1
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Skog A, Paracini N, Gerelli Y, Skepö M. Translocation of Antimicrobial Peptides across Model Membranes: The Role of Peptide Chain Length. Mol Pharm 2024; 21:4082-4097. [PMID: 38993084 PMCID: PMC11304388 DOI: 10.1021/acs.molpharmaceut.4c00450] [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: 04/25/2024] [Revised: 06/28/2024] [Accepted: 06/28/2024] [Indexed: 07/13/2024]
Abstract
Cushioned lipid bilayers are structures consisting of a lipid bilayer supported on a solid substrate with an intervening layer of soft material. They offer possibilities for studying the behavior and interactions of biological membranes more accurately under physiological conditions. In this work, we continue our studies of cushion formation induced by histatin 5 (24Hst5), focusing on the effect of the length of the peptide chain. 24Hst5 is a short, positively charged, intrinsically disordered saliva peptide, and here, both a shorter (14Hst5) and a longer (48Hst5) peptide variant were evaluated. Experimental surface active techniques were combined with coarse-grained Monte Carlo simulations to obtain information about these peptides. Results show that at 10 mM NaCl, both the shorter and the longer peptide variants behave like 24Hst5 and a cushion below the bilayer is formed. At 150 mM NaCl, however, no interaction is observed for 24Hst5. On the contrary, a cushion is formed both in the case of 14Hst5 and 48Hst5, and in the latter, an additional thick, diffuse, and highly hydrated layer of peptide and lipid molecules is formed, on top of the bilayer. Similar trends were observed from the simulations, which allowed us to hypothesize that positively charged patches of the amino acids lysine and arginine in all three peptides are essential for them to interact with and translocate over the bilayer. We therefore hypothesize that electrostatic interactions are important for the interaction between the solid-supported lipid bilayers and the peptide depending on the linear charge density through the primary sequence and the positively charged patches in the sequence. The understanding of how, why, and when the cushion is formed opens up the possibility for this system to be used in the research and development of new drugs and pharmaceuticals.
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Affiliation(s)
- Amanda
E. Skog
- Division
of Computational Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00, Lund, Sweden
| | - Nicolò Paracini
- Institut
Laue-Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Yuri Gerelli
- Institute
for Complex Systems - National Research Council (ISC−CNR), Piazzale Aldo Moro 2, 00185 Roma, Italy
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Marie Skepö
- Division
of Computational Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00, Lund, Sweden
- NanoLund, Lund
University, Box
118, 22100 Lund, Sweden
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2
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Villanueva ME, Bar L, Porcar L, Gerelli Y, Losada-Pérez P. Resolving the interactions between hydrophilic CdTe quantum dots and positively charged membranes at the nanoscale. J Colloid Interface Sci 2024; 677:620-631. [PMID: 39116560 DOI: 10.1016/j.jcis.2024.07.220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 07/21/2024] [Accepted: 07/27/2024] [Indexed: 08/10/2024]
Abstract
The use of quantum dot nanoparticles (QDs) in bio-applications has gained quite some interest and requires a deep understanding of their interactions with model cell membranes. This involves assessing the extent of nanoparticle disruption of the membrane and how it depends on both nanoparticle and membrane physicochemical properties. Surface charge plays an important role in nanoparticle adsorption, which is primarily driven by electrostatic interactions; yet, once adsorbed, most reported works overlook the subsequent spatial nanoparticle insertion and location within the membrane. There is therefore a need for studies to assess the mutual role of membrane and nanoparticle charge into membrane structure and stability at the nanoscale, with a view to better design and control the functionality of these nanomaterials. In this work, we have resolved the extent of the interactions between hydrophilic, negatively charged CdTe QDs and positively charged lipid bilayers. A multiscale combination of surface-sensitive techniques enabled probing how surface charge mediates QD adsorption and membrane reorganization. Increasing membrane surface charge results into a larger adsorption of oppositely charged QDs, concomitantly inducing structural changes. Hydration of the membrane hydrophobic parts by QDs goes deeper into the inner leaflet with increasing membrane charge, resulting in supported lipid bilayers with decreased nanomechanical stability.
