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Finney TJ, Parikh SJ, Berman A, Sasaki DY, Kuhl TL. Characterizing and Tuning the Properties of Polydiacetylene Films for Sensing Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12940-12951. [PMID: 34699228 DOI: 10.1021/acs.langmuir.1c02004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Self-assembled, polymerized diacetylene (DA) nanostructures and two-dimensional films have been studied over the past two decades for sensor applications because of their straightforward visual readout. DA monomers, when exposed to UV light, polymerize to produce a visibly blue polymer. Blue phase polydiacetylenes (PDAs) when exposed to an external stimuli, such as temperature or UV light, undergo a chromatic phase transition to a fluorescent, visibly red phase. The tunability of the monomer to blue to red chromatic phase transitions by choice of diacetylene monomer in the presence of metal cations is systematically and comprehensively investigated to determine their effects on the properties of PDA Langmuir films. The polymerization kinetics and domain morphology of the PDA films were characterized using polarized fluorescent microscopy, UV-vis-fluorescent spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Increasing the monomer alkyl tail length was found to strongly increase the UV dose necessary to produce optimally blue films and fully red films. A decrease in the polymer domain size was also correlated with longer-tailed DA molecules. Metal cations have a diverse effect on the film behavior. Alkaline-earth metals such as Mg, Ca, and Ba have a negligible effect on the phase transition kinetics but can be used to tune PDA polymer domain sizes. The Ni and Fe cations increase the UV dose necessary to produce red phase PDA films and significantly decrease the polymer domain sizes. The Zn, Cd, and Cu ions exhibit strong directed interactions with the PDA carboxylic acid headgroups, resulting in quenched fluorescence and a unique film morphology. FTIR analysis provides insight into the metal-PDA binding mechanisms and demonstrates that the coordination between the PDA film headgroups and the metal cations can be correlated with changes in the film morphology and kinetics. The findings from these studies will have broad utility for tuning PDA-based sensors for different applications and sensitivity ranges.
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Affiliation(s)
- Tanner J Finney
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Sanjai J Parikh
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, United States
| | - Amir Berman
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beersheba 8410501, Israel
| | - Darryl Y Sasaki
- Biotechnology and Bioengineering Department, Sandia National Laboratories, Livermore, California 94550, United States
| | - Tonya L Kuhl
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
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2
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Bergendal E, Campbell RA, Pilkington GA, Müller-Buschbaum P, Rutland MW. 3D texturing of the air-water interface by biomimetic self-assembly. NANOSCALE HORIZONS 2020; 5:839-846. [PMID: 32364200 DOI: 10.1039/c9nh00722a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air-water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air-water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air-water interface.
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Affiliation(s)
- Erik Bergendal
- KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Chemistry, Drottning Kristinas väg 51, 10044 Stockholm, Sweden.
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3
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Das K, Sah BK, Kundu S. Cation-induced monolayer collapse at lower surface pressure follows specific headgroup percolation. Phys Rev E 2017; 95:022804. [PMID: 28298005 DOI: 10.1103/physreve.95.022804] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Indexed: 11/07/2022]
Abstract
A Langmuir monolayer can be considered as a two-dimensional (2D) sheet at higher surface pressure which structurally deform with mechanical compression depending upon the elastic nature of the monolayer. The deformed structures formed after a certain elastic limit are called collapsed structures. To explore monolayer collapses at lower surface pressure and to see the effect of ions on such monolayer collapses, out-of-plane structures and in-plane morphologies of stearic acid Langmuir monolayers have been studied both at lower (≈6.8) and higher (≈9.5) subphase pH in the presence of Mg^{2+},Ca^{2+},Zn^{2+},Cd^{2+}, and Ba^{2+} ions. At lower subphase pH and in the presence of all cations, the stearic acid monolayer remains as a monolayer before collapse, which generally takes place at higher surface pressure (π_{c}>50mN/m). However, at higher subphase pH, structural changes of stearic acid monolayers occur at relatively lower surface pressure depending upon the specific dissolved ions. Among the same group elements of Mg^{2+},Ca^{2+}, and Ba^{2+}, only for Ba^{2+} ions does monolayer to multilayer transition take place from a much lower surface pressure of the monolayer, remaining, however, as a monolayer for Mg^{2+} and Ca^{2+} ions. For another same group elements of Zn^{2+} and Cd^{2+} ions, a less covered bilayer structure forms on top of the monolayer structure at lower surface pressure, which is evidenced from both x-ray reflectometry and atomic force microscopy. Fourier transform infrared spectroscopy confirms the presence of two coexisting conformations formed by the two different metal-headgroup coordinations and the monolayer to trilayer or multilayer transformation takes place when the coverage ratio of the two molecular conformations changes from the critical value (p_{c}) of ≈0.66. Such ion-specific monolayer collapses are correlated with the 2D lattice percolation model.
