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Preparing giant unilamellar vesicles (GUVs) of complex lipid mixtures on demand: Mixing small unilamellar vesicles of compositionally heterogeneous mixtures. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:3175-80. [DOI: 10.1016/j.bbamem.2015.09.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/16/2015] [Accepted: 09/22/2015] [Indexed: 11/18/2022]
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52
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Majhi AK, Kanchi S, Venkataraman V, Ayappa KG, Maiti PK. Estimation of activation energy for electroporation and pore growth rate in liquid crystalline and gel phases of lipid bilayers using molecular dynamics simulations. SOFT MATTER 2015; 11:8632-8640. [PMID: 26372335 DOI: 10.1039/c5sm02029h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Molecular dynamics simulations of electroporation in POPC and DPPC lipid bilayers have been carried out at different temperatures ranging from 230 K to 350 K for varying electric fields. The dynamics of pore formation, including threshold field, pore initiation time, pore growth rate, and pore closure rate after the field is switched off, was studied in both the gel and liquid crystalline (Lα) phases of the bilayers. Using an Arrhenius model of pore initiation kinetics, the activation energy for pore opening was estimated to be 25.6 kJ mol(-1) and 32.6 kJ mol(-1) in the Lα phase of POPC and DPPC lipids respectively at a field strength of 0.32 V nm(-1). The activation energy decreases to 24.2 kJ mol(-1) and 23.7 kJ mol(-1) respectively at a higher field strength of 1.1 V nm(-1). At temperatures below the melting point, the activation energy in the gel phase of POPC and DPPC increases to 28.8 kJ mol(-1) and 34.4 kJ mol(-1) respectively at the same field of 1.1 V nm(-1). The pore closing time was found to be higher in the gel than in the Lα phase. The pore growth rate increases linearly with temperature and quadratically with field, consistent with viscosity limited growth models.
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Affiliation(s)
- Amit Kumar Majhi
- Department of Physics, Indian Institute of Science, Bangalore, India.
| | - Subbarao Kanchi
- Department of Physics, Indian Institute of Science, Bangalore, India.
| | - V Venkataraman
- Department of Physics, Indian Institute of Science, Bangalore, India.
| | - K G Ayappa
- Department of Chemical Engineering, Center for Biosystems Science and Engineering, Bangalore, India.
| | - Prabal K Maiti
- Department of Physics, Indian Institute of Science, Bangalore, India.
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53
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Jeppesen JC, Solovyeva V, Brewer JR, Johannes L, Hansen PL, Simonsen AC. Slow Relaxation of Shape and Orientational Texture in Membrane Gel Domains. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12699-12707. [PMID: 26501924 DOI: 10.1021/acs.langmuir.5b03168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Gel domains in lipid bilayers are structurally more complex than fluid domains. Growth dynamics can lead to noncircular domains with a heterogeneous orientational texture. Most model membrane studies involving gel domain morphology and lateral organization assume the domains to be static. Here we show that rosette shaped gel domains, with heterogeneous orientational texture and a central topological defect, after early stage growth, undergo slow relaxation. On a time scale of days to weeks domains converge to circular shapes and approach uniform texture. 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) enriched gel domains are grown by cooling 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC):DPPC bilayers into the solid-liquid phase coexistence region and are visualized with fluorescence microscopy. The relaxation of individual domains is quantified through image analysis of time-lapse image series. We find a shape relaxation mechanism which is inconsistent with Ostwald ripening and coalescence as observed in membrane systems with coexisting liquid phases. Moreover, domain texture changes in parallel with the changes in domain shape, and selective melting and growth of particular subdomains cause the texture to become more uniform. We propose a relaxation mechanism based on relocation of lipids from high-energy lattice positions, through evaporation-condensation and edge diffusion, to low-energy positions. The relaxation process is modified significantly by binding Shiga toxin, a bacterial toxin from Shigella dysenteriae, to the membrane surface. Binding alters the equilibrium shape of the gel domains from circular to eroded rosettes with disjointed subdomains. This observation may be explained by edge diffusion while evaporation-condensation is restricted, and it provides further support for the proposed overall relaxation mechanism.
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Affiliation(s)
| | | | | | - Ludger Johannes
- Institut Curie, UMR3666 CNRS, U1143 INSERM, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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Abstract
Lipid rafts are submicron proteolipid domains thought to be responsible for membrane trafficking and signaling. Their small size and transient nature put an understanding of their dynamics beyond the reach of existing techniques, leading to much contention as to their exact role. Here, we exploit the differences in light scattering from lipid bilayer phases to achieve dynamic imaging of nanoscopic lipid domains without any labels. Using phase-separated droplet interface bilayers we resolve the diffusion of domains as small as 50 nm in radius and observe nanodomain formation, destruction, and dynamic coalescence with a domain lifetime of 220±60 ms. Domain dynamics on this timescale suggests an important role in modulating membrane protein function.
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55
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Sommer B, Overy DP, Kerr RG. Identification and characterization of lipases fromMalassezia restricta, a causative agent of dandruff. FEMS Yeast Res 2015; 15:fov078. [DOI: 10.1093/femsyr/fov078] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2015] [Indexed: 01/13/2023] Open
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56
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Pauly AC, Schöller K, Baumann L, Rossi RM, Dustmann K, Ziener U, de Courten D, Wolf M, Boesel LF, Scherer LJ. ATRP-based synthesis and characterization of light-responsive coatings for transdermal delivery systems. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2015; 16:034604. [PMID: 27877791 PMCID: PMC5099828 DOI: 10.1088/1468-6996/16/3/034604] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 03/24/2015] [Accepted: 03/25/2015] [Indexed: 06/06/2023]
Abstract
The grafting of poly(hydroxyethylmethacrylate) on polymeric porous membranes via atom transfer radical polymerization (ATRP) and subsequent modification with a photo-responsive spiropyran derivative is described. This method leads to photo-responsive membranes with desirable properties such as light-controlled permeability changes, exceptional photo-stability and repeatability of the photo-responsive switching. Conventional track etched polyester membranes were first treated with plasma polymer coating introducing anchoring groups, which allowed the attachment of ATRP-initiator molecules on the membrane surface. Surface initiated ARGET-ATRP of hydroxyethylmethacrylate (where ARGET stands for activator regenerated by electron transfer) leads to a membrane covered with a polymer layer, whereas the controlled polymerization procedure allows good control over the thickness of the polymer layer in respect to the polymerization conditions. Therefore, the final permeability of the membranes could be tailored by choice of pore diameter of the initial membranes, applied monomer concentration or polymerization time. Moreover a remarkable switch in permeability (more than 1000%) upon irradiation with UV-light could be achieved. These properties enable possible applications in the field of transdermal drug delivery, filtration, or sensing.
