaneous chirality. SOFT MATTER 2016; 12:8588-8594. [PMID: 27722663 DOI: 10.1039/c6sm01669c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dissipative particle dynamics (DPD) simulations are used to model the aqueous self-assembly of three variants of the non-ionic triphenylene-based chromonic mesogen, TP6EO2M. In the variants studied, one to three of the six methoxy poly(ethylene glycol) chains of TP6EO2M are replaced by short hydrophobic-lipophobic chains, causing a remarkable change in the structure of the mesophases formed. In the 100 wt% limit, corresponding to pure thermotropic phases, complex columnar phases arise, in which the underlying hexagonal packing is supplemented by additional order resulting from microphase separation of hydrophobic-lipophobic regions. With addition of water an array of novel chromonic phases are seen. In these phases supramolecular aggregates form in which hydrophobic-lipophobic chains are excluded from water by the joining together of single molecule chromonic stacks into dimers or trimers. These aggregates form chromonic N and M phases and, in the case of a "Janus mesogen" (with three hydrophobic-lipophobic chains on one side of the molecule), form a novel smectic chromonic phase. Spontaneous symmetry breaking is seen in columns composed of trimer stacks with defects. Here achiral molecular aggregates develop a spontaneous twist, inducing the formation of either left-handed or right-handed chiral aggregates. On the long time-scales accessible to DPD simulations, chiral aggregates are seen to be dynamic structures in which chirality inversion can take place over long periods of time.
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Affiliation(s)
- Martin Walker
- Durham University, Department of Chemistry, Lower Mountjoy, South Road, Durham DH1 3LE, UK.
| | - Mark R Wilson
- Durham University, Department of Chemistry, Lower Mountjoy, South Road, Durham DH1 3LE, UK.
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26
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Yao X, Nayani K, Park JO, Srinivasarao M. Orientational Order of a Lyotropic Chromonic Liquid Crystal Measured by Polarized Raman Spectroscopy. J Phys Chem B 2016; 120:4508-12. [PMID: 27074395 DOI: 10.1021/acs.jpcb.6b02054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lyotropic chromonic liquid crystals are distinct from thermotropic nematics from a fundamental standpoint as the structure of the aggregating columns is a function of both the temperature and concentration. We report on the thermal evolution of orientational order parameters, both the second (=scalar) (⟨P200⟩ (=S)) and fourth (⟨P400⟩) order, of sunset yellow FCF aqueous solutions, measured using polarized Raman spectroscopy for different concentrations. The order parameter increases with the concentration, and their values are high in comparison with those of thermotropic liquid crystals. On the basis of Raman spectroscopy, we provide the strongest evidence yet that the hydrozone tautomer of SSY is the predominant form in aqueous solutions in the isotropic, nematic, and columnar phases, as well as what we believe to be the first measurements of (⟨P400⟩) for this system.
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Affiliation(s)
- Xuxia Yao
- School of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, and §Center for Advanced Research on Optical Microscopy, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Karthik Nayani
- School of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, and §Center for Advanced Research on Optical Microscopy, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Jung Ok Park
- School of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, and §Center for Advanced Research on Optical Microscopy, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Mohan Srinivasarao
- School of Materials Science and Engineering, ‡School of Chemistry and Biochemistry, and §Center for Advanced Research on Optical Microscopy, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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Im P, Kang DG, Kim DY, Choi YJ, Yoon WJ, Lee MH, Lee IH, Lee CR, Jeong KU. Flexible and Patterned Thin Film Polarizer: Photopolymerization of Perylene-based Lyotropic Chromonic Reactive Mesogens. ACS APPLIED MATERIALS & INTERFACES 2016; 8:762-771. [PMID: 26616135 DOI: 10.1021/acsami.5b09995] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A perylene-based reactive mesogen (DAPDI) forming a lyotropic chromonic liquid crystal (LCLC) phase was newly designed and synthesized for the fabrication of macroscopically oriented and patterned thin film polarizer (TFP) on the flexible polymer substrates. The anisotropic optical property and molecular self-assembly of DAPDI were investigated by the combination of microscopic, scattering and spectroscopic techniques. The main driving forces of molecular self-assembly were the face-to-face π-π intermolecular interaction among aromatic cores and the nanophase separation between hydrophilic ionic groups and hydrophobic aromatic cores. Degree of polarization for the macroscopically oriented and photopolymerized DAPDI TFP was estimated to be 99.81% at the λmax = 491 nm. After mechanically shearing the DAPDI LCLC aqueous solution on the flexible polymer substrates, we successfully fabricated the patterned DAPDI TFP by etching the unpolymerized regions selectively blocked by a photomask during the photopolymerization process. Chemical and mechanical stabilities were confirmed by the solvent and pencil hardness tests, and its surface morphology was further investigated by optical microscopy, atomic force microscopy, and three-dimensional surface nanoprofiler. The flexible and patterned DAPDI TFP with robust chemical and mechanical stabilities can be a stepping stone for the advanced flexible optoelectronic devices.