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Affiliation(s)
- Kaushik Das
- Soft Nano Laboratory, Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035, India
| | - Bijay Kumar Sah
- Soft Nano Laboratory, Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035, India
| | - Sarathi Kundu
- Soft Nano Laboratory, Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035, India
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4
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Sachan AK, Choi SQ, Kim KH, Tang Q, Hwang L, Lee KYC, Squires TM, Zasadzinski JA. Interfacial rheology of coexisting solid and fluid monolayers. SOFT MATTER 2017; 13:1481-1492. [PMID: 28125114 PMCID: PMC5720834 DOI: 10.1039/c6sm02797k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Biologically relevant monolayer and bilayer films often consist of micron-scale high viscosity domains in a continuous low viscosity matrix. Here we show that this morphology can cause the overall monolayer fluidity to vary by orders of magnitude over a limited range of monolayer compositions. Modeling the system as a two-dimensional suspension in analogy with classic three-dimensional suspensions of hard spheres in a liquid solvent explains the rheological data with no adjustable parameters. In monolayers with ordered, highly viscous domains dispersed in a continuous low viscosity matrix, the surface viscosity increases as a power law with the area fraction of viscous domains. Changing the phase of the continuous matrix from a disordered fluid phase to a more ordered, condensed phase dramatically changes the overall monolayer viscosity. Small changes in the domain density and/or continuous matrix composition can alter the monolayer viscosity by orders of magnitude.
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Affiliation(s)
- A K Sachan
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - S Q Choi
- Departments of Chemical and Biomolecular Engineering and KINC, KAIST, Daejeon, 305-701, Korea
| | - K H Kim
- Departments of Chemical and Biomolecular Engineering and KINC, KAIST, Daejeon, 305-701, Korea
| | - Q Tang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
| | - L Hwang
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - K Y C Lee
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - T M Squires
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA
| | - J A Zasadzinski
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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5
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Tamam L, Ocko BM, Deutsch M. Two-dimensional order in mercury-supported langmuir films of fatty diacids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15586-15597. [PMID: 23072520 DOI: 10.1021/la3034325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The structure of mercury-supported Langmuir films of dicarboxylic acid molecules with 13 ≤ n ≤ 22 carbons is studied by X-ray methods and surface tensiometry. The molecules lie surface-parallel, forming mono-, bi-, or trilayers, depending on coverage. All films exhibit a full 2D order of the same single-molecule oblique unit cell. In particular, the distinct odd-even structure difference of 3D crystals of the same molecules is not observed. The unit cell's width and angle show a small systematic decrease with n, while the length increases commensurately with the molecular length. These results show the films to consist of closely packed, extended, polymer-like chains of diacid molecules, bound by their carboxyl end groups. Evidence is presented for the inclusion of a single mercury atom in the carboxyl-carboxyl bond. The possible conformation of this bond and implications of the parity-independent structure are discussed.
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Affiliation(s)
- Lilach Tamam
- Physics Department, Bar-Ilan University, Ramat-Gan, Israel
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6
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Petersen S, Glyvradal M, Bøggild P, Hu W, Feidenhans'l R, Laursen BW. Graphene oxide as a monoatomic blocking layer. ACS NANO 2012; 6:8022-8029. [PMID: 22891605 DOI: 10.1021/nn302628q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Monolayer graphene oxide (mGO) is shown to effectively protect molecular thin films from reorganization and function as an atomically thin barrier for vapor-deposited Ti/Al metal top electrodes. Fragile organic Langmuir-Blodgett (LB) films of C(22) fatty acid cadmium salts (cadmium(II) behenate) were covered by a compressed mosaic LB film of mGO flakes. These hybrid LB films were examined with atomic force microscopy (AFM) and X-ray reflectivity, both with and without the metal top electrodes. While the AFM enabled surface and morphology analysis, the X-ray reflectivity allowed for a detailed structural depth profiling of the organic film and mGO layer below the metal top layers. The structure of the mGO-protected LB films was found to be perfectly preserved; in contrast, it has previously been shown that metal deposition completely destroys the first two LB layers of unprotected films. This study provides clear evidence of the efficient protection offered by a single atomic layer of GO.
