51
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Ren Y, Hossain MM, Iimura KI, Kato T. CH3(CH2)nCOOH/Cd2+System on the Aqueous Cadmium Acetate Solution Investigated in Situ by Polarization Modulation Infrared Spectroscopy. J Phys Chem B 2001. [DOI: 10.1021/jp010689+] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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52
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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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53
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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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54
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Ren Y, Iimura KI, Kato T. Crystal lattice of the cadmium alkanoate monolayer at the air/water interface investigated by polarization modulation infrared spectroscopy. J Chem Phys 2001. [DOI: 10.1063/1.1342862] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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55
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Dufrêne YF, Lee GU. Advances in the characterization of supported lipid films with the atomic force microscope. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1509:14-41. [PMID: 11118515 DOI: 10.1016/s0005-2736(00)00346-1] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
During the past decade, the atomic force microscope (AFM) has become a key technique in biochemistry and biophysics to characterize supported lipid films, as testified by the continuous growth in the number of papers published in the field. The unique capabilities of AFM are: (i) capacity to probe, in real time and in aqueous environment, the surface structure of lipid films; (ii) ability to directly measure physical properties at high spatial resolution; (iii) possibility to modify the film structure and biophysical processes in a controlled way. Such experiments, published up to June 2000, are the focus of the present review. First, we provide a general introduction on the preparation and characterization of supported lipid films as well as on the principles of AFM. The section 'Structural properties' focuses on the various applications of AFM for characterizing the structure of supported lipid films: visualization of molecular structure, formation of structural defects, effect of external agents, formation of supported films, organization of phase-separated films (coexistence region, mixed films) and, finally, the use of supported lipid bilayers for anchoring biomolecules such as DNA, enzymes and crystalline protein arrays. The section 'Physical properties' introduces the principles of force measurements by AFM, interpretation of these measurements and their recent application to supported lipid films and related structures. Finally, we highlight the major achievements brought by the technique and some of the current limitations.
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Affiliation(s)
- Y F Dufrêne
- Unité de chimie des interfaces, Université catholique de Louvain, Belgium.
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56
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Lanteri N, Rolandi R, Cavatorta P, Polverini E, Riccio P, Gliozzi A. Myelin basic protein–lipid complex: an atomic force microscopy study. Colloids Surf A Physicochem Eng Asp 2000. [DOI: 10.1016/s0927-7757(00)00460-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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57
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Liu A, Wu RC, Eschenazi E, Papadopoulos K. AFM on humic acid adsorption on mica. Colloids Surf A Physicochem Eng Asp 2000. [DOI: 10.1016/s0927-7757(00)00535-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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58
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Schneider J, Dufrêne YF, Barger WR, Lee GU. Atomic force microscope image contrast mechanisms on supported lipid bilayers. Biophys J 2000; 79:1107-18. [PMID: 10920040 PMCID: PMC1301006 DOI: 10.1016/s0006-3495(00)76364-8] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
This work presents a methodology to measure and quantitatively interpret force curves on supported lipid bilayers in water. We then use this method to correlate topographic imaging contrast in atomic force microscopy (AFM) images of phase-separated Langmuir-Blodgett bilayers with imaging load. Force curves collected on pure monolayers of both distearoylphosphatidylethanolamine (DSPE) and monogalactosylethanolamine (MGDG) and dioleoylethanolamine (DOPE) deposited at similar surface pressures onto a monolayer of DSPE show an abrupt breakthrough event at a repeatable, material-dependent force. The breakthrough force for DSPE and MGDG is sizable, whereas the breakthrough force for DOPE is too small to measure accurately. Contact-mode AFM images on 1:1 mixed monolayers of DSPE/DOPE and MGDG/DOPE have a high topographic contrast at loads between the breakthrough force of each phase, and a low topographic contrast at loads above the breakthrough force of both phases. Frictional contrast is inverted and magnified at loads above the breakthrough force of both phases. These results emphasize the important role that surface forces and mechanics can play in imaging multicomponent biomembranes with AFM.