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Affiliation(s)
- Pureun Im
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Dong-Gue Kang
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Dae-Yoon Kim
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Yu-Jin Choi
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Won-Jin Yoon
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Myong-Hoon Lee
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - In-Hwan Lee
- Division of Advanced Materials Engineering, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Cheul-Ro Lee
- Division of Advanced Materials Engineering, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
| | - Kwang-Un Jeong
- Polymer Materials Fusion Research Center, Department of Polymer-Nano Science and Technology & Department of Flexible and Printable Electronics, Chonbuk National University , Jeonju, Jeonbuk 561-756, Korea
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29
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Magana JR, Homs M, Solans C, Obiols-Rabasa M, Salonen LM, Rodríguez-Abreu C. Self-Assembly and Formation of Chromonic Liquid Crystals from the Dyes Quinaldine Red Acetate and Pyronin Y. J Phys Chem B 2016; 120:250-8. [PMID: 26700729 DOI: 10.1021/acs.jpcb.5b10567] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aqueous self-assembly behavior of the dyes Quinaldine red acetate and Pyronin Y in a wide range of concentrations is reported here for the first time. (1)H NMR spectroscopy, polarized-light optical microscopy, and small and wide X-ray scattering were used to get insight into molecular interactions, phase boundaries and aggregate structure. Quinaldine red acetate and Pyronin Y self-organize into unimolecular stacks driven by attractive aromatic interactions. At high concentrations, spatial correlation among the molecular stacks gives rise to nematic liquid crystals in both systems. Quinaldine red acetate additionally produces a rare chromonic O phase built of columnar aggregates with anisotropic cross-section ordered in a rectangular lattice. The O phase changes into a columnar lamellar structure as a result of a temperature-induced phase transition. Results open the possibility of finding chromonic liquid crystals in other commercially available dyes with a similar molecular structure. This would eventually expand the availability of these unique soft materials and thus introduce new applications for marketed dyes.
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Affiliation(s)
- J R Magana
- Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain
| | - M Homs
- Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain
| | - C Solans
- Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona, Spain
| | - M Obiols-Rabasa
- Division of Physical Chemistry, Lund University , Getingevägen 60, SE-22241 Lund, Sweden
| | - L M Salonen
- International Iberian Nanotechnology Laboratory , Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal
| | - C Rodríguez-Abreu
- International Iberian Nanotechnology Laboratory , Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal
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30
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Yamaguchi A, Smith GP, Yi Y, Xu C, Biffi S, Serra F, Bellini T, Zhu C, Clark NA. Phases and structures of sunset yellow and disodium cromoglycate mixtures in water. Phys Rev E 2016; 93:012704. [PMID: 26871132 DOI: 10.1103/physreve.93.012704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Indexed: 06/05/2023]
Abstract
We study phases and structures of mixtures of two representative chromonic liquid crystal materials, sunset yellow FCF (SSY) and disodium cromoglycate (DSCG), in water. A variety of combinations of isotropic, nematic (N), and columnar (also called M) phases are observed depending on their concentrations, and a phase diagram is made. We find a tendency for DSCG-rich regions to show higher-order phases while SSY-rich regions show lower-order ones. We observe uniform mesophases only when one of the materials is sparse in the N phases. Their miscibility in M phases is so low that essentially complete phase separation occurs. X-ray scattering and spectroscopy studies confirm that SSY and DSCG molecules do not mix when they form chromonic aggregates and neither do their aggregates when they form M phases.