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Affiliation(s)
- Søren Petersen
- Nano-Science Center & Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
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7
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Upcher A, Lifshitz Y, Zeiri L, Golan Y, Berman A. Effect of metal cations on polydiacetylene Langmuir films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:4248-4258. [PMID: 22288778 DOI: 10.1021/la204735t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Polydiacetylene (PDA) Langmuir films (LFs) are a unique class of materials that couple a highly aligned conjugated backbone with tailorable pendant side groups and terminal functionalities. The films exhibit chromatic transitions from monomer to blue polymer and finally to a red phase that can be activated optically, thermally, chemically, and mechanically. The properties of PDA LFs are strongly affected by the presence of metal cations in the aqueous subphase of the film due to their interaction with the carboxylic head groups of the polymer. In the present study the influence of divalent cadmium, barium, copper, and lead cations on the structural, morphological, and optical properties of PDA LFs was investigated by means of surface pressure-molecular area (π-A) isotherms, atomic force microscopy, optical absorbance, and Raman spectroscopy. The threshold concentrations for the influence of metal cations on the film structure, stability, and phase transformation were determined by π-A analyses. It was found that each of the investigated cations has a unique influence on the properties of PDA LFs. Cadmium cations induce moderate phase transition kinetics with reduced domain size and fragmented morphology. Barium cations contribute to stabilization of the PDA blue phase and enhanced linear strand morphology. On the other hand, copper cations enhance rapid formation of the PDA red phase and cause fragmented morphology of the film, while the presence of lead cations results in severe perturbation of the film with only a small area of the film able to be effectively polymerized. The influence of the metal cations is correlated with the solubility product (K(sp)), association strength, and ionic-covalent bond nature between the metal cations and the PDA carboxylic head groups.
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Affiliation(s)
- Alexander Upcher
- Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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8
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Mukherjee S, Datta A, Giglia A, Mahne N, Nannarone S. Chemistry at air/water interface versus reaction in a flask: tuning molecular conformation in thin films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3519-3528. [PMID: 19708145 DOI: 10.1021/la8023502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Atomic force microscopy and X-ray reflectivity studies of cobalt stearate Langmuir-Blodgett (LB) films (CoStp) deposited from a preformed bulk sample on quartz substrates showed formation of a Volmer-Weber type monolayer but no multilayers as compared to the excellent multilayers of cobalt stearate films (CoStn) deposited at the air/water interface by the usual LB technique, in spite of both showing bidentate bridging type coordination of cobalt ions with the carboxylate group. The difference is attributed to existence of different headgroup conformers, observed from Fourier transform infrared (FTIR) studies. The CoStp films had a higher energy 'boat' conformation with linear O-Co-O linkage, whereas CoStn formed a low energy conformer with a bent O-Co-O configuration (bond angle of 105 degrees). Present results support the necessity of bidentate bridging coordination in multilayer deposition, but rejects its sufficiency by bringing out the crucial role played by air/water interface. Differences in surface pressure-molecular area isotherms and hydrocarbon tail-tail interactions (evident from FTIR spectra) of the films support the above statement. Methyl-methyl interactions observed in CoStn samples suggest hierarchy of supramolecular chemistry at the air/water interface in tuning the C-O-Co bond angle essential to satisfy the wetting condition with the substrate and subsequently form LB multilayers.
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Affiliation(s)
- Smita Mukherjee
- Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India
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9
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Oncins G, Picas L, Hernández-Borrell J, Garcia-Manyes S, Sanz F. Thermal response of Langmuir-Blodgett films of dipalmitoylphosphatidylcholine studied by atomic force microscopy and force spectroscopy. Biophys J 2007; 93:2713-25. [PMID: 17586574 PMCID: PMC1989725 DOI: 10.1529/biophysj.107.110916] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Accepted: 06/15/2007] [Indexed: 11/18/2022] Open
Abstract
The topographic evolution of supported dipalmitoylphosphatidylcholine (DPPC) monolayers with temperature has been followed by atomic force microscopy in liquid environment, revealing the presence of only one phase transition event at approximately 46 degrees C. This finding is a direct experimental proof that the two phase transitions observed in the corresponding bilayers correspond to the individual phase transition of the two leaflets composing the bilayer. The transition temperature and its dependency on the measuring medium (liquid saline solution or air) is discussed in terms of changes in van der Waals, hydration, and hydrophobic/hydrophilic interactions, and it is directly compared with the transition temperatures observed in the related bilayers under the same experimental conditions. Force spectroscopy allows us to probe the nanomechanical properties of such monolayers as a function of temperature. These measurements show that the force needed to puncture the monolayers is highly dependent on the temperature and on the phospholipid phase, ranging from 120+/-4 pN at room temperature (liquid condensed phase) to 49+/-2 pN at 65 degrees C (liquid expanded phase), which represents a two orders-of-magnitude decrease respective to the forces needed to puncture DPPC bilayers. The topographic study of the monolayers in air around the transition temperature revealed the presence of boundary domains in the monolayer surface forming 120 degrees angles between them, thus suggesting that the cooling process from the liquid-expanded to the liquid-condensed phase follows a nucleation and growth mechanism.