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Affiliation(s)
- J Schneider
- Chemistry Division, Code 6170, Naval Research Laboratory, Washington, DC 20375-5342 USA
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59
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Ren Y, Iimura KI, Kato T. Polarized infrared study on the structure of two-dimensional nanoclusters of partially fluorinated long-chain fatty acid salts at ambient and elevated temperatures. J Chem Phys 2000. [DOI: 10.1063/1.481894] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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60
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Reitzel N, Greve DR, Kjaer K, Howes PB, Jayaraman M, Savoy S, McCullough RD, McDevitt JT, Bjørnholm T. Self-Assembly of Conjugated Polymers at the Air/Water Interface. Structure and Properties of Langmuir and Langmuir−Blodgett Films of Amphiphilic Regioregular Polythiophenes. J Am Chem Soc 2000. [DOI: 10.1021/ja9924501] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Niels Reitzel
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Daniel R. Greve
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Kristian Kjaer
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Paul B. Howes
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Manikandan Jayaraman
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Steve Savoy
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Richard D. McCullough
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - John T. McDevitt
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
| | - Thomas Bjørnholm
- CISMI, Laboratory for Materials Science, Department of Chemistry, University of Copenhagen, Fruebjergvej 3, DK-2100 Copenhagen, Denmark, Condensed Matter Physics and Chemistry Department, RISØ National Laboratory, DK-4000 Roskilde, Denmark, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
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61
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Vitta S, Metzger TH, Major SS. Structural assembly of Cd-arachidate molecules in multilayers. J Chem Phys 1999. [DOI: 10.1063/1.480467] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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62
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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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63
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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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64
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Santos NC, Ter-Ovanesyan E, Zasadzinski JA, Prieto M, Castanho MA. Filipin-induced lesions in planar phospholipid bilayers imaged by atomic force microscopy. Biophys J 1998; 75:1869-73. [PMID: 9746527 PMCID: PMC1299857 DOI: 10.1016/s0006-3495(98)77627-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Filipin is a macrolide polyene with antifungal activity belonging to the same family of antibiotics as amphotericin B and nystatin. Despite the spectroscopy and electron microscopy studies of its interaction with natural membranes and membrane model systems, several aspects of its biochemical action, such as the role of membrane sterols, remain to be completely understood. We have used atomic force microscopy (AFM) to study the effect of filipin on dipalmitoylphosphatidylethanolamine bilayers in the presence and absence of cholesterol. The bilayers were prepared by Langmuir-Blodgett deposition over mica and imaged under water. It was shown that filipin-induced lesions could only be found in membranes with cholesterol. In close agreement with electron microscopy results, we have reported the presence of densely packed circular protrusions in the membrane with a mean diameter of 19 nm (corrected for convolution with AFM tip) and 0.4 nm height. Larger circular protrusions (90 nm diameter and 2.5 nm height) and doughnut-shaped lesions were also detected. These results demonstrate that filipin-induced lesions in membranes previously observed by electron microscopy are not biased by artifacts resulting from sample preparation. Filipin aggregates in aqueous solution could also be imaged for the first time. These polydisperse spherical structures were observed in samples with and without cholesterol.
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Affiliation(s)
- N C Santos
- Centro de Química-Física Molecular, Complexo I, Instituto Superior Técnico, 1096 Lisboa Codex, Portugal
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65
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Sikes HD, Schwartz DK. Two-dimensional melting of an anisotropic crystal observed at the molecular level. Science 1997; 278:1604-7. [PMID: 9374455 DOI: 10.1126/science.278.5343.1604] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A distinctive two-dimensional (2D) melting transition occurring at nearly 100 degrees Celsius ( degrees C) has been observed in Langmuir-Blodgett films by in situ atomic force microscopy (AFM). A 2D orthorhombic crystal phase melted to a 2D smectic phase at about 91 degrees C. The smectic phase was characterized by 1D molecular periodicity with short-range correlations (about 40 angstroms). At 95 degrees C, the smectic order melted to form a hexatic phase. Infrared spectroscopy measurements were consistent with the AFM observations. These observations support the dislocation-mediated melting scenario for an anisotropic 2D crystal predicted by Ostlund and Halperin. A longer wavelength height modulation was also observed in the smectic and hexatic phases.
