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Hemmerle A, Aubert N, Moreno T, Kékicheff P, Heinrich B, Spagnoli S, Goldmann M, Ciatto G, Fontaine P. Opportunities and new developments for the study of surfaces and interfaces in soft condensed matter at the SIRIUS beamline of Synchrotron SOLEIL. JOURNAL OF SYNCHROTRON RADIATION 2024; 31:162-176. [PMID: 37933848 PMCID: PMC10833424 DOI: 10.1107/s1600577523008810] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 10/08/2023] [Indexed: 11/08/2023]
Abstract
The SIRIUS beamline of Synchrotron SOLEIL is dedicated to X-ray scattering and spectroscopy of surfaces and interfaces, covering the tender to mid-hard X-ray range (1.1-13 keV). The beamline has hosted a wide range of experiments in the field of soft interfaces and beyond, providing various grazing-incidence techniques such as diffraction and wide-angle scattering (GIXD/GIWAXS), small-angle scattering (GISAXS) and X-ray fluorescence in total reflection (TXRF). SIRIUS also offers specific sample environments tailored for in situ complementary experiments on solid and liquid surfaces. Recently, the beamline has added compound refractive lenses associated with a transfocator, allowing for the X-ray beam to be focused down to 10 µm × 10 µm while maintaining a reasonable flux on the sample. This new feature opens up new possibilities for faster GIXD measurements at the liquid-air interface and for measurements on samples with narrow geometries.
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Affiliation(s)
- Arnaud Hemmerle
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Nicolas Aubert
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Thierry Moreno
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Patrick Kékicheff
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
- Institut Charles Sadron, Université de Strasbourg, CNRS UPR22, 67034 Strasbourg, France
| | - Benoît Heinrich
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR7504, 67034 Strasbourg, France
| | - Sylvie Spagnoli
- Institut des NanoSciences de Paris, UMR 7588 CNRS, Sorbonne Université, 75252 Paris Cedex 05, France
| | - Michel Goldmann
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
- Institut des NanoSciences de Paris, UMR 7588 CNRS, Sorbonne Université, 75252 Paris Cedex 05, France
| | - Gianluca Ciatto
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Philippe Fontaine
- Synchrotron SOLEIL, L’Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
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2
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Kovalchuk VI, Aksenenko EV, Schneck E, Miller R. Surfactant Adsorption Layers: Experiments and Modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3537-3545. [PMID: 36853274 DOI: 10.1021/acs.langmuir.2c03511] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
During recent years, great progress has been made in understanding the adsorption of surfactants at liquid interfaces. In addition to tensiometry, new efficient methodologies have been developed, in particular interfacial selective optical methods which allow direct access to the adsorbed amounts and interfacial layer compositions. In addition to these new experimental tools, the thermodynamic description by equations of state now allows one to provide a quantitative picture of surfactant interfacial layers. This is most notable for surfactant layers at water/oil interfaces. Additional knowledge about the structure of interfacial layers was gained through different types of molecular modeling. Improved interrelationships between these three aspects are the challenges for current and future work. Particular attention must be paid to dilational interfacial rheology studies, as these mechanical quantities are much more sensitive to small changes in the interfacial composition and structure.
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Affiliation(s)
- V I Kovalchuk
- Institute of Biocolloid Chemistry, National Academy of Sciences of Ukraine, Kyiv 03680, Ukraine
| | - E V Aksenenko
- Institute of Colloid Chemistry and Chemistry of Water, National Academy of Sciences of Ukraine, Kyiv 03680, Ukraine
| | - E Schneck
- Institute of Condensed Matter Physics, Technical University Darmstadt, 64289 Darmstadt, Germany
| | - R Miller
- Institute of Condensed Matter Physics, Technical University Darmstadt, 64289 Darmstadt, Germany
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3
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Oliveira ON, Caseli L, Ariga K. The Past and the Future of Langmuir and Langmuir-Blodgett Films. Chem Rev 2022; 122:6459-6513. [PMID: 35113523 DOI: 10.1021/acs.chemrev.1c00754] [Citation(s) in RCA: 118] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Langmuir-Blodgett (LB) technique, through which monolayers are transferred from the air/water interface onto a solid substrate, was the first method to allow for the controlled assembly of organic molecules. With its almost 100 year history, it has been the inspiration for most methods to functionalize surfaces and produce nanocoatings, in addition to serving to explore concepts in molecular electronics and nanoarchitectonics. This paper provides an overview of the history of Langmuir monolayers and LB films, including the potential use in devices and a discussion on why LB films are seldom considered for practical applications today. Emphasis is then given to two areas where these films offer unique opportunities, namely, in mimicking cell membrane models and exploiting nanoarchitectonics concepts to produce sensors, investigate molecular recognitions, and assemble molecular machines. The most promising topics for the short- and long-term prospects of the LB technique are also highlighted.
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Affiliation(s)
- Osvaldo N Oliveira
- São Carlos Institute of Physics, University of Sao Paulo, CP 369, 13560-970 Sao Carlos, SP, Brazil
| | - Luciano Caseli
- Department of Chemistry, Federal University of São Paulo, 09913-030 Diadema, SP, Brazil
| | - Katsuhiko Ariga
- World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 305-0044 Tsukuba, Japan.,Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-0827, Japan
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4
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Pham T, Plata PL, Zhang P, Vellara A, Bu W, Lin B, Cheng G, Liu Y. Knowledge-Based Design of 5-Fluororacil Prodrug Liposomal Formulation: Molecular Packing and Interaction Revealed by Interfacial Isotherms and X-ray Scattering Techniques. Mol Pharm 2021; 18:4331-4340. [PMID: 34739257 DOI: 10.1021/acs.molpharmaceut.1c00494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prodrugs and nanoformulations are two effective strategies for sustained drug release and targeting drug delivery. In this study, we combined the two strategies to judiciously design the liposome formulation incorporating an amphiphilic prodrug of 5-fouroracil (5-FU), named 5-FCPal, for sustained drug release and enhanced bioavailability. 5-FCPal is an analogue of capecitabine (N4-pentyloxycarbonyl-5'-deoxy-5-fluorocytidine, Xeloda) by substituting the pentyl group at the N4 position with the palmityl. The amphiphilic molecule of 5-FCPal can self-assemble with the phospholipids to form stable vesicle structures with high drug loading. Although lipid vesicles have been widely studied and commercially used for clinical applications, because of the enormous options of the lipids and the equitable balance of hydrophobicity and bioavailability, it is essential to fundamentally understand the molecular interactions when designing and optimizing the liposomal prodrug formulations. We report the study of using X-ray liquid surface scattering techniques integrated with a Langmuir trough to explicitly reveal the interfacial behavior of the monolayer membrane of 5-FCPal with various saturated and unsaturated lipids with positively charged, neutral, and negatively charged head groups. More specifically, interfacial packing of the molecules was quantified using interfacial isotherms, X-ray reflectivity (XR), and grazing-incidence diffraction (GIXD). The results indicate that the interactions between the prodrug and the cationic lipids are most favorable. The highest drug loading is quantified by increasing the molar ratio of the prodrug until stable monolayer structures were disrupted by the multiple-layer domain of prodrug aggregates. Stable liposomes of 100 nm with 50% drug loading of 5-FCPal were generated based on the findings from the X-ray studies.