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Affiliation(s)
- Anja C Pauly
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - Katrin Schöller
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - Lukas Baumann
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - René M Rossi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - Kathrin Dustmann
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
- Ulm University, Institute of Organic Chemistry III, Macromolecular Chemistry and Organic Materials, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Ulrich Ziener
- Ulm University, Institute of Organic Chemistry III, Macromolecular Chemistry and Organic Materials, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Damien de Courten
- Division of Neonatology, University Hospital Zürich, Frauenklinikstrasse 10, 8091 Zürich, Switzerland
| | - Martin Wolf
- Division of Neonatology, University Hospital Zürich, Frauenklinikstrasse 10, 8091 Zürich, Switzerland
| | - Luciano F Boesel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
| | - Lukas J Scherer
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Protection and Physiology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
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57
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Bagatolli LA. Monitoring Membrane Hydration with 2-(Dimethylamino)-6-Acylnaphtalenes Fluorescent Probes. Subcell Biochem 2015; 71:105-125. [PMID: 26438263 DOI: 10.1007/978-3-319-19060-0_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A family of polarity sensitive fluorescent probes (2-(dimethylamino)-6-acylnaphtalenes, i.e. LAURDAN, PRODAN, ACDAN) was introduced by Gregorio Weber in 1979, with the aim to monitor solvent relaxation phenomena on protein matrices. In the following years, however, PRODAN and particularly LAURDAN, were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane/water interface. For instance, when glycerophospholipid containing membranes undertake a solid ordered (gel) to liquid disordered phase transition the fluorescence emission maximum of these probes shift ~ 50 nm with a significant change in their fluorescence lifetime. Furthermore, the fluorescence parameters of LAURDAN and PRODAN are exquisitely sensitive to cholesterol effects, allowing interpretations that correlate changes in membrane packing with membrane hydration. Different membrane model systems as well as innate biological membranes have been studied with this family of probes allowing interesting comparative studies. This chapter presents a short historical overview about these fluorescent reporters, discusses on different models proposed to explain their sensitivity to membrane hydration, and includes relevant examples from experiments performed in artificial and biological membranes.
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Affiliation(s)
- Luis A Bagatolli
- Membrane Biophysics and Biophotonics Group/MEMPHYS-Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
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58
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Baoukina S, Tieleman DP. Computer simulations of phase separation in lipid bilayers and monolayers. Methods Mol Biol 2015; 1232:307-322. [PMID: 25331143 DOI: 10.1007/978-1-4939-1752-5_21] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Studying phase coexistence in lipid bilayers and monolayers is important for understanding lipid-lipid interactions underlying lateral organization in biological membranes. Computer simulations follow experimental approaches and use model lipid mixtures of simplified composition. Atomistic simulations give detailed information on the specificity of intermolecular interactions, while coarse-grained simulations achieve large time and length scales and provide a bridge towards state-of-the-art experimental techniques. Computer simulations allow characterizing the structure and composition of domains during phase transformations at Angstrom and picosecond resolution, and bring new insights into phase behavior of lipid membranes.
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Affiliation(s)
- Svetlana Baoukina
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, 2500 University Dr. NW, Calgary, AB, Canada, T2N 1N4,
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59
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Dreier J, Brewer J, Simonsen AC. Systematic variation of gel-phase texture in phospholipid membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:10678-10685. [PMID: 25122542 DOI: 10.1021/la5023054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The tilted gel phase of lipid bilayers can display in-plane orientational texture due to long-range alignment of the molecular director. We explore systematic variations of texture defects in a series of binary phospholipid membranes. Using polarized two-photon fluorescence microscopy, the texture pattern of single domains is revealed. The appearance of a central vortex-type defect in each domain correlates with a particular range of hydrophobic mismatch values h > 1 nm at the domain border while domains with h < 1 nm correlate with uniformly aligned texture. The central vortex defect is characterized by a defect angle, indicating its bend or splay nature. Using image analysis, we measure the defect angle and find that it has primarily bend character for small mismatch values (h ≈ 1 nm) and primarily splay nature for larger values of h. For domains containing a vortex, the domain shape is decoupled from the texture while for uniformly textured domains there is a preferred texture orientation of ≃45° along the domain border. The results establish a foundation for understanding texture phenomena in compositionally complex membranes.
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Affiliation(s)
- Jes Dreier
- MEMPHYS - Center for Biomembrane Physics, †Department of Physics Chemistry and Pharmacy and ‡Department of Biochemistry and Molecular Biology, University of Southern Denmark , Campusvej 55, 5230 Odense M, Denmark
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60
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Tfayli A, Bonnier F, Farhane Z, Libong D, Byrne HJ, Baillet-Guffroy A. Comparison of structure and organization of cutaneous lipids in a reconstructed skin model and human skin: spectroscopic imaging and chromatographic profiling. Exp Dermatol 2014; 23:441-3. [DOI: 10.1111/exd.12423] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Ali Tfayli
- Group of Analytical Chemistry of Paris-Sud (GCAPS); Faculty of Pharmacy; University Paris-Sud; Chatenay-Malabry France
| | - Franck Bonnier
- Focas Research Institute; Dublin Institute of Technology; Dublin 8 Ireland
| | - Zeineb Farhane
- Group of Analytical Chemistry of Paris-Sud (GCAPS); Faculty of Pharmacy; University Paris-Sud; Chatenay-Malabry France
| | - Danielle Libong
- Group of Analytical Chemistry of Paris-Sud (GCAPS); Faculty of Pharmacy; University Paris-Sud; Chatenay-Malabry France
| | - Hugh J. Byrne
- Focas Research Institute; Dublin Institute of Technology; Dublin 8 Ireland
| | - Arlette Baillet-Guffroy
- Group of Analytical Chemistry of Paris-Sud (GCAPS); Faculty of Pharmacy; University Paris-Sud; Chatenay-Malabry France
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61
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Eeman M, Olofsson G, Sparr E, Nasir MN, Nylander T, Deleu M. Interaction of fengycin with stratum corneum mimicking model membranes: a calorimetry study. Colloids Surf B Biointerfaces 2014; 121:27-35. [PMID: 24929530 DOI: 10.1016/j.colsurfb.2014.05.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 05/07/2014] [Accepted: 05/10/2014] [Indexed: 12/28/2022]
Abstract
Based on its outstanding antifungal properties, it is reasonable to believe that fengycin might be efficient to topically treat localized dermatomycoses. Since most of the fungi species involved in the formation of those mycotic skin diseases colonize primarily the stratum corneum (SC), studying the interaction between fengycin and SC-mimicking lipid membranes is a primary step to determine the potential of fengycin to overcome the physical barrier of the skin. In this respect, multilamellar lipid vesicles (MLVs), with a lipid composition mimicking that of the SC, were prepared and characterized by differential scanning calorimetry (DSC). The critical micelle concentration (CMC) of fengycin was also assessed under skin conditions and found to be 1.2±0.1μM. The molecular interactions of fengycin with SC-mimicking MLVs were investigated by both DSC and isothermal titration calorimetry (ITC). Results showed that the interactions were considerably affected by changes in lipid phase behaviour. At 40°C and below, fengycin induced exothermic changes in the lipid structures suggesting that less-ordered lipid domains became more-ordered in presence of fengycin. At 60°C, clearly endothermic interaction enthalpies were observed, which could arise from the "melting" of remaining solid domains enriched in high melting lipids that without fengycin melt at higher temperatures.
