1
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Hatta E. Hierarchical structure growth across different length scales in the two-phase coexistence region of myristic acid Langmuir monolayers: correlation of static and dynamic heterogeneities. Phys Chem Chem Phys 2024; 26:11370-11378. [PMID: 38567464 DOI: 10.1039/d4cp00427b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
We investigated the hierarchical structure growth of myristic acid monolayers at the air-water interface across different length scales in the two-phase coexistence region of the first order liquid expanded (LE)-liquid condensed (LC) phase transition. A combined study of surface pressure-area (π-A) isotherm measurements with Brewster angle microscopy (BAM) observations was done at different temperatures. At the nanometer scale, the analysis of the π-A isotherm by application of a thermodynamic cluster equation allowed us to obtain the π dependence of cluster size (cluster distribution) in the LE-LC coexistence region. The cluster distributions showed a peak at the midpoint pressure of the transition. At higher temperature the larger nanocluster size was obtained at the transition midpoint. At the micrometer scale, BAM showed that LC domains have characteristic textures depending on the temperature. At low temperature domain density was lower and the average size of circular domains was larger. A large number of circular domains revealed a virtual boojum texture from the initial to the late stage of the transition. At the final stage some circular domains coalesced to form larger circular stripe domains and others coalesced to each other without the formation of stripe domains, finally resulting in a uniform texture over the entire water surface. At high temperature the domain texture was predominantly uniform, and a small number of domains only included straight line defects from the intermediate to the late stage of the transition. All domains coalesced to each other without the development of any texture including the stripe, different from the case at low temperature. The phase boundary line tension is highly likely to play a key role for understanding the hierarchical growth and coarsening (coalescence) process in the LE-LC transition between the different length scales from the nanometer to the micrometer scale consistently together.
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Affiliation(s)
- E Hatta
- Nanoelectronics Laboratory, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, 060-0814, Japan.
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2
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Hanisch DT, Schneider MF. Specific Regulation of Enzymatic Activity by Interface Pulses. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 38330005 DOI: 10.1021/acs.langmuir.3c02658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
The thermodynamic state of the interface in which an enzyme is embedded can regulate the enzymatic activity. Indeed, it has been demonstrated by others and us that close to the maximum in compressibility, the activity of the enzyme is at a maximum as well. Pulses propagating along the interface can modulate the interface state and were demonstrated to be able to modulate the activity of interface-associated acetylcholinesterase (AChE). Here, we demonstrate that enzyme activity modulation by interface pulses depends specifically on the pulse type. Using membrane-embedded enzyme phospholipase A2 (PLA2), enzyme activity can be monitored by detecting the lateral pressure without an additional assay required. We show that pulses that shift the state toward higher pressure and higher lateral density increase the enzymatic activity, while pulses that reduce the pressure induce the opposite effect. These results further support a physical mechanism for enzyme-enzyme communication where compressibility, lateral density, and pressure (thermodynamic state) and not specific molecular modifications regulate enzymatic activity.
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Affiliation(s)
- Daniel T Hanisch
- Medical and Biological Physics, Department of Physics, TU Dortmund University, Otto-Hahn-Str. 4, 44227 Dortmund, Germany
| | - Matthias F Schneider
- Medical and Biological Physics, Department of Physics, TU Dortmund University, Otto-Hahn-Str. 4, 44227 Dortmund, Germany
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3
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Dynarowicz-Latka P, Wnętrzak A, Chachaj-Brekiesz A. Advantages of the classical thermodynamic analysis of single-and multi-component Langmuir monolayers from molecules of biomedical importance-theory and applications. J R Soc Interface 2024; 21:20230559. [PMID: 38196377 PMCID: PMC10777166 DOI: 10.1098/rsif.2023.0559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 12/08/2023] [Indexed: 01/11/2024] Open
Abstract
The Langmuir monolayer technique has been successfully used for decades to model biological membranes and processes occurring at their interfaces. Classically, this method involves surface pressure measurements to study interactions within membrane components as well as between external bioactive molecules (e.g. drugs) and the membrane. In recent years, surface-sensitive techniques were developed to investigate monolayers in situ; however, the obtained results are in many cases insufficient for a full characterization of biomolecule-membrane interactions. As result, description of systems using parameters such as mixing or excess thermodynamic functions is still relevant, valuable and irreplaceable in biophysical research. This review article summarizes the theory of thermodynamics of single- and multi-component Langmuir monolayers. In addition, recent applications of this approach to characterize surface behaviour and interactions (e.g. orientation of bipolar molecules, drug-membrane affinity, lateral membrane heterogeneity) are presented.
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Affiliation(s)
| | - Anita Wnętrzak
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
| | - Anna Chachaj-Brekiesz
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland
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4
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Raghavendra, Kumar B, Chari SN. Effect of γ-Oryzanol on the LE-LC Phase Coexistence Region of DPPC Langmuir Monolayer. J Membr Biol 2023; 256:413-422. [PMID: 37269365 DOI: 10.1007/s00232-023-00288-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 05/06/2023] [Indexed: 06/05/2023]
Abstract
We have studied the effect of relative composition of γ-Oryzanol (γ-Or) on the liquid expanded-liquid condensed phase coexistence region in the mixed Langmuir monolayer of γ-Or and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) molecules at air-water interface. The surface manometry studies at a fixed temperature show that the mixture of γ-Or and DPPC forms a stable monolayer at air-water interface. As the relative composition of γ-Or increases the range of area per molecule over which the coexistence of liquid expanded (LE)-liquid condensed (LC) phases exists reduces. Although the LE-LC phase coexistence corresponds to the first-order phase transition, the slope of the surface pressure-area per molecule isotherm is non-zero. Earlier studies have attributed the non-zero slope in LE-LC phase coexistence region to the influence of the strain between the ordered LC phase and disordered LE phase. The effect of strain on the coexistence of LE-LC phases can be studied in terms of molecular density-strain coupling. Our analysis of the liquid condensed-liquid expanded coexistence region in the isotherms of mixed monolayers of DPPC and γ-Or shows that with the increase in the mole fraction of sterol in the mixed monolayer the molecular lateral density-strain coupling increases. However, at 0.6 mole fraction of γ-Or in the mixed monolayer the coupling decreases. This is corroborated by the observation of minimum Gibb's free energy of the mixed monolayer at this relative composition of γ-Or indicating better packing of molecules.
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Affiliation(s)
- Raghavendra
- Department of Physics, Central University of Karnataka, Aland Road, Kadaganchi, Kalaburagi, Karnataka, 585102, India
| | - Bharat Kumar
- Department of Physics, Central University of Karnataka, Aland Road, Kadaganchi, Kalaburagi, Karnataka, 585102, India.
| | - Siva N Chari
- Department of Physics, Central University of Karnataka, Aland Road, Kadaganchi, Kalaburagi, Karnataka, 585102, India
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Mukhina T, Richter L, Vollhardt D, Brezesinski G, Schneck E. The Complete Phase Diagram of Monolayers of Enantiomeric N-Stearoyl-threonine Mixtures with Preferred Heterochiral Interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:12521-12529. [PMID: 36209408 PMCID: PMC9583611 DOI: 10.1021/acs.langmuir.2c01936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/30/2022] [Indexed: 06/16/2023]
Abstract
Langmuir monolayers of chiral amphiphiles are well-controlled model systems for the investigation of phenomena related to stereochemistry. Here, we have investigated mixed monolayers of one pair of enantiomers (l and d) of the amino-acid-based amphiphile N-stearoyl-threonine. The monolayer characteristics were studied by pressure-area isotherm measurements and grazing incidence X-ray diffraction (GIXD) over a wide range of mixing ratios defined by the d-enantiomer mole fraction xD. While the isotherms provide insights into thermodynamical aspects, such as transition pressure, compression/decompression hysteresis, and preferential homo- and heterochiral interactions, GIXD reveals the molecular structural arrangements on the Ångström scale. Dominant heterochiral interactions in the racemic mixture lead to compound formation and the appearance of a nonchiral rectangular lattice, although the pure enantiomers form a chiral oblique lattice. Miscibility was found to be limited to mixtures with 0.27 ≲ xD ≲ 0.73, as well as to both outer edges (xD ≲ 0.08 and xD ≳ 0.92). Beyond this range, coexistence of oblique and rectangular lattices occurs, as is clearly seen in the GIXD patterns. Based on the results, a complete phase diagram with two eutectic points at xD ≈ 0.25 and xD ≈ 0.75 is proposed. Moreover, N-stearoyl-threonine was found to have a strong tendency to form a hydrogen-bonding network between the headgroups, which promotes superlattice formation.
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Affiliation(s)
- Tetiana Mukhina
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstraße 8, 64289Darmstadt, Germany
| | - Lars Richter
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstraße 8, 64289Darmstadt, Germany
| | - Dieter Vollhardt
- Max-Planck
Institute for Polymer Research, Ackermannweg 10, D-55128Mainz, Germany
| | - Gerald Brezesinski
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstraße 8, 64289Darmstadt, Germany
| | - Emanuel Schneck
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstraße 8, 64289Darmstadt, Germany
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6
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Berrio Escobar JF, Giordani C, Russo S, Castelli F, Sarpietro MG. Interaction of Lipophilic Cytarabine Derivatives with Biomembrane Model at the Air/Water Interface. MEMBRANES 2022; 12:membranes12100937. [PMID: 36295696 PMCID: PMC9611095 DOI: 10.3390/membranes12100937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/23/2022] [Accepted: 09/24/2022] [Indexed: 06/12/2023]
Abstract
Cell membrane models are useful for obtaining molecular-level information on the interaction of biologically active molecules whose activity is believed to depend also on their effects on the membrane. Cytarabine was conjugated with fatty acids to improve the drug lipophilicity and the interaction with the biomembrane model. Cytarabine was conjugated with fatty acids of different lengths to form the trimyristoyl cytarabine and the tristearoyl cytarabine derivatives. Their interaction with biomembrane models constituted by dimyristoylphosphatidylcholine (DMPC) monolayers was studied by employing the Langmuir-Blodgett technique. DMPC/cytarabine, DMPC/trimyristoyl cytarabine and DMPC/tristearoyl cytarabine mixed monolayers at increasing molar fractions of the compound were prepared and placed on the subphase. The mean molecular area/surface pressure isotherms were recorded at 37 °C. Between the molecules of DMPC and those of cytarabine or prodrugs, repulsive forces act. However, these forces are very weak between DMPC and cytarabine and stronger between DMPC and the cytarabine derivatives, thus avoiding the expulsion of the compounds at higher surface pressure and modifying the stability of the mixed monolayer. The fatty acid moieties could then modulate the affinity of cytarabine for biomembranes.