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Affiliation(s)
- Tiep Pham
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608 United States
| | - Paola Leon Plata
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608 United States
| | - Pin Zhang
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608 United States
| | - Anand Vellara
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608 United States
| | - Wei Bu
- NSF's ChemMatCARS and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- NSF's ChemMatCARS and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Gang Cheng
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608 United States
| | - Ying Liu
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608 United States.,Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States.,Department of Biopharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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5
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Zhang P, Pham T, Liu C, Leon Plata P, Kalkowski J, Cheng G, Bu W, Lin B, Liu Y. Impeded Molecular Reorganization by Polyethylene Glycol Conjugation Revealed by X-ray Reflectivity and Diffraction Measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:7573-7581. [PMID: 32501715 DOI: 10.1021/acs.langmuir.0c01202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Polyethylene glycol (PEG) coatings have been widely applied in pharmaceutical and biomedical systems to prevent nonspecific protein absorption, increase vesicle blood circulation time, and sustain drug release. This study systematically investigated the planar interfacial organization of phospholipid monolayers containing various amounts of PEG conjugations before and after enzyme-catalyzed degradation of the lipids using X-ray reflectivity and grazing incidence X-ray diffraction techniques. Results showed that attaching PEG to the headgroup of the lipids up to 15 mol % had limited effects on molecular packing of the lipid monolayers in the condensed phase at the gas-liquid interface and negligible effects on the enzyme adsorption to the interface. After enzyme-catalyzed degradation, equimolar fatty acids and lyso PC were generated. The fatty acids together with the subphase Ca2+ self-assembled into highly organized multilayer domains at the interface. The X-ray measurements unambiguously revealed that the densely packed PEG markedly hindered microphase separation and formation of the palmitic acid-Ca2+ complexes.
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Affiliation(s)
- Pin Zhang
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
| | - Tiep Pham
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
| | - Chang Liu
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
| | - Paola Leon Plata
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
| | - Joseph Kalkowski
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
| | - Gang Cheng
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
| | - Wei Bu
- NSF's ChemMatCARS, University of Chicago, Chicago, Illinois 60637, United States
| | - Binhua Lin
- NSF's ChemMatCARS, University of Chicago, Chicago, Illinois 60637, United States
| | - Ying Liu
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60608, United States
- Richard & Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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6
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Bhattacharyya A, Sanyal MK, Mogera U, George SJ, Dhiman S, Kulkarni GU, Fontaine P. Formation of Two-Dimensional Network of Organic Charge-Transfer Complexes at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:12630-12635. [PMID: 31532685 DOI: 10.1021/acs.langmuir.9b01635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The air-water interface is an ideal platform to produce two-dimensional (2D) structures involving anything from simple organic molecules to supramolecular moieties by exploiting hydrophobic-hydrophilic interactions. Here, we show, using grazing incidence X-ray scattering, the formation of a 2D ordered structure of a charge-transfer (C-T) complex, namely, dodecyl methyl viologen (DMV) as acceptor and coronene tetracarboxylate potassium salt (CS) as donor, at the air-water interface. We have observed a phase transition in the 2D ordered structure as the area per molecule is decreased with increasing surface pressure in a Langmuir trough. The high-pressure ordering of the hydrocarbon chains associated with DMV destroys long-range C-T conjugation of DMV and CS at the air-water interface. Our results also explain the formation of DMV-CS cylindrical reverse micelles and eventually long nanowires that get formed in the self-assembly process in the bulk medium to preserve both the C-T conjugation and the organic tail-tail organization.
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Affiliation(s)
- Arpan Bhattacharyya
- Saha Institute of Nuclear Physics , 1/AF , Bidhannagar , Kolkata 700064 , India
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064 , India
| | - Milan K Sanyal
- Saha Institute of Nuclear Physics , 1/AF , Bidhannagar , Kolkata 700064 , India
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064 , India
| | - Umesha Mogera
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064 , India
| | - Subi J George
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064 , India
| | - Shikha Dhiman
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064 , India
| | - Giridhar U Kulkarni
- Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064 , India
- Centre for Nano and Soft Matter Sciences , Jalahalli P.O. , Bangalore 560013 , India
| | - Philippe Fontaine
- SOLEIL Synchrotron, L'Orme des Merisiers , Saint-Aubin - BP48 , 91192 GIF-sur-YVETTE CEDEX, France
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7
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Zhang P, Villanueva V, Kalkowski J, Liu C, Pham T, Perez-Salas U, Bu W, Lin B, Liu Y. Polyunsaturated Phospholipid Modified Membrane Degradation Catalyzed by a Secreted Phospholipase A2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11643-11650. [PMID: 31401834 DOI: 10.1021/acs.langmuir.9b01476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To optimize the compositions of the lipid-based nanomedicine and to advance understanding of the roles of polyunsaturated phospholipids in biological membranes, this study examined the effects of polyunsaturated phospholipids on the degradation of giant unilamellar vesicles catalyzed by a secreted phospholipase A2 (sPLA2) using fluorescence microscopy. Molecular interfacial packing, interaction, and degradation of the films containing various mixing ratios of saturated and polyunsaturated phospholipids were quantified using a Langmuir trough integrated with synchrotron X-ray surface scattering techniques. It was found that a high molar fraction (0.63 and above) of polyunsaturated phospholipids not only enhanced the rate of sPLA2-catalyzed vesicle degradation but also changed the vesicle deformation process and degradation product morphology. Hydrolysis of the saturated phospholipids generated highly ordered liquid crystal domains, which was reduced or prohibited by the presence of the polyunsaturated phospholipids in the reactant film.
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Affiliation(s)
| | | | | | | | | | | | - Wei Bu
- NSF's ChemMatCARS , University of Chicago , Chicago , Illinois 60637 , United States
| | - Binhua Lin
- NSF's ChemMatCARS , University of Chicago , Chicago , Illinois 60637 , United States
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8
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Zumbuehl A. Artificial Phospholipids and Their Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10223-10232. [PMID: 30278137 DOI: 10.1021/acs.langmuir.8b02601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Phospholipids are at the heart and origin of life on this planet. The possibilities in terms of phospholipid self-assembly and biological functions seem limitless. Nonetheless, nature exploits only a small fraction of the available chemical space of phospholipids. Using chemical synthesis, artificial phospholipid structures become accessible, and the study of their biophysics may reveal unprecedented properties. In this article, the recent advances by our work group in the field of chemical lipidology are summarized. The family of diamidophospholipids is discussed in detail from monolayer characterization to the formation of faceted vesicles, culminating in the template-free self-assembly of phospholipid cubes and the possible applications of vesicle origami in modern personalized medicine.
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Affiliation(s)
- Andreas Zumbuehl
- Department of Chemistry , University of Fribourg , Chemin du Musée 9 , 1700 Fribourg , Switzerland
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9
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Delcea M, Helm CA. X-ray and Neutron Reflectometry of Thin Films at Liquid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8519-8530. [PMID: 30901219 DOI: 10.1021/acs.langmuir.8b04315] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the 1980s, Helmuth Möhwald studied lipid monolayers at the air/water interface to understand the thermodynamically characterized phases at the molecular level. In collaboration with Jens Als-Nielsen, X-ray reflectometry was used and further developed to determine the electron density profile perpendicular to the water surface. Using a slab model, parameters such as thickness and density of the individual molecular regions, as well as the roughness of the individual interfaces, were determined. Later, X-ray and neutron reflectometry helped to understand the coverage and conformation of anchored and adsorbed polymers. Nowadays, they resolve molecular properties in emerging topics such as liquid metals and ionic liquids. Much is still to be learned about buried interfaces (e.g., liquid/liquid interfaces). In this Article, a historical and theoretical background of X-ray reflectivity is given, recent developments of X-ray and neutron reflectometry for polymers at interfaces and thin layers are highlighted, and emerging research topics involving these techniques are emphasized.