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Affiliation(s)
- Marc Eeman
- Université de Liège, Gembloux Agro-Bio-Tech, Unité de Chimie Biologique Industrielle, Passage des Déportés, 2, B-5030 Gembloux, Belgium
| | - Gerd Olofsson
- Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Emma Sparr
- Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Mehmet Nail Nasir
- Université de Liège, Gembloux Agro-Bio-Tech, Laboratoire de Biophysique Moléculaire aux Interfaces, Passage des Déportés, 2, B-5030 Gembloux, Belgium
| | - Tommy Nylander
- Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Magali Deleu
- Université de Liège, Gembloux Agro-Bio-Tech, Laboratoire de Biophysique Moléculaire aux Interfaces, Passage des Déportés, 2, B-5030 Gembloux, Belgium.
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62
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Carquin M, Pollet H, Veiga-da-Cunha M, Cominelli A, Van Der Smissen P, N'kuli F, Emonard H, Henriet P, Mizuno H, Courtoy PJ, Tyteca D. Endogenous sphingomyelin segregates into submicrometric domains in the living erythrocyte membrane. J Lipid Res 2014; 55:1331-42. [PMID: 24826836 DOI: 10.1194/jlr.m048538] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Indexed: 11/20/2022] Open
Abstract
We recently reported that trace insertion of exogenous fluorescent (green BODIPY) analogs of sphingomyelin (SM) into living red blood cells (RBCs), partially spread onto coverslips, labels submicrometric domains, visible by confocal microscopy. We here extend this feature to endogenous SM, upon binding of a SM-specific nontoxic (NT) fragment of the earthworm toxin, lysenin, fused to the red monomeric fluorescent protein, mCherry [construct named His-mCherry-NT-lysenin (lysenin*)]. Specificity of lysenin* binding was verified with composition-defined liposomes and by loss of (125)I-lysenin* binding to erythrocytes upon SM depletion by SMase. The (125)I-lysenin* binding isotherm indicated saturation at 3.5 × 10(6) molecules/RBC, i.e., ∼3% of SM coverage. Nonsaturating lysenin* concentration also labeled sub-micrometric domains on the plasma membrane of partially spread erythrocytes, colocalizing with inserted green BODIPY-SM, and abrogated by SMase. Lysenin*-labeled domains were stable in time and space and were regulated by temperature and cholesterol. The abundance, size, positioning, and segregation of lysenin*-labeled domains from other lipids (BODIPY-phosphatidylcholine or -glycosphingolipids) depended on membrane tension. Similar lysenin*-labeled domains were evidenced in RBCs gently suspended in 3D-gel. Taken together, these data demonstrate submicrometric compartmentation of endogenous SM at the membrane of a living cell in vitro, and suggest it may be a genuine feature of erythrocytes in vivo.
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Affiliation(s)
- Mélanie Carquin
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | - Hélène Pollet
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | - Maria Veiga-da-Cunha
- Laboratory of Physiological Chemistry, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | - Antoine Cominelli
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | | | - Francisca N'kuli
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | - Hervé Emonard
- "Matrice Extracellulaire et Dynamique Cellulaire" Unit (MEDyC), CNRS UMR 7369, Université de Reims Champagne-Ardenne, Laboratoire SiRMa, 51 100 Reims, France
| | - Patrick Henriet
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | - Hideaki Mizuno
- Department of Chemistry, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium
| | - Pierre J Courtoy
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
| | - Donatienne Tyteca
- CELL Unit, de Duve Institute and Université catholique de Louvain, 1200 Brussels, Belgium
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63
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Bagatolli LA, Needham D. Quantitative optical microscopy and micromanipulation studies on the lipid bilayer membranes of giant unilamellar vesicles. Chem Phys Lipids 2014; 181:99-120. [PMID: 24632023 DOI: 10.1016/j.chemphyslip.2014.02.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/25/2014] [Accepted: 02/26/2014] [Indexed: 12/01/2022]
Abstract
This manuscript discusses basic methodological aspects of optical microscopy and micromanipulation methods to study membranes and reviews methods to generate giant unilamellar vesicles (GUVs). In particular, we focus on the use of fluorescence microscopy and micropipet manipulation techniques to study composition-structure-property materials relationships of free-standing lipid bilayer membranes. Because their size (∼5-100 μm diameter) that is well above the resolution limit of regular light microscopes, GUVs are suitable membrane models for optical microscopy and micromanipulation experimentation. For instance, using different fluorescent reporters, fluorescence microscopy allows strategies to study membrane lateral structure/dynamics at the level of single vesicles of diverse compositions. The micropipet manipulation technique on the other hand, uses Hoffman modulation contrast microscopy and allows studies on the mechanical, thermal, molecular exchange and adhesive-interactive properties of compositionally different membranes under controlled environmental conditions. The goal of this review is to (i) provide a historical perspective for both techniques; (ii) present and discuss some of their most important contributions to our understanding of lipid bilayer membranes; and (iii) outline studies that would utilize both techniques simultaneously on the same vesicle thus bringing the ability to characterize structure and strain responses together with the direct application of well-defined stresses to a single membrane or observe the effects of adhesive spreading. Knowledge gained by these studies has informed several applications of lipid membranes including their use as lung surfactants and drug delivery systems for cancer.
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Affiliation(s)
- Luis A Bagatolli
- Membrane Biophysics and Biophotonics Group/MEMPHYS - Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
| | - David Needham
- DNRF Niels Bohr Professorship, Center for Single Particle Science and Engineering, Institute for Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark; Department of Mechanical Engineering and Material Science, Duke University, Durham, NC, USA
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64
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Bloksgaard M, Neess D, Færgeman NJ, Mandrup S. Acyl-CoA binding protein and epidermal barrier function. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:369-76. [DOI: 10.1016/j.bbalip.2013.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/20/2013] [Accepted: 09/23/2013] [Indexed: 11/29/2022]
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65
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Intake of Xylooligosaccharides Alters the Structural Organization of Liver Plasma Membrane Bilayer. FOOD BIOPHYS 2013. [DOI: 10.1007/s11483-013-9326-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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66
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Bagatolli LA, Mouritsen OG. Is the fluid mosaic (and the accompanying raft hypothesis) a suitable model to describe fundamental features of biological membranes? What may be missing? FRONTIERS IN PLANT SCIENCE 2013; 4:457. [PMID: 24312108 PMCID: PMC3826152 DOI: 10.3389/fpls.2013.00457] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/24/2013] [Indexed: 05/08/2023]
Abstract
The structure, dynamics, and stability of lipid bilayers are controlled by thermodynamic forces, leading to overall tensionless membranes with a distinct lateral organization and a conspicuous lateral pressure profile. Bilayers are also subject to built-in curvature-stress instabilities that may be released locally or globally in terms of morphological changes leading to the formation of non-lamellar and curved structures. A key controller of the bilayer's propensity to form curved structures is the average molecular shape of the different lipid molecules. Via the curvature stress, molecular shape mediates a coupling to membrane-protein function and provides a set of physical mechanisms for formation of lipid domains and laterally differentiated regions in the plane of the membrane. Unfortunately, these relevant physical features of membranes are often ignored in the most popular models for biological membranes. Results from a number of experimental and theoretical studies emphasize the significance of these fundamental physical properties and call for a refinement of the fluid mosaic model (and the accompanying raft hypothesis).