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Affiliation(s)
- Akihiro Yamaguchi
- Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - Gregory P Smith
- Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - Youngwoo Yi
- Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
| | - Charles Xu
- Fairview High School, Boulder, Colorado 80305, USA
| | - Silvia Biffi
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Italy
| | - Francesca Serra
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Italy
| | - Tommaso Bellini
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Italy
| | - Chenhui Zhu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Noel A Clark
- Soft Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA
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31
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Kim JY, Nayani K, Jeong HS, Jeon HJ, Yoo HW, Lee EH, Park JO, Srinivasarao M, Jung HT. Macroscopic alignment of chromonic liquid crystals using patterned substrates. Phys Chem Chem Phys 2016; 18:10362-6. [DOI: 10.1039/c5cp07570j] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stable alignment of lyotropic chromonic liquid crystals (LCLCs) is demonstrated, along with an explanation of why such alignment has been difficult.
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Affiliation(s)
- Jeong Yeon Kim
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon
- Korea
| | - Karthik Nayani
- School of Materials Science and Engineering
- Georgia Institute of Technology
- Atlanta
- USA
| | - Hyeon Su Jeong
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon
- Korea
| | - Hwan-Jin Jeon
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon
- Korea
| | - Hae-Wook Yoo
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon
- Korea
| | - Eun Hyung Lee
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon
- Korea
| | - Jung Ok Park
- School of Materials Science and Engineering
- Georgia Institute of Technology
- Atlanta
- USA
| | - Mohan Srinivasarao
- School of Materials Science and Engineering
- Georgia Institute of Technology
- Atlanta
- USA
- School of Chemistry and Biochemistry
| | - Hee-Tae Jung
- National Research Laboratory for Organic Opto-Electronic Materials
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology
- Daejeon
- Korea
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32
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Briffitt R, Day IJ. Influence of structural isomerism and fluorine atom substitution on the self-association of naphthoic acid. J Phys Chem B 2015; 119:6703-10. [PMID: 25973655 DOI: 10.1021/acs.jpcb.5b02381] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The self-association of small aromatic systems driven by π-π stacking and hydrophobic interactions is well-known. Understanding the nature of these interactions is important if they are to be used to control association. Here, we present results of an NMR study into the self-association of two isomers of naphthoic acid along with an investigation into the role of a fluorine substituent on that self-association. We interpret the results in terms of a simple isodesmic model of self-association and show that the addition of the fluorine atom appears to increase the stability of the aggregates by an order of magnitude (e.g., 1-naphthoic acid vs 4-fluoro-1-naphthoic acid, Keq = 0.05 increases to 0.35 M(-1)), a result which is supported by computational studies in the literature on the role of substituent effects on interaction energy. The use of fluorinated isomers to probe the assembly is also presented, with differing trends in fluorine-19 chemical shifts observed depending on the isomer substitution pattern.
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Affiliation(s)
- Roseanne Briffitt
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, U.K
| | - Iain J Day
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, U.K
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33
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Shinde S, Asha S. Self-assembly directed template photopolymerization of perylenebisimide-poly (4-vinylpyridine): Nano organization. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.03.062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Chiral structures from achiral liquid crystals in cylindrical capillaries. Proc Natl Acad Sci U S A 2015; 112:E1837-44. [PMID: 25825733 DOI: 10.1073/pnas.1423220112] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects.
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Van Hecke GR, Karukstis KK, Rayermann S. Deriving binary phase diagrams for chromonic materials in water mixtures via fluorescence spectroscopy: cromolyn and water. Phys Chem Chem Phys 2015; 17:1047-52. [DOI: 10.1039/c4cp03539a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here the first example of a new and novel method of determining the binary temperature–composition phase diagram of a chromonic material in water using its intrinsic fluorescence.
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de Almeida Martins JP, Chávez FV, Sebastião PJ. NMR molecular dynamics study of chromonic liquid crystals Edicol Sunset Yellow doped with salts. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:540-545. [PMID: 24975451 DOI: 10.1002/mrc.4091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/15/2014] [Accepted: 05/18/2014] [Indexed: 06/03/2023]
Abstract
We investigate the effect of monoatomic salts on the molecular dynamics in the nematic and isotropic phases formed by the chromonic liquid crystal Edicol Sunset Yellow. The study was carried out using proton nuclear magnetic resonance relaxometry. To analyse the effect of incorporation of additional sodium chloride or lithium chloride on the solutions' molecular dynamics, the spin-lattice relaxation time was measured for Larmor frequencies between 10 kHz and 100 MHz. In the nematic phase, the presence of additional sodium or lithium ions seems to contribute to an increase of the rotations/reorientations corr elation times in comparison with the mixture without extra ions. The collective motions detected by proton NMR relaxometry are associated with collective fluctuations of molecules within the stacks in the nematic phase and with order parameter fluctuations in the isotropic phase.