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Affiliation(s)
- Gerard Oncins
- Department of Physical Chemistry, Chemistry Faculty, University of Barcelona and Institut de Bioenginyeria de Catalunya, Barcelona, Spain
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10
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Callaway MJ, Tildesley DJ, Quirke N. Molecular Dynamics Simulation of a Langmuir-Blodgett Patch. MOLECULAR SIMULATION 2006. [DOI: 10.1080/08927029608024125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Dong WF, Wang R, Mao G, Möhwald H. Self-assembled molecular patterns of fatty acid on graphite in the presence of metal ions. SOFT MATTER 2006; 2:686-692. [PMID: 32680226 DOI: 10.1039/b604213a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The stripe phase formed by long-chain alkane derivatives on the graphite lattice provides a unique opportunity for the study of molecular adsorption, aggregation, and reaction on patterns. Fatty acids, such as arachidic acid (AA), self-assemble on graphite into a sheet of parallel stripes with a periodicity of twice its molecular chain length. The molecular pattern is thus defined precisely by the size and functionality of the headgroup and tailgroup of the amphiphile. Complexation of metal ions to AA fixes the number and location of the ion, which can serve as a precursor to semiconductor nanocrystal arrays. In order to understand the effect of the ion complexation, we carry out atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) investigations of AA self-assembly in the presence of various metal ions. While the stripe orientation is dictated by the graphite lattice and the stripe periodicity is determined by the AA chain length, the size, shape, and degree of order of the stripe crystalline domain are influenced by the metal ion bond strength to the carboxylic ligand. The change of morphology in the self-assembled pattern shows a trend along the Irving-Williams series.
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Affiliation(s)
- Wen-Fei Dong
- Key Laboratory of Automobile Materials (Jilin University), Ministry of Education and Department of Materials Science and Engineering, Jilin University, Changchun, 130025, China and Max Planck Institute of Colloids and Interfaces, Golm/Potsdam, D-14476, Germany
| | - Ruomiao Wang
- Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, USA.
| | - Guangzhao Mao
- Department of Chemical Engineering and Materials Science, Wayne State University, 5050 Anthony Wayne Drive, Detroit, Michigan 48202, USA.
| | - Helmuth Möhwald
- Max Planck Institute of Colloids and Interfaces, Golm/Potsdam, D-14476, Germany
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12
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Sabín J, Prieto G, Messina PV, Ruso JM, Hidalgo-Alvarez R, Sarmiento F. On the effect of Ca2+ and La3+ on the colloidal stability of liposomes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:10968-75. [PMID: 16285760 DOI: 10.1021/la051397t] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This work deals with the effect of Ca2+ and La3+ on the colloidal stability of phosphatidylcholine (PC) liposomes in aqueous media. As physical techniques, nephelometry, photon correlation spectroscopy, electrophoretic mobility, and surface tension were used. The theoretical predictions of the colloidal stability of liposomes were followed using the Derjaguin-Landau-Verwey-Overbeek theory. Changes in the size of liposomes and high polydispersity values were observed as La3+ concentration increases, suggesting that this cation induces the aggregation of liposomes. However, changes in polydispersity were not observed with Ca2+, suggesting a coalescence mechanism or fusion of liposomes. The stability factor (W), calculated from the nephelometry measurements indicated that aggregation/fusion occurs at a critical concentration (c.c.) of 0.3 and 0.7 M for La3+ and Ca2+, respectively. To gain a better insight into the interaction mechanism between the liposomes and the studied ions, the interaction between PC monolayers and Ca2+ and La3+ was studied. Changes in the surface area per lipid molecule (A0) in the monolayer at the c.c. values were found for both ions, with a more pronounced effect in the case of Ca2+. This corresponds with a larger reduction of the steric repulsive interaction between the headgroups at the phospholipid membrane (pi(head)). The experimental result validates the hypothesis made on the liposome fusion in the presence of Ca2+ and liposome aggregation in the presence of La3+. These aggregation mechanisms have also been confirmed by transmission electron microscopy.
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Affiliation(s)
- Juan Sabín
- Grupo de Biofísica e Interfases, Departamento de Física Aplicada. Facultade de Física, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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13
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Chen S, Seidel MT, Zewail AH. Atomic-scale dynamical structures of fatty acid bilayers observed by ultrafast electron crystallography. Proc Natl Acad Sci U S A 2005; 102:8854-9. [PMID: 15956181 PMCID: PMC1150297 DOI: 10.1073/pnas.0504022102] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structure and dynamics of a biological model bilayer are reported with atomic-scale resolution by using ultrafast electron crystallography. The bilayer was deposited as a Langmuir-Blodgett structure of arachidic (eicosanoic) fatty acids with the two chains containing 40 carbon atoms (approximately = 50 angstroms), on a hydrophobic substrate, the hydrogen terminated silicon(111) surface. We determined the structure of the 2D assembly, establishing the orientation of the chains and the subunit cell of the CH2 distances: a0 = 4.7 angstroms, b0 = 8.0 angstroms, and c0 = 2.54 angstroms. For structural dynamics, the diffraction frames were taken every 1 picosecond after a femtosecond temperature jump. The observed motions, with sub-angstroms resolution and monolayer sensitivity, clearly indicate the coherent anisotropic expansion of the bilayer solely along the aliphatic chains, followed by nonequilibrium contraction and restructuring at longer times. This motion is indicative of a nonlinear behavior among the anharmonically coupled bonds on the ultrashort time scale and energy redistribution and diffusion on the longer time scale. The ability to observe such atomic motions of complex structures and at interfaces is a significant leap forward for the determination of macromolecular dynamical structures by using ultrafast electron crystallography.