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Affiliation(s)
- Luis A. Bagatolli
- Center for Biomembrane Physics (MEMPHYS), University of Southern DenmarkOdense, Denmark
- Membrane Biophysics and Biophotonics group, Department of Biochemistry and Molecular Biology, University of Southern DenmarkOdense, Denmark
- *Correspondence: Luis A. Bagatolli, Center for Biomembrane Physics (MEMPHYS), University of Southern Denmark, Campusvej 55, Odense 5230, Denmark e-mail:
| | - Ole G. Mouritsen
- Center for Biomembrane Physics (MEMPHYS), University of Southern DenmarkOdense, Denmark
- Department of Physics, Chemistry, and Pharmacy, University of Southern DenmarkOdense, Denmark
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67
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Hansen JS, Thompson JR, Hélix-Nielsen C, Malmstadt N. Lipid directed intrinsic membrane protein segregation. J Am Chem Soc 2013; 135:17294-7. [PMID: 24180248 DOI: 10.1021/ja409708e] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We demonstrate a new approach for direct reconstitution of membrane proteins during giant vesicle formation. We show that it is straightforward to create a tissue-like giant vesicle film swelled with membrane protein using aquaporin SoPIP2;1 as an illustration. These vesicles can also be easily harvested for individual study. By controlling the lipid composition we are able to direct the aquaporin into specific immiscible liquid domains in giant vesicles. The oligomeric α-helical protein cosegregates with the cholesterol-poor domains in phase separating ternary mixtures.
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Affiliation(s)
- Jesper S Hansen
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California , 925 Bloom Walk, Los Angeles, California 90089, United States
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68
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Bloksgaard M, Brewer JR, Pashkovski E, Ananthapadmanabhan KP, Sørensen JA, Bagatolli LA. Effect of detergents on the physicochemical properties of skin stratum corneum: a two-photon excitation fluorescence microscopy study. Int J Cosmet Sci 2013; 36:39-45. [PMID: 23962033 DOI: 10.1111/ics.12089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 08/17/2013] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Understanding the structural and dynamical features of skin is critical for advancing innovation in personal care and drug discovery. Synthetic detergent mixtures used in commercially available body wash products are thought to be less aggressive towards the skin barrier when compared to conventional detergents. The aim of this work is to comparatively characterize the effect of a mild synthetic cleanser mixture (SCM) and sodium dodecyl sulphate (SDS) on the hydration state of the intercellular lipid matrix and on proton activity of excised skin stratum corneum (SC). METHOD Experiments were performed using two-photon excitation fluorescence microscopy. Fluorescent images of fluorescence reporters sensitive to proton activity and hydration of SC were obtained in excised skin and examined in the presence and absence of SCM and SDS detergents. RESULTS Hydration of the intercellular lipid matrix to a depth of 10 μm into the SC was increased upon treatment with SCM, whereas SDS shows this effect only at the very surface of SC. The proton activity of SC remained unaffected by treatment with either detergent. CONCLUSION While our study indicates that the SC is very resistant to external stimuli, it also shows that, in contrast to the response to SDS, SCM to some extent modulates the in-depth hydration properties of the intercellular lipid matrix within excised skin SC.
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Affiliation(s)
- M Bloksgaard
- Membrane Biophysics and Biophotonics Group/MEMPHYS-Center, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
| | - J R Brewer
- Membrane Biophysics and Biophotonics Group/MEMPHYS-Center, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
| | - E Pashkovski
- Unilever R&D, 40 Merritt Blvd., Trumbull, CT, 06611, USA
| | | | - J A Sørensen
- Department of Plastic Surgery, Odense University Hospital, DK-5000, Odense C, Denmark
| | - L A Bagatolli
- Membrane Biophysics and Biophotonics Group/MEMPHYS-Center, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark
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69
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Das C, Noro MG, Olmsted PD. Lamellar and inverse micellar structures of skin lipids: effect of templating. PHYSICAL REVIEW LETTERS 2013; 111:148101. [PMID: 24138273 DOI: 10.1103/physrevlett.111.148101] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Indexed: 06/02/2023]
Abstract
The outermost layer of skin comprises rigid nonviable cells (corneocytes) in a layered lipid matrix. Using atomistic simulations we find that the equilibrium phase of the skin lipids is inverse micellar. A model of the corneocyte is used to demonstrate that lamellar layering is induced by the patterned corneocyte wall. The inverse micellar phase is consistent with in vivo observations in regions where corneocyte walls are well separated (lacunar spaces) and in the inner layers of skin, and suggests a functional role in the lipid synthesis pathway in vivo.
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Affiliation(s)
- Chinmay Das
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
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70
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Pashinyan AG, Heidar SA, Arutyunyan GB, Dontsova YV. Skin moisturizing as a factor preventing premature skin ageing. VESTNIK DERMATOLOGII I VENEROLOGII 2013. [DOI: 10.25208/vdv634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
The authors describe issues related to age-related changes in the skin. They present data confirming the clinical efficacy of hydration cosmetic drugs belonging to the Noreva Aquareva line by Laboratoires Dermatologiques d’Uriage aimed at renewing the natural moisture-preserving epidermis structure in patients with dry skin within a short period of time.
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71
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Bloksgaard M, Brewer J, Bagatolli LA. Structural and dynamical aspects of skin studied by multiphoton excitation fluorescence microscopy-based methods. Eur J Pharm Sci 2013; 50:586-94. [PMID: 23608611 DOI: 10.1016/j.ejps.2013.04.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 04/08/2013] [Accepted: 04/10/2013] [Indexed: 11/19/2022]
Abstract
This mini-review reports on applications of particular multiphoton excitation microscopy-based methodologies employed in our laboratory to study skin. These approaches allow in-depth optical sectioning of the tissue, providing spatially resolved information on specific fluorescence probes' parameters. Specifically, by applying these methods, spatially resolved maps of water dipolar relaxation (generalized polarization function using the 6-lauroyl-2-(N,N-dimethylamino)naphthale probe), activity of protons (fluorescence lifetime imaging using a proton sensitive fluorescence probe--2,7-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein) and diffusion coefficients of distinct fluorescence probes (raster imaging correlation spectroscopy) can be obtained from different regions of the tissue. Comparative studies of different tissue strata, but also between equivalent regions of normal and abnormal excised skin, including applications of fluctuation correlation spectroscopy on transdermal penetration of liposomes are presented and discussed. The data from the different studies reported reveal the intrinsic heterogeneity of skin and also prove these strategies to be powerful noninvasive tools to explore structural and dynamical aspects of the tissue.