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Affiliation(s)
- Mihaela Delcea
- Institute of Biochemistry , University of Greifswald , Felix-Hausdorff-Straße 4 , 17489 Greifswald , Germany
- ZIK HIKE- Zentrum für Innovationskompetenz , Humorale Immunreaktionen bei kardiovaskulären Erkrankungen , Fleischmannstraße 42 , 17489 Greifswald , Germany
| | - Christiane A Helm
- Institute of Physics , University of Greifswald , Felix-Hausdorff-Straße 4 , 17489 Greifswald , Germany
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10
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Brezesinski G, Schneck E. Investigating Ions at Amphiphilic Monolayers with X-ray Fluorescence. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8531-8542. [PMID: 30835476 PMCID: PMC6727669 DOI: 10.1021/acs.langmuir.9b00191] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 03/04/2019] [Indexed: 06/09/2023]
Abstract
Amphiphilic monolayers formed at the soft air/liquid interface are easy-to-handle and versatile model systems for material and life sciences. Helmuth Möhwald was one of the pioneers in this field. Over the last few decades, total-reflection X-ray fluorescence (TRXF) has become an important analytical tool for the investigation of monolayer interactions with ions. Here, the theoretical background of TRXF is described, and practical aspects are discussed. The experimentally determined fluorescence intensity from the adsorbed ions can be interpreted quantitatively either by a calibration procedure utilizing monolayers with known charge density or by calibration with respect to the bare aqueous surface. Both calibration approaches yield quantitatively consistent results within <10% accuracy. Some examples demonstrating the power of TRXF for the study of ion adsorption to charged and noncharged monolayers as well as for the characterization of the physicochemical properties of novel cationic lipids used for improved gene delivery are given.
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Affiliation(s)
- Gerald Brezesinski
- Max Planck Institute of
Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Emanuel Schneck
- Max Planck Institute of
Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
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11
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Zhang P, Villanueva V, Kalkowski J, Liu C, Donovan AJ, Bu W, Schlossman ML, Lin B, Liu Y. Molecular interactions of phospholipid monolayers with a model phospholipase. SOFT MATTER 2019; 15:4068-4077. [PMID: 30958491 DOI: 10.1039/c8sm01154k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The intrinsic overexpression of secretory phospholipase A2 (sPLA2) in various pro-inflammatory diseases and cancers has the potential to be exploited as a therapeutic strategy for diagnostics and treatment. To explore this potential and advance our knowledge of the role of sPLA2 in related diseases, it is necessary to systematically investigate the molecular interaction of the enzyme with lipids. By employing a Langmuir trough integrated with X-ray reflectivity and grazing incidence X-ray diffraction techniques, this study examined the molecular packing structure of 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) films before and after enzyme adsorption and enzyme-catalyzed degradation. Molecular interaction of sPLA2 (from bee venom) with the DPPC monolayer exhibited Ca2+ dependence. DPPC molecules at the interface without Ca2+ retained a monolayer organization; upon adsorption of sPLA2 to the monolayer the packing became tighter. In contrast, sPLA2-catalyzed degradation of DPPC occurred in the presence of Ca2+, leading to disruption of the ordered monolayer structure of DPPC. The interfacial film became a mixture of highly ordered multilayer domains of palmitic acid (PA) and loosely packed monolayer phase of 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (lysoPC) that potentially contained the remaining un-degraded DPPC. The redistribution of lipid degradation products into the third dimension, which produced multilayer PA domains, damaged the structural integrity of the original lipid layer and may explain the bursting of liposomes observed in other studies after a latency period of mixing liposomes with sPLA2. A quantitative understanding of the lipid packing and lipid-enzyme interaction provides an intuitive means of designing and optimizing lipid-related drug delivery systems.
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Affiliation(s)
- Pin Zhang
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
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12
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Wölk C, Janich C, Bakowsky U, Langner A, Brezesinski G. Malonic acid based cationic lipids - The way to highly efficient DNA-carriers. Adv Colloid Interface Sci 2017; 248:20-34. [PMID: 28842122 DOI: 10.1016/j.cis.2017.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/10/2017] [Accepted: 08/10/2017] [Indexed: 01/21/2023]
Abstract
Cationic lipids play an important role as non-viral nucleic acid carriers in gene therapy since 3 decades. This review will introduce malonic acid derived cationic lipids as nucleic acid carriers which appeared in the literature dealing with lipofection 10years ago. The family of amino-functionalized branched fatty acid amides will be presented as well as different generations of malonic acid diamides. Both groups of cationic lipids yield lipid mixtures with highly efficient nucleic acid transfer activities in in-vitro cell culture models. The DNA transfer screening of lipid libraries with directed structural variations in the lipophilic as well as in the hydrophilic part of the amphiphiles yields structure/activity relationships. Furthermore, the detailed characterizations of selected lipid composites at the air/water interface and in bulk systems are summarized with regard to transfection determining physical-chemical properties. The findings are also discussed in comparison to results obtained with other families of cationic lipids.
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Affiliation(s)
- Christian Wölk
- Martin Luther University Halle-Wittenberg, Institute of Pharmacy, Wolfgang-Langenbeck-Strasse 4, 06120 Halle, Saale, Germany.
| | - Christopher Janich
- Martin Luther University Halle-Wittenberg, Institute of Pharmacy, Wolfgang-Langenbeck-Strasse 4, 06120 Halle, Saale, Germany
| | - Udo Bakowsky
- Department of Pharmaceutics and Biopharmaceutics, University Marburg, Robert-Koch-Straße 4, 35037 Marburg, Germany
| | - Andreas Langner
- Martin Luther University Halle-Wittenberg, Institute of Pharmacy, Wolfgang-Langenbeck-Strasse 4, 06120 Halle, Saale, Germany
| | - Gerald Brezesinski
- Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, Am Mühlenberg 1, 14476 Potsdam, Germany.
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Tajuelo J, Guzmán E, Ortega F, Rubio RG, Rubio MA. Phase Diagram of Fatty Acid Langmuir Monolayers from Rheological Measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:4280-4290. [PMID: 28363024 DOI: 10.1021/acs.langmuir.7b00613] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Langmuir monolayers of fatty acids and alcohols are two-dimensional systems with a rich equilibrium phase diagram. We have explored the temperature and surface-pressure-dependent shear response of monolayers formed by fatty acids of different chain lengths and a fatty alcohol. This has been accomplished with an interfacial shear rheometer utilizing magnetic tweezers and equipped with a refined temperature control and acquisition system. Our rheological results have allowed us to draw a phase diagram from the viscoelastic properties of these 2-D systems and show new phenomena that strongly depend on temperature: the existence of a maximum in viscosity at the L2' phase, the behavior of the elastic modulus to the storage modulus ratio at the L2 phase, and the increase or decrease in viscosity at the L2-LS phase transition. In addition, we unambiguously show that the LS phase displays a counterintuitive behavior in which the loss modulus increases with temperature. We demonstrate, through isothermal surface pressure sweeps and isobaric temperature sweeps, that the exponential dependence of the loss modulus on temperature at the LS phase appears for all hydrophobic tail lengths studied and for both acid and alcohol head groups.