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Affiliation(s)
- HD Sikes
- Department of Chemistry, Tulane University, New Orleans, LA 70118, USA
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66
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Surface roughness in Langmuir-Blodgett multilayer films studied by AFM and X-ray diffraction. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0968-5677(97)00040-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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67
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Abstract
This work describes composite structures composed of lipid bilayer or tetraetherlipid monolayer films attached to solid supports with associated crystalline bacterial cell surface layers (S-layers). The bilayer system was established by making use of the strong chemisorption of a first monolayer of thiolipids (1-octadecanethiol or 1,2-dimyristoyl-sn-glycero-3-phosphothioethanol) on gold and attaching a second monolayer of 1,2-dipalmitoyl-sn-3-phosphatidylethanolamine by the Langmuir Schaefer technique. The tetraetherlipid monolayer was composed of Glycerol-dialkyl-nonitol tetraetherlipid (GDNT). The monolayer of GDNT exhibits the thickness of a bilayer with hydrophilic headgroups on both sides and a hydrophobic inner part. Isolated S-layer protein from Bacillus sphaericus (CCM2177, which was injected into the subphase of an LB-trough, recrystallized into a coherent monolayer at the solid supported phospholipid bilayer and at the tetraehtherlipid monolayer. The composite lipid/S-layer structures were stable enough to allow lifting from the air-water interface, rinsing in water, and transfer into a scanning force microscope.
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Affiliation(s)
- B Wetzer
- Zentrum für Ultrastrukturforschung, Universität für Bodenkultur, Vienna, Austria
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68
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Henderson P, Beyer D, Jonas U, Karthaus O, Ringsdorf H, Heiney PA, Maliszewskyj NC, Ghosh SS, Mindyuk OY, Josefowicz JY. Complex Ordering in Thin Films of Di- and Trifunctionalized Hexaalkoxytriphenylene Derivatives. J Am Chem Soc 1997. [DOI: 10.1021/ja964036w] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Philippe Henderson
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Dierk Beyer
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Ulrich Jonas
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Olaf Karthaus
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Helmut Ringsdorf
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Paul A. Heiney
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Nicholas C. Maliszewskyj
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Surya S. Ghosh
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Oksana Y. Mindyuk
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Jack Y. Josefowicz
- Contribution from the Institut für Organische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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69
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Woodward JT, Zasadzinski JA. High-resolution scanning tunneling microscopy of fully hydrated ripple-phase bilayers. Biophys J 1997; 72:964-76. [PMID: 9017222 PMCID: PMC1185620 DOI: 10.1016/s0006-3495(97)78731-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A modified freeze-fracture replication technique for use with the scanning tunneling microscope (STM) has provided a quantitative, high-resolution description of the waveform and amplitude of rippled bilayers in the P beta' phase of dimyristoylphosphatidylcholine (DMPC) in excess water. The ripples are uniaxial and asymmetrical, with a temperature-dependent amplitude of 2.4 nm near the chain melting temperature that decreases to zero at the chain crystallization temperature. The wavelength of 11 nm does not change with temperature. The observed ripple shape and the temperature-induced structural changes are not predicted by any current theory. Calibration and reproducibility of the STM/replica technique were tested with replicas of well-characterized bilayers of cadmium arachidate on mica that provide regular 5.5-nm steps. STM images were analyzed using a cross-correlation averaging program to eliminate the effects of noise and the finite size and shapes of the metal grains that make up the replica. The correlation averaging allowed us to develop a composite ripple profile averaged over hundreds of individual ripples measured on different samples with different STM tips. The STM/replica technique avoids many of the previous artifacts of biological STM imaging and can be used to examine a variety of periodic hydrated lipid and protein samples at a lateral resolution of about 1 nm and a vertical resolution of about 0.3 nm. This resolution is superior to conventional and tapping mode AFM to soft biological materials; the technique is substrate-free, and the conductive and chemically uniform replicas make image interpretation simple and direct.