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Affiliation(s)
- Songye Chen
- Laboratory for Molecular Sciences, Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
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14
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Structure and thermal stability of Langmuir–Blodgett films of barium arachidate. Colloids Surf A Physicochem Eng Asp 2005. [DOI: 10.1016/j.colsurfa.2004.10.103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Bantchev GB, Schwartz DK. Structure of beta-casein layers at the air/solution interface: atomic force microscopy studies of transferred layers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:11692-11697. [PMID: 15595799 DOI: 10.1021/la048380f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We report the nanoscale structural changes associated with the interfacial gelation of adsorbed beta-casein layers as a function of aging time. Adsorbed layers were transferred to solid supports and imaged by atomic force microscopy. The aging of the layer was accompanied by the formation of distinct disk-shaped protein nanoparticles ( approximately 20 nm in diameter). Under conditions where a gelled layer was expected (from previous interfacial rheology experiments), we observed ordering of the particles and the formation of elongated aggregates or linear rows. Brewster angle microscopy images were also obtained during the adsorption and gelation processes and during the degradation of the protein layer following addition of the surfactant sodium dodecyl sulfate (SDS). If SDS was added prior to interfacial protein gelation, the layer developed a foamlike morphology consistent with a fluid interfacial protein layer. However, if SDS was added after gelation, the protein layer was observed to fracture, consistent with the behavior of a solid phase.
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Affiliation(s)
- Grigor B Bantchev
- Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, USA
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16
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Karabaliev M, Kochev V. The potential of manganese in construction of electrodes modified with thin liquid films of lipids. J Electroanal Chem (Lausanne) 2004. [DOI: 10.1016/j.jelechem.2004.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Abstract
Alzheimer's disease is defined in part by the intraneuronal accumulation of filaments comprised of the microtubule-associated protein tau. In vitro, fibrillization of full-length, unphosphorylated recombinant tau can be induced under near-physiological conditions by treatment with various agents, including anionic surfactants. Here we examine the pathway through which anionic surfactants promote tau fibrillization using a combination of electron microscopy and fluorescence spectroscopy. Protein and surfactant first interacted in solution to form micelles, which then provided negatively charged surfaces that accumulated tau aggregates. Surface aggregation of tau protein was followed by the time-dependent appearance of a thioflavin S reactive intermediate that accumulated over a period of hours. The intermediate was unstable in the absence of anionic surfaces, suggesting it was not filamentous. Fibrillization proceeded after intermediate formation with classic nucleation-dependent kinetics, consisting of lag phase followed by the exponential increase in filament lengths, followed by an equilibrium phase reached in approximately 24 h. The pathway did not require protein insertion into the micelle hydrophobic core or conformational change arising from mixed micelle formation, because anionic microspheres constructed from impermeable polystyrene were capable of qualitatively reproducing all aspects of the fibrillization reaction. It is proposed that the progression from amorphous aggregation through intermediate formation and fibrillization may underlie the activity of other inducers such as hyperphosphorylation and may be operative in vivo.
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Affiliation(s)
- Carmen N Chirita
- Biophysics Program, The Ohio State University College of Medicine and Public Health, Columbus, Ohio 43210, USA
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18
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Karabaliev M, Kochev V. Interaction of thin wetting films of lecithin with some divalent cations. Bioelectrochemistry 2004; 63:177-81. [PMID: 15110269 DOI: 10.1016/j.bioelechem.2003.10.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Revised: 09/25/2003] [Accepted: 10/09/2003] [Indexed: 10/26/2022]
Abstract
The impact of some divalent cations on the structure of a model membrane system, comprising wetting lipid films, is assayed in this work. The results from impedimetry suggest prominent structural changes upon the addition of the discussed ions to the electrolyte solution contacting the film. These changes are manifested by the increase of resistivity of the films as well as by the decrease of capacitance dispersion. In accordance with other data in the literature, manganese (Mn(2+)) turned out to have an effect greater than those of Mg(2+) and Ca(2+).
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Affiliation(s)
- Miroslav Karabaliev
- Department of Physics and Biophysics, Faculty of Medicine, Trakia University, 11 Armeiska, Stara Zagora 6003, Bulgaria.