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Affiliation(s)
- João P de Almeida Martins
- Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal
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Katz JR, Day IJ. Investigating the interaction of sunset yellow aggregates and 6-fluoro-2-naphthoic acid: increasing probe molecule complexity. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:435-439. [PMID: 24861207 DOI: 10.1002/mrc.4084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 04/28/2014] [Indexed: 06/03/2023]
Abstract
The interaction of small molecules with non-covalent assemblies is of wide interest. The use of a magnetically active reporter nucleus allows information to be obtained in the presence of spectral overlap or in cases of high dynamic range. In this paper, we explore the interaction of a larger probe molecule, 6-fluoro-2-naphthoic acid with assemblies of sunset yellow using (19)F chemical shifts and diffusion NMR methods. Comparing the observations with previous studies using fluorophenols, 6-fluoro-2-naphthoic acid prefers to associate as clusters at the ends of the sunset yellow stacks.
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Affiliation(s)
- Jonathan R Katz
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, UK
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Mcguire A, Yi Y, Clark NA. Orthogonal orientation of chromonic liquid crystals by rubbed polyamide films. Chemphyschem 2014; 15:1376-80. [PMID: 24470318 DOI: 10.1002/cphc.201301040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 12/10/2013] [Indexed: 11/09/2022]
Abstract
Chromonic liquid crystals (CLCs) have drawn attention for applications to organic electronics and optical films as well as biological materials. Understanding the alignment mechanism of CLCs is important for those applications. Using a polarized transmission optical microscope, we observe the optical texture, dichroism, and birefringence of CLC films of sunset yellow (SSY) confined by polyamide (nylon) films that are rubbed with a brush. The films align with the stacks of SSY molecules oriented, surprisingly, perpendicular to the rubbing direction. We propose that this alignment is stabilized by molecular interaction between the stretched nylon chains and molecular grooves of the SSY stacks rather than elastic energy of the CLCs due to surface topography induced by the rubbing.
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Affiliation(s)
- Aya Mcguire
- Department of Physics, Reed College, Portland, OR 97202 (USA)
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Jeong J, Han G, Johnson ATC, Collings PJ, Lubensky TC, Yodh AG. Homeotropic alignment of lyotropic chromonic liquid crystals using noncovalent interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:2914-20. [PMID: 24559290 DOI: 10.1021/la404893t] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We report on the homeotropic alignment of lyotropic chromonic liquid crystals (LCLCs). Homeotropic anchoring of LCLCs is difficult to achieve, and this challenge has limited development of applications for LCLCs. In this work, homeotropic alignment is achieved using noncovalent interactions between the LCLC molecules and various alignment layers including graphene, parylene films, poly(methyl methacrylate) films, and fluoropolymer films. The LCLC molecules are unique in that they self-assemble via noncovalent interactions in water into elongated aggregates which, in turn, form nematic and columnar liquid crystal (LC) phases. Here we exploit these same noncovalent interactions to induce homeotropic anchoring of the nematic LCLC. Homeotropic alignment is confirmed by polarized optical microscopy and conoscopy. We also report on novel transient stripe textures that occur when an initial flow-induced planar alignment transforms into the equilibrium homeotropic alignment required by boundary conditions. An understanding of this behavior could be important for switching applications.