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Affiliation(s)
- J T Woodward
- Department of Physics, University of California, Santa Barbara 93106-5080, USA
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70
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Spectroscopic and morphological studies of 3-(2-benzothiazolyl)-7-hexadecyloxycoumarin assembled in Langmuir—Blodgett films. J Photochem Photobiol A Chem 1996. [DOI: 10.1016/s1010-6030(96)04429-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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71
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Fang Y, Yang J. Role of the Bilayer−Bilayer Interaction on the Ripple Structure of Supported Bilayers in Solution. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp961054r] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ye Fang
- Physics Department, University of Vermont, Cook Building, Burlington, Vermont 05405
| | - Jie Yang
- Physics Department, University of Vermont, Cook Building, Burlington, Vermont 05405
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72
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Nitz V, Tolan M, Schlomka J, Seeck OH, Stettner J, Press W, Stelzle M, Sackmann E. Correlations in the interface structure of Langmuir-Blodgett films observed by x-ray scattering. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:5038-5050. [PMID: 9986468 DOI: 10.1103/physrevb.54.5038] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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73
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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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74
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Kurnaz ML, Schwartz DK. Morphology of Microphase Separation in Arachidic Acid/Cadmium Arachidate Langmuir-Blodgett Multilayers. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960665g] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. L. Kurnaz
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118
| | - D. K. Schwartz
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118
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75
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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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76
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Hansma HG, Revenko I, Kim K, Laney DE. Atomic force microscopy of long and short double-stranded, single-stranded and triple-stranded nucleic acids. Nucleic Acids Res 1996; 24:713-20. [PMID: 8604315 PMCID: PMC145671 DOI: 10.1093/nar/24.4.713] [Citation(s) in RCA: 263] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Atomic force microscopy (AFM, also called scanning force microscopy) is proving to be a useful technique for imaging DNA. Thus it is important to push the limits of AFM imaging in order to explore both what types of DNA can be reliably imaged and identified and also what substrates and methods of sample preparation are suitable. The following advances in AFM of DNA are presented here. (i) DNA molecules as short as 25 bases can be seen by AFM. The short single-stranded DNAs imaged here (25 and 50 bases long) appeared globular in the AFM, perhaps because they are all capable of intramolecular base pairing and because the DNAs were in a Mg(ll) buffer, which facilitates intramolecular cross-bridging. (ii) AFM images in air of short double-stranded DNA molecules, 100-200 bp, gave lengths consistent with A-DNA. (iii) AFM images of poly (A) show both short bent lumpy molecules with an apparent persistence length of 40 nm and long straight molecules with an apparent persistence length of 600 nm. For comparison, the apparent persistence length for double-stranded DNA from phX-174 under the same conditions was 80 nm. (iv) Structures believed to be triple- stranded DNA were seen in samples of poly(dA.poly(dT) and poly (dG).poly(dC). These structures were twice as high as double-stranded DNA and the same width. (v) Entire molecules of lambda DNA, approx. 16 micron long, were imaged clearly in overlapping scans. (vi) Plasmid DNA was imaged on oxidized silicon, although less clearly than on mica.
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Affiliation(s)
- H G Hansma
- Department of Physics, University of California, Santa Barbara, 93106, USA
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77
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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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78
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Bos MA, Kleijn JM. Determination of the orientation distribution of adsorbed fluorophores using TIRF. I. Theory. Biophys J 1995; 68:2566-72. [PMID: 7647259 PMCID: PMC1282166 DOI: 10.1016/s0006-3495(95)80439-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The spectroscopic technique total internal reflection fluorescence can be used for determination of the orientation of adsorbed fluorescent molecules. The underlying theory is presented in general terms and elaborated in detail for the case that the fluorescent group is a porphyrin ring. It is shown that order parameters of the orientation distribution can be obtained if both the fluorescence intensity and its polarization are measured as functions of the polarization of the incident laser beam. From these order parameters an approximation of the orientation distribution can be derived by the maximum-entropy method.
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Affiliation(s)
- M A Bos
- Department of Physical and Colloid Chemistry, Agricultural University, Wageningen, The Netherlands
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79
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Tsukruk VV, Reneker DH. Scanning probe microscopy of organic and polymeric films: from self-assembled monolayers to composite multilayers. POLYMER 1995. [DOI: 10.1016/0032-3861(95)90925-r] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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80
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Vikholm I, Peltonen J, Teleman O. Atomic force microscope images of lipid layers spread from vesicle suspensions. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1233:111-17. [PMID: 7865535 DOI: 10.1016/0005-2736(94)00221-a] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The layer formation of unilamellar vesicles of L-alpha-dimyristoyl phosphatidylcholine (DMPC) spread onto the air/liquid interface has been investigated. The layers were transferred to clean glass slides and onto slides made hydrophobic with multilayers of Cd arachidate. Aged vesicle suspensions aggregate during storage and are transferred as large domains as imaged with atomic force microscopy (AFM). Freshly prepared vesicles fuse and can be transferred as monolayers to hydrophobic supports. Furthermore, AFM images reveal the importance of positioning the solid support parallel to the moving barrier in order to obtain more uniform deposition of Cd arachidate.