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Affiliation(s)
- M E Villanueva
- Experimental Soft Matter and Thermal Physics (EST) Group, Department of Physics, Université libre de Bruxelles, Boulevard du Triomphe CP223, 1050 Brussels, Belgium
| | - L Bar
- Experimental Soft Matter and Thermal Physics (EST) Group, Department of Physics, Université libre de Bruxelles, Boulevard du Triomphe CP223, 1050 Brussels, Belgium
| | - L Porcar
- Large-Scale Structure Group, Institut Laue-Langevin, 71 avenue des Martyrs, 38000 Grenoble, France
| | - Y Gerelli
- Italian National Research Council - Institute for Complex Systems (CNR-ISC), and Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy.
| | - P Losada-Pérez
- Experimental Soft Matter and Thermal Physics (EST) Group, Department of Physics, Université libre de Bruxelles, Boulevard du Triomphe CP223, 1050 Brussels, Belgium.
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3
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Bange L, Mukhina T, Fragneto G, Rondelli V, Schneck E. Influence of adhesion-promoting glycolipids on the structure and stability of solid-supported lipid double-bilayers. SOFT MATTER 2024; 20:2113-2125. [PMID: 38349522 DOI: 10.1039/d3sm01615c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
Glycolipids have a considerable influence on the interaction between adjacent biomembranes and can promote membrane adhesion trough favorable sugar-sugar "bonds" even at low glycolipid fractions. Here, in order to obtain structural insights into this phenomenon, we utilize neutron reflectometry in combination with a floating lipid bilayer architecture that brings two glycolipid-loaded lipid bilayers to close proximity. We find that selected glycolipids with di-, or oligosaccharide headgroups affect the inter-bilayer water layer thickness and appear to contribute to the stability of the double-bilayer architecture by promoting adhesion of adjacent bilayers even against induced electrostatic repulsion. However, we do not observe any redistribution of glycolipids that would maximize the density of sugar-sugar contacts. Our results point towards possible strategies for the investigation of interactions between cell surfaces involving specific protein-protein, lipid-lipid, or protein-lipid binding.
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Affiliation(s)
- Lukas Bange
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Tetiana Mukhina
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Giovanna Fragneto
- Institut Laue-Langevin, Grenoble, France
- The European Spallation Source, ERIC, Lund, Sweden
| | - Valeria Rondelli
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Italy.
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
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4
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Giefer P, Bäther S, Kaufmes N, Kieserling H, Heyse A, Wagemans W, Barthel L, Meyer V, Schneck E, Fritsching U, Wagemans AM. Characterization of β-lactoglobulin adsorption on silica membrane pore surfaces and its impact on membrane emulsification processes. J Colloid Interface Sci 2023; 652:1074-1084. [PMID: 37647716 DOI: 10.1016/j.jcis.2023.08.103] [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: 03/30/2023] [Revised: 07/21/2023] [Accepted: 08/16/2023] [Indexed: 09/01/2023]
Abstract
Protein adsorption plays a key role in membrane fouling in liquid processing, but the specific underlying molecular mechanisms of β-lactoglobulin adsorption on ceramic silica surfaces in premix membrane emulsification have not been investigated yet. In this study, we aimed to elucidate the β-lactoglobulin adsorption and its effect on the premix membrane emulsification of β-lactoglobulin-stabilized oil-in-water emulsions. In particular, the conformation, molecular interactions, layer thickness, surface energy of the adsorbed β-lactoglobulin and resulting droplet size distribution are investigated in relation to the solvent properties (aggregation state of β-lactoglobulin) and the treatment of the silica surface (hydrophilization). The β-lactoglobulin adsorption is driven by attractive electrostatic interactions between positively charged amino acid residues, i.e., lysin and negatively charged silanol groups, and is stabilized by hydrophobic interactions. The strong negative charges of the treated silica surfaces result in a high apparent layer thickness of β-lactoglobulin. Although the conformation of the adsorbed β-lactoglobulin layer varies with membrane treatment and the solvent properties, the β-lactoglobulin adsorption offsets the effect of hydrophilization of the membrane so that the surface energies after β-lactoglobulin adsorption are comparable. The resulting droplet size distribution of oil-in-water emulsions produced by premix membrane emulsification are similar for treated and untreated silica surfaces.