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Affiliation(s)
- Jhon Fernando Berrio Escobar
- Grupo Productos Naturales Marinos, Facultad de Ciencias Farmacéuticas y Alimentarias, Universidad de Antioquia, Calle 70 No. 52-21, Medellín 050010, Colombia
| | - Cristiano Giordani
- Grupo Productos Naturales Marinos, Facultad de Ciencias Farmacéuticas y Alimentarias, Universidad de Antioquia, Calle 70 No. 52-21, Medellín 050010, Colombia
- Instituto de Física, Universidad de Antioquia, Calle 70 No. 52-21, Medellín 050010, Colombia
| | - Stefano Russo
- Dipartimento di Scienze del Farmaco e della Salute, Università degli Studi di Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Francesco Castelli
- Dipartimento di Scienze del Farmaco e della Salute, Università degli Studi di Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Maria Grazia Sarpietro
- Dipartimento di Scienze del Farmaco e della Salute, Università degli Studi di Catania, Viale A. Doria 6, 95125 Catania, Italy
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7
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Grava M, Helmy S, Gimona M, Parisse P, Casalis L, Brocca P, Rondelli V. Calorimetry of extracellular vesicles fusion to single phospholipid membrane. Biomol Concepts 2022; 13:148-155. [PMID: 35312244 DOI: 10.1515/bmc-2022-0011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/01/2022] [Indexed: 12/12/2022] Open
Abstract
Extracellular vesicles (EVs)-mediated communication relies not only on the delivery of complex molecular cargoes as lipids, proteins, genetic material, and metabolites to their target cells but also on the modification of the cell surface local properties induced by the eventual fusion of EVs' membranes with the cells' plasma membrane. Here we applied scanning calorimetry to study the phase transition of single phospholipid (DMPC) monolamellar vesicles, investigating the thermodynamical effects caused by the fusion of doping amounts of mesenchymal stem cells-derived EVs. Specifically, we studied EVs-induced consequences on the lipids distributed in the differently curved membrane leaflets, having different density and order. The effect of EV components was found to be not homogeneous in the two leaflets, the inner (more disordered one) being mainly affected. Fusion resulted in phospholipid membrane flattening associated with lipid ordering, while the transition cooperativity, linked to membrane domains' coexistence during the transition process, was decreased. Our results open new horizons for the investigation of the peculiar effects of EVs of different origins on target cell membrane properties and functionality.
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Affiliation(s)
- Miriam Grava
- Institute for Condensed Matter Physics, Department of Physics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Sally Helmy
- Department of Medical Biotechnology and Translational Medicine, Università Degli Studi di Milano, Milano, Italy.,Biophysics Group, Physics Department, Faculty of Science, Ain Shams University, Cairo, Egypt
| | - Mario Gimona
- GMP Unit, Spinal Cord Injury and Tissue Regeneration Center Salzburg, Paracelsus Medical University (PMU), Salzburg, Austria.,Research Program "Nanovesicular Therapies", Paracelsus Medical University, Salzburg, Austria
| | - Pietro Parisse
- Istituto Officina dei Materiali, Department of Physical sciences and technologies of matter, Italian National Research Council, Trieste, Italy
| | | | - Paola Brocca
- Department of Medical Biotechnology and Translational Medicine, Università Degli Studi di Milano, Milano, Italy
| | - Valeria Rondelli
- Department of Medical Biotechnology and Translational Medicine, Università Degli Studi di Milano, Milano, Italy
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8
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Bronstein LG, Cressey P, Abuillan W, Konovalov O, Jankowski M, Rosilio V, Makky A. Influence of the porphyrin structure and linker length on the interfacial behavior of phospholipid-porphyrin conjugates. J Colloid Interface Sci 2021; 611:441-450. [PMID: 34968963 DOI: 10.1016/j.jcis.2021.12.114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 12/11/2022]
Abstract
HYPOTHESIS Phospholipid-porphyrin (Pl-Por) conjugates consist of porphyrin derivatives grafted to a lysophosphatidylcholine backbone. Owing to their structural similarities with phospholipids, Pl-Por conjugates can self-assemble into liposome-like assemblies. However, there is a significant lack of information concerning the impact of the porphyrin type and the length of the alkyl chain bearing the porphyrin on the interfacial behavior of the Pl-Por conjugates. We hypothesized that changing the chain length and the porphyrin type could impact their two-dimensional phase behavior and modulate the alignment between the two chains. EXPERIMENTS 6 Pl-Por conjugates with different alkyl chain lengths in the sn2 position of C16 lysophosphatidylcholine and coupled to either pheophorbide-a or pyropheophorbide-a were synthesized. Their interfacial behavior at the air/water interface was assessed using Langmuir balance combined to a variety of other physical techniques including Brewster angle microscopy, atomic force microscopy and X-ray reflectometry. FINDINGS Our results showed that all 6 Pl-Por form stable monolayers with the porphyrin moiety at the air/water interface. We also showed that changing the porphyrin moiety controlled the packing of the monolayer and thus the formation of organized domains. The chain length dictated the structure of the formed domains with no evidence of the alignment between the two chains.
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Affiliation(s)
| | - Paul Cressey
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 92296 Châtenay-Malabry, France
| | - Wasim Abuillan
- Physical Chemistry of Biosystems, Physical Chemistry Institute, University of Heidelberg, 69120 Heidelberg, Germany
| | - Oleg Konovalov
- European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France
| | - Maciej Jankowski
- European Synchrotron Radiation Facility (ESRF), Grenoble 38043, France
| | - Véronique Rosilio
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 92296 Châtenay-Malabry, France
| | - Ali Makky
- Université Paris-Saclay, CNRS, Institut Galien Paris-Saclay, 92296 Châtenay-Malabry, France.
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9
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Sabin J, Alatorre-Meda M, Miñones J, Domínguez-Arca V, Prieto G. New insights on the mechanism of polyethylenimine transfection and their implications on gene therapy and DNA vaccines. Colloids Surf B Biointerfaces 2021; 210:112219. [PMID: 34836707 DOI: 10.1016/j.colsurfb.2021.112219] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/30/2021] [Accepted: 11/12/2021] [Indexed: 12/28/2022]
Abstract
Polyethylenimine (PEI) has been demonstrated as an efficient DNA delivery vehicle both in vitro and in vivo. There is a consensus that PEI-DNA complexes enter the cells by endocytosis and escape from endosomes by the so-called "proton sponge" effect. However, little is known on how and where the polyplexes are de-complexed for DNA transcription and replication to occur inside the cell nucleus. To better understand this issue, we (i) tracked the cell internalization of PEI upon transfection to human epithelial cells and (ii) studied the interaction of PEI with phospholipidic layers mimicking nuclear membranes. Both the biological and physicochemical experiments provided evidence of a strong binding affinity between PEI and the lipidic bilayer. Firstly, confocal microscopy revealed that PEI alone could not penetrate the cell nucleus; instead, it arranged throughout the cytoplasm and formed a sort of aureole surrounding the nuclei periphery. Secondly, surface tension measurements, fluorescence dye leakage assays, and differential scanning calorimetry demonstrated that a combination of hydrophobic and electrostatic interactions between PEI and the phospholipidic monolayers/bilayers led to the formation of stable defects along the model membranes, allowing the intercalation of PEI through the monolayer/bilayer structure. Results are also supported by molecular dynamics simulation of the pore formation in PEI-lipidic bilayers. As discussed throughout the text, these results might shed light on a the mechanism in which the interaction between PEI and the nucleus membrane might play an active role on the DNA release: on the one hand, the PEI-membrane interaction is anticipated to facilitate the DNA disassembly from the polyplex by establishing a competition with DNA for the PEI binding and on the other hand, the forming defects are expected to serve as channels for the entrance of de-complexed DNA into the cell nucleus. A better understanding of the mechanism of transfection of cationic polymers opens paths to development of more efficiency vectors to improve gene therapy treatment and the new generation of DNA vaccines.
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Affiliation(s)
- Juan Sabin
- Biophysics and Interfaces Group, Applied Physics Department, Universidade de Santiago de Compostela, Spain; AFFINImeter-Software 4 Science Developments S.L. Edificio Emprendia s/n Campus Vida, Santiago de Compostela, Spain.
| | - Manuel Alatorre-Meda
- Cátedras CONACyT-Tecnológico Nacional de México/I. T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Blvd. Alberto Limón Padilla S/N, 22510 Tijuana, BC, Mexico
| | - Jose Miñones
- Department of Physical Chemistry, Faculty of Pharmacy Universidade de Santiago de Compostela, Spain
| | - Vicente Domínguez-Arca
- Biophysics and Interfaces Group, Applied Physics Department, Universidade de Santiago de Compostela, Spain.
| | - Gerardo Prieto
- Biophysics and Interfaces Group, Applied Physics Department, Universidade de Santiago de Compostela, Spain
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10
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Hatta E, Nihei K. Statistical mechanical determination of nanocluster size distributions in the phase coexistence region of a first order phase transition from the isotherms of DMPC monolayers at the air-water interface. Phys Chem Chem Phys 2021; 23:22543-22550. [PMID: 34590663 DOI: 10.1039/d1cp03178c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A statistical mechanical deconvolution procedure for the experimentally measured surface pressure-area isotherms has been presented to obtain the surface pressure dependence of the liquid expanded (LE) and liquid condensed (LC) nanocluster size distributions in the LE-LC phase coexistence region of the first order phase transition of Dimyristoyl phosphatidylcholine (DMPC) monolayers at the air-water interface. This study presents the application of the deconvolution formulation introduced originally by Freire and Biltonen for the experimentally measured specific heat to calculate the submicroscopic lipid cluster distribution function in the phase coexistence region [E. Freire, R. L. Biltonen, Biopolymers, 1978, 17, 481-496] and extends their formulation to surface pressure isotherms. The present procedure involves the extraction of the pressure partition function calculated from the isotherm and utilizes the general relation between molecular density fluctuations and macroscopic lateral compressibility. In this procedure the high-density LC phase boundary has been determined uniquely. The average nanoscopic cluster sizes obtained in this study have been compared with the results from previous experimental studies. The cause of the finite difference between the values of the LC phase boundary area obtained from the present deconvolution procedure and the conventional extrapolation method on the same isotherm has been discussed from the viewpoint of slow hierarchical growth from nanoscopic clusters to macroscopic domains in the coexistence region.
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Affiliation(s)
- E Hatta
- Nanoelectronics Laboratory, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, 060-0814, Japan.
| | - K Nihei
- Nanoelectronics Laboratory, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, 060-0814, Japan.