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Affiliation(s)
- I Vikholm
- Technical Research Centre of Finland, Tampere
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81
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Hui SW, Viswanathan R, Zasadzinski JA, Israelachvili JN. The structure and stability of phospholipid bilayers by atomic force microscopy. Biophys J 1995; 68:171-8. [PMID: 7711239 PMCID: PMC1281674 DOI: 10.1016/s0006-3495(95)80172-4] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Atomic force microscopy (AFM) was used to investigate the structure, stability, and defects of the hydrophilic surfaces of Langmuir-Blodgett bilayer films of distearoylphosphatidylcholine (DSPC) and dipalmitoylphosphatidylethanolamine (DPPE) in the solid phase, and dilinoleoylphosphatidylethanolamine (DLPE) in the fluid phase. Their relative resilience to external mechanical stress by the scanning tip and by fluid exchange were also investigated. DPPE monolayers showed parallel ridges at the surface with a period of 0.49 nm, corresponding to the rows of aligned headgroups consistent with the known crystallographic structure. DSPC and DLPE monolayers did not show any periodic order. The solid DSPC and DPPE monolayers were stable to continued rastering by the AFM tip; however, the stability of DLPE monolayers depended on the pH of the aqueous environment. Structural defects in the form of monolayer gaps and holes were observed after fluid exchange, but the defects in DLPE monolayer at pH 11 were stable during consecutive scanning. At pH 9 and below, the defects induced by fluid exchange over DLPE monolayers were more extensive and were deformed easily by consecutive scanning of the AFM tip at a force of 10 nN. The pH dependence of resilience was explained by the increasing bending energy or frustration due to the high spontaneous curvature of DLPE monolayers at low pH. The tangential stress exerted by the AFM tip on the deformable monolayers eventually produced a ripple pattern, which could be described as a periodic buckling known as Shallamach waves.
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Affiliation(s)
- S W Hui
- Department of Biophysics, Roswell Park Cancer Institute, Buffalo, NY 14263
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82
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Valdrè G, Muscatello U, Valdrè U. Resolution Limits in the Study of Cardiolipin Crystals by TEM, SAED and AFM. ACTA ACUST UNITED AC 1995. [DOI: 10.1051/mmm:1995155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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83
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Applications of atomic force microscopy to structural characterization of organic thin films. Colloids Surf A Physicochem Eng Asp 1994. [DOI: 10.1016/0927-7757(94)80002-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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84
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Karaborni S. Order-disorder transition during approach and separation of two parallel surfaces. PHYSICAL REVIEW LETTERS 1994; 73:1668-1671. [PMID: 10056853 DOI: 10.1103/physrevlett.73.1668] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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85
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86
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Radmacher M, Cleveland JP, Fritz M, Hansma HG, Hansma PK. Mapping interaction forces with the atomic force microscope. Biophys J 1994; 66:2159-65. [PMID: 8075349 PMCID: PMC1275941 DOI: 10.1016/s0006-3495(94)81011-2] [Citation(s) in RCA: 180] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Force curves were recorded as the sample was raster-scanned under the tip. This opens new opportunities for imaging with the atomic force microscope: several characteristics of the samples can be measured simultaneously, for example, topography, adhesion forces, elasticity, van der Waals, and electrostatic interactions. The new opportunities are illustrated by images of several characteristics of thin metal films, aggregates of lysozyme, and single molecules of DNA.
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Affiliation(s)
- M Radmacher
- Physics Department, University of California, Santa Barbara 83106
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87
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Garnaes J, Larsen NB, Bjørnholm T, Jørgensen M, Kjaer K, Als-Nielsen J, Jørgensen JF, Zasadzinski JA. Langmuir-Blodgett Films of a Functionalized Molecule with Cross-Sectional Mismatch Between Head and Tail. Science 1994; 264:1301-4. [PMID: 17780847 DOI: 10.1126/science.264.5163.1301] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A functionalized surfactant has been investigated as floating monolayers by synchrotron x-ray diffraction and as bilayers transferred to solid supports by the Langmuir-Blodgett technique through atomic force microscopy. The transfer process is accompanied by an increase of the unit cell area (about 17 percent) and by an increase of the average domain diameter of nanometer-scale domains (about three times). The unit cell area of the floating monolayer corresponds to close packing of the head groups and a noncharacteristic packing of the tifted alkyl chains. The larger unit cell area of the bilayer film is consistent with a particular ordered packing of the alkyl chains, leaving free space for the head groups.