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Affiliation(s)
- Patrick Giefer
- Leibniz Institute for Materials Engineering-IWT, Badgasteiner Straße 3, 28359 Bremen, Germany; University of Bremen, Particles and Process Engineering, Bibliothekstraße 1, 28359 Bremen, Germany
| | - Sabrina Bäther
- Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Department of Food Biosciences, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Nadine Kaufmes
- Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Department of Food Biosciences, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Helena Kieserling
- Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Department of Food Biosciences, Straße des 17. Juni 135, 10623 Berlin, Germany; Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Department of Food Chemistry and Analysis, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Anja Heyse
- Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Department of Food Technology and Food Material Science, Straße des 17. Juni 135, 10623 Berlin, Germany
| | | | - Lars Barthel
- Technische Universität Berlin, Institute of Biotechnology, Department of Applied and Molecular Microbiology, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Vera Meyer
- Technische Universität Berlin, Institute of Biotechnology, Department of Applied and Molecular Microbiology, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Emanuel Schneck
- Technical University of Darmstadt, Department of Physics, 64277 Darmstadt, Germany
| | - Udo Fritsching
- Leibniz Institute for Materials Engineering-IWT, Badgasteiner Straße 3, 28359 Bremen, Germany; University of Bremen, Particles and Process Engineering, Bibliothekstraße 1, 28359 Bremen, Germany
| | - Anja Maria Wagemans
- Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Department of Food Biosciences, Straße des 17. Juni 135, 10623 Berlin, Germany.
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5
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Baer A, Hoffmann I, Mahmoudi N, Poulhazan A, Harrington MJ, Mayer G, Schmidt S, Schneck E. The Internal Structure of the Velvet Worm Projectile Slime: A Small-Angle Scattering Study. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300516. [PMID: 36828797 DOI: 10.1002/smll.202300516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/03/2023] [Indexed: 06/02/2023]
Abstract
For prey capture and defense, velvet worms eject an adhesive slime which has been established as a model system for recyclable complex liquids. Triggered by mechanical agitation, the liquid bio-adhesive rapidly transitions into solid fibers. In order to understand this mechanoresponsive behavior, here, the nanostructural organization of slime components are studied using small-angle scattering with neutrons and X-rays. The scattering intensities are successfully described with a three-component model accounting for proteins of two dominant molecular weight fractions and nanoscale globules. In contrast to the previous assumption that high molecular weight proteins-the presumed building blocks of the fiber core-are contained in the nanoglobules, it is found that the majority of slime proteins exist freely in solution. Only less than 10% of the slime proteins are contained in the nanoglobules, necessitating a reassessment of their function in fiber formation. Comparing scattering data of slime re-hydrated with light and heavy water reveals that the majority of lipids in slime are contained in the nanoglobules with homogeneous distribution. Vibrating mechanical impact under exclusion of air neither leads to formation of fibers nor alters the bulk structure of slime significantly, suggesting that interfacial phenomena and directional shearing are required for fiber formation.