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11
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Man Ngo F, Tse ECM. Bioinorganic Platforms for Sensing, Biomimicry, and Energy Catalysis. CHEM LETT 2021. [DOI: 10.1246/cl.200875] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Fung Man Ngo
- Department of Chemistry, CAS-HKU Joint Laboratory of Metallomics on Health and Environment, University of Hong Kong, Hong Kong SAR, P. R. China
- Advanced Functional Materials Laboratory, HKU Zhejiang Institute of Research and Innovation, Zhejiang 311305, P. R. China
| | - Edmund C. M. Tse
- Department of Chemistry, CAS-HKU Joint Laboratory of Metallomics on Health and Environment, University of Hong Kong, Hong Kong SAR, P. R. China
- Advanced Functional Materials Laboratory, HKU Zhejiang Institute of Research and Innovation, Zhejiang 311305, P. R. China
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12
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Bergendal E, Gutfreund P, Pilkington GA, Campbell RA, Müller-Buschbaum P, Holt SA, Rutland MW. Tuneable interfacial surfactant aggregates mimic lyotropic phases and facilitate large scale nanopatterning. NANOSCALE 2021; 13:371-379. [PMID: 33351024 DOI: 10.1039/d0nr06621d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
It is shown that the air-liquid interface can be made to display the same rich curvature phenomena as common lyotropic liquid crystal systems. Through mixing an insoluble, naturally occurring, branched fatty acid, with an unbranched fatty acid of the same length, systematic variation in the packing constraints at the air-water interface could be obtained. The combination of atomic force microscopy and neutron reflectometry is used to demonstrate that the water surface exhibits significant tuneable topography. By systematic variation of the two fatty acid proportions, ordered arrays of monodisperse spherical caps, cylindrical sections, and a mesh phase are all observed, as well as the expected lamellar structure. The tuneable deformability of the air-water interface permits this hitherto unexplored topological diversity, which is analogous to the phase elaboration displayed by amphiphiles in solution. It offers a wealth of novel possibilities for the tailoring of nanostructure.
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Affiliation(s)
- Erik Bergendal
- Department of Chemistry, KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, Drottning Kristinas väg 51, 100 44, Stockholm, Sweden.
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13
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Gellert F, Ahrens H, Helm CA. Oxidation of Unsaturated Phospholipids: A Monolayer Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12213-12220. [PMID: 32988204 DOI: 10.1021/acs.langmuir.0c01950] [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
Lipid oxidation does strongly influence the self-organization of plasma membranes; the detailed influence is not yet clear. In this work, phospholipid monolayers at the air/water interface were used as model membranes. Oxidation was induced by the reactive oxygen species formed in a H2O2-enriched solution. The reaction was found to be diffusion-limited; the concentration of the reactive oxygen species was about 50 nM. Isotherms were recorded for different phosphatidylcholines with saturated and unsaturated acyl chains. For unsaturated lipids, the isotherms showed a constant relative molecular area increase after oxidization, independent of the molecular area and dependent on the degree of peroxidation. Similarly, the compressibility modulus was unchanged, but shifted to larger molecular areas. The correlation between peroxidation and changes of the interaction forces between the lipid molecules is discussed.
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Affiliation(s)
- Florian Gellert
- Institute of Physics, University of Greifswald, Felix-Hausdorff-Straße 6, Greifswald D-17489, Germany
| | - Heiko Ahrens
- Institute of Physics, University of Greifswald, Felix-Hausdorff-Straße 6, Greifswald D-17489, Germany
| | - Christiane A Helm
- Institute of Physics, University of Greifswald, Felix-Hausdorff-Straße 6, Greifswald D-17489, Germany
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14
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Das A, Noack S, Schlaad H, Reiter G, Reiter R. Exploring Pathways to Equilibrate Langmuir Polymer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8184-8192. [PMID: 32569470 DOI: 10.1021/acs.langmuir.0c01268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Focusing on the phase-coexistence region in Langmuir films of poly(l-lactide), we investigated changes in nonequilibrated morphologies and the corresponding features of the isotherms induced by different experimental pathways of lateral compression and expansion. In this coexistence region, the surface pressure Π was larger than the expected equilibrium value and was found to increase upon compression, i.e., exhibited a nonhorizontal plateau. As shown earlier by using microscopic techniques [Langmuir 2019, 35, 6129-6136], in this plateau region, well-ordered mesoscopic clusters coexisted with a surrounding matrix phase. We succeeded in reducing Π either by slowing down the rate of compression or through increasing the waiting time after stopping the movement of the barriers, which allowed for relaxations in the coexistence region. Intriguingly, the most significant pressure reduction was observed when recompressing a film that had already been compressed and expanded, if the recompression was started from an area value smaller than the one anticipated for the onset of the coexistence region. This observation suggests a "self-seeding" behavior, i.e., pre-existing nuclei allowed to circumvent the nucleation step. The decrease in Π was accompanied by a transformation of the initially formed metastable mesoscopic clusters into a thermodynamically favored filamentary morphology. Our results demonstrate that it is practically impossible to obtain fully equilibrated coexisting phases in a Langmuir polymer film, neither under conditions of extremely slow continuous compression nor for long waiting times at a constant area in the coexistence region which allow for reorganization.
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Affiliation(s)
- Abhijna Das
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, Freiburg 79104, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT), University of Freiburg, Georges-Köhler-Allee 105, Freiburg 79110, Germany
| | - Sebastian Noack
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht Str. 24-25, Potsdam 14476, Germany
| | - Helmut Schlaad
- Institute of Chemistry, University of Potsdam, Karl-Liebknecht Str. 24-25, Potsdam 14476, Germany
| | - Günter Reiter
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, Freiburg 79104, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT), University of Freiburg, Georges-Köhler-Allee 105, Freiburg 79110, Germany
| | - Renate Reiter
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, Freiburg 79104, Germany
- Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT), University of Freiburg, Georges-Köhler-Allee 105, Freiburg 79110, Germany
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15
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On the Origin of the Anomalous Behavior of Lipid Membrane Properties in the Vicinity of the Chain-Melting Phase Transition. Sci Rep 2020; 10:5749. [PMID: 32238845 PMCID: PMC7113312 DOI: 10.1038/s41598-020-62577-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/28/2020] [Indexed: 11/08/2022] Open
Abstract
Biomembranes are key objects of numerous studies in biology and biophysics of great importance to medicine. A few nanometers thin quasi two-dimensional liquid crystalline membranes with bending rigidity of a few kT exhibit unusual properties and they are the focus of theoretical and experimental physics. The first order chain-melting phase transition of lipid membranes is observed to be accompanied by a pseudocritical behavior of membrane physical-chemical properties. However, the investigation of the nature of the anomalous swelling of a stack of lipid membranes in the vicinity of the transition by different groups led to conflicting conclusions about the level of critical density fluctuations and their impact on the membrane softening. Correspondingly, conclusions about the contribution of Helfrich's undulations to the effect of swelling were different. In our work we present a comprehensive complementary neutron small-angle and spin-echo study directly showing the presence of significant critical fluctuations in the vicinity of the transition which induce membrane softening. However, contrary to the existing paradigm, we demonstrate that the increased undulation forces cannot explain the anomalous swelling. We suggest that the observed effect is instead determined by the dominating increase of short-range entropic repulsion.
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16
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Langeveld SAG, Schwieger C, Beekers I, Blaffert J, van Rooij T, Blume A, Kooiman K. Ligand Distribution and Lipid Phase Behavior in Phospholipid-Coated Microbubbles and Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:3221-3233. [PMID: 32109064 PMCID: PMC7279639 DOI: 10.1021/acs.langmuir.9b03912] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Phospholipid-coated targeted microbubbles are ultrasound contrast agents that can be used for molecular imaging and enhanced drug delivery. However, a better understanding is needed of their targeting capabilities and how they relate to microstructures in the microbubble coating. Here, we investigated the ligand distribution, lipid phase behavior, and their correlation in targeted microbubbles of clinically relevant sizes, coated with a ternary mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), with PEG40-stearate and DSPE-PEG2000. To investigate the effect of lipid handling prior to microbubble production in DSPC-based microbubbles, the components were either dispersed in aqueous medium (direct method) or first dissolved and mixed in an organic solvent (indirect method). To determine the lipid-phase behavior of all components, experiments were conducted on monolayers at the air/water interface. In comparison to pure DSPC and DPPC, the ternary mixtures had an additional transition plateau around 10-12 mN/m. As confirmed by infrared reflection absorption spectroscopy (IRRAS), this plateau was due to a transition in the conformation of the PEGylated components (mushroom to brush). While the condensed phase domains had a different morphology in the ternary DPPC and DSPC monolayers on the Langmuir trough, the domain morphology was similar in the coating of both ternary DPPC and DSPC microbubbles (1.5-8 μm diameter). The ternary DPPC microbubbles had a homogenous ligand distribution and significantly less liquid condensed (LC) phase area in their coating than the DSPC-based microbubbles. For ternary DSPC microbubbles, the ligand distribution and LC phase area in the coating depended on the lipid handling. The direct method resulted in a heterogeneous ligand distribution, less LC phase area than the indirect method, and the ligand colocalizing with the liquid expanded (LE) phase area. The indirect method resulted in a homogenous ligand distribution with the largest LC phase area. In conclusion, lipid handling prior to microbubble production is of importance for a ternary mixture of DSPC, PEG40-stearate, and DSPE-PEG2000.
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Affiliation(s)
- Simone A. G. Langeveld
- Department
of Biomedical Engineering, Thoraxcenter,
Erasmus MC, 3000 CA Rotterdam, The Netherlands
- E-mail: . Phone: +31107044041
| | - Christian Schwieger
- Physical
Chemistry, Institute of Chemistry, Martin
Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
- Institute
for Biochemistry and Biotechnology, Interdisciplinary Research Center
HALOmem, Martin Luther University Halle-Wittenberg, Charles Tanford Protein Center, 06120 Halle (Saale), Germany
| | - Inés Beekers
- Department
of Biomedical Engineering, Thoraxcenter,
Erasmus MC, 3000 CA Rotterdam, The Netherlands
| | - Jacob Blaffert
- Physical
Chemistry, Institute of Chemistry, Martin
Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
| | - Tom van Rooij
- Department
of Biomedical Engineering, Thoraxcenter,
Erasmus MC, 3000 CA Rotterdam, The Netherlands
| | - Alfred Blume
- Physical
Chemistry, Institute of Chemistry, Martin
Luther University Halle-Wittenberg, 06099 Halle (Saale), Germany
| | - Klazina Kooiman
- Department
of Biomedical Engineering, Thoraxcenter,
Erasmus MC, 3000 CA Rotterdam, The Netherlands
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17
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Mussel M, Schneider MF. It sounds like an action potential: unification of electrical, chemical and mechanical aspects of acoustic pulses in lipids. J R Soc Interface 2020; 16:20180743. [PMID: 30958199 DOI: 10.1098/rsif.2018.0743] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In an ongoing debate on the physical nature of the action potential (AP), one group adheres to the electrical model of Hodgkin and Huxley, while the other describes the AP as a nonlinear acoustic pulse propagating within an interface near a transition. However, despite remarkable similarities, acoustics remains a non-intuitive mechanism for APs for the following reason. While acoustic pulses are typically associated with the propagation of density, pressure and temperature variation, APs are most commonly measured electrically. Here, we show that this discrepancy is lifted upon considering the electrical and chemical aspects of the interface, in addition to its mechanical properties. Specifically, we demonstrate how electrical and pH aspects of acoustic pulses emerge from an idealized description of the lipid interface, which is based on classical physical principles and contains no fit parameters. The pulses that emerge from the model show similarities to APs not only in qualitative shape and scales (time, velocity and voltage), but also demonstrate saturation of amplitude and annihilation upon collision.