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Affiliation(s)
- Maria Bloksgaard
- Membrane Biophysics and Biophotonics group/MEMPHYS, Center for Biomembrane Physics, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
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72
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Kezutyte T, Desbenoit N, Brunelle A, Briedis V. Studying the penetration of fatty acids into human skin by ex vivo TOF-SIMS imaging. Biointerphases 2013; 8:3. [PMID: 24706116 DOI: 10.1186/1559-4106-8-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 12/26/2012] [Indexed: 11/10/2022] Open
Abstract
Fatty acids classified as chemical penetration enhancers (CPEs) might cause the fluidization and perturbation of stratum corneum (SC) lipid matrix. The penetration of oleic, linoleic, lauric and capric acids into human skin was studied by time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging and related to fatty acids enhancing effect on lipophilic model drug tolnaftate penetration into human epidermis and dermis ex vivo. Fatty acid enhancing effect on tolnaftate penetration into human skin was evaluated using Bronaugh-type flow-through diffusion cells. After in vitro penetration studies visualization and spatial localization of fatty acid molecules in human skin were performed using TOF-SIMS. Penetration of oleic, linoleic, lauric and capric acids into human skin was compared to the control skin sections by ion images and intensity profiles. Only oleic acid significantly (P<0.05) enhanced tolnaftate penetration into epidermis (enhancing ratio equal to 1.867). CPE might have no effect on model drug penetration enhancement, but might penetrate itself into the skin.
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Affiliation(s)
- Toma Kezutyte
- Department of Clinical Pharmacy, Lithuanian University of Health Sciences, Kaunas, Lithuania,
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73
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Overview of a Quest for Bending Elasticity Measurement. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/b978-0-12-411516-3.00003-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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74
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Staneva G, Puff N, Seigneuret M, Conjeaud H, Angelova MI. Segregative clustering of Lo and Ld membrane microdomains induced by local pH gradients in GM1-containing giant vesicles: a lipid model for cellular polarization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:16327-37. [PMID: 23121205 DOI: 10.1021/la3031107] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Several cell polarization processes are coupled to local pH gradients at the membrane surface. We have investigated the involvement of a lipid-mediated effect in such coupling. The influence of lateral pH gradients along the membrane surface on lipid microdomain dynamics in giant unilamellar vesicles containing phosphatidylcholine, sphingomyelin, cholesterol, and the ganglioside GM1 was studied. Lo/Ld phase separation was generated by photosensitization. A lateral pH gradient was established along the external membrane surface by acid local microinjection. The gradient promotes the segregation of microdomains: Lo domains within an Ld phase move toward the higher pH side, whereas Ld domains within an Lo phase move toward the lower pH side. This results in a polarization of the vesicle membrane into Lo and Ld phases poles in the axis of the proton source. A secondary effect is inward tubulation in the Ld phase. None of these processes occurs without GM1 or with the analog asialo-GM1. These are therefore related to the acidic character of the GM1 headgroup. LAURDAN fluorescence experiments on large unilamellar vesicles indicated that, with GM1, an increase in lipid packing occurs with decreasing pH, attributed to the lowering of repulsion between GM1 molecules. Packing increase is much higher for Ld phase vesicles than for Lo phase vesicles. It is proposed that the driving forces for domain vectorial segregative clustering and vesicle polarization are related to such differences in packing variations with pH decrease between the Lo and Ld phases. Such pH-driven domain clustering might play a role in cellular membrane polarization processes in which local lateral pH gradients are known to be important, such as migrating cells and epithelial cells.
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Affiliation(s)
- Galya Staneva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
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75
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Teixeira F, Popa AM, Guimond S, Hegemann D, Rossi RM. Synthesis of poly(oligo(ethylene glycol)methacrylate)-functionalized membranes for thermally controlled drug delivery. J Appl Polym Sci 2012. [DOI: 10.1002/app.38730] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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76
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Abstract
Tremendous progress has been made in recent years in understanding the working of the living cell, including its micro-anatomy, signalling networks, and regulation of genes. However, an understanding of cellular phenomena using fundamental laws starting from first principles is still very far away. Part of the reason is that a cell is an active and exquisitely complex system where every part is linked to the other. Thus, it is difficult or even impossible to design experiments that selectively and exclusively probe a chosen aspect of the cell. Various kinds of idealised systems and cell models have been used to circumvent this problem. An important example is a giant unilamellar vesicle (GUV, also called giant liposome), which provides a cell-sized confined volume to study biochemical reactions as well as self-assembly processes that occur on the membrane. The GUV membrane can be designed suitably to present selected, correctly-oriented cell-membrane proteins, whose mobility is confined to two dimensions. Here, we present recent advances in GUV design and the use of GUVs as cell models that enable quantitative testing leading to insight into the working of real cells. We briefly recapitulate important classical concepts in membrane biophysics emphasising the advantages and limitations of GUVs. We then present results obtained over the last decades using GUVs, choosing the formation of membrane domains and cell adhesion as examples for in-depth treatment. Insight into cell adhesion obtained using micro-interferometry is treated in detail. We conclude by summarising the open questions and possible future directions.
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Affiliation(s)
- Susanne F Fenz
- Leiden Institute of Physics: Physics of Life Processes, Leiden University, The Netherlands
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77
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Bloksgaard M, Bek S, Marcher AB, Neess D, Brewer J, Hannibal-Bach HK, Helledie T, Fenger C, Due M, Berzina Z, Neubert R, Chemnitz J, Finsen B, Clemmensen A, Wilbertz J, Saxtorph H, Knudsen J, Bagatolli L, Mandrup S. The acyl-CoA binding protein is required for normal epidermal barrier function in mice. J Lipid Res 2012; 53:2162-2174. [PMID: 22829653 DOI: 10.1194/jlr.m029553] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The acyl-CoA binding protein (ACBP) is a 10 kDa intracellular protein expressed in all eukaryotic species. Mice with targeted disruption of Acbp (ACBP(-/-) mice) are viable and fertile but present a visible skin and fur phenotype characterized by greasy fur and development of alopecia and scaling with age. Morphology and development of skin and appendages are normal in ACBP(-/-) mice; however, the stratum corneum display altered biophysical properties with reduced proton activity and decreased water content. Mass spectrometry analyses of lipids from epidermis and stratum corneum of ACBP(+/+) and ACBP(-/-) mice showed very similar composition, except for a significant and specific decrease in the very long chain free fatty acids (VLC-FFA) in stratum corneum of ACBP(-/-) mice. This finding indicates that ACBP is critically involved in the processes that lead to production of stratum corneum VLC-FFAs via complex phospholipids in the lamellar bodies. Importantly, we show that ACBP(-/-) mice display a ∼50% increased transepidermal water loss compared with ACBP(+/+) mice. Furthermore, skin and fur sebum monoalkyl diacylglycerol (MADAG) levels are significantly increased, suggesting that ACBP limits MADAG synthesis in sebaceous glands. In summary, our study shows that ACBP is required for production of VLC-FFA for stratum corneum and for maintaining normal epidermal barrier function.
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Affiliation(s)
- Maria Bloksgaard
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Signe Bek
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Ann-Britt Marcher
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Ditte Neess
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Jonathan Brewer
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark
| | | | - Torben Helledie
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Christina Fenger
- Institute of Molecular Medicine, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Marianne Due
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Zane Berzina
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Reinhard Neubert
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - John Chemnitz
- Institute of Molecular Medicine, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Bente Finsen
- Institute of Molecular Medicine, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Anders Clemmensen
- Department of Dermatology, Odense University Hospital, Odense, Denmark; and
| | - Johannes Wilbertz
- Department of Dermatology, Karolinska Center of Transgene Technologies, Stockholm, Sweden
| | - Henrik Saxtorph
- Laboratory Animal Science and Comparative Medicine, University of Southern Denmark, DK-5230 Odense, Denmark and
| | - Jens Knudsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark
| | - Luis Bagatolli
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark; MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense, Denmark; Danish Molecular Biomedical Imaging Center (DaMBIC), University of Southern Denmark, DK-5230 Odense, Denmark.