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88
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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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89
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90
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Allara DL, Parikh AN, Judge E. The existence of structure progressions and wetting transitions in intermediately disordered monolayer alkyl chain assemblies. J Chem Phys 1994. [DOI: 10.1063/1.466604] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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91
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92
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Mikrut JM, Dutta P, Ketterson JB, MacDonald RC. Atomic-force and fluorescence microscopy of Langmuir-Blodgett monolayers of L- alpha -dimyristoylphosphatidic acid. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:14479-14487. [PMID: 10007868 DOI: 10.1103/physrevb.48.14479] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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93
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Affiliation(s)
- J Yang
- Bio-SPM Laboratory, University of Virginia School of Medicine, Charlottesville 22908
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94
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Viswanathan R, Zasadzinski JA, Schwartz DK. Strained-layer van der Waals epitaxy in a Langmuir-Blodgett film. Science 1993; 261:449-52. [PMID: 8392751 DOI: 10.1126/science.8392751] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Atomic force microscope images of Langmuir-Blodgett films of lead and manganese fatty acid salts show that these monolayers have long-range order and are oriented with respect to the mica substrate, although the lattice symmetries of the monolayers and substrate are dramatically different. The surface lattice of sequentially thicker films evolves toward the bulk structure while retaining the substrate alignment. This behavior is in distinct contrast to films of cadmium fatty acid salts on mica, or all films on amorphous silicon oxide, in which the monolayer structure is disordered and a three-layer-thick film displays the bulk structure.
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Affiliation(s)
- R Viswanathan
- Department of Chemical and Nuclear Engineering, University of California, Santa Barbara 93106
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95
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Kajiyama T, Oishi Y, Hirose F, Shuto K, Kuri T. Molecular Resolution Image of Lignoceric Acid Monolayer with Atomic Force Microscope. CHEM LETT 1993. [DOI: 10.1246/cl.1993.1121] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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96
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Zhong Q, Inniss D, Kjoller K, Elings V. Fractured polymer/silica fiber surface studied by tapping mode atomic force microscopy. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0167-2584(93)90906-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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97
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Leckband D, Israelachvili J. Molecular basis of protein function as determined by direct force measurements. Enzyme Microb Technol 1993; 15:450-9. [PMID: 7763679 DOI: 10.1016/0141-0229(93)90077-f] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- D Leckband
- Department of Chemical Engineering, School of Engineering and Applied Sciences, State University of New York, Buffalo 14260
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98
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Steinberg S, Ducker W, Vigil G, Hyukjin C, Frank C, Tseng MZ, Clarke DR, Israelachvili JN. Van der Waals Epitaxial Growth of agr-Alumina Nanocrystals on Mica. Science 1993; 260:656-9. [PMID: 17812223 DOI: 10.1126/science.260.5108.656] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Lattice mismatch stresses, which severely restrict heteroepitaxial growth, are greatly minimized when thin alumina films are grown by means of van der Waals forces on inert mica substrates. A 10-nanometer-thick epitaxial film exhibits crystallographic sixfold symmetry, a lattice constant close to that of the basal plane [0001] of alpha-alumina (sapphire), and an aluminum: oxygen atomic ratio of 1:1.51 +/- 0.02 (measured by x-ray photoelectron spectroscopy), again the same as for bulk sapphire. The film is free of steps and grain boundaries over large areas and appears to be an ideal model system for studying adhesion, tribology, and other surface phenomena at atomic scales.
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99
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Josefowicz JY, Maliszewskyj NC, Idziak SH, Heiney PA, McCauley JP, Smith AB. Structure of Langmuir-Blodgett Films of Disk-Shaped Molecules Determined by Atomic Force Microscopy. Science 1993; 260:323-6. [PMID: 17838247 DOI: 10.1126/science.260.5106.323] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Monolayer Langmuir-Blodgett films of a discotic mesogen have been studied with atomic force microscopy (AFM). These measurements confirm the "edge on" arrangement for the disk-shaped molecules suggested by surface pressure-area isotherms and show that the molecules form columns that are separated by 17.7 angstroms +/- 10 percent. Column alignment is found to be predominantly along the film deposition direction, with an angular spread of 35 degrees . The AFM images also show that the mean disk separation within the columns is 5.1 +/- 1.3 angstroms, in good agreement with x-ray diffraction (XRD) results. Roomtemperature XRD measurements on bulk samples of the same material indicate a disordered-hexagonal liquid crystalline mesophase, with a column-to-column spacing of 19.9 +/- 0.2 angstroms.
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100
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