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Affiliation(s)
- Matan Mussel
- 1 Department of Physics, Technical University of Dortmund , 44227 Dortmund , Germany.,2 Department of Physics, University of Augsburg , 86159 Augsburg , Germany
| | - Matthias F Schneider
- 1 Department of Physics, Technical University of Dortmund , 44227 Dortmund , Germany
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18
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Baba T, Takagi T, Sumaru K, Kanamori T. Effect of the fluorination degree of partially fluorinated octyl-phosphocholine surfactants on their interfacial properties and interactions with purple membrane as a membrane protein model. Chem Phys Lipids 2020; 227:104870. [DOI: 10.1016/j.chemphyslip.2020.104870] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/02/2019] [Accepted: 01/02/2020] [Indexed: 12/30/2022]
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19
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Kang KH, Schneider MF. Nonlinear pulses at the interface and its relation to state and temperature. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2020; 43:8. [PMID: 32016590 DOI: 10.1140/epje/i2020-11903-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
Environmental temperature has a well-conserved effect on the pulse velocity and excitability of excitable biological systems. The consistency suggests that the cause originates from a fundamental principle. A physical (hydrodynamic) approach has proposed that the thermodynamic state of the hydrated interface (e.g., plasma membrane) determines the pulse behavior. This implies that the temperature effect happens because the environmental temperature affects the state of the interface in any given system. To test the hypothesis, we measured temperature-dependent phase diagrams of a lipid monolayer and studied the properties of nonlinear acoustic pulses excited along the membrane. We observed that the membrane in the fluid-gel transition regime exhibited lower compressibility (i.e., stiffer) overall with increasing temperature. Nonlinear pulses excited near the transition state propagated with greater velocity with increasing temperature, and these observations were consistent with the compressibility profiles. Excitability was suppressed significantly or ceased completely when the state departed too far from the transition regime either by cooling or by heating. The overall correlation between the pulses in the membrane and in living systems as a function of temperature supports the view that the thermodynamic state of the interface and phase transition are the key to understanding pulse propagation in excitable systems.
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Affiliation(s)
- Kevin H Kang
- Department of Physics, Technical University of Dortmund, Dortmund, Germany
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20
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Luviano AS, Campos-Terán J, Langevin D, Castillo R, Espinosa G. Mechanical Properties of DPPC-POPE Mixed Langmuir Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16734-16744. [PMID: 31790592 DOI: 10.1021/acs.langmuir.9b02995] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The mechanical properties of lipid monolayers and their responses to shear and compression stresses play an important role in processes such as breathing and eye blinking. We studied the mechanical properties of Langmuir monolayers of a model mixture, composed of an unsaturated lipid, 1-palmitoyl-2-oleoyl-sn-glycero-phosphoethanolamine (POPE), and a saturated lipid, 1,2-dipalmitoyl-sn-glycero-phosphocholine (DPPC). We performed isothermal compressions and sinusoidal shear deformations of these mixed monolayers. Also, the different phases were observed with Brewster angle microscopy. We found that the mechanical behavior is affected by the miscibility of both lipids. In the two-phase region, the compression elastic modulus increases with the amount of the LC phase but does not follow the predictions of a simple effective medium model. The discrepancies arise from the fact that, upon compression, the domains grow at a rate faster than the compression rate but not fast enough to reach thermodynamic equilibrium. Before reaching the LC phase, domain percolation is observed and compression and shear moduli become equal to those of the pure LC phase. Most of the monolayers behave as viscoelastic fluids at the frequencies investigated. A minimum in the compression modulus and shear viscosity was observed for mixtures close to equimolar composition, with the minimum being accompanied by a change in domain shapes.
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Affiliation(s)
- Alberto S Luviano
- Instituto de Física y Matemáticas , Universidad Michoacana de San Nicolás de Hidalgo , 58060 Morelia , México
| | - José Campos-Terán
- Departamento de Procesos y Tecnología , Universidad Autónoma Metropolitana, Unidad Cuajimalpa , 05348 Ciudad de México , México
| | - Dominique Langevin
- Laboratoire de Physique des Solides , Université Paris-Sud , 91405 Orsay , France
| | - Rolando Castillo
- Instituto de Física , Universidad Autónoma de México , P.O. Box 20-264, 01000 Ciudad de México , México
| | - Gabriel Espinosa
- Instituto de Física y Matemáticas , Universidad Michoacana de San Nicolás de Hidalgo , 58060 Morelia , México
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21
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Shrivastava S, Kang KH, Schneider MF. Collision and annihilation of nonlinear sound waves and action potentials in interfaces. J R Soc Interface 2019; 15:rsif.2017.0803. [PMID: 29925577 DOI: 10.1098/rsif.2017.0803] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/18/2018] [Indexed: 11/12/2022] Open
Abstract
Nerve impulses, previously proposed as manifestations of nonlinear acoustic pulses localized at the plasma membrane, can annihilate upon collision. However, whether annihilation of acoustic waves at interfaces takes place is unclear. We previously showed the propagation of nonlinear sound waves that propagate as solitary waves above a threshold (super-threshold) excitation in a lipid monolayer near a phase transition. Here we investigate the interaction of these waves. Sound waves were excited mechanically via a piezo cantilever in a lipid monolayer at the air-water interface and their amplitude is reported before and after a collision. The compression amplitude was observed via Förster resonance energy transfer between donor and acceptor dyes, measured at fixed points along the propagation path in the lipid monolayer. We provide direct experimental evidence for the annihilation of two super-threshold interfacial pulses upon head-on collision in a lipid monolayer and conclude that sound waves propagating in a lipid interface can interact linearly, nonlinearly, or annihilate upon collision depending on the state of the system. Thus we show that the main characteristics of nerve impulses, i.e. solitary character, velocity, couplings, all-or-none behaviour, threshold and even annihilation are also demonstrated by nonlinear sound waves in a lipid monolayer, where they follow directly from the thermodynamic principles applied to an interface. As these principles are equally unavoidable in a nerve membrane, our observations strongly suggest that the underlying physical basis of action potentials and the observed nonlinear-pules is identical.
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Affiliation(s)
| | - Kevin H Kang
- Medizinische und Biologische Physik, Technische Universität Dortmund, Dortmund, Germany
| | - Matthias F Schneider
- Medizinische und Biologische Physik, Technische Universität Dortmund, Dortmund, Germany
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22
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Owen J, Kamila S, Shrivastava S, Carugo D, Bernardino de la Serna J, Mannaris C, Pereno V, Browning R, Beguin E, McHale AP, Callan JF, Stride E. The Role of PEG-40-stearate in the Production, Morphology, and Stability of Microbubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10014-10024. [PMID: 30485112 DOI: 10.1021/acs.langmuir.8b02516] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Phospholipid coated microbubbles are currently in widespread clinical use as ultrasound contrast agents and under investigation for therapeutic applications. Previous studies have demonstrated the importance of the coating nanostructure in determining microbubble stability and its dependence upon both composition and processing method. While the influence of different phospholipids has been widely investigated, the role of other constituents such as emulsifiers has received comparatively little attention. Herein, we present an examination of the impact of polyethylene glycol (PEG) derivatives upon microbubble structure and properties. We present data using both pegylated phospholipids and a fluorescent PEG-40-stearate analogue synthesized in-house to directly observe its distribution in the microbubble coating. We examined microbubbles of clinically relevant sizes, investigating both their surface properties and population size distribution and stability. Domain formation was observed only on the surface of larger microbubbles, which were found to contain a higher concentration of PEG-40-stearate. Lipid analogue dyes were also found to influence domain formation compared with PEG-40-stearate alone. "Squeezing out" of PEG-40-stearate was not observed from any of the microbubble sizes investigated. At ambient temperature, microbubbles formulated with DSPE-PEG(2000) were found to be more stable than those containing PEG-40-stearate. At 37 °C, however, the stability in serum was found to be the same for both formulations, and no difference in acoustic backscatter was detected. This could potentially reduce the cost of PEGylated microbubbles and facilitate simpler attachment of targeting or therapeutic species. However, whether PEG-40-stearate sufficiently shields microbubbles to inhibit physiological clearance mechanisms still requires investigation.
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Affiliation(s)
- Joshua Owen
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Sukanta Kamila
- School of Pharmacy and Pharmaceutical Science , University of Ulster , Coleraine BT52 1SA , United Kingdom
| | - Shamit Shrivastava
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Dario Carugo
- Faculty of Engineering and the Environment , University of Southampton , Highfield, Southampton SO17 1BJ , United Kingdom
| | - Jorge Bernardino de la Serna
- Central Laser Facility , STFC Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , United Kingdom
| | - Christophoros Mannaris
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Valerio Pereno
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Richard Browning
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Estelle Beguin
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
| | - Anthony P McHale
- School of Pharmacy and Pharmaceutical Science , University of Ulster , Coleraine BT52 1SA , United Kingdom
| | - John F Callan
- School of Pharmacy and Pharmaceutical Science , University of Ulster , Coleraine BT52 1SA , United Kingdom
| | - Eleanor Stride
- Old Road Campus Research Building , University of Oxford , Oxford OX3 7DQ , United Kingdom
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23
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Hatta E, Nihei K. Emergence of a linear slope region of the isotherm in the first-order liquid-expanded-liquid-condensed phase transition in Langmuir monolayers. Phys Rev E 2019; 100:022801. [PMID: 31574626 DOI: 10.1103/physreve.100.022801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Indexed: 06/10/2023]
Abstract
A nonhorizontal slope in the isotherm has been observed in the two-phase coexisting region of the first-order liquid-expanded (LE)-liquid-condensed (LC) phase transition in Langmuir monolayers for many decades. We show that the simple analysis of a phenomenological Landau free energy involving the coupling-energy contributions of molecular lateral density (ρ) with spontaneous collective chain tilt (θ) and two-dimensional strain (ɛ_{s}) inside the LC domain enables one to understand the origin of a nonhorizontal straight-line slope in the LE-LC phase coexistence region of the isotherm. The presence of ρ-ɛ_{s} coupling must be essential for the appearance of the straight-line shape of a nonhorizontal plateau in the isotherm. Moreover, it is found from the comparison of the two-dimensional contour plots of the free energy that an LE phase may persist significantly even at the later stage of the straight-line regime beyond a transition midpoint surface pressure in the presence of this coupling. The persistence of the LE phase may lead to the delay of transition progress as manifested more clearly by the appearance of a compressibility plateau in the coexistence region that indicates the existence of persistent equilibrium density fluctuations in the monolayer.