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Affiliation(s)
- Alexander Baer
- Department of Zoology, Institute of Biology, University of Kassel, D-34132, Kassel, Germany
| | - Ingo Hoffmann
- Spectroscopy Group, Institut Laue-Langevin, 38000, Grenoble, France
| | - Najet Mahmoudi
- Small-Angle Neutron Scattering Group, ISIS Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Alexandre Poulhazan
- Department of Chemistry, University of Quebec at Montreal, Montreal, QC, H2X 2J6, Canada
| | | | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, D-34132, Kassel, Germany
| | - Stephan Schmidt
- Chemistry Department, Heinrich-Heine-Universität Düsseldorf, D-40225, Düsseldorf, Germany
| | - Emanuel Schneck
- Physics Department, Technische Universität Darmstadt, D-64289, Darmstadt, Germany
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, D-14476, Potsdam, Germany
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6
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Pusterla J, Scoppola E, Appel C, Mukhina T, Shen C, Brezesinski G, Schneck E. Characterization of lipid bilayers adsorbed to functionalized air/water interfaces. NANOSCALE 2022; 14:15048-15059. [PMID: 36200471 DOI: 10.1039/d2nr03334h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Lipid bilayers immobilized in planar geometries, such as solid-supported or "floating" bilayers, have enabled detailed studies of biological membranes with numerous experimental techniques, notably X-ray and neutron reflectometry. However, the presence of a solid support also has disadvantages as it complicates the use of spectroscopic techniques as well as surface rheological measurements that would require surface deformations. Here, in order to overcome these limitations, we investigate lipid bilayers adsorbed to inherently soft and experimentally well accessible air/water interfaces that are functionalized with Langmuir monolayers of amphiphiles. The bilayers are characterized with ellipsometry, X-ray scattering, and X-ray fluorescence. Grazing-incidence X-ray diffraction reveals that lipid bilayers in a chain-ordered state can have significantly different structural features than regular Langmuir monolayers of the same composition. Our results suggest that bilayers at air/water interfaces may be well suited for fundamental studies in the field of membrane biophysics.
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Affiliation(s)
- Julio Pusterla
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Ernesto Scoppola
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Christian Appel
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Tetiana Mukhina
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Chen Shen
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Gerald Brezesinski
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrasse 8, 64289 Darmstadt, Germany.
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7
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Gochev GG, Scoppola E, Campbell RA, Noskov BA, Miller R, Schneck E. β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 3. Neutron Reflectometry Study on the Effect of pH. J Phys Chem B 2019; 123:10877-10889. [PMID: 31725291 DOI: 10.1021/acs.jpcb.9b07733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Several characteristics of β-lactoglobulin (BLG) layers adsorbed at the air/water interface exhibit a strong pH dependence, but our knowledge on the underlying structure-property relations is still fragmental. Here, we therefore extend our recent studies by neutron reflectometry (NR) and provide a comprehensive overview through direct measurements of the surface excess Γ and the layers' molecular structure. This enables comparison with available literature data to draw general conclusions. The NR experiments were performed at various pH values and within a wide range of protein concentrations, CBLG. Adsorption kinetics measurements in air-contrast-matched-water and over a narrow Qz range enabled direct quantification of the dynamic surface excess Γ(t) and are found to be consistent with ellipsometry data. Near the isoelectric point, pI, the rates of adsorption and Γ are maximal but only at sufficiently high CBLG. NR data collected over a wider Qz range and in two aqueous isotopic contrasts revealed the structure of adsorbed BLG layers at a steady state close to equilibrium. Independent of the pH, BLG was found to form dense monolayers with average thicknesses of 1.1 nm, suggesting flattening of the BLG globules upon adsorption as compared with their bulk dimensions (≈3.5 nm). Near pI and at sufficiently high CBLG, a thick (≈5.5 nm) but looser secondary sublayer is additionally formed adjacent to the dense primary monolayer. The thickness of this sublayer can be interpreted in terms of disordered BLG dimers. The results obtained and notably the specific interfacial structuring of BLG near pI complement previous observations relating the impact of solution pH and CBLG on other interfacial characteristics such as surface pressure and surface dilational viscoelasticity modulus.