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Affiliation(s)
- J Tajuelo
- Departamento de Física Fundamental, Universidad Nacional de Educación a Distancia , 28040 Madrid, Spain
| | - E Guzmán
- Departamento de Química Física I, Universidad Complutense de Madrid , 28040 Madrid, Spain
| | - F Ortega
- Departamento de Química Física I, Universidad Complutense de Madrid , 28040 Madrid, Spain
- Instituto Pluridisciplinar, Universidad Complutense , 28040 Madrid, Spain
| | - R G Rubio
- Departamento de Química Física I, Universidad Complutense de Madrid , 28040 Madrid, Spain
- Instituto Pluridisciplinar, Universidad Complutense , 28040 Madrid, Spain
| | - M A Rubio
- Departamento de Física Fundamental, Universidad Nacional de Educación a Distancia , 28040 Madrid, Spain
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14
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Lund R, Ang J, Shu JY, Xu T. Understanding Peptide Oligomeric State in Langmuir Monolayers of Amphiphilic 3-Helix Bundle-Forming Peptide-PEG Conjugates. Biomacromolecules 2016; 17:3964-3972. [PMID: 27784156 DOI: 10.1021/acs.biomac.6b01356] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Coiled-coil peptide-polymer conjugates are an emerging class of biomaterials. Fundamental understanding of the coiled-coil oligomeric state and assembly process of these hybrid building blocks is necessary to exert control over their assembly into well-defined structures. Here, we studied the effect of peptide structure and PEGylation on the self-assembly process and oligomeric state of a Langmuir monolayer of amphiphilic coiled-coil peptide-polymer conjugates using X-ray reflectivity (XR) and grazing-incidence X-ray diffraction (GIXD). Our results show that the oligomeric state of PEGylated amphiphiles based on 3-helix bundle-forming peptide is surface pressure dependent, a mixture of dimers and trimers was formed at intermediate surface pressure but transitions into trimers completely upon increasing surface pressure. Moreover, the interhelical distance within the coiled-coil bundle of 3-helix peptide-PEG conjugate amphiphiles was not perturbed under high surface pressure. Present studies provide valuable insights into the self-assembly process of hybrid peptide-polymer conjugates and guidance to develop biomaterials with controlled multivalency of ligand presentation.
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Affiliation(s)
- Reidar Lund
- Department of Materials Science and Engineering, University of California, Berkeley 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley 94720, United States
| | - JooChuan Ang
- Department of Materials Science and Engineering, University of California, Berkeley 94720, United States
| | - Jessica Y Shu
- Department of Materials Science and Engineering, University of California, Berkeley 94720, United States
| | - Ting Xu
- Department of Materials Science and Engineering, University of California, Berkeley 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley 94720, United States.,Department of Chemistry, University of California, Berkeley 94720, United States
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Moehwald H, Brezesinski G. From Langmuir Monolayers to Multilayer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10445-10458. [PMID: 27540629 DOI: 10.1021/acs.langmuir.6b02518] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This feature article is intended to describe a route from Langmuir monolayers as the most suitable and well-defined models to polyelectrolyte multilayers. The latter are structurally controlled not with angstrom but with nanometer precision; however, they are very modular with regard to building blocks and function and are robust, therefore promising many diverse applications. There have been many methods developed to structurally characterize Langmuir monolayers; therefore, they serve as models in membrane biophysics and materials science as well as in general physics as two-dimensional model systems. Many of these methods as well as ideas to control interfaces could be taken over to study polyelectrolyte multilayers with their extended internal interfaces. Finally, as an outlook we try to sketch various aspects to transit toward systems with higher structural hierarchy, enabling the coupling of different functions and arriving at responsive three-dimensional systems.
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Affiliation(s)
- Helmuth Moehwald
- Max-Planck-Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476 Potsdam, Germany
| | - Gerald Brezesinski
- Max-Planck-Institute of Colloids and Interfaces, Am Muehlenberg 1, 14476 Potsdam, Germany
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16
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17
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Stefaniu C, Brezesinski G, Möhwald H. Langmuir monolayers as models to study processes at membrane surfaces. Adv Colloid Interface Sci 2014; 208:197-213. [PMID: 24612663 DOI: 10.1016/j.cis.2014.02.013] [Citation(s) in RCA: 161] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 12/12/2022]
Abstract
The use of new sophisticated and highly surface sensitive techniques as synchrotron based X-ray scattering techniques and in-house infrared reflection absorption spectroscopy (IRRAS) has revolutionized the monolayer research. Not only the determination of monolayer structures but also interactions between amphiphilic monolayers at the soft air/liquid interface and molecules dissolved in the subphase are important for many areas in material and life sciences. Monolayers are convenient quasi-two-dimensional model systems. This review focuses on interactions between amphiphilic molecules in binary and ternary mixtures as well as on interfacial interactions with interesting biomolecules dissolved in the subphase. The phase state of monolayers can be easily triggered at constant temperature by increasing the packing density of the lipids by compression. Simultaneously the monolayer structure changes are followed in situ by grazing incidence X-ray diffraction or IRRAS. The interactions can be indirectly determined by the observed structure changes. Additionally, the yield of enzymatic reaction can be quantitatively determined, secondary structures of peptides and proteins can be measured and compared with those observed in bulk. In this way, the influence of a confinement on the structural properties of biomolecules can be determined. The adsorption of DNA can be quantified as well as the competing adsorption of ions at charged interfaces. The influence of modified nanoparticles on model membranes can be clearly determined. In this review, the relevance and utility of Langmuir monolayers as suitable models to study physical and chemical interactions at membrane surfaces are clearly demonstrated.
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Affiliation(s)
- Cristina Stefaniu
- Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Gerald Brezesinski
- Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Helmuth Möhwald
- Max Planck Institute of Colloids and Interfaces, Science Park Potsdam-Golm, Am Mühlenberg 1, D-14476 Potsdam, Germany.
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Stefaniu C, Brezesinski G. X-ray investigation of monolayers formed at the soft air/water interface. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2014.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Stefaniu C, Brezesinski G. Grazing incidence X-ray diffraction studies of condensed double-chain phospholipid monolayers formed at the soft air/water interface. Adv Colloid Interface Sci 2014; 207:265-79. [PMID: 24507806 DOI: 10.1016/j.cis.2014.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/13/2014] [Accepted: 01/14/2014] [Indexed: 10/25/2022]
Abstract
The use of highly brilliant synchrotron light sources in the middle of the 1980s for X-ray diffraction has revolutionized the research of condensed monolayers. Since then, monolayers gained popularity as convenient quasi two-dimensional model systems widely used in biophysics and material science. This review focuses on structures observed in one-component phospholipid monolayers used as simplified two-dimensional models of biological membranes. In a monolayer system the phase transitions can be easily triggered at constant temperature by increasing the packing density of the lipids by compression. Simultaneously the monolayer structure changes are followed in situ by grazing incidence X-ray diffraction. Competing interactions between the different parts of the molecule are responsible for the different monolayer structures. These forces can be modified by chemical variations of the hydrophobic chain region, of the hydrophilic head group region or of the interfacial region between chains and head groups. Modifications of monolayer structures triggered by changes of the chemical structure of double-chain phospholipids are highlighted in this paper.