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19
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Lu L, Wang H, Zhang H, Xi S. Molecular construction of oriented crystalline NaMnF(3) and KMnF(3) with perovskite structures at room temperature. J Colloid Interface Sci 2003; 266:115-9. [PMID: 12957589 DOI: 10.1016/s0021-9797(03)00539-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this work, we report the fabrication of high-quality (101)-oriented orthorhombic NaMnF(3) and (100)-oriented cubic KMnF(3) perovskites via an organic monolayer template at room temperature. The controlled crystallization under the organic monolayer template is explained in terms of the electrostatic interactions and beneficial lattice matching between the organic template and the ions undergoing nucleation. The present study is of great importance in the preparation of oriented perovskite materials as well as in the understanding of the mechanism for organic-template-directed crystallization.
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Affiliation(s)
- Lehui Lu
- Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
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20
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Dupres V, Cantin S, Perrot F, Fontaine P, Goldmann M. Evidence of a tilted and herringbone structure in cadmium behenate Langmuir–Blodgett ultrathin films: Comparison with Langmuir monolayers. J Chem Phys 2002. [DOI: 10.1063/1.1447909] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Prasanth Kumar N, Major S, Vitta S, Talwar S, Dubcek P, Amenitsch H, Bernstorff S, Ganesan V, Gupta A, Dasannacharya B. Molecular packing in cadmium and zinc arachidate LB multilayers. Colloids Surf A Physicochem Eng Asp 2002. [DOI: 10.1016/s0927-7757(01)00917-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Kmetko J, Datta A, Evmenenko G, Dutta P. The Effects of Divalent Ions on Langmuir Monolayer and Subphase Structure: A Grazing-Incidence Diffraction and Bragg Rod Study. J Phys Chem B 2001. [DOI: 10.1021/jp0122169] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Takamoto DY, Aydil E, Zasadzinski JA, Ivanova AT, Schwartz DK, Yang T, Cremer PS. Stable ordering in Langmuir-Blodgett films. Science 2001; 293:1292-5. [PMID: 11509723 DOI: 10.1126/science.1060018] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Defects in the layering of Langmuir-Blodgett (LB) films can be eliminated by depositing from the appropriate monolayer phase at the air-water interface. LB films deposited from the hexagonal phase of cadmium arachidate (CdA2) at pH 7 spontaneously transform into the bulk soap structure, a centrosymmetric bilayer with an orthorhombic herringbone packing. A large wavelength folding mechanism accelerates the conversion between the two structures, leading to a disruption of the desired layering. At pH > 8.5, though it is more difficult to draw LB films, almost perfect layering is obtained due to the inability to convert from the as-deposited structure to the equilibrium one.
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Affiliation(s)
- D Y Takamoto
- Department of Chemical Engineering and Materials, University of California, Santa Barbara, CA 93106, USA
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24
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Peng JB, Barnes GT, Gentle IR. The structures of Langmuir-Blodgett films of fatty acids and their salts. Adv Colloid Interface Sci 2001; 91:163-219. [PMID: 11392356 DOI: 10.1016/s0001-8686(99)00031-7] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent advances in several experimental techniques have enabled detailed structural information to be obtained for floating (Langmuir) monolayers and Langmuir-Blodgett films. These techniques are described briefly and their application to the study of films of fatty acids and their salts is discussed. Floating monolayers on aqueous subphases have been shown to possess a complex polymorphism with phases whose structures may be compared to those of smectic mesophases. However, only those phases that exist at high surface pressures are normally used in Langmuir-Blodgett (LB) deposition. In single LB monolayers of fatty acids and fatty acid salts the acyl chains are in the all-trans conformation with their long axes normal to the substrate. The in-plane molecular packing is hexagonal with long-range bond orientational order and short-range positional order: known as the hexatic-B structure. This structure is found irrespective of the phase of the parent floating monolayer. The structures of multilayer LB films are similar to the structures of their bulk crystals, consisting of stacked bilayer lamellae. Each lamella is formed from two monolayers of fatty acid molecules or ions arranged head to head and held together by hydrogen bonding between pairs of acids or ionic bonding through the divalent cations. With acids the acyl chains are tilted with respect to the substrate normal and have a monoclinic structure, whereas the salts with divalent cations may have the chains normal to the substrate or tilted. The in-plane structures are usually centred rectangular with the chains in the trans conformation and packed in a herringbone pattern. Multilayer films of the acids show only a single-step order-disorder transition at the melting point. This temperature tends to rise as the number of layers increases. Complex changes occur when multilayer films of the salts are heated. Disorder of the chains begins at low temperatures but the arrangement of the head groups does not alter until the melting temperature is reached. Slow heating to a temperature just below the melting temperature gives, with some salts, a radical change in phase. The lamellar structure disappears and a new phase consisting of cylindrical rods lying parallel to the substrate surface and stacked in a hexagonal pattern is formed. In each rod the cations are aligned along the central axis surrounded by the disordered acyl chains.