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Affiliation(s)
- Joonwoo Jeong
- Department of Physics and Astronomy, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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40
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Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy. Proc Natl Acad Sci U S A 2014; 111:1742-7. [PMID: 24449880 DOI: 10.1073/pnas.1315121111] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Confined liquid crystals (LC) provide a unique platform for technological applications and for the study of LC properties, such as bulk elasticity, surface anchoring, and topological defects. In this work, lyotropic chromonic liquid crystals (LCLCs) are confined in spherical droplets, and their director configurations are investigated as a function of mesogen concentration using bright-field and polarized optical microscopy. Because of the unusually small twist elastic modulus of the nematic phase of LCLCs, droplets of this phase exhibit a twisted bipolar configuration with remarkably large chiral symmetry breaking. Further, the hexagonal ordering of columns and the resultant strong suppression of twist and splay but not bend deformation in the columnar phase, cause droplets of this phase to adopt a concentric director configuration around a central bend disclination line and, at sufficiently high mesogen concentration, to exhibit surface faceting. Observations of director configurations are consistent with Jones matrix calculations and are understood theoretically to be a result of the giant elastic anisotropy of LCLCs.
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41
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Walker M, Masters AJ, Wilson MR. Self-assembly and mesophase formation in a non-ionic chromonic liquid crystal system: insights from dissipative particle dynamics simulations. Phys Chem Chem Phys 2014; 16:23074-81. [DOI: 10.1039/c4cp03092c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Results are presented from a dissipative particle dynamics (DPD) simulation of a model non-ionic chromonic system, TP6EO2M, composed of a poly(ethylene glycol) functionalised aromatic (triphenylene) core.
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Affiliation(s)
- Martin Walker
- Department of Chemistry
- Durham University Science Laboratories
- Durham, UK
| | - Andrew J. Masters
- School of Chemical Engineering and Analytical Science
- University of Manchester
- Manchester, UK
| | - Mark R. Wilson
- Department of Chemistry
- Durham University Science Laboratories
- Durham, UK
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42
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Katz JR, Day LJ, Day IJ. NMR Investigations of the Interaction Between the Azo-Dye Sunset Yellow and Fluorophenol. J Phys Chem B 2013; 117:11793-800. [DOI: 10.1021/jp407686p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Jonathan R. Katz
- School
of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, United Kingdom
| | - Lucy J. Day
- BHASVIC, 205 Dyke Road, Hove, East Sussex, BN3
6EG, United Kingdom
| | - Iain J. Day
- School
of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, United Kingdom
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43
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Yang S, Wang B, Cui D, Kerwood D, Wilkens S, Han J, Luk YY. Stereochemical Control of Nonamphiphilic Lyotropic Liquid Crystals: Chiral Nematic Phase of Assemblies Separated by Six Nanometers of Aqueous Solvents. J Phys Chem B 2013; 117:7133-43. [DOI: 10.1021/jp401382h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Sijie Yang
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United
States
| | - Bing Wang
- Novartis Institutes for BioMedical Research, Inc., Cambridge, Massachusetts
02139, United States
| | - Dawei Cui
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United
States
| | - Deborah Kerwood
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United
States
| | - Stephan Wilkens
- Department
of Biochemistry and
Molecular Biology, Upstate Medical University, State University of New York, Syracuse, New York 13210, United
States
| | - Junjie Han
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United
States
| | - Yan-Yeung Luk
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United
States
- Department of Biomedical
and
Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
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44
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Sassano MF, Doak AK, Roth BL, Shoichet BK. Colloidal aggregation causes inhibition of G protein-coupled receptors. J Med Chem 2013; 56:2406-14. [PMID: 23437772 PMCID: PMC3613083 DOI: 10.1021/jm301749y] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
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Colloidal
aggregation is the dominant mechanism for artifactual
inhibition of soluble proteins, and controls against it are now widely
deployed. Conversely, investigating this mechanism for membrane-bound
receptors has proven difficult. Here we investigate the activity of
four well-characterized aggregators against three G protein-coupled
receptors (GPCRs) recognizing peptide and protein ligands. Each of
the aggregators was active at micromolar concentrations against the
three GPCRs in cell-based assays. This activity could be attenuated
by either centrifugation of the inhibitor stock solution or by addition
of Tween-80 detergent. In the absence of agonist, the aggregators
acted as inverse agonists, consistent with a direct receptor interaction.
Meanwhile, several literature GPCR ligands that resemble aggregators
themselves formed colloids, by both physical and enzymological tests.
These observations suggest that some GPCRs may be artifactually antagonized
by colloidal aggregates, an effect that merits the attention of investigators
in this field.