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Affiliation(s)
- Eiji Hatta
- Nanoelectronics Laboratory, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, 060-0814, Japan
| | - Ko Nihei
- Nanoelectronics Laboratory, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, 060-0814, Japan
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24
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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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25
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de Oliveira FO, Tamashiro MN. Phase Transitions in Phospholipid Monolayers: Theory Versus Experiments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:3848-3858. [PMID: 30681859 DOI: 10.1021/acs.langmuir.8b03244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Doniach lattice gas (DLG) represents a ternary-mixture statistical model, whose components, water molecules (w), ordered-chain lipids (o), and disordered-chain lipids (d)-the latter carrying a high degenerescence ω ≫ 1-are located at each site of a two-dimensional lattice. The DLG model was introduced to describe phospholipid Langmuir films at the air-water interface and can be mapped into a spin-1 model, with the single-site states s i = 0, +1, and -1 representing the three types of molecules in the system (w, o, and d), respectively. The model allows lipid-density fluctuations and has been analyzed at the mean-field approximation (Guidi, H. S.; Henriques, V. B. Phys. Rev. E 2014, 90, 052705) as well as at the pair approximation (de Oliveira, F. O.; Tamashiro, M. N. Phys. Rev. E 2019, 99, 012147). In this work, we focus on performing an explicit comparison of the theoretical predictions obtained for the DLG model at the pair approximation with isothermal monolayer compression experiments (Nielsen, L. K.; Bjørnholm, T.; Mouritsen, O. G. Langmuir 2007, 23, 11684) for the two most commonly studied saturated zwitterionic phospholipids, DMPC (1,2-dimyristoyl- sn-glycero-3-phosphocholine) and DPPC (1,2-dipalmitoyl- sn-glycero-3-phosphocholine). The model parameters obtained by fitting to the experimental data yield phase diagrams that are qualitatively consistent with the observed phase transitions on DMPC and DPPC monolayers, with the absence of a low-density gas phase. Quantitative agreement, however, was less significant partially because of the challenging reproducibility of Langmuir monolayer compression experiments, claimed in the literature to be influenced by kinetic effects.
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Affiliation(s)
- F O de Oliveira
- Instituto de Física "Gleb Wataghin" , Universidade Estadual de Campinas (UNICAMP) , Rua Sérgio Buarque de Holanda, 777, Cidade Universitária , Campinas SP 13083-859 , Brazil
| | - M N Tamashiro
- Instituto de Física "Gleb Wataghin" , Universidade Estadual de Campinas (UNICAMP) , Rua Sérgio Buarque de Holanda, 777, Cidade Universitária , Campinas SP 13083-859 , Brazil
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26
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Kensbock R, Ahrens H, Helm CA. Interactions of Monovalent and Divalent Cations with Cardiolipin Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:3624-3633. [PMID: 30732452 DOI: 10.1021/acs.langmuir.8b03637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cardiolipin is a mitochondrial phospholipid with four alkyl chains and two phosphate moieties. Tetramyristoyl cardiolipin (TMCL, (14:0)4CL) monolayers at the air-water interface are characterized by compression isotherms, which show a liquid expanded/liquid condensed phase transition. The phase transition surface pressure πc depends on the composition of the aqueous solution. In a calculation, this is attributed to the electrostatic double layer, which is induced by the head groups of the model membrane, and competitive ion binding. The intrinsic binding constant is large for protons ( KH = 10 L/mol) and small for monovalent cations ( KM (Na+, K+, Cs+) = 10-3 L/mol). The different intrinsic binding constants explain the non-monotonic behavior of πc on increasing the salt concentration: raising the monovalent salt concentration increases πc by charging the TMCL monolayer until 0.1 mol/L, then screening effects dominate and decrease πc by reducing the electrostatic repulsion between lipid head groups. When at fixed 0.15 mol/L NaCl concentration, the concentration of divalent cations is increased, πc decreases. The intrinsic binding constants of divalent cations follow the sequence Sr2+ < Mg2+ < Mn2+ ≈ Zn2+ ≈ Ca2+ ( KD,Ca = 1.2 L/mol). The predictive power of the calculations was tested with different solutions.
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Affiliation(s)
- Renko Kensbock
- Institute of Physics , University of Greifswald , Felix-Hausdorff-Straße 6 , D-17487 Greifswald , Germany
| | - Heiko Ahrens
- Institute of Physics , University of Greifswald , Felix-Hausdorff-Straße 6 , D-17487 Greifswald , Germany
| | - Christiane A Helm
- Institute of Physics , University of Greifswald , Felix-Hausdorff-Straße 6 , D-17487 Greifswald , Germany
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27
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Mussel M, Schneider MF. Similarities between action potentials and acoustic pulses in a van der Waals fluid. Sci Rep 2019; 9:2467. [PMID: 30792493 PMCID: PMC6385226 DOI: 10.1038/s41598-019-38826-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 01/08/2019] [Indexed: 11/10/2022] Open
Abstract
An action potential is typically described as a purely electrical change that propagates along the membrane of excitable cells. However, recent experiments have demonstrated that non-linear acoustic pulses that propagate along lipid interfaces and traverse the melting transition, share many similar properties with action potentials. Despite the striking experimental similarities, a comprehensive theoretical study of acoustic pulses in lipid systems is still lacking. Here we demonstrate that an idealized description of an interface near phase transition captures many properties of acoustic pulses in lipid monolayers, as well as action potentials in living cells. The possibility that action potentials may better be described as acoustic pulses in soft interfaces near phase transition is illustrated by the following similar properties: correspondence of time and velocity scales, qualitative pulse shape, sigmoidal response to stimulation amplitude (an 'all-or-none' behavior), appearance in multiple observables (particularly, an adiabatic change of temperature), excitation by many types of stimulations, as well as annihilation upon collision. An implication of this work is that crucial functional information of the cell may be overlooked by focusing only on electrical measurements.
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Affiliation(s)
- Matan Mussel
- Department of Physics, Technical University of Dortmund, 44227, Dortmund, Germany.
- Department of Physics, University of Augsburg, 86159, Augsburg, Germany.
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Matthias F Schneider
- Department of Physics, Technical University of Dortmund, 44227, Dortmund, Germany
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Micro-Surface and -Interfacial Tensions Measured Using the Micropipette Technique: Applications in Ultrasound-Microbubbles, Oil-Recovery, Lung-Surfactants, Nanoprecipitation, and Microfluidics. MICROMACHINES 2019; 10:mi10020105. [PMID: 30717224 PMCID: PMC6413238 DOI: 10.3390/mi10020105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/23/2019] [Accepted: 01/25/2019] [Indexed: 01/08/2023]
Abstract
This review presents a series of measurements of the surface and interfacial tensions we have been able to make using the micropipette technique. These include: equilibrium tensions at the air-water surface and oil-water interface, as well as equilibrium and dynamic adsorption of water-soluble surfactants and water-insoluble and lipids. At its essence, the micropipette technique is one of capillary-action, glass-wetting, and applied pressure. A micropipette, as a parallel or tapered shaft, is mounted horizontally in a microchamber and viewed in an inverted microscope. When filled with air or oil, and inserted into an aqueous-filled chamber, the position of the surface or interface meniscus is controlled by applied micropipette pressure. The position and hence radius of curvature of the meniscus can be moved in a controlled fashion from dimensions associated with the capillary tip (~5–10 μm), to back down the micropipette that can taper out to 450 μm. All measurements are therefore actually made at the microscale. Following the Young–Laplace equation and geometry of the capillary, the surface or interfacial tension value is simply obtained from the radius of the meniscus in the tapered pipette and the applied pressure to keep it there. Motivated by Franklin’s early experiments that demonstrated molecularity and monolayer formation, we also give a brief potted-historical perspective that includes fundamental surfactancy driven by margarine, the first use of a micropipette to circuitously measure bilayer membrane tensions and free energies of formation, and its basis for revolutionising the study and applications of membrane ion-channels in Droplet Interface Bilayers. Finally, we give five examples of where our measurements have had an impact on applications in micro-surfaces and microfluidics, including gas microbubbles for ultrasound contrast; interfacial tensions for micro-oil droplets in oil recovery; surface tensions and tensions-in-the surface for natural and synthetic lung surfactants; interfacial tension in nanoprecipitation; and micro-surface tensions in microfluidics.
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Wang T, Mužić T, Jackson AD, Heimburg T. The free energy of biomembrane and nerve excitation and the role of anesthetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2145-2153. [DOI: 10.1016/j.bbamem.2018.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/26/2018] [Accepted: 04/11/2018] [Indexed: 11/26/2022]
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Stetten AZ, Iasella SV, Corcoran TE, Garoff S, Przybycien TM, Tilton RD. Surfactant-induced Marangoni transport of lipids and therapeutics within the lung. Curr Opin Colloid Interface Sci 2018; 36:58-69. [PMID: 30147429 PMCID: PMC6103298 DOI: 10.1016/j.cocis.2018.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Understanding the fundamentals of surface transport on thin viscous films has important application in pulmonary drug delivery. The human lung contains a large-area interface between its complex fluid lining and inhaled air. Marangoni flows driven by surface tension gradients along this interface would promote enhanced distribution of inhaled therapeutics by carrying them from where they are deposited in the upper airways, along the fluid interface to deeper regions of the lung. Motivated by the potential to improve therapies for acute and chronic lung diseases, we review recent progress in modeling and experimental studies of Marangoni transport induced by the deposition of surfactant-containing microliter drops and liquid aerosols (picoliter drops) onto a fluid interface. The roles of key system variables are identified, including surfactant solubility, drop miscibility with the subphase, and the thickness, composition and surface properties of the subphase liquid. Of particular interest is the unanticipated but crucial role of aerosol processing to achieve Marangoni transport via phospholipid vesicle dispersions, which are likely candidates for a biocompatible delivery system. Progress in this field has the potential to not only improve outcomes in patients with chronic and acute lung diseases, but also to further our understanding of surface transport in complex systems.
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Affiliation(s)
- Amy Z. Stetten
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Steven V. Iasella
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | | | - Stephen Garoff
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Todd M. Przybycien
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Robert D. Tilton
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Carnegie Mellon Center for Complex Fluids Engineering, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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Xu L, Bosiljevac G, Yu K, Zuo YY. Melting of the Dipalmitoylphosphatidylcholine Monolayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:4688-4694. [PMID: 29565138 DOI: 10.1021/acs.langmuir.8b00579] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Langmuir monolayer self-assembled at the air-water interface represents an excellent model for studying phase transition and lipid polymorphism in two dimensions. Compared with numerous studies of phospholipid phase transitions induced by isothermal compression, there are very scarce reports on two-dimensional phase transitions induced by isobaric heating. This is mainly due to technical difficulties of continuously regulating temperature variations while maintaining a constant surface pressure in a classical Langmuir-type film balance. Here, with technological advances in constrained drop surfactometry and closed-loop axisymmetric drop shape analysis, we studied the isobaric heating process of the dipalmitoylphosphatidylcholine (DPPC) monolayer. It is found that temperature and surface pressure are two equally important intensive properties that jointly determine the phase behavior of the phospholipid monolayer. We have determined a critical point of the DPPC monolayer at a temperature of 44 °C and a surface pressure of 57 mN/m. Beyond this critical point, no phase transition can exist in the DPPC monolayer, either by isothermal compression or by isobaric heating. The melting process of the DPPC monolayer studied here provides novel insights into the understanding of a wide range of physicochemical and biophysical phenomena, such as surface thermodynamics, critical phenomena, and biophysical study of pulmonary surfactants.