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Affiliation(s)
- J B Peng
- Department of Chemistry, The University of Queensland, Brisbane, Australia
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25
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Balashev K, Jensen TR, Kjaer K, Bjørnholm T. Novel methods for studying lipids and lipases and their mutual interaction at interfaces. Part I. Atomic force microscopy. Biochimie 2001; 83:387-97. [PMID: 11368846 DOI: 10.1016/s0300-9084(01)01264-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mono-layers of lipids and their interaction with surface active enzymes (lipases) have been studied for more than a century. During the past decade new insight into this area has been obtained due to the development of scanning probe microscopy. This novel method provides direct microscopic information about the system in question and allows in situ investigations under near physiological conditions. In the present review the theory, experimental set-up and sample requirements of atomic force microscopy (AFM) are described. An overview of recent results is also presented with special emphasis on lipase hydrolysis and kinetics investigated in situ using AFM.
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Affiliation(s)
- K Balashev
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
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26
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Peng JB, Barnes GT, Gentle IR, Foran GJ. Superstructures and Correlated Metal Ion Layers in Langmuir−Blodgett Films of Cadmium Soaps Observed with Grazing Incidence X-ray Diffraction. J Phys Chem B 2000. [DOI: 10.1021/jp000075p] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. B. Peng
- Department of Chemistry, The University of Queensland, Brisbane, QLD 4072, Australia
| | - G. T. Barnes
- Department of Chemistry, The University of Queensland, Brisbane, QLD 4072, Australia
| | - I. R. Gentle
- Department of Chemistry, The University of Queensland, Brisbane, QLD 4072, Australia
| | - G. J. Foran
- Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234, Australia
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27
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Chaly T, Montrel M. Hydrogen-ion binding of polycytidylic acid immobilized between Langmuir layers of dimethyldioctadecylammonium (DODA) in thin multilayer films. Biosens Bioelectron 2000; 15:93-8. [PMID: 10826648 DOI: 10.1016/s0956-5663(99)00071-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The report describes the study of hydrogen-ion binding of Langmuir-Blodgett films contained with polycytidylic acid. A variety of multilayer films are analyzed and their UV absorption spectra are recorded. Poly (C) molecules established between dimethyldioctadecylammonium (DODA) layers are shown to exist in double stranded and semiprotonated form, independent of the pH value of the solution from which the films were made. A large hysteresis was found between forward and back proton titration of poly(C) immobilized in the LB films. This hysteresis points to a marked transference of both types of molecules during the film titration. This behavior also depends upon the types of molecules from which the films were made.
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Affiliation(s)
- T Chaly
- Department of Research, PET Research Facility, North Shore University Hospital, NYU Medical College, Manhasset, NY, 11030, USA
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Consalvo C, Panebianco S, Pignataro B, Compagnini G, Puglisi O. Thermal Stability of Stearic AcidBarium Stearate Langmuir−Blodgett Monolayers on Plasma-Oxidized Silicon Substrate Probed by Atomic Force Microscopy. J Phys Chem B 1999. [DOI: 10.1021/jp990213e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. Consalvo
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, V.le A. Doria 6, 95125 Catania, Italy
| | - S. Panebianco
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, V.le A. Doria 6, 95125 Catania, Italy
| | - B. Pignataro
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, V.le A. Doria 6, 95125 Catania, Italy
| | - G. Compagnini
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, V.le A. Doria 6, 95125 Catania, Italy
| | - O. Puglisi
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, V.le A. Doria 6, 95125 Catania, Italy
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Chunbo Y, Desheng D, Zuhong L, Juzheng L. Molecular positional order in a dipalmitoylphosphatidic acid Langmuir–Blodgett monolayer by atomic force microscopy. Colloids Surf A Physicochem Eng Asp 1999. [DOI: 10.1016/s0927-7757(97)00147-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Geue T, Schultz M, Englisch U, Stömmer R, Pietsch U, Meine K, Vollhardt D. Investigations of pH-dependent domain structure of lead arachidate Langmuir-Blodgett films by means of x-ray specular and diffuse scattering and atomic force microscopy. J Chem Phys 1999. [DOI: 10.1063/1.478713] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Sastry M, Ganguly P. Determination of C 1s Core Level Chemical Shifts in Some Langmuir−Blodgett Films Using a Modified Sanderson Formalism. J Phys Chem A 1998. [DOI: 10.1021/jp971423z] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Murali Sastry
- Materials Chemistry Division, National Chemical Laboratory, Pune 411 008, India
| | - P. Ganguly
- Materials Chemistry Division, National Chemical Laboratory, Pune 411 008, India
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32
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Datta A, Sanyal MK, Dhanabalan A, Major SS. Formation of Highly Condensed Ferric Stearate Monolayers at the Air−Water Interface. J Phys Chem B 1997. [DOI: 10.1021/jp971703e] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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33
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Seip CT, Granroth GE, Meisel MW, Talham DR. Langmuir−Blodgett Films of Known Layered Solids: Preparation and Structural Properties of Octadecylphosphonate Bilayers with Divalent Metals and Characterization of a Magnetic Langmuir−Blodgett Film. J Am Chem Soc 1997. [DOI: 10.1021/ja963598c] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Candace T. Seip