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense, Denmark.
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78
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79
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Rodríguez G, Cócera M, Rubio L, López-Iglesias C, Pons R, de la Maza A, López O. A Unique Bicellar Nanosystem Combining Two Effects on Stratum Corneum Lipids. Mol Pharm 2012; 9:482-91. [DOI: 10.1021/mp200075h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Gelen Rodríguez
- Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/ Jordi
Girona 18-26, 08034 Barcelona, Spain
| | - Mercedes Cócera
- Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/ Jordi
Girona 18-26, 08034 Barcelona, Spain
| | - Laia Rubio
- Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/ Jordi
Girona 18-26, 08034 Barcelona, Spain
| | - Carmen López-Iglesias
- University of Barcelona’s Scientific and Technological Centers (CCiT-UB), Barcelona Science Park, C/ Baldiri
Reixac, 10, 08028 Barcelona, Spain
| | - Ramon Pons
- Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/ Jordi
Girona 18-26, 08034 Barcelona, Spain
| | - Alfons de la Maza
- Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/ Jordi
Girona 18-26, 08034 Barcelona, Spain
| | - Olga López
- Department of Chemical and Surfactants Technology, Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/ Jordi
Girona 18-26, 08034 Barcelona, Spain
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80
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Rodríguez G, Cócera M, Rubio L, Alonso C, Pons R, Sandt C, Dumas P, López-Iglesias C, de la Maza A, López O. Bicellar systems to modify the phase behaviour of skin stratum corneum lipids. Phys Chem Chem Phys 2012; 14:14523-33. [DOI: 10.1039/c2cp42421e] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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81
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Bagatolli LA. LAURDAN Fluorescence Properties in Membranes: A Journey from the Fluorometer to the Microscope. SPRINGER SERIES ON FLUORESCENCE 2012. [DOI: 10.1007/4243_2012_42] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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82
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Yang Y, Jiang Y, Wang Z, Liu J, Yan L, Ye J, Huang Y. Skin-permeable quaternary nanoparticles with layer-by-layer structure enabling improved gene delivery. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm00121g] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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83
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Husen P, Fidorra M, Härtel S, Bagatolli LA, Ipsen JH. A method for analysis of lipid vesicle domain structure from confocal image data. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 41:161-75. [PMID: 22068825 DOI: 10.1007/s00249-011-0768-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 07/27/2011] [Accepted: 10/13/2011] [Indexed: 01/20/2023]
Abstract
Quantitative characterization of the lateral structure of curved membranes based on fluorescence microscopy requires knowledge of the fluorophore distribution on the surface. We present an image analysis approach for extraction of the fluorophore distribution on a spherical lipid vesicle from confocal imaging stacks. The technique involves projection of volumetric image data onto a triangulated surface mesh representation of the membrane, correction of photoselection effects and global motion of the vesicle during image acquisition and segmentation of the surface into domains using histograms. The analysis allows for investigation of the morphology and size distribution of domains on the surface.
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Affiliation(s)
- Peter Husen
- Department of Physics and Chemistry, MEMPHYS Centre for Biomembrane Physics, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
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84
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An epifluorescence microscopy method for generalized polarization imaging. Biochem Biophys Res Commun 2011; 415:686-90. [PMID: 22079294 DOI: 10.1016/j.bbrc.2011.10.138] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 10/28/2011] [Indexed: 12/17/2022]
Abstract
Generalized polarization (GP) microscopy represents an excellent tool to study lipid-lipid and lipid-protein interactions in situ and in vitro. Here, we present an efficient and cost effective method to perform GP microscopy using a standard light-emitting diode (LED) epifluorescence microscope equipped with a digital color camera.
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85
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Méléard P, Pott T, Bouvrais H, Ipsen JH. Advantages of statistical analysis of giant vesicle flickering for bending elasticity measurements. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:116. [PMID: 22038341 DOI: 10.1140/epje/i2011-11116-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/23/2011] [Indexed: 05/17/2023]
Abstract
We show how to greatly improve precision when determining bending elasticity of giant unilamellar vesicles. Taking advantage of the well-known quasi-spherical model of liposome flickering, we analyze the full probability distributions of the configurational fluctuations instead of limiting the analysis to the second moment measurements only as usually done in previously published works. This leads to objective criteria to reject vesicles that do not behave according to the model. As a result, the confidence in the bending elasticity determination of individual vesicles that fit the model is improved and, consequently, the reproducibility of this measurement for a given membrane system. This approach uncovers new possibilities for bending elasticity studies like detection of minute influences by solutes in the buffer or into the membrane. In the same way, we are now able to detect the inhomogeneous behavior of giant vesicle systems such as the hazardous production of peroxide in bilayers containing fluorescent dyes.
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Affiliation(s)
- P Méléard
- Université Européenne de Bretagne, UMR CNRS-ENSCR 6226 Sciences Chimiques de Rennes, ENSCR, Avenue du Général Leclerc, CS 50837, F-35708 Rennes Cedex 7, France.
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86
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Souza SL, Valério J, Funari SS, Melo E. The thermotropism and prototropism of ternary mixtures of ceramide C16, cholesterol and palmitic acid. An exploratory study. Chem Phys Lipids 2011; 164:643-53. [DOI: 10.1016/j.chemphyslip.2011.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/01/2011] [Accepted: 06/15/2011] [Indexed: 12/21/2022]
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87
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88
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Structural organization of plasma membrane lipids isolated from cells cultured as a monolayer and in tissue-like conditions. J Colloid Interface Sci 2011; 359:202-9. [PMID: 21507411 DOI: 10.1016/j.jcis.2011.03.085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 11/20/2022]
Abstract
Complementary biophysical approaches were used to study the structural organization of plasma membrane lipids obtained from fibroblasts cultured as two-dimensional (2D) monolayer and in tissue-like three-dimensional (3D) conditions. Fluorescence microscopy experiments demonstrated different domain patterns for 2D and 3D plasma membrane lipid extracts. ESR demonstrated that 3D lipid extract is characterized with lower order parameter than 2D in the deep hydrophobic core of the lipid bilayer. Higher cholesterol and sphingomyelin content in 3D extract, known to increase the order in the glycerophospholipid matrix, was not able to compensate higher fatty acid polyunsaturation of the phospholipids. The interfacial region of the bilayer was probed by the fluorescent probe Laurdan. A higher general polarization value for 3D extract was measured. It is assigned to the increased content of sphingomyelin, cholesterol, phosphatidylethanolamine and phosphatidylserine in the 3D membranes. These results demonstrate that cells cultured under different conditions exhibit compositional heterogeneity of the constituent lipids which determine different structural organization of the membranes.