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Affiliation(s)
- Lu Xu
- Department of Mechanical Engineering , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - Gordon Bosiljevac
- Department of Mechanical Engineering , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - Kyle Yu
- Department of Mechanical Engineering , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - Yi Y Zuo
- Department of Mechanical Engineering , University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
- Department of Pediatrics, John A. Burns School of Medicine , University of Hawaii , Honolulu , Hawaii 96826 , United States
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Gonçalves da Silva AMPS. Interaction of Hydrophobic Ionic Liquids with Lipids in Langmuir Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3797-3805. [PMID: 29518336 DOI: 10.1021/acs.langmuir.7b04164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The interaction of two ionic liquids, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)-imide and trihexyl(tetradecyl)phosphonium dicyanamide, [P6 6 6 14][Ntf2] and [P6 6 6 14]/[N(CN)2], with several long-chained lipids with a different net charge at the hydrophilic group, a cationic surfactant, dioctadecyldimethylammonium bromide (DODAB), a zwitterionic phospholipid (DPPC), an anionic phospholipid (DPPG), and the neutral stearic acid (SA), was investigated at the air-water interface using the Langmuir trough technique. The experimental surface pressure-area (π- A) isotherms obtained for selected compositions of each binary system reveal distinct interfacial behavior. The degree and the nature of the IL-lipid interaction strongly depend on the charge distribution in the lipid polar group. Miscibility, or immiscibility, at the monolayer was inferred from the comparison of the experimental π- A isotherm with the theoretical curve calculated for the corresponding ideal mixture based on the π- A isotherms of the pure components. Phase separation and partial miscibility occurred in IL/DODAB and IL/DPPC systems, respectively. In both the IL/DPPG and the IL/SA systems, a new catanionic complex was found. For the IL/SA system, the catanionic complex formation varies with the subphase pH.
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Mielke S, Habe T, Veschgini M, Liu X, Yoshikawa K, Krafft MP, Tanaka M. Emergence of Strong Nonlinear Viscoelastic Response of Semifluorinated Alkane Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2489-2496. [PMID: 29359940 DOI: 10.1021/acs.langmuir.7b03997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Viscoelasticity of monolayers of fluorocarbon/hydrocarbon tetrablock amphiphiles di(FnHm) ((CnF2n+1CH2)(Cm-2H2m-3)CH-CH(CnF2n+1CH2)(Cm-2H2m-3)) was characterized by interfacial dilational rheology under periodic oscillation of the moving barriers at the air/water interface. Because the frequency dispersion of the response function indicated that di(FnHm) form two-dimensional gels at the interface, the viscosity and elasticity of di(FnHm) were first analyzed with the classical Kelvin-Voigt model. However, the global shape of stress response functions clearly indicated the emergence of a nonlinearity even at very low surface pressures (π ≈ 5 mN/m) and small strain amplitudes (u0 = 1%). The Fourier-transformed response function of higher harmonics exhibited a clear increase in the intensity only from odd modes, corresponding to the nonlinear elastic component under reflection because of mirror symmetry. The emergence of strong nonlinear viscoelasticity of di(FnHm) at low surface pressures and strain amplitudes is highly unique compared to the nonlinear viscoelasticity of other surfactant systems reported previously, suggesting a large potential of such fluorocarbon/hydrocarbon molecules to modulate the mechanics of interfaces using the self-assembled domains of small molecules.
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Affiliation(s)
- Salomé Mielke
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
| | - Taichi Habe
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
| | - Mariam Veschgini
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
| | - Xianhe Liu
- Institut Charles Sadron (CNRS), University of Strasbourg , 67034 Strasbourg, France
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University , 610-0321 Kyotanabe, Japan
| | - Marie Pierre Krafft
- Institut Charles Sadron (CNRS), University of Strasbourg , 67034 Strasbourg, France
| | - Motomu Tanaka
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
- Institute for Advanced Study, Kyoto University , 606-8501 Kyoto, Japan
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Pérez-Camacho MI, Ruiz-Suárez JC. Propagation of a thermo-mechanical perturbation on a lipid membrane. SOFT MATTER 2017; 13:6555-6561. [PMID: 28895965 DOI: 10.1039/c7sm00978j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The propagation of sound waves on lipid monolayers supported on water has been previously studied during the melting transition. Since changes in volume, area, and compressibility in lipid membranes have biological relevance, the observed sound propagation is of paramount importance. However, it is unknown what would occur on a lipid bilayer, which is a more approximate model of a cell membrane. With the aim to answer this relevant question, we built an experimental setup to assemble long artificial lipid membranes. We found that if these membranes are heated in order to force local melting, a thermo-mechanical perturbation propagates a long distance. Our findings may support the existence of solitary waves, postulated to explain the propagation of isentropic signals together with the action potential in neurons.
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Affiliation(s)
- M I Pérez-Camacho
- CINVESTAV-Monterrey, Autopista Nueva al Aeropuerto Km. 9.5, Apodaca, Nuevo León 66600, Mexico.
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Borrell JH, Domènech Ò. Critical Temperature of 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine Monolayers and Its Possible Biological Relevance. J Phys Chem B 2017. [PMID: 28636818 DOI: 10.1021/acs.jpcb.7b04021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Because transmembrane proteins (TMPs) can be obtained with sufficient purity for X-ray diffraction studies more frequently than decades ago, their mechanisms of action may now be elucidated. One of the pending issues is the actual interplay between transmembrane proteins and membrane lipids. There is strong evidence of the involvement of specific lipids with some membrane proteins, such as the potassium crystallographically sited activation channel (KcsA) of Streptomyces lividans and the secondary transporter of lactose LacY of Escherichia coli, the activities of which are associated with the presence of anionic phospholipids such as the phosphatidylglycerol (PG) and phosphatidyethanolamine (PE), respectively. Other proteins such as the large conductance mechanosensitive channel (MscL) of E. coli seem to depend on the adaptation of specific phospholipids to the irregular surface of the integral membrane protein. In this work we investigated the lateral compressibility of two homoacid phosphatidylethanolamines (one with both acyl chains unsaturated (DOPE), the other with the acyl chains saturated (DPPE)) and the heteroacid phosphatidyletanolamine (POPE) and their mixtures with POPG. The liquid expanded (LE) to liquid condensed (LC) transition was observed in POPE at a temperature below its critical temperature (Tc = 36 °C). Because Tc lies below the physiological temperature, the occurrence of this phase transition may have something to do with the functioning of LacY. This magnitude is discussed within the context of the experiments carried out at temperatures below the Tc of POPE at which the activity of Lac Y and other TMPs are frequently studied.
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Affiliation(s)
- Jordi H Borrell
- Department of Pharmacy, Pharmaceutical Technology and Physical Chemistry, Faculty of Pharmacy and Food Sciences and ‡Institute of Nanoscience and Nanotechnology (IN2UB), University of Barcelona (UB) , E-08028 Barcelona, Spain
| | - Òscar Domènech
- Department of Pharmacy, Pharmaceutical Technology and Physical Chemistry, Faculty of Pharmacy and Food Sciences and ‡Institute of Nanoscience and Nanotechnology (IN2UB), University of Barcelona (UB) , E-08028 Barcelona, Spain
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The Flip-Flop Diffusion Mechanism across Lipids in a Hybrid Bilayer Membrane. Biophys J 2017; 110:2451-2462. [PMID: 27276263 DOI: 10.1016/j.bpj.2016.04.041] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 04/03/2016] [Accepted: 04/25/2016] [Indexed: 12/31/2022] Open
Abstract
In this study, we examine the mechanism of flip-flop diffusion of proton carriers across the lipid layer of a hybrid bilayer membrane (HBM). The HBM consists of a lipid monolayer appended on top of a self-assembled monolayer containing a Cu-based O2 reduction catalyst on a Au electrode. The flip-flop diffusion rates of the proton carriers dictate the kinetics of O2 reduction by the electrocatalyst. By varying both the tail lengths of the proton carriers and the lipids, we find the combinations of lengths that maximize the flip-flop diffusion rate. These experimental results combined with biophysical modeling studies allow us to propose a detailed mechanism for transmembrane flip-flop diffusion in HBM systems, which involves the bending of the alkyl tail of the proton carrier as the rate-determining step. Additional studies with an unbendable proton carrier further validate these mechanistic findings.
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Boisselier É, Demers É, Cantin L, Salesse C. How to gather useful and valuable information from protein binding measurements using Langmuir lipid monolayers. Adv Colloid Interface Sci 2017; 243:60-76. [PMID: 28372794 DOI: 10.1016/j.cis.2017.03.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 03/14/2017] [Accepted: 03/15/2017] [Indexed: 12/22/2022]
Abstract
This review presents data on the influence of various experimental parameters on the binding of proteins onto Langmuir lipid monolayers. The users of the Langmuir methodology are often unaware of the importance of choosing appropriate experimental conditions to validate the data acquired with this method. The protein Retinitis pigmentosa 2 (RP2) has been used throughout this review to illustrate the influence of these experimental parameters on the data gathered with Langmuir monolayers. The methods detailed in this review include the determination of protein binding parameters from the measurement of adsorption isotherms, infrared spectra of the protein in solution and in monolayers, ellipsometric isotherms and fluorescence micrographs.
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Affiliation(s)
- Élodie Boisselier
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
| | - Éric Demers
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Christian Salesse
- CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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da Rocha Junior C, Caseli L. Adsorption and enzyme activity of asparaginase at lipid Langmuir and Langmuir-Blodgett films. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 73:579-584. [PMID: 28183647 DOI: 10.1016/j.msec.2016.12.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/23/2016] [Accepted: 12/09/2016] [Indexed: 11/25/2022]
Abstract
In this present work, the surface activity of the enzyme asparaginase was investigated at the air-water interface, presenting surface activity in high ionic strengths. Asparaginase was incorporated in Langmuir monolayers of the phospholipid dipalmitoylphosphatidylcholine (DPPC), forming a mixed film, which was characterized with surface pressure-area isotherms, surface potential-area isotherms, polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS), and Brewster angle microscopy (BAM). The adsorption of the enzyme at the air-water interface condensed the lipid monolayer and increased the film compressibility at high surface pressures. Amide bands in the PM-IRRAS spectra were identified, with the CN and CO dipole moments lying parallel to monolayer plane, revealing the structuring of the enzyme into α-helices and β-sheets. The floating monolayers were transferred to solid supports as Langmuir-Blodgett (LB) films and characterized with fluorescence spectroscopy and atomic force microscopy. Catalytic activities of the films were measured and compared to the homogenous medium. The enzyme accommodated in the LB films preserved more than 78% of the enzyme activity after 30days, in contrast for the homogeneous medium, which preserved less than 13%. The method presented in this work not only allows for an enhanced catalytic activity, but also can help explain why certain film architectures exhibit better performance.