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Konovalov OV, Vorobiev AA. Fast acquisition of extensive X-ray diffraction patterns of a gas–liquid interface in grazing-incidence geometry. J Appl Crystallogr 2012. [DOI: 10.1107/s0021889812046948] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The development of third-generation synchrotron sources has inspired qualitative and quantitative breakthroughs in structural studies of monomolecular organic layers. To study such systems formed at the gas–liquid interface, grazing-incidence diffraction (GID) has proved to be the most powerful technique. Until quite recently, in most cases, GID was performedviaa scanning approach with use of a collimating system in front of the detector to eliminate the effect of parallax and to achieve the required angular resolution. Owing to the long counting time required, this kind of measurement often introduces significant radiation damage to a sample and considerably restricts time-resolved studies, preventing the pursuit of emerging scientific areas such as the investigation of fast kinetic structural changes in two-dimensional systems. This problem can apparently become a real obstacle for the application of the scanning GID technique at fourth-generation synchrotron sources because of the extremely high X-ray fluxes involved. This article discusses the possibility of significantly reducing the measuring time and avoiding the beam parallax problem by using a high-brilliance submillimetre beam and a large-area two-dimensional detector (e.g.PILATUS) in a single-shot GID measurement on large-area sample surfaces. Both theoretical considerations of the problem and experimental GID results from monomolecular layers of behenic acid at the gas–water interface are presented, with a detailed description of the experimental conditions. The possibility of a diffraction imaging study of the texture of Langmuir monomolecular layers is demonstrated.
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Risović D, Frka S, Kozarac Z. The Structure of Percolating Lipid Monolayers. J Colloid Interface Sci 2012; 373:116-21. [DOI: 10.1016/j.jcis.2011.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/01/2011] [Accepted: 12/04/2011] [Indexed: 10/14/2022]
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22
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Fu D, Liu Y, Gao X, Su Y, Liu G, Wang D. Binary n-Alkane Mixtures from Total Miscibility to Phase Separation in Microcapsules: Enrichment of Shorter Component in Surface Freezing and Enhanced Stability of Rotator Phases. J Phys Chem B 2012; 116:3099-105. [DOI: 10.1021/jp2125119] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dongsheng Fu
- Beijing National Laboratory for Molecular
Sciences, Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yufeng Liu
- Beijing National Laboratory for Molecular
Sciences, Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Xia Gao
- Beijing National Laboratory for Molecular
Sciences, Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yunlan Su
- Beijing National Laboratory for Molecular
Sciences, Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Guoming Liu
- Beijing National Laboratory for Molecular
Sciences, Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Dujin Wang
- Beijing National Laboratory for Molecular
Sciences, Key Laboratory of Engineering Plastics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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Ziblat R, Leiserowitz L, Addadi L. Kristalline Lipiddomänen: Charakterisierung durch Röntgenbeugung und ihre Rolle in der Biologie. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201004470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Ziblat R, Leiserowitz L, Addadi L. Crystalline lipid domains: characterization by X-ray diffraction and their relation to biology. Angew Chem Int Ed Engl 2011; 50:3620-9. [PMID: 21472900 DOI: 10.1002/anie.201004470] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Indexed: 12/29/2022]
Abstract
Biological membranes comprise thousands of different lipids, differing in their alkyl chains, headgroups, and degree of saturation. It is estimated that 5% of the genes in the human genome are responsible for regulating the lipid composition of cell membranes. Conceivably, the functional explanation for this diversity is found, at least in part, in the propensity of lipids to segregate into distinct domains, which are important for cell function. X-ray diffraction has been used increasingly to characterize the packing and phase behavior of lipids in membranes. Crystalline domains have been studied in synthetic membranes using wide- and small-angle X-ray scattering, and grazing incidence X-ray diffraction. Herein we summarize recent results obtained using the various X-ray methods, discuss the correlation between crystalline domains and liquid ordered domains studied with other techniques, and the relevance of crystalline domains to functional lipid domains in biological membranes.
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Affiliation(s)
- Roy Ziblat
- Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel
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Abstract
ABSTRACTRecently, modulated phases of insoluble monolayers of fatty acids and phospholipids spread on the water/air interface have been observed by fluorescence microscopy experiments. We propose a theoretical explanation of this observation by including electrostatic (dipolar) interactions in the total free energy calculation for the monolayer. Dipoles can originate from two sources: neutral amphiphiles have a permanent dipole and charged amphiphiles have an induced one. Modulated phases are found to be stable in two different limits: close to the liquid-gas transition and at low temperatures. Several phases with stripe and hexagonal symmetry are predicted and the phase transitions between them are calculated.
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Abstract
AbstractMolecular dynamics calculations were carried out for a Langmuir monolayer at high density. A model was employed in which the motions of both the amphiphiles and the water are allowed, enabling investigation of the details of the water-monolayer interaction and the structure of the interface. Results are presented for the density profiles of the water and the amphiphiles and for the distribution of gauche defects.
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Leveiller F, Jacquemain D, Lahav M, Leiserowitz L, Deutsch M, Kjaer K, Als-Nielsen J. Crystallinity of the double layer of cadmium arachidate films at the water surface. Science 2010; 252:1532-6. [PMID: 17834878 DOI: 10.1126/science.252.5012.1532] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A crystalline counterionic layer at the interface between an electrolyte solution and a charged layer of insoluble amphiphilic molecules was observed with grazing incidence synchrotron x-ray diffraction. Uncompressed arachidic films spread over 10(-3) molar cadmium chloride solution (pH 8.8) spontaneously form crystalline clusters with coherence lengths of approximately 1000 angstroms at 9 degrees C. Ten distinct diffraction peaks were observed, seven of which were attributed to scattering only from a crystalline Cd(2+) layer and the other three to scattering primarily from the arachidate layer. The reflections from the Cd(2+) layer were indexed according to a 2 x 3 supercell of the arachidate lattice with three Cd(2+) ions per cadmium unit cell.
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28
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Daillant J. Recent developments and applications of grazing incidence scattering. Curr Opin Colloid Interface Sci 2009. [DOI: 10.1016/j.cocis.2009.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Tamam L, Menahem T, Mastai Y, Sloutskin E, Yefet S, Deutsch M. Langmuir films of chiral molecules on mercury. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:5111-5119. [PMID: 19256463 DOI: 10.1021/la804109h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Homo- and heterochiral Langmuir films of a chiral derivative of stearic acid are studied in situ on the surface of liquid mercury as a function of surface coverage by surface tensiometry and surface-specific synchrotron X-ray diffraction and reflectivity. A transition from a phase of surface-parallel molecules to a phase of standing-up molecules is found. The former shows no surface-parallel long-range order. The standing-up phase of both homochiral and heterochiral compositions exhibit long-range order. However, the former has an oblique unit cell with parallel molecular planes, and the later has a centered rectangular unit cell with a herringbone molecular packing. For both cases, the standing-up molecules are tilted by 44 degrees from the surface normal and pack at a density of 19.5 A(2)/molecule in the plane normal to the molecular long axis. Important differences are found, and discussed, between this behavior and that of a Langmuir film of the nonchiral stearic acid on mercury.