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89
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Geusens B, Strobbe T, Bracke S, Dynoodt P, Sanders N, Gele MV, Lambert J. Lipid-mediated gene delivery to the skin. Eur J Pharm Sci 2011; 43:199-211. [DOI: 10.1016/j.ejps.2011.04.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 11/16/2010] [Accepted: 04/09/2011] [Indexed: 11/29/2022]
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90
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Nitsche JM, Frederick Frasch H. Dynamics of diffusion with reversible binding in microscopically heterogeneous membranes: General theory and applications to dermal penetration. Chem Eng Sci 2011. [DOI: 10.1016/j.ces.2011.01.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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91
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Kubiak J, Brewer J, Hansen S, Bagatolli LA. Lipid lateral organization on giant unilamellar vesicles containing lipopolysaccharides. Biophys J 2011; 100:978-86. [PMID: 21320442 DOI: 10.1016/j.bpj.2011.01.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 01/04/2011] [Accepted: 01/06/2011] [Indexed: 01/23/2023] Open
Abstract
We developed a new (to our knowledge) protocol to generate giant unilamellar vesicles (GUVs) composed of mixtures of single lipopolysaccharide (LPS) species and Escherichia coli polar lipid extracts. Four different LPSs that differed in the size of the polar headgroup (i.e., LPS smooth > LPS-Ra > LPS-Rc > LPS-Rd) were selected to generate GUVs composed of different LPS/E. coli polar lipid mixtures. Our procedure consists of two main steps: 1), generation and purification of oligolamellar liposomes containing LPSs; and 2), electroformation of GUVs using the LPS-containing oligolamellar vesicles at physiological salt and pH conditions. Analysis of LPS incorporation into the membrane models (both oligolamellar vesicles and GUVs) shows that the final concentration of LPS is lower than that expected from the initial E. coli lipids/LPS mixture. In particular, our protocol allows incorporation of no more than 15 mol % for LPS-smooth and LPS-Ra, and up to 25 mol % for LPS-Rc and LPS-Rd (with respect to total lipids). We used the GUVs to evaluate the impact of different LPS species on the lateral structure of the host membrane (i.e., E. coli polar lipid extract). Rhodamine-DPPE-labeled GUVs show the presence of elongated micrometer-sized lipid domains for GUVs containing either LPS-Rc or LPS-Rd above 10 mol %. Laurdan GP images confirm this finding and show that this particular lateral scenario corresponds to the coexistence of fluid disordered and gel (LPS-enriched)-like micron-sized domains, in similarity to what is observed when LPS is replaced with lipid A. For LPSs containing the more bulky polar headgroup (i.e., LPS-smooth and LPS-Ra), an absence of micrometer-sized domains is observed for all LPS concentrations explored in the GUVs (up to ∼15 mol %). However, fluorescence correlation spectroscopy (using fluorescently labeled LPS) and Laurdan GP experiments in these microscopically homogeneous membranes suggests the presence of LPS clusters with dimensions below our microscope's resolution (∼380 nm radial). Our results indicate that LPSs can cluster into gel-like domains in these bacterial model membranes, and that the size of these domains depends on the chemical structure and concentration of the LPSs.
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Affiliation(s)
- Jakubs Kubiak
- Membrane Biophysics and Biophotonics Group/MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
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92
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Hoopes MI, Noro MG, Longo ML, Faller R. Bilayer structure and lipid dynamics in a model stratum corneum with oleic acid. J Phys Chem B 2011; 115:3164-71. [PMID: 21370846 DOI: 10.1021/jp109563s] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The stratum corneum is the uppermost layer of the skin and acts as a barrier to keep out contaminants and retain moisture. Understanding the molecular structure and behavior of this layer will provide guidance for optimizing its biological function. In this study we use a model mixture comprised of equimolar portions of ceramide NS (24:0), lignoceric acid, and cholesterol to model the effect of the addition of small amounts of oleic acid to the bilayer at 300 and 340 K. Five systems at each temperature have been simulated with concentrations between 0 and 0.1 mol % oleic acid. Our major finding is that subdiffusive behavior over the 200 ns time scale is evident in systems at 340 K, with cholesterol diffusion being enhanced with increased oleic acid. Importantly, cholesterol and other species diffuse faster when radial densities indicate nearest neighbors include more cholesterol. We also find that, with the addition of oleic acid, the bilayer midplane and interfacial densities are reduced and there is a 3% decrease in total thickness occurring mostly near the hydrophilic interface at 300 K with reduced overall density at 340 K. Increased interdigitation occurs independent of oleic acid with a temperature increase. Slight ordering of the long non-hydroxy fatty acid of the ceramide occurs near the hydrophilic interface as a function of the oleic acid concentration, but no significant impact on hydrogen bonding is seen in the chosen oleic acid concentrations.
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Affiliation(s)
- Matthew I Hoopes
- Biophysics Graduate Group, University of California, Davis, California 95616, USA
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93
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Wheeler G, Tyler KM. Widefield microscopy for live imaging of lipid domains and membrane dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:634-41. [PMID: 21126508 PMCID: PMC3048960 DOI: 10.1016/j.bbamem.2010.11.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Revised: 11/09/2010] [Accepted: 11/12/2010] [Indexed: 12/19/2022]
Abstract
Within the lateral organisation of plasma membranes of polarized cell types there exist heterogenous microdomains of distinct lipid composition, the small size of which (10–200 nm) makes them difficult to discern with traditional microscopic techniques, but which can be distinguished on the basis of lipid packing. These microdomains or rafts can be concentrated in larger more visible liquid-ordered regions, particularly by cross-linking of their constituents as in the immunological synapse or in features of the polarized cell such as pseudopodia or flagella. One technique, Laurdan fluorescence microscopy, has proven very useful for distinguishing such regions but has hitherto relied on 2-photon confocal microscopy. This has to some extent limited its utility to living systems and its widespread adoption in studying membrane dynamics on the surface of living cells. Here we describe and validate the adaptation of a standard widefield fluorescence microscope for live imaging of Laurdan stained cell membranes.
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Affiliation(s)
- Guy Wheeler
- BioMedical Research Centre, Norwich School of Medicine, University of East Anglia, Norwich NR47TJ, UK
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94
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Bagatolli LA, Ipsen JH, Simonsen AC, Mouritsen OG. An outlook on organization of lipids in membranes: Searching for a realistic connection with the organization of biological membranes. Prog Lipid Res 2010; 49:378-89. [DOI: 10.1016/j.plipres.2010.05.001] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/30/2010] [Accepted: 05/01/2010] [Indexed: 12/20/2022]
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95
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Huang Y, Yu F, Park YS, Wang J, Shin MC, Chung HS, Yang VC. Co-administration of protein drugs with gold nanoparticles to enable percutaneous delivery. Biomaterials 2010; 31:9086-91. [PMID: 20828812 DOI: 10.1016/j.biomaterials.2010.08.046] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 08/19/2010] [Indexed: 01/12/2023]
Abstract
An interesting nanoscale interfacial phenomenon mediated by gold nanoparticles (Au-NPs) was found, in that co-administration with Au-NPs enables percutaneous delivery of protein drugs. The Au-NPs with a mean size of 5 nm were revealed to be skin permeable, presumably due to the nano-bio interaction with skin lipids and the consequent induction of transient and reversible openings on the stratum corneum. Importantly, when simultaneously applied with Au-NPs, the protein drugs were also granted the ability to penetrate the skin barrier and migrate into the deep layers. This indicated that co-administration with the skin-permeable Au-NPs could mediate proteins across the skin barrier. Such co-delivery effect highlights a simple yet effective method for overcoming the skin barrier for percutaneous protein drug delivery. Employing this method, a non-invasive vaccine delivery strategy was developed, and by topically co-administrating antigens with Au-NPs, robust immune responses were elicited in the tested animals. The results provide the promise for achieving a needleless and self-administrable transcutaneous vaccination.