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Affiliation(s)
- Carlos da Rocha Junior
- Institute of Environmental, Chemical and Phamaceutical Sciences, Federal University of São Paulo, Diadema, SP, Brazil
| | - Luciano Caseli
- Institute of Environmental, Chemical and Phamaceutical Sciences, Federal University of São Paulo, Diadema, SP, Brazil.
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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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Zuo YY, Chen R, Wang X, Yang J, Policova Z, Neumann AW. Phase Transitions in Dipalmitoylphosphatidylcholine Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8501-6. [PMID: 27479299 PMCID: PMC5522960 DOI: 10.1021/acs.langmuir.6b01482] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A self-assembled phospholipid monolayer at an air-water interface is a well-defined model system for studying surface thermodynamics, membrane biophysics, thin-film materials, and colloidal soft matter. Here we report a study of two-dimensional phase transitions in the dipalmitoylphosphatidylcholine (DPPC) monolayer at the air-water interface using a newly developed methodology called constrained drop surfactometry (CDS). CDS is superior to the classical Langmuir balance in its capacity for rigorous temperature control and leak-proof environments, thus making it an ideal alternative to the Langmuir balance for studying lipid polymorphism. In addition, we have developed a novel Langmuir-Blodgett (LB) transfer technique that allows the direct transfer of lipid monolayers from the droplet surface under well-controlled conditions. This LB transfer technique permits the direct visualization of phase coexistence in the DPPC monolayer. With these technological advances, we found that the two-dimensional phase behavior of the DPPC monolayer is analogous to the three-dimensional phase transition of a pure substance. This study has implications in the fundamental understanding of surface thermodynamics as well as applications such as self-assembled monolayers and pulmonary surfactant biophysics.
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Affiliation(s)
- Yi Y. Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
- Department of Pediatrics, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96826, United States
| | - Rimei Chen
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Xianju Wang
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
- College of Electronic Engineering, South China Agricultural University, Guangzhou, China 510642
| | - Jinlong Yang
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Zdenka Policova
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario Canada, M5S 3G8
| | - A. Wilhelm Neumann
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario Canada, M5S 3G8
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Schwieger C, Blaffert J, Li Z, Kressler J, Blume A. Perfluorinated Moieties Increase the Interaction of Amphiphilic Block Copolymers with Lipid Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8102-15. [PMID: 27442444 DOI: 10.1021/acs.langmuir.6b01574] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The interaction of amphiphilic and triphilic block copolymers with lipid monolayers has been studied. Amphiphilic triblock copolymer PGMA20-PPO34-PGMA20 (GP) is composed of a hydrophobic poly(propylene oxide) (PPO) middle block that is flanked by two hydrophilic poly(glycerol monomethacrylate) (PGMA) side blocks. The attachment of a perfluoro-n-nonyl residue (F9) to either end of GP yields a triphilic polymer with the sequence F9-PGMA20-PPO34-PGMA20-F9 (F-GP). The F9 chains are fluorophilic, i.e., they have a tendency to demix in hydrophilic as well as in lipophilic environments. We investigated (i) the adsorption of both polymers to differently composed lipid monolayers and (ii) the compression behavior of mixed polymer/lipid monolayers. The lipid monolayers are composed of phospholipids with PC or PE headgroups and acyl chains of different length and saturation. Both polymers interact with lipid monolayers by inserting their hydrophobic moieties (PPO, F9). The interaction is markedly enhanced in the presence of F9 chains, which act as membrane anchors. GP inserts into lipid monolayers up to a surface pressure of 30 mN/m, whereas F-GP inserts into monolayers at up to 45 mN/m, suggesting that F-GP also inserts into lipid bilayer membranes. The adsorption of both polymers to lipid monolayers with short acyl chains is favored. Upon compression, a two-step squeeze-out of F-GP occurs, with PPO blocks being released into the aqueous subphase at 28 mN/m and the F9 chains being squeezed out at 48 mN/m. GP is squeezed out in one step at 28 mN/m because of the lack of F9 anchor groups. The liquid expanded (LE) to liquid condensed (LC) phase transition of DPPC and DMPE is maintained in the presence of the polymers, indicating that the polymers can be accommodated in LE- and LC-phase monolayers. These results show how fluorinated moieties can be included in the rational design of membrane-binding polymers.
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Affiliation(s)
- Christian Schwieger
- Institute of Chemistry, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany
| | - Jacob Blaffert
- Institute of Chemistry, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany
| | - Zheng Li
- Institute of Chemistry, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany
| | - Jörg Kressler
- Institute of Chemistry, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany
| | - Alfred Blume
- Institute of Chemistry, Martin Luther University Halle-Wittenberg , D-06099 Halle (Saale), Germany
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42
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Tse ECM, Barile CJ, Kirchschlager NA, Li Y, Gewargis JP, Zimmerman SC, Hosseini A, Gewirth AA. Proton transfer dynamics control the mechanism of O2 reduction by a non-precious metal electrocatalyst. NATURE MATERIALS 2016; 15:754-9. [PMID: 27135859 DOI: 10.1038/nmat4636] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 01/28/2016] [Indexed: 05/25/2023]
Abstract
Many chemical and biological processes involve the transfer of both protons and electrons. The complex mechanistic details of these proton-coupled electron transfer (PCET) reactions require independent control of both electron and proton transfer. In this report, we make use of lipid-modified electrodes to modulate proton transport to a Cu-based catalyst that facilitates the O2 reduction reaction (ORR), a PCET process important in fuel cells and O2 reduction enzymes. By quantitatively controlling the kinetics of proton transport to the catalyst, we demonstrate that undesired side products such as H2O2 and O2(-) arise from a mismatch between proton and electron transfer rates. Whereas fast proton kinetics induce H2O2 formation and sluggish proton flux produces O2(-), proton transfer rates commensurate with O-O bond breaking rates ensure that only the desired H2O product forms. This fundamental insight aids in the development of a comprehensive framework for understanding the ORR and PCET processes in general.
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Affiliation(s)
- Edmund C M Tse
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Christopher J Barile
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Nicholas A Kirchschlager
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Ying Li
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - John P Gewargis
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Steven C Zimmerman
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Ali Hosseini
- Manufacturing Systems Ltd., Auckland 0632, New Zealand
| | - Andrew A Gewirth
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
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43
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Fichtl B, Shrivastava S, Schneider MF. Protons at the speed of sound: Predicting specific biological signaling from physics. Sci Rep 2016; 6:22874. [PMID: 27216038 PMCID: PMC4877590 DOI: 10.1038/srep22874] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 02/22/2016] [Indexed: 01/23/2023] Open
Abstract
Local changes in pH are known to significantly alter the state and activity of proteins and enzymes. pH variations induced by pulses propagating along soft interfaces (e.g. membranes) would therefore constitute an important pillar towards a physical mechanism of biological signaling. Here we investigate the pH-induced physical perturbation of a lipid interface and the physicochemical nature of the subsequent acoustic propagation. Pulses are stimulated by local acidification and propagate - in analogy to sound - at velocities controlled by the interface's compressibility. With transient local pH changes of 0.6 directly observed at the interface and velocities up to 1.4 m/s this represents hitherto the fastest protonic communication observed. Furthermore simultaneously propagating mechanical and electrical changes in the lipid interface are detected, exposing the thermodynamic nature of these pulses. Finally, these pulses are excitable only beyond a threshold for protonation, determined by the pKa of the lipid head groups. This protonation-transition plus the existence of an enzymatic pH-optimum offer a physical basis for intra- and intercellular signaling via sound waves at interfaces, where not molecular structure and mechano-enyzmatic couplings, but interface thermodynamics and thermodynamic transitions are the origin of the observations.
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Affiliation(s)
- Bernhard Fichtl
- University of Augsburg, Experimental Physics I, Augsburg, 86159, Germany.,Nanosystems Initiative Munich NIM, Schellingstr. 4, 80799 München, Germany
| | - Shamit Shrivastava
- Medizinische und Biologische Physik, Technische Universität Dortmund, Otto-Hahn Str. 4, 44227 Dortmund, Germany.,University of Oxford, IBME Old Road Campus Research Building Oxford, OX3 7DQ, UK
| | - Matthias F Schneider
- Medizinische und Biologische Physik, Technische Universität Dortmund, Otto-Hahn Str. 4, 44227 Dortmund, Germany
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Degen P, Wieland DCF, Strötges C. Mixed Layers of Nonionic Dendritic Amphiphiles and DPPC at the Water Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:11851-11857. [PMID: 26447650 DOI: 10.1021/acs.langmuir.5b02702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nonionic dendritic amphiphiles that self-assemble into defined supramolecular aggregates are useful for the efficient solubilization of active agents, for example, in drug delivery. We investigated a new class of dendritic amphiphiles based on a hydrophilic polyol dendron head connected to a two-chain hydrophobic block. In analogy to phospholipids, these molecules form well-organized layers in bulk (vesicles) or at the water surface (Langmuir monolayer). The actual study focuses on the phase behavior and microscopic structure of mixed Langmuir layers of theses dendritic amphiphiles with the well-known phospholipid DPPC. The combination of surface pressure area isotherms with X-ray grazing incident diffraction and Brewster angle microscopy gives us information on the phase behavior of the mixed monolayers and the orientation of the amphiphiles inside the condensed domains with molecular resolution. We could prove that the dendritic generation and, by this, the headgroup size of the amphiphilic molecules have a significant influence on their interaction with DPPC at the air-water interface. Thus, our findings are important for the understanding of mixed lipid membranes in general as well as for the preparation of artificial membranes and vesicles with adjustable properties, e.g., their drug delivery potential.