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Affiliation(s)
- Maria F Sassano
- Department of Pharmacology and the NIMH Psychoactive Drug Screening Program, University of North Carolina Chapel Hill School of Medicine , Chapel Hill, North Carolina 27759, USA
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45
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Abstract
A theory is introduced to describe self-assembly of liquid crystalline AB diblock copolymers, consisting of a homopolymer (A) and a side-chain liquid crystalline polymer (B). We derive the free energy of the liquid crystalline micellar solutions and examine the equilibrium solution properties: critical micelle concentration (CMC), nematic-isotropic phase transition (NIT) of the rigid side-chains inside the micelle core, and phase separations. It is shown that there is a critical micelle size below which the NIT becomes continuous due to a packing effect. We also find re-entrant micellizations near the NIT temperature. The phase diagrams, including binodal, spinodal, CMC, and NIT curves are also examined on the temperature-concentration plane.
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Affiliation(s)
- Akihiko Matsuyama
- Department of Bioscience and Bioinformatics, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Kawazu 680-4, Iizuka, Fukuoka 820-8502, Japan.
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46
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Varghese N, Shetye GS, Bandyopadhyay D, Gobalasingham N, Seo J, Wang JH, Theiler B, Luk YY. Emulsion of aqueous-based nonspherical droplets in aqueous solutions by single-chain surfactants: templated assembly by nonamphiphilic lyotropic liquid crystals in water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10797-10807. [PMID: 22726240 DOI: 10.1021/la302396c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Single-chain surfactants usually emulsify and stabilize oily substances into droplets in an aqueous solution. Here, we report a coassembly system, in which single types of anionic or non-ionic surfactants emulsify a class of water-soluble nonamphiphilic organic salts with fused aromatic rings in aqueous solutions. The nonamphiphilic organic salts are in turn promoted to form droplets of water-based liquid crystals (chromonic liquid crystals) encapsulated by single-chain surfactants. The droplets, stabilized against coalescence by encapsulated in a layer (or layers) of single chain surfactants, are of both nonspherical tactoid (elongated ellipsoid with pointy ends) and spherical shapes. The tactoids have an average long axis of ∼9 μm and a short axis of ∼3.5 μm with the liquid crystal aligning parallel to the droplet surface. The spherical droplets are 5-10 μm in diameter and have the liquid crystal aligning perpendicular to the droplet surface and a point defect in the center. Cationic and zwitterionic surfactants studied in this work did not promote the organic salt to form droplets. These results illustrate the complex interplay of self-association and thermodynamic incompatibility of molecules in water, which can cause new assembly behavior, including potential formation of vesicles or other assemblies, from surfactants that usually form only micelles. These unprecedented tactoidal shaped droplets also provide potential for the fabrication of new soft organic microcapsules.
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Affiliation(s)
- Nisha Varghese
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
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47
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Zhou S, Nastishin YA, Omelchenko MM, Tortora L, Nazarenko VG, Boiko OP, Ostapenko T, Hu T, Almasan CC, Sprunt SN, Gleeson JT, Lavrentovich OD. Elasticity of lyotropic chromonic liquid crystals probed by director reorientation in a magnetic field. PHYSICAL REVIEW LETTERS 2012; 109:037801. [PMID: 22861899 DOI: 10.1103/physrevlett.109.037801] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Indexed: 05/16/2023]
Abstract
Using a magnetic Frederiks transition technique, we measure the temperature and concentration dependences of splay K1, twist K2, and bend K3 elastic constants for the lyotropic chromonic liquid crystal sunset yellow formed through noncovalent reversible aggregation of organic molecules in water. K1 and K3 are comparable to each other and are an order of magnitude higher than K2. At higher concentrations and lower temperatures, K1 and the ratios K1/K3 and K1/K2 increase, which is attributed to elongation of self-assembled lyotropic chromonic liquid crystal aggregates, a feature not found in conventional thermotropic and lyotropic liquid crystals formed by covalently bound units of a fixed length.