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Affiliation(s)
- Yongzhuo Huang
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Hai-ke Road, Shanghai 201203, China
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96
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Rodríguez G, Rubio L, Cócera M, Estelrich J, Pons R, de la Maza A, López O. Application of bicellar systems on skin: diffusion and molecular organization effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:10578-10584. [PMID: 20380392 DOI: 10.1021/la100691m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The effect of bicelles formed by dipalmitoylphosphatidylcholine (DPPC)/dihexanoylphosphatidylcholine (DHPC) on stratum corneum (SC) lipids was studied by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy at different temperatures. Analysis of the lipid organization in terms of chain conformational order and lateral packing shows that the use of bicelles hampers the fluidification of SC lipids with temperature and leads to a lateral packing corresponding to a stable hexagonal phase. Grazing incidence small- and wide-angle X-ray scattering (GISAXS and GIWAXS) techniques confirm these results and give evidence of higher lamellar order after treatment with these bicelles. Additionally, the effects of DPPC/DHPC and dimyristoylphosphatidylcholine (DMPC)/DHPC bicelles at different SC depths were compared. The combination of ATR-FTIR spectroscopy and the tape-stripping method was very useful for this purpose.
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Affiliation(s)
- Gelen Rodríguez
- Departament de Tecnologia Química i de Tensioactius, Institut de Quimica Avançada de Catalunya, Consejo Superior de Investigaciones Científicas, C/Jordi Girona 18-26, 08034 Barcelona, Spain.
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97
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van Schooneveld MM, Gloter A, Stephan O, Zagonel LF, Koole R, Meijerink A, Mulder WJM, de Groot FMF. Imaging and quantifying the morphology of an organic-inorganic nanoparticle at the sub-nanometre level. NATURE NANOTECHNOLOGY 2010; 5:538-44. [PMID: 20526325 DOI: 10.1038/nnano.2010.105] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 04/26/2010] [Indexed: 05/24/2023]
Abstract
The development of hybrid organic-inorganic nanoparticles is of interest for applications such as drug delivery, DNA and protein recognition, and medical diagnostics. However, the characterization of such nanoparticles remains a significant challenge due to the heterogeneous nature of these particles. Here, we report the direct visualization and quantification of the organic and inorganic components of a lipid-coated silica particle that contains a smaller semiconductor quantum dot. High-angle annular dark-field scanning transmission electron microscopy combined with electron energy loss spectroscopy was used to determine the thickness and chemical signature of molecular coating layers, the element atomic ratios, and the exact positions of different elements in single nanoparticles. Moreover, the lipid ratio and lipid phase segregation were also quantified.
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Affiliation(s)
- Matti M van Schooneveld
- Inorganic Chemistry & Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3584 CA, The Netherlands.
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98
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Gallier S, Gragson D, Jiménez-Flores R, Everett D. Using confocal laser scanning microscopy to probe the milk fat globule membrane and associated proteins. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:4250-4257. [PMID: 20218614 PMCID: PMC2853928 DOI: 10.1021/jf9032409] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The bovine milk fat globule membrane (MFGM) is an important, biologically relevant membrane due to its functional and health properties. Its composition has been thoroughly studied, but its structure, especially the lateral organization of its components, still remains unclear. We have used confocal laser scanning microscopy (CLSM) to investigate the surface structure of the MFGM in globules with different degrees of processing using two types of fluorescently labeled phospholipid probes and a protein dye. Using this technique, we have observed heterogeneities in the distribution of MFGM lipids and proteins relating to the processing and size of the globules. The effect of pretreating the milk (centrifugation, pasteurization-homogenization and churning) was studied by double-staining the surface of the milk fat globules, followed by observation using CLSM, and by determining the phospholipid profile of raw milk, raw cream, processed milk and buttermilk powder. Our findings agree with other techniques by showing that the composition of the MFGM changes with processing through the loss of phospholipids and the adsorption of caseins and whey proteins onto the surface.
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Affiliation(s)
- Sophie Gallier
- Department of Food Science, University of Otago, Dunedin, New Zealand
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99
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Huang Y, Park YS, Moon C, David AE, Chung HS, Yang VC. Synthetic skin-permeable proteins enabling needleless immunization. Angew Chem Int Ed Engl 2010; 49:2724-7. [PMID: 20232417 PMCID: PMC3480632 DOI: 10.1002/anie.200906153] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Yongzhuo Huang
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109, USA, Fax: (+1)734–763–9772
| | - Yoon Shin Park
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109, USA, Fax: (+1)734–763–9772
| | - Cheol Moon
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109, USA, Fax: (+1)734–763–9772
| | - Allan E. David
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109, USA, Fax: (+1)734–763–9772
| | - Hee Sun Chung
- College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, MI 48109, USA, Fax: (+1)734–763–9772
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100
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The microstructure of the stratum corneum lipid barrier: mid-infrared spectroscopic studies of hydrated ceramide:palmitic acid:cholesterol model systems. Biophys Chem 2010; 150:144-56. [PMID: 20457485 DOI: 10.1016/j.bpc.2010.03.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/06/2010] [Accepted: 03/08/2010] [Indexed: 11/19/2022]
Abstract
The current mid-infrared spectroscopic study is a systematic investigation of hydrated stratum corneum lipid barrier model systems composed of an equimolar mixture of a ceramide, free palmitic acid and cholesterol. Four different ceramide molecules (CER NS, CER NP, CER NP-18:1, CER AS) were investigated with regard to their microstructure arrangement in a stratum corneum lipid barrier model system. Ceramide molecules were chosen from the sphingosine and phytosphingosine groups. The main differences in the used ceramide molecules result from their polar head group architecture as well as hydrocarbon chain properties. The mixing properties with cholesterol and palmitic acid are considered. This is feasible by using perdeuterated palmitic acid and proteated ceramides. Both molecules can be monitored separately, within the same experiment, using mid-infrared spectroscopy; no external label is necessary. At physiological relevant temperatures, between 30 and 35 degrees C, orthorhombic as well as hexagonal chain packing of the ceramide molecules is observed. The formation of these chain packings are extremely dependent on lipid hydration, with a decrease in ceramide hydration favouring the formation of orthorhombic hydrocarbon chain packing, as well as temperature. The presented data suggest in specific cases phase segregation in ceramide and palmitic acid rich phases. However, other ceramides like CER NP-18:1 show a rather high miscibility with palmitic acid and cholesterol. For all investigated ternary systems, more or less mixing of palmitic acid with