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Affiliation(s)
- Patrick Degen
- Institut für Physikalische Chemie II, Technische Universität Dortmund , Otto-Hahn-Str. 6, 44227 Dortmund, Germany
| | - D C Florian Wieland
- Institut für Metallische Biomaterialien, Helmholtz Zentrum Geestacht , Max-Planck Straße 1, 21502 Geesthacht, Germany
| | - Christian Strötges
- Institut für Physikalische Chemie II, Technische Universität Dortmund , Otto-Hahn-Str. 6, 44227 Dortmund, Germany
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Deschênes L, Lyklema J, Danis C, Saint-Germain F. Phase transitions in polymer monolayers: Application of the Clapeyron equation to PEO in PPO-PEO Langmuir films. Adv Colloid Interface Sci 2015; 222:199-214. [PMID: 25488283 DOI: 10.1016/j.cis.2014.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 11/04/2014] [Accepted: 11/05/2014] [Indexed: 11/19/2022]
Abstract
In this paper we investigate the application of the two-dimensional Clapeyron law to polymer monolayers. This is a largely unexplored area of research. The main problems are (1) establishing if equilibrium is reached and (2) if so, identifying and defining phases as functions of the temperature. Once this is validated, the Clapeyron law allows us to obtain the entropy and enthalpy differences between two coexisting phases. In turn, this information can be used to obtain insight into the conformational properties of the films and changes therein. This approach has a wide potential for obtaining additional information on polymer adsorption at interfaces and the structure of their monolayer films. The 2D Clapeyron law was applied emphasizing polyethylene oxide (PEO) in polypropylene oxide (PPO)-PEO block copolymers, based on new well-defined data for their Langmuir films. Values for enthalpy per monomer of 0.12 and 0.23 kT were obtained for the phase transition of two different PEO chains (Neo of 2295 and 409, respectively). This enthalpy was estimated to correspond to 1.2±0.4 kT per EO monomer present in train conformation at the air/water interface.
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Affiliation(s)
- Louise Deschênes
- Food Research and Development Centre, 3600 Casavant Blvd West, Saint-Hyacinthe, QC J2S 8E3, Canada
| | - Johannes Lyklema
- Laboratory for Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, Netherlands
| | - Claude Danis
- Food Research and Development Centre, 3600 Casavant Blvd West, Saint-Hyacinthe, QC J2S 8E3, Canada
| | - François Saint-Germain
- Food Research and Development Centre, 3600 Casavant Blvd West, Saint-Hyacinthe, QC J2S 8E3, Canada
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46
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Chandran S, Dold S, Buvignier A, Krannig KS, Schlaad H, Reiter G, Reiter R. Tuning Morphologies of Langmuir Polymer Films Through Controlled Relaxations of Non-Equilibrium States. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6426-6435. [PMID: 26000718 DOI: 10.1021/acs.langmuir.5b01212] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Langmuir polymers films (LPFs) frequently form nonequilibrium states which are manifested in a decay of the surface pressure with time when the system is allowed to relax. Monitoring and manipulating the temporal evolution of these relaxations experimentally helps to shed light on the associated molecular reorganization processes. We present a systematic study based on different compression protocols and show how these reorganization processes impact the morphology of LPFs of poly(γ-benzyl-L-glutamate)(PBLG), visualized by means of atomic force microscopy. Upon continuous compression, a fibrillar morphology was formed with a surface decorated by squeezed-out islands. By contrast, stepwise compression promoted the formation of a fibrillar network with a bimodal distribution of fibril diameters, caused by merging of fibrils. Finally, isobaric compression induced in-plane compaction of the monolayer. We correlate these morphological observations with the kinetics of the corresponding relaxations, described best by a sum of two exponential functions with different time scales representing two molecular processes. We discuss the observed kinetics and the resulting morphologies in the context of nucleation and growth, characteristic for first-order phase transitions. Our results demonstrate that the preparation conditions of LPFs have tremendous impact on ordering of the molecules and hence various macroscopic properties of such films.
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Affiliation(s)
| | - Stefanie Dold
- †Institute of Physics, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany
| | - Amaury Buvignier
- ‡Ecole Nationale Superieure de Chimie de Rennes, 35708 Rennes Cedex 7, France
| | - Kai-Steffen Krannig
- §Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Potsdam D-14424, Germany
| | - Helmut Schlaad
- §Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Potsdam D-14424, Germany
- ∥Institute of Chemistry, Universität Potsdam, Potsdam D-14476, Germany
| | - Günter Reiter
- †Institute of Physics, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany
- #Freiburg Centre for Interactive Materials and Bio-inspired Technologies, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany
- ¶Freiburg Materials Research Center, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany
| | - Renate Reiter
- †Institute of Physics, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany
- ¶Freiburg Materials Research Center, Albert Ludwigs Universität Freiburg, Freiburg 79085, Germany
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47
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McUmber AC, Larson NR, Randolph TW, Schwartz DK. Molecular trajectories provide signatures of protein clustering and crowding at the oil/water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5882-5890. [PMID: 25950404 DOI: 10.1021/acs.langmuir.5b00984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using high throughput single-molecule total internal reflection fluorescence microscopy (TIRFM), we have acquired molecular trajectories of bovine serum albumin (BSA) and hen egg white lysozyme during protein layer formation at the silicone oil-water interface. These trajectories were analyzed to determine the distribution of molecular diffusion coefficients, and for signatures of molecular crowding/caging, including subdiffusive motion and temporal anticorrelation of the instantaneous velocity vector. The evolution of these properties with aging time of the interface was compared with dynamic interfacial tension measurements. For both lysozyme and BSA, we observed an overall slowing of protein objects, the onset of both subdiffusive and anticorrelated motion (associated with crowding), and a decrease in the interfacial tension with aging time. For lysozyme, all of these phenomena occurred virtually simultaneously, consistent with a homogeneous model of layer formation that involves gradual crowding of weakly interacting proteins. For BSA, however, the slowing occurred first, followed by the signatures of crowding/caging, followed by a decrease in interfacial tension, consistent with a heterogeneous model of layer formation involving the formation of protein clusters. The application of microrheological methods to single molecule trajectories described here provides an unprecedented level of mechanistic interpretation of interfacial events that occurred over a wide range of interfacial protein coverage.
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Affiliation(s)
- Aaron C McUmber
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Nicholas R Larson
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Theodore W Randolph
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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48
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Ghazvini S, Ricke B, Zasadzinski JA, Dhar P. Monitoring phases and phase transitions in phosphatidylethanolamine monolayers using active interfacial microrheology. SOFT MATTER 2015; 11:3313-21. [PMID: 25782993 PMCID: PMC4408260 DOI: 10.1039/c4sm02900c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Active interfacial microrheology is a sensitive tool to detect phase transitions and headgroup order in phospholipid monolayers. The re-orientation of a magnetic nickel nanorod is used to explore changes in the surface rheology of 1,2-dilauroyl-sn-glycero-3-phosphoethanolamine (DLPE) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), which differ by two CH2 groups in their alkyl chains. Phosphatidylethanolamines such as DLPE and DMPE are a major component of cell membranes in bacteria and in the nervous system. At room temperature, DLPE has a liquid expanded (LE) phase for surface pressure, Π < ∼38 mN m(-1); DMPE has an LE phase for Π < ∼7 mN m(-1). In their respective LE phases, DLPE and DMPE show no measurable change in surface viscosity with Π, consistent with a surface viscosity <10(-9) N s m(-1), the resolution of our technique. However, there is a measurable, discontinuous change in the surface viscosity at the LE to liquid condensed (LC) transition for both DLPE and DMPE. This discontinuous change is correlated with a significant increase in the surface compressibility modulus (or isothermal two-dimensional bulk modulus). In the LC phase of DMPE there is an exponential increase in surface viscosity with Π consistent with a two-dimensional free area model. The second-order LC to solid (S) transition in DMPE is marked by an abrupt onset of surface elasticity; there is no measurable elasticity in the LC phase. A measurable surface elasticity in the S phase suggests a change in the molecular ordering or interactions of the DMPE headgroups that is not reflected in isotherms or in grazing incidence X-ray diffraction. This onset of measurable elasticity is also seen in DLPE, even though no indication of a LC-S transition is visible in the isotherms.
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Affiliation(s)
- Saba Ghazvini
- Department of Chemical Engineering, University of Kansas, Lawrence, KS 66045, USA.
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49
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Catapano ER, Lillo MP, García Rodríguez C, Natale P, Langevin D, Monroy F, López-Montero I. Thermomechanical transitions of egg-ceramide monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3912-3918. [PMID: 25763506 DOI: 10.1021/acs.langmuir.5b00229] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ceramides have unique biophysical properties. Their high melting temperature and their ability to form lateral domains have converted ceramides into the paradigm of rigid lipids. Here, using shear surface rheology of egg-ceramide Langmuir monolayers, a solid to fluid transition was evidenced as a vanishing shear rigidity at lower temperatures than the lipid melting temperature. Such a mechanical transition, which depends on the lipid lateral pressure, was found in a broad range temperature (40-50 °C). The solid to fluid transition was correlated to a LC to LC+LE phase transition, as confirmed by BAM experiments. Interestingly, together with the softening transition, a supercooling process compatible with a glassy behavior was found upon freezing. A new phase scenario is then depicted that broadens the mechanical behavior of natural ceramides. The phase diversity of ceramides might have important implications in their physiological roles.
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Affiliation(s)
- Elisa R Catapano
- †Departamento de Química Física I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
- ‡Instituto de Investigación Hospital 12 de Octubre (i+12), Avda. de Córdoba s/n, 28041 Madrid, Spain
| | - M P Lillo
- §Grupo de Biofísica Molecular, Instituto Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | - C García Rodríguez
- §Grupo de Biofísica Molecular, Instituto Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | - P Natale
- †Departamento de Química Física I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
- ‡Instituto de Investigación Hospital 12 de Octubre (i+12), Avda. de Córdoba s/n, 28041 Madrid, Spain
| | - D Langevin
- ∥Laboratoire de Physique des Solides, Université Paris-Sud, Rue Nicolas Appert Bâtiment 510, 91405 Orsay, France
| | - F Monroy
- †Departamento de Química Física I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
- ‡Instituto de Investigación Hospital 12 de Octubre (i+12), Avda. de Córdoba s/n, 28041 Madrid, Spain
| | - I López-Montero
- †Departamento de Química Física I, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
- ‡Instituto de Investigación Hospital 12 de Octubre (i+12), Avda. de Córdoba s/n, 28041 Madrid, Spain
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50
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Shrivastava S, Schneider MF. Evidence for two-dimensional solitary sound waves in a lipid controlled interface and its implications for biological signalling. J R Soc Interface 2015; 11:20140098. [PMID: 24942845 DOI: 10.1098/rsif.2014.0098] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biological membranes by virtue of their elastic properties should be capable of propagating localized perturbations analogous to sound waves. However, the existence and the possible role of such waves in communication in biology remain unexplored. Here, we report the first observations of two-dimensional solitary elastic pulses in lipid interfaces, excited mechanically and detected by FRET. We demonstrate that the nonlinearity near a maximum in the susceptibility of the lipid monolayer results in solitary pulses that also have a threshold for excitation. These experiments clearly demonstrate that the state of the interface regulates the propagation of pulses both qualitatively and quantitatively. Finally, we elaborate on the striking similarity of the observed phenomenon to nerve pulse propagation and a thermodynamic basis of cell signalling in general.
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Affiliation(s)
- Shamit Shrivastava
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
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