- Contribution from the Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, and Department of Physics and Center for Ultralow Temperature Research, University of Florida, Gainesville, Florida 32611-8440
| | - Garrett E. Granroth
- Contribution from the Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, and Department of Physics and Center for Ultralow Temperature Research, University of Florida, Gainesville, Florida 32611-8440
| | - Mark W. Meisel
- Contribution from the Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, and Department of Physics and Center for Ultralow Temperature Research, University of Florida, Gainesville, Florida 32611-8440
| | - Daniel R. Talham
- Contribution from the Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, and Department of Physics and Center for Ultralow Temperature Research, University of Florida, Gainesville, Florida 32611-8440
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Oishi Y, Kato T, Kuramori M, Suehiro K, Ariga K, Kamino A, Koyano H, Kunitake T. Atomic Force Microscopic Observation of Random Molecular Arrangement in Dialkyl Guanidinium Monolayer. CHEM LETT 1996. [DOI: 10.1246/cl.1996.857] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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36
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Evenson SA, Badyal JPS, Pearson C, Petty MC. Variation in Intermolecular Spacing with Dipping Pressure for Arachidic Acid LB Films. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960009g] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sikes HD, Woodward, Schwartz DK. Pattern Formation in a Substrate-Induced Phase Transition during Langmuir−Blodgett Transfer. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960663w] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. D. Sikes
- Department of Chemistry, Tulane University, New Orleans, Lousiana 70118
| | - Woodward
- Department of Chemistry, Tulane University, New Orleans, Lousiana 70118
| | - D. K. Schwartz
- Department of Chemistry, Tulane University, New Orleans, Lousiana 70118
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Viswanathan R, Madsen LL, Zasadzinski JA, Schwartz DK. Liquid to hexatic to crystalline order in Langmuir-Blodgett films. Science 1995; 269:51-4. [PMID: 7604278 DOI: 10.1126/science.7604278] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Atomic force microscope images of zinc arachidate (ZnA2) Langmuir-Blodgett films show that three- and five-layer films are "hexatic," with long-range bond-orientational order and short-range positional correlations of three to five lattice repeats. The monolayer in contact with the substrate is disordered. Films of seven or more layers of ZnA2 are crystalline. A population of dislocations, most likely originating at the substrate, disrupts the positional but not the orientational order of the lattice, leading to hexatic layers intermediate between crystal and liquid. The influence of the substrate propagates farther into ZnA2 films than into cadmium arachidate films because the molecular cohesion is much weaker in ZnA2 than in cadmium arachidate, as evidenced by a less dense molecular packing.
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Affiliation(s)
- R Viswanathan
- Department of Chemical Engineering, University of California, Santa Barbara 93106, USA
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Stiger R, Virtanen J, Lee S, Virtanen S, Penner R. Scanning tunneling microscopic observations of commensurate crystalline structures for horizontally deposited cadmium stearate bilayers on graphite. Anal Chim Acta 1995. [DOI: 10.1016/0003-2670(94)00525-q] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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40
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Kajiyama T, Oishi Y, Suehiro K, Hirose F, Kuri T. Direct Observation of Edge Dislocation in Lignoceric Acid Monolayer Based on Atomic Force Microscopy. CHEM LETT 1995. [DOI: 10.1246/cl.1995.241] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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41
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Schwartz DK, Viswanathan R, Zasadzinski JA. Head–tail competition and modulated structures in planar surfactant (Langmuir–Blodgett) films. J Chem Phys 1994. [DOI: 10.1063/1.468300] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Abstract
The controlled transfer of organized monolayers of amphiphilic molecules from the airwater interface to a solid substrate was the first molecular-scale technology for the creation of new materials. However, the potential benefits of the technology envisioned by Langmuir and Blodgett in the 1930s have yet to be fully realized. Problems of reproducibility and defects and the lack of basic understanding of the packing of complex molecules in thin films have continued to thwart practical applications of Langmuir-Blodgett films and devices made from such films. However, modern high-resolution x-ray diffraction and scanning probe microscopy have proven to be ideal tools to resolve many of the basic questions involving thin organic films. Here, studies are presented of molecular order and organization in thin films of fatty acid salts, the prototypical system of Katharine Blodgett. Even these relatively simple systems present liquid, hexatic, and crystalline order; van der Waals and strained layer epitaxy on various substrates; wide variations in crystal symmetry and interfacial area with counterions; modulated superstructures; and coexisting lattice structures. The wide variety of possible structures presents both a challenge and an opportunity for future molecular design of organic thin-film devices.
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Affiliation(s)
- J A Zasadzinski
- Department of Chemical and Nuclear Engineering, University of California, Santa Barbara 93106
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