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Affiliation(s)
- Georgi G Gochev
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany.,Institute of Physical Chemistry , Bulgarian Academy of Sciences , 1113 Sofia , Bulgaria
| | - Ernesto Scoppola
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany
| | - Richard A Campbell
- Institut Laue-Langevin , 71 Avenue des Martyrs, CS20156 , 38042 Grenoble , France.,Division of Pharmacy and Optometry , University of Manchester , M13 9PT Manchester , U.K
| | - Boris A Noskov
- Institute of Chemistry , St. Petersburg State University , 198504 Saint-Petersburg , Russia
| | - Reinhard Miller
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam , Germany
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8
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Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces. Molecules 2019; 24:molecules24224113. [PMID: 31739471 PMCID: PMC6891303 DOI: 10.3390/molecules24224113] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/06/2019] [Accepted: 11/09/2019] [Indexed: 12/04/2022] Open
Abstract
Bare interfaces between water and hydrophobic media like air or oil are of fundamental scientific interest and of great relevance for numerous applications. A number of observations involving water/hydrophobic interfaces have, however, eluded a consensus mechanistic interpretation so far. Recent theoretical studies ascribe these phenomena to an interfacial accumulation of charged surfactant impurities in water. In the present work, we show that identifying surfactant accumulation with X-ray reflectometry (XRR) or neutron reflectometry (NR) is challenging under conventional contrast configurations because interfacial surfactant layers are then hardly visible. On the other hand, both XRR and NR become more sensitive to surfactant accumulation when a suitable scattering length contrast is generated by using fluorinated oil. With this approach, significant interfacial accumulation of surfactant impurities at the bare oil/water interface is observed in experiments involving standard cleaning procedures. These results suggest that surfactant impurities may be a limiting factor for the investigation of fundamental phenomena involving water/hydrophobic interfaces.
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9
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Abstract
Polymer brushes are outstanding lubricants that can strongly reduce wear and friction between surfaces in sliding motion. In recent decades, many researchers have put great effort in obtaining a clear understanding of the origin of the lubricating performance of these brushes. In particular, molecular dynamics simulations have been a key technique in this scientific journey. They have given us a microscopic interpretation of the tribo-mechanical response of brushes and have led to the prediction of their shear-thinning behavior, which has been shown to agree with experimental observations. However, most studies so far have focused on parallel plate geometries, while the brush-covered surfaces might be highly curved in many applications. Here, we present molecular dynamics simulations that are set up to study the friction for brushes grafted on the exterior of cylinders that are moving inside larger cylinders that bear brushes on their interior. Our simulations show that the density distributions for brushes on the interior or exterior of these cylinders are qualitatively different from the density profiles of brushes on flat surfaces. In agreement with theoretical predictions, we find that brushes on the exterior of cylinders display a more gradual decay, while brushes on the interior of cylinders becomes denser compared to flat substrates. When motion is imposed, the density profiles for cylinder-grafted brushes adapt qualitatively differently to the shear motion than observed for the parallel plate geometry: the zone where brushes overlap moves away from its equilibrium position. Surprisingly, and despite all these differences, we observe that the effective viscosity is independent of the radius of the brush-grafted cylinders. The reason for this is that the viscosity is determined by the overlap between the brushes, which turns out to be insensitive to the exact density profiles. Our results provide a microscopic interpretation of the friction mechanism for polymer brushes in cylindrical geometries and will aid the design of effective lubricants for these systems.
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10
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Welbourn R, Clarke S. New insights into the solid–liquid interface exploiting neutron reflectivity. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.03.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Rodriguez-Loureiro I, Latza VM, Fragneto G, Schneck E. Conformation of Single and Interacting Lipopolysaccharide Surfaces Bearing O-Side Chains. Biophys J 2019; 114:1624-1635. [PMID: 29642032 DOI: 10.1016/j.bpj.2018.02.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/08/2018] [Accepted: 02/13/2018] [Indexed: 10/17/2022] Open
Abstract
The outer surfaces of Gram-negative bacteria are composed of lipopolysaccharide (LPS) molecules exposing oligo- and polysaccharides to the aqueous environment. This unique, structurally complex biological interface is of great scientific interest as it mediates the interaction of bacteria with antimicrobial agents as well as with neighboring bacteria in colonies and biofilms. Structural studies on LPS surfaces, however, have so far dealt almost exclusively with rough mutant LPS of reduced molecular complexity and limited biological relevance. Here, by using neutron reflectometry, we structurally characterize planar monolayers of wild-type LPS from Escherichia coli O55:B5 featuring strain-specific O-side chains in the presence and absence of divalent cations and under controlled interaction conditions. The model used for the reflectivity analysis is self-consistent and based on the volume fraction profiles of all chemical components. The saccharide profiles are found to be bimodal, with dense inner oligosaccharides and more dilute, extended O-side chains. For interacting LPS monolayers, we establish the pressure-distance curve and determine the distance-dependent saccharide conformation.