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Affiliation(s)
- L Tamam
- Physics Department, Bar-Ilan University, Ramat-Gan 52900, Israel
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Iwamoto M, Yamamoto T, Liu F, Ou-Yang ZC. Shear-induced domain deformation in a tilted lipid monolayer: from circle to ellipse and kinked stripe. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:051704. [PMID: 19113140 DOI: 10.1103/physreve.78.051704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 08/19/2008] [Indexed: 05/27/2023]
Abstract
The shear-induced domain deformation in a lipid monolayer comprised of tilted molecules is studied as a mechanical balance between surface pressure, line tension, electrostatic energy due to the dipole-dipole interaction, hexatic-elastic stress, and viscous stress. It is found that a simple shear can deform a circular domain into an elliptic shape with the long axis inclined 45 degrees from the shear direction. The "ellipse" is elongated in the long axis as shear rate increases, and evolves to a straight or kinked stripe, which was observed as a "shear band" by Fuller's group [Science 274, 233 (1996)] and "avalanche-like fronts" by Schwaltz's group [Langmuir 17, 3017 (2001)], at a threshold shear rate. The propagation of stripe-shaped domains is discussed in the context of electrostatic energy. The dependence of the threshold shear rate on surface pressure is predicted in good agreement with observation and can be used to estimate surface viscosity. The shear-induced domain deformation is maintained by the effect of the lattice elastic stress when shear ceases.
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Affiliation(s)
- Mitsumasa Iwamoto
- Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 S3-33 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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Giner-Casares JJ, Camacho L, Martín-Romero MT, Cascales JJL. A DMPA Langmuir monolayer study: from gas to solid phase. An atomistic description by molecular dynamics Simulation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:1823-1828. [PMID: 18225932 DOI: 10.1021/la7030297] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this work, a DMPA Langmuir monolayer at the air/water interface was studied by molecular dynamics simulations. Thus, an atomistic picture of a Langmuir monolayer was drawn from its expanded gas phase to its final solid condensed one. In this sense, some properties of monolayers that were traditionally poorly or even not reproduced in computer simulations, such as lipid domain formation or pressure-area per lipid isotherm, were properly reproduced in this work. Thus, the physical laws that control the lipid domain formation in the gas phase and the structure of lipid monolayers from the gas to solid condensed phase were studied. Thanks to the atomistic information provided by the molecular dynamics simulations, we were able to add valuable information to the experimental description of these processes and to access experimental data related to the lipid monolayers in their expanded phase, which is difficult or inaccessible to study by experimental techniques. In this sense, properties such as lipids head hydration and lipid structure were studied.
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Affiliation(s)
- J J Giner-Casares
- Universidad de Córdoba, Dpto. Química Física y TermodinAmica Aplicada, Ed. Marie Curie, Campus de Rabanales, 14014 Córdoba, Spain
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Recent Developments in the Study of Monolayers at the Air-Water Interface. ADVANCES IN CHEMICAL PHYSICS 2007. [DOI: 10.1002/9780470141267.ch7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
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He Q, Li J. Hydrolysis characterization of phospholipid monolayers catalyzed by different phospholipases at the air-water interface. Adv Colloid Interface Sci 2007; 131:91-8. [PMID: 17210114 DOI: 10.1016/j.cis.2006.11.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 11/11/2006] [Indexed: 11/22/2022]
Abstract
Combination of some newly developed microscopic and spectroscopic techniques with conventional Langmuir monolayer method can provide more quantitative information with the molecular orientation and reorganization process of spread amphiphilic molecules at the air/water interface. These techniques are extended to investigate the hydrolysis process of spreading lipid monolayer catalyzed by different enzymes, phospholipases A2, C and D, respectively. Synchrotron X-ray diffraction and infrared reflection absorption spectroscopy are able directly to give the structural information of the assembled monolayer, interfacial activity of amphiphiles and their components at the interface. Microscopic technique such as Brewster angle microscopy (BAM), fluorescence microscopy (FM) can be used to trace the morphological changes dynamically as the spreading lipid monolayer is hydrolyzed at the air/water interface. We summary here some latest progress in this filed and give a brief review over the hydrolysis features of phospholipid monolayer catalyzed by different enzymes. It is attempted to establish a model of membrane hydrolysis process in order to better understand the mechanism of membrane metabolism and signal transduction in a living system.
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Affiliation(s)
- Qiang He
- Beijing National Laboratory for Molecular Sciences, International Joint Lab CAS Key Lab of Colloid and Interface Science, Institute of Chemistry, Chinese Academy of Sciences, Zhong Guan Cun, Beijing, PR China
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34
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DiMasi E, Kwak SY, Pichon BP, Sommerdijk NAJM. Structural adaptability in an organic template for CaCO3 mineralization. CrystEngComm 2007. [DOI: 10.1039/b711153c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Pignat J, Daillant J, Leiserowitz L, Perrot F. Grazing Incidence X-ray Diffraction on Langmuir Films: Toward Atomic Resolution. J Phys Chem B 2006; 110:22178-84. [PMID: 17078655 DOI: 10.1021/jp056770k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have analyzed grazing incidence diffration (GIXD) data from condensed phases of Langmuir films of long-chain fatty acids at the air-water interface by using a new method consisting of a careful extraction of the structure factors followed by fitting of molecular parameters. We show that, contrary to the general belief, the information contained in GIXD spectra is enough to obtain near-atomic structural information. In particular, we directly determine for the first time the orientation of the chain backbone planes and of the carboxylic headgroups and we evaluate chain conformation defects. This new method allowed us to evidence a new phase of symmetry p2gm at high pressure, corresponding to a minimum in lattice energy, but never observed.
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Affiliation(s)
- J Pignat
- Service de Chimie Moléculaire/LIONS, CEA-Saclay, Bât. 125, F-91191 Gif-sur-Yvette Cedex, France
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Wang Y, Bai G, Marques EF, Yan H. Phase Behavior and Thermodynamics of a Mixture of Cationic Gemini and Anionic Surfactant. J Phys Chem B 2006; 110:5294-300. [PMID: 16539460 DOI: 10.1021/jp054323z] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present the phase behavior and thermodynamics of the catanionic mixture of the gemini surfactant hexanediyl-alpha,omega-bis(dodecyldimethylammonium bromide), designated here as 12-6-12Br(2), and sodium dodecyl sulfate (SDS) over the full range of composition, at the water-rich corner. Visual and turbidity measurements of the mixtures provide some basic macroscopic information on phase behavior. The structure of the aggregates formed spontaneously in the mixtures has been observed with TEM. As the molar fraction of SDS, X(SDS), is increased, at constant total surfactant concentration, the aggregation morphologies change gradually from gemini-rich micelles, through multiphase regions containing a precipitate (catanionic surfactant) and a vesicle region, to SDS-rich micelles. From isothermal titration calorimetry measurements, the phase boundaries and corresponding enthalpy changes for phase transitions have been obtained. The formation of the different microstructures, in particular, the spontaneously formed vesicles in the SDS-rich side, is discussed on the basis of geometric and electrostatic effects occurring in the SDS-gemini mixture.
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Affiliation(s)
- Yujie Wang
- Centro de Investigação em Química, Department of Chemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, no. 687, P-4169-007 Porto, Portugal
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Weis M, Kopáni M, Michalka P, Biró C, Celec P, Danisovic L, Jakubovský J. Conformation study of the membrane models by the Maxwell displacement current technique and oxidative stress. ACTA ACUST UNITED AC 2005; 65:81-7. [PMID: 16325259 DOI: 10.1016/j.jbbm.2005.10.005] [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: 09/05/2005] [Revised: 10/23/2005] [Accepted: 10/23/2005] [Indexed: 11/17/2022]
Abstract
The role of biological membranes as a target in biological radiation damage is still unclear. Recently much attention has been paid to the dynamic behaviour of the cell membrane. Maxwell displacement current technique (MDC) provides new possibility of conformation study of the membrane models. Oxidative stress can impair macromolecules in the cell on a molecular level. MDC technique enables to study the changes in molecular orientations and/or conformations of cell membranes. The combination of different methods in structural biology can clarify membrane chemical and physical properties.