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Affiliation(s)
- Shuang Zhou
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, USA
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48
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Rodríguez-Abreu C, Aubery-Torres C, Solans C, López-Quintela A, Tiddy GJT. Characterization of perylene diimide dye self-assemblies and their use as templates for the synthesis of hybrid and supermicroporous nanotubules. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4133-4141. [PMID: 21942535 DOI: 10.1021/am201016m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The self-organizing structures formed by a water-soluble perylene diimide dye (PDI) have been studied by several experimental techniques as potential templates for the preparation of hybrid nanomaterials. The dye forms chromonic-nematic and hexagonal liquid crystals in water. The aggregates in liquid crystals consist of one-molecule-wide stacks. From the changes in the solution proton NMR chemical shifts with concentration, it appears that adjacent molecules are twisted. There is significant broadening of the aromatic resonances at higher concentrations, arising from nonmotionally averaged dipole-dipole coupling between adjacent aromatic hydrogens. This is attributed to slow overall rotation of the aggregates in solution, suggesting that they grow up to several tens of nanometers. Dye aggregates serve as templates for the formation of silica tubules (1-5 μm length, average diameter ≈300 nm), with aligned and very thin (1-2 nm) dye nanostripes embedded in the walls. The silica tubes precipitated from solution are formed by the cooperative interaction between PDI and silica species during the sol-gel reaction. Upon calcination, silica nanotubules with supermicroporous walls are obtained. In comparison with conventional surfactant systems, the use of π-π stacked chromonic aggregates brings new possibilities for the templated fabrication of pores with sizes below the mesoporous range. Materials could find applications in photovoltaics as well as in shape selective catalysis and adsorption.
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Affiliation(s)
- Carlos Rodríguez-Abreu
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal.
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49
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Day IJ. On the inversion of diffusion NMR data: Tikhonov regularization and optimal choice of the regularization parameter. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 211:178-185. [PMID: 21683632 DOI: 10.1016/j.jmr.2011.05.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 05/16/2011] [Accepted: 05/25/2011] [Indexed: 05/30/2023]
Abstract
The analysis of diffusion NMR data in terms of distributions of diffusion coefficients is hampered by the ill-posed nature of the required inverse Laplace transformation. Naïve approaches such as multiexponential fitting or standard least-squares algorithms are numerically unstable and often fail. This paper updates the CONTIN approach of the application of Tikhonov regularization to stabilise this numerical inversion problem and demonstrates two methods for automatically choosing the optimal value of the regularization parameter. These approaches are computationally efficient and easy to implement using standard matrix algebra techniques. Example analyses are presenting using both synthetic data and experimental results of diffusion NMR studies on the azo-dye sunset yellow and some polymer molecular weight reference standards.
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Affiliation(s)
- Iain J Day
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, UK.
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50
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Park HS, Kang SW, Tortora L, Kumar S, Lavrentovich OD. Condensation of self-assembled lyotropic chromonic liquid crystal sunset yellow in aqueous solutions crowded with polyethylene glycol and doped with salt. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:4164-4175. [PMID: 21391644 DOI: 10.1021/la200505y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We use optical and fluorescence microscopy, densitometry, cryo-transmission electron microscopy (cryo-TEM), spectroscopy, and synchrotron X-ray scattering to study the phase behavior of the reversible self-assembled chromonic aggregates of an anionic dye Sunset Yellow (SSY) in aqueous solutions crowded with an electrically neutral polymer polyethylene glycol (PEG) and doped with the salt NaCl. PEG causes the isotropic SSY solutions to condense into a liquid-crystalline region with a high concentration of SSY aggregates, coexisting with a PEG-rich isotropic (I) region. PEG added to the homogeneous nematic (N) phase causes separation into the coexisting N and I domains; the SSY concentration in the N domains is higher than the original concentration of PEG-free N phase. Finally, addition of PEG to the highly concentrated homogeneous N phase causes separation into the coexisting columnar hexagonal (C) phase and I phase. This behavior can be qualitatively explained by the depletion (excluded volume) effects that act at two different levels: at the level of aggregate assembly from monomers and short aggregates and at the level of interaggregate packing. We also show a strong effect of a monovalent salt NaCl on phase diagrams that is different for high and low concentrations of SSY. Upon the addition of salt, dilute I solutions of SSY show appearance of the condensed N domains, but the highly concentrated C phase transforms into a coexisting I and N domains. We suggest that the salt-induced screening of electric charges at the surface of chromonic aggregates leads to two different effects: (a) increase of the scission energy and the contour length of aggregates and (b) decrease of the persistence length of SSY aggregates.
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Affiliation(s)
- Heung-Shik Park
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States
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