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Affiliation(s)
| | - Victoria M Latza
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Giovanna Fragneto
- Large Scale Structures (LSS) Group, Institut Laue-Langevin, Grenoble, France
| | - Emanuel Schneck
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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12
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Micciulla S, Gerelli Y, Schneck E. Structure and Conformation of Wild-Type Bacterial Lipopolysaccharide Layers at Air-Water Interfaces. Biophys J 2019; 116:1259-1269. [PMID: 30878200 DOI: 10.1016/j.bpj.2019.02.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/13/2019] [Accepted: 02/21/2019] [Indexed: 10/27/2022] Open
Abstract
The outer membrane of Gram-negative bacteria is of great scientific interest because it mediates the action of antimicrobial agents. The membrane surface is composed of lipopolysaccharide (LPS) molecules with negatively charged oligosaccharide headgroups. To a certain fraction, LPSs additionally display linear polysaccharides termed O-side chains (OSCs). Structural studies on bacterial outer surfaces models, based on LPS monolayers at air-water interfaces, have so far dealt only with rough mutant LPSs lacking these OSCs. Here, we characterize monolayers of wild-type LPS from Escherichia coli O55:B5 featuring strain-specific OSCs in the presence of defined concentrations of monovalent and divalent ions. Pressure-area isotherms yield insight into in-plane molecular interactions and monolayer elastic moduli. Structural investigations by x-ray and neutron reflectometry reveal the saccharide conformation and allow quantifying the area per molecule and the fraction of LPS molecules carrying OSCs. The OSC conformation is satisfactorily described by the self-consistent field theory for end-grafted polymer brushes. The monolayers exhibit a significant structural response to divalent cations, which goes beyond generic electrostatic screening.
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Affiliation(s)
- Samantha Micciulla
- Institut Laue-Langevin, Grenoble, France; Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | | | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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13
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Latza VM, Rodriguez-Loureiro I, Fragneto G, Schneck E. End Point Versus Backbone Specificity Governs Characteristics of Antibody Binding to Poly(ethylene glycol) Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:13946-13955. [PMID: 30354149 DOI: 10.1021/acs.langmuir.8b02774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
End-grafted poly(ethylene glycol) (PEG) brushes are widely used in order to suppress undesired protein adsorption to surfaces exposed to blood or other biological fluids. The specific adsorption of antibodies (Abs) to PEG brushes associated with PEG's antigenicity is drawing increasing attention because it can affect clinical applications. Here, the adsorption to PEG brushes of two Ab types, specifically binding the polymer backbone and the polymer endpoints, is structurally characterized by neutron reflectometry. The measurements yield volume fraction profiles of PEG and of the adsorbed Abs with sub-nanometer resolution perpendicular to the surface. For all brush parameters in terms of grafting density and polymerization degree, the Ab profiles clearly differ between backbone binders and endpoint binders. The adsorbed Ab amount per unit area is substantial for both Ab types and for all brush parameters investigated, even for dense brushes, which impose a considerable osmotic barrier to Ab insertion. The results therefore indicate that variation of brush parameters alone is insufficient to prevent undesired Ab adsorption. Instead, our work motivates further efforts in the search for nonantigenic brush chemistry.