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Affiliation(s)
- M Weis
- Slovak University of Technology, Faculty of Electrical Engineering and Information Technology, Department of Physics, Bratislava, Slovakia
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39
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Wang Y, Marques EF. Thermotropic Phase Behavior of Cationic Gemini Surfactants and Their Equicharge Mixtures with Sodium Dodecyl Sulfate. J Phys Chem B 2005; 110:1151-7. [PMID: 16471657 DOI: 10.1021/jp0552729] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The lyotropic phase behavior for the neat cationic gemini surfactants alkanediyl-alpha,omega-bis(alkyldimethylammonium bromide), designated here as m-s-m, has been investigated previously in several works, but the thermotropic behavior has not been well characterized. Only for 15-s-15 and 14-s-12 have thermotropic liquid crystals (Lc) been reported. In this work, for the first time and in contrast to previous reports, we observe thermotropic Lc formation for m-2-m geminis with m = 12, 14, 16, and 18, by means of polarizing microscopy and differential scanning calorimetry (DSC). Furthermore, we investigate mixtures of m-2-m and SDS, m-2-m Br2.2SDS, which exhibit crystal-to-crystal phase transitions at lower temperature and, at high temperature, smectic Lc phases. The transition temperatures and enthalpies for Lc phases, obtained by DSC, present clear trends upon increase of the chain lengths. Combining Langmuir film experiments, possible lamellar arrangements for the different phases are tentatively discussed.
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Affiliation(s)
- Yujie Wang
- Centro de Investigação em Química, Department of Chemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, No. 687, P-4169-007 Porto, Portugal
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Iwamoto M, Zhong-Can OY. Flow-induced molecular orientation of amphiphile monolayers: incorporation of hexatic elasticity into Ericksen-Leslie theory. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:021704. [PMID: 16196582 DOI: 10.1103/physreve.72.021704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 12/03/2004] [Indexed: 05/04/2023]
Abstract
By introducing the local lattice elasticity into the pure Ericksen-Leslie (EL) theory which only considers the deformation of the director, we developed a more general theory for understanding the behaviors of hexatic liquid crystal under flow. In the cases of amphiphilic monolayers in tilted phases (L2 and L'2), the exact solutions of the new EL equation in two types of flow, pure extension and simple shear, explain well most of the features of flow-induced tilt azimuth orientation observed by Fuller's group [Science, 274, 233 (1996)] and Schwartz's group [Nature (London) 410, 348 (2001)]. In particular, the "shear band" domain generated by flow discovered by the former is proved theoretically as the result of two-dimensional Wulf construction in L2 and L'2 phases.
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Affiliation(s)
- Mitsumasa Iwamoto
- Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1-S3-33 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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41
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Lee DK, Kim YH, Kang YS, Stroeve P. Preparation of a Vast CoFe2O4 Magnetic Monolayer by Langmuir−Blodgett Technique. J Phys Chem B 2005; 109:14939-44. [PMID: 16852892 DOI: 10.1021/jp052363x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The preparation of ultrathin films of CoFe2O4 nanocrystallites is reported. TEM images of them showed 2-dimensional assembly of particles, demonstrating the uniformity of these nanocrystallites. The formation of a Langmuir monolayer of the surface coated CoFe2O4 nanocrystallites with oleate at the air/water interface and its stability were studied with pressure-area isotherm curves and Brewster Angle Microscope (BAM) images. Surface pressure vs surface area isotherms and TEM studies demonstrated that the increasing surface pressure resulted in a transition from a complex with well-separated domains of nanocrystallites to well-compressed, monoparticulate layers, and, ultimately, to multiparticulate layers.
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Affiliation(s)
- Don Keun Lee
- Department of Chemistry, Pukyong National University, 599-1 Daeyeon-3-dong, Nam-gu, Pusan 608-737, South Korea
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42
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Electron microscopic studies of Langmuir–Blodgett films of CoFe2O4 nanocrystallites. Colloids Surf A Physicochem Eng Asp 2005. [DOI: 10.1016/j.colsurfa.2004.07.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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43
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Deng J, Viers BD, Esker AR, Anseth JW, Fuller GG. Phase behavior and viscoelastic properties of trisilanolcyclohexyl-POSS at the air/water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2375-2385. [PMID: 15752028 DOI: 10.1021/la047568w] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A trisilanol polyhedral oligomeric silsesquioxane (POSS), trisilanolcyclohexyl-POSS (TCyP), has recently been reported to undergo a series of phase transitions from traditional Langmuir monolayers to unique rodlike hydrophobic aggregates in multilayer films that are different from "collapsed" morphologies seen in other systems at the air/water interface. This paper focuses on the phase transitions and morphology of films varying in average thickness from monolayers to trilayers and the corresponding viscoelastic properties of trisilanolcyclohexyl-POSS molecules at the air/water interface by means of surface pressure-area per molecule (Pi-A) isotherms, Brewster angle microscopy (BAM), and interfacial stress rheometry (ISR) measurements. The morphology studies by BAM reveal that the TCyP monolayer can collapse into different 3D structures by homogeneous or heterogeneous nucleation mechanisms. For homogeneous nucleation, analysis by Vollhardt et al.'s nucleation and growth model reveals that TCyP collapse is consistent with instantaneous nucleation with hemispherical edge growth at Pi = 3.7 mN.m(-1). Both surface storage (Gs') and loss (Gs") moduli obtained by ISR reveal three different non-Newtonian flow regimes that correlate with phase transitions in the Pi-A isotherms: (A) A viscous liquidlike "monolayer"; (B) a "biphasic regime"between a liquidlike viscous monolayer and a more rigid trilayer; and (C) an elastic solidlike "trilayer". These observations provide interesting insights into collapse mechanisms and structures in Langmuir films.
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Affiliation(s)
- Jianjun Deng
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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44
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Dyck M, Krüger P, Lösche M. Headgroup organization and hydration of methylated phosphatidylethanolamines in Langmuir monolayers. Phys Chem Chem Phys 2005; 7:150-6. [DOI: 10.1039/b410863a] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Tian CH, Liu DJ, Gronheid R, Van der Auweraer M, De Schryver FC. Mesoscopic organization of two-dimensional J-aggregates of thiacyanine in Langmuir-Schaefer films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:11569-11576. [PMID: 15595785 DOI: 10.1021/la048449j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
When dioctadecyl dimethylammonium bromide (DODAB) is compressed on a subphase containing 3,3'-disulfopropyl-5,5'-dichlorothiacyanine (THIAMS), adsorption of the dye to the DODAB monolayer results in the formation of J-aggregates which spontaneously organize into polygonal domains of micron size. The features of the domains depend on the surface pressure. The fluorescence of the individual domains is polarized. The shapes of the domains determined by fluorescence microscopy and atomic force microscopy (AFM) are identical. The domains differ however significantly from those observed after injection of a 3,3'-disulfopropyl-5,5'-dichloro-9-ethylthiacarbocyanine (THIATS) or THIAMS solution below a precompressed DODAB film, as well as from the domains observed upon compression of a DODAB monolayer on a subphase containing 10(-6) M THIATS.