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Affiliation(s)
- Victoria M Latza
- Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
| | | | - Giovanna Fragneto
- Institut Laue-Langevin , 71 Avenue des Martyrs , 38042 Grenoble Cedex 9 , France
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1 , 14476 Potsdam , Germany
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14
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Boyaciyan D, Braun L, Löhmann O, Silvi L, Schneck E, von Klitzing R. Gold nanoparticle distribution in polyelectrolyte brushes loaded at different pH conditions. J Chem Phys 2018; 149:163322. [DOI: 10.1063/1.5035554] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Dikran Boyaciyan
- Soft Matter at Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt,
Germany
| | - Larissa Braun
- Soft Matter at Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt,
Germany
| | - Oliver Löhmann
- Soft Matter at Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt,
Germany
| | - Luca Silvi
- Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin,
Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, 14476 Potsdam,
Germany
| | - Regine von Klitzing
- Soft Matter at Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt,
Germany
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15
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Interacting Bacteria Surfaces. Biophys J 2018; 114:1515-1517. [PMID: 29642022 DOI: 10.1016/j.bpj.2018.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 02/23/2018] [Accepted: 03/05/2018] [Indexed: 11/21/2022] Open
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16
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Löhmann O, Micciulla S, Soltwedel O, Schneck E, von Klitzing R. Swelling Behavior of Composite Systems: Mutual Effects between Polyelectrolyte Brushes and Multilayers. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00359] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oliver Löhmann
- Department of Physics, Technische Universität Darmstadt, Darmstadt 64287, Germany
| | - Samantha Micciulla
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
| | - Olaf Soltwedel
- Department of Physics, Technische Universität München, München 80333, Germany
| | - Emanuel Schneck
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
| | - Regine von Klitzing
- Department of Physics, Technische Universität Darmstadt, Darmstadt 64287, Germany
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17
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Micciulla S, Gerelli Y, Campbell RA, Schneck E. A Versatile Method for the Distance-Dependent Structural Characterization of Interacting Soft Interfaces by Neutron Reflectometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:789-800. [PMID: 29039954 DOI: 10.1021/acs.langmuir.7b02971] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Interactions between soft interfaces govern the behavior of emulsions and foams and crucially influence the functions of biological entities like membranes. To understand the character of these interactions, detailed insight into the interfaces' structural response in terms of molecular arrangements and conformations is often essential. This requires the realization of controlled interaction conditions and surface-sensitive techniques capable of resolving the structure of buried interfaces. Here, we present a new approach to determine the distance-dependent structure of interacting soft interfaces by neutron reflectometry. A solid/water interface and a water/oil interface are functionalized independently and initially macroscopically separated. They are then brought into contact and structurally characterized under interacting conditions. The nanometric distance between the two interfaces can be varied via the exertion of osmotic pressures. Our first experiments on lipid-anchored polymer brushes interacting across water with solid-grafted polyelectrolyte brushes and with bare silicon surfaces reveal qualitatively different interaction scenarios depending on the chemical composition of the two involved interfaces.
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Affiliation(s)
- Samantha Micciulla
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam, Germany
- Institut Laue-Langevin , 38000 Grenoble, France
| | | | | | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam, Germany
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18
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Latza VM, Rodriguez-Loureiro I, Kiesel I, Halperin A, Fragneto G, Schneck E. Neutron Reflectometry Elucidates Protein Adsorption from Human Blood Serum onto PEG Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12708-12718. [PMID: 29023130 DOI: 10.1021/acs.langmuir.7b03048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Poly(ethylene glycol) (PEG) brushes are reputed for their ability to prevent undesired protein adsorption to material surfaces exposed to biological fluids. Here, protein adsorption out of human blood serum onto PEG brushes anchored to solid-supported lipid monolayers was characterized by neutron reflectometry, yielding volume fraction profiles of lipid headgroups, PEG, and adsorbed proteins at subnanometer resolution. For both PEGylated and non-PEGylated lipid surfaces, serum proteins adsorb as a thin layer of approximately 10 Å, overlapping with the headgroup region. This layer corresponds to primary adsorption at the grafting surface and resists rinsing. A second diffuse protein layer overlaps with the periphery of the PEG brush and is attributed to ternary adsorption due to protein-PEG attraction. This second layer disappears upon rinsing, thus providing a first observation of the structural effect of rinsing on protein adsorption to PEG brushes.
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Affiliation(s)
- Victoria M Latza
- Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany
| | | | - Irena Kiesel
- Institut Laue-Langevin , 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
- TU Dortmund University , Otto-Hahn-Straße 4a, 44227 Dortmund, Germany
| | | | - Giovanna Fragneto
- Institut Laue-Langevin , 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany
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