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Affiliation(s)
- Chun-Hong Tian
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, Katholieke University Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
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46
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Kraack H, Ocko BM, Pershan PS, Tamam L, Deutsch M. Temperature dependence of the structure of Langmuir films of normal-alkanes on liquid mercury. J Chem Phys 2004; 121:8003-9. [PMID: 15485263 DOI: 10.1063/1.1799993] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The temperature dependent phase behavior of Langmuir films of n-alkanes [CH3(CH2)(n-2)CH3, denote Cn] on mercury was studied for chain lengths 19< or =n< or =22 and temperatures 15< or =T< or =44 degrees C, using surface tensiometry and surface x-ray diffraction methods. In contrast with Langmuir films on water, where molecules invariably orient roughly surface normal, alkanes on mercury are always oriented surface parallel and show no long-range in-plane order at any surface pressure. A gas and several condensed phases of single, double, and triple layers of lying-down molecules are found, depending on n and T. At high coverages, the alkanes studied here show transitions from a triple to a double to a single layer with increasing temperature. The transition temperature from a double to a single layer is found to be approximately 5 degrees C, lower than the bulk rotator-to-liquid melting temperature, while the transition from a triple to a double layer is about as much below the double-to-single layer transition. Both monolayer and bulk transition temperatures show a linear increase with n with identical slopes of approximately 4.5 degrees C/CH2 within the range of n values addressed here. It is suggested that the film and bulk transitions are both driven by a common cause: the proliferation of gauche defects in the chain with increasing temperature.
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Affiliation(s)
- H Kraack
- Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel
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47
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Saccani J, Castano S, Beaurain F, Laguerre M, Desbat B. Stabilization of phospholipid multilayers at the air-water interface by compression beyond the collapse: a BAM, PM-IRRAS, and molecular dynamics study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:9190-9197. [PMID: 15461505 DOI: 10.1021/la0489920] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Compression beyond the collapse of phospholipid monolayers on a modified Langmuir trough has revealed the formation of stable multilayers at the air-water interface. Those systems are relevant new models for studying the properties of biological membranes and for understanding the nature of interactions between membranes and peptides or proteins. The collapse of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-di[cis-9-octadecenoyl]-sn-glycero-3-[phospho-l-serine] (DOPS), 1,2-di[cis-9-octadecenoyl]-sn-glycero-3-phosphocholine (DOPC), and 1,2-di[cis-9-octadecenoyl]-sn-glycero-3-[phospho-1-rac-glycerol] (DOPG) monolayers has been investigated by isotherm measurements, Brewster angle microscopy (BAM), and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). In the cases of DMPC and DOPS, the collapse of the monolayers revealed the formation of bilayer and trilayer structures, respectively. The DMPC bilayer stability has been analyzed also by a molecular dynamics study. The collapse of the DOPC and DOPG systems shows a different behavior, and the Brewster angle microscopy reveals the formation of luminous bundles, which can be interpreted as diving multilayers in the subphase.
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Affiliation(s)
- J Saccani
- Laboratoire de Physico-Chimie Moléculaire, UMR 5803-CNRS, 351 cours de la Libération, 33405 Talence Cedex, France
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Vemparala S, Kalia RK, Nakano A, Vashishta P. Electric field induced switching of poly(ethylene glycol) terminated self-assembled monolayers: A parallel molecular dynamics simulation. J Chem Phys 2004; 121:5427-33. [PMID: 15352837 DOI: 10.1063/1.1781120] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Effects of electric field on the structure of poly(ethylene glycol) (PEG) terminated alkanethiol self-assembled monolayer (SAM) on gold have been studied using parallel molecular dynamics method. An applied electric field triggers a conformational transition from all-trans to a mostly gauche conformation. The polarity of the electric field has a significant effect on the surface structure of PEG leading to a profound effect on the hydrophilicity of the surface. The electric field applied antiparallel to the surface normal causes a reversible transition to an ordered state in which the oxygen atoms are exposed. On the other hand, an electric field applied in a direction parallel to the surface normal introduces considerable disorder in the system and the oxygen atoms are buried inside. The parallel field affects the overall tilt structure of SAMs more adversely than the antiparallel field.
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Affiliation(s)
- Satyavani Vemparala
- Collaboratory for Advanced Computing and Simulations, Department of Materials Science & Engineering, University of Southern California, Los Angeles, California 90089-0242, USA
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Vemparala S, Karki BB, Kalia RK, Nakano A, Vashishta P. Large-scale molecular dynamics simulations of alkanethiol self-assembled monolayers. J Chem Phys 2004; 121:4323-30. [PMID: 15332982 DOI: 10.1063/1.1775779] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Large-scale molecular dynamics simulations of self-assembled alkanethiol monolayer systems have been carried out using an all-atom model involving a million atoms to investigate their structural properties as a function of temperature, lattice spacing, and molecular chain length. Our simulations show that the alkanethiol chains of 13-carbons tilt from the surface normal by a collective angle of 25 degrees along next-nearest-neighbor direction at 300 K. The tilt structure of 13-carbon alkanethiol system is found to depend strongly on temperature and exhibits hysteresis. At 350 K the 13-carbon alkanethiol system transforms to a disordered phase characterized by small collective tilt angle, flexible tilt direction, and random distribution of backbone planes. The tilt structure also depends on lattice spacing: With increasing lattice spacing a the tilt angle increases rapidly from a nearly zero value at a=4.7 A to as high as 34 degrees at a=5.3 A at 300 K for 13-carbon alkanethiol system. Finally, the effects of the molecular chain length on the tilt structure are significant at high temperatures.
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Affiliation(s)
- Satyavani Vemparala
- Biological Computation and Visualization Center, Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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50
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Deng J, Hottle JR, Polidan JT, Kim HJ, Farmer-Creely CE, Viers BD, Esker AR. Polyhedral oligomeric silsesquioxane amphiphiles: isotherm and brewster angle microscopy studies of trisilanolisobutyl-POSS at the air/water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:109-115. [PMID: 15745007 DOI: 10.1021/la035240h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A trisilanol derivative of polyhedral oligomeric silsesquioxanes (POSS), trisilanolisobutyl-POSS, has recently been reported to form stable monolayers at the air/water interface. Moreover, the trisilanolisobutyl-POSS monolayer undergoes a nonequilibrium structural transition (collapse) around a surface pressure of Rho approximately 18 mN.m(-1). This paper explores the mono- and multilayer properties of POSS molecules at the air/water interface by the Wilhelmy plate technique and Brewster angle microscopy. Surface concentrations are controlled by four mechanisms: (1) compression at a constant rate, (2) stepwise compression followed by surface pressure relaxation to an "equilibrium" value, (3) successive additions of spreading solution followed by relaxation to a stable surface pressure value, and (4) hysteresis loops to test the reversibility of the structural transitions. Results show that both an increasing compression rate and a decreasing temperature lead to an increase in the surface pressure of the structural transition, which is consistent with the formation of solidlike multilayer domains during the collapse process. For the case of compression at a constant rate, small domains initially form and later aggregate to form large solid masses. Cessation of compression allows these large solid masses to relax into equilibrium ringlike structures with a lower surface pressure, Rho approximately 13 mN.m(-1). In contrast, if the film is expanded rapidly, these large solidlike domains relax into "spaghetti" like networks with a residual surface pressure that depends on the initial amount of the solidlike collapsed phase. Finally, successive addition and stepwise compression isotherm experiments lead to different and time-dependent morphologies. Understanding these surface properties of POSS molecules affords an excellent opportunity to design and study POSS/polymer blends for coating applications where POSS molecules with rigid inorganic cores, soft organic coronae, and dimensions comparable to polymeric monolayers can serve as perfectly monodisperse nanofillers.
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Affiliation(s)
- Jianjun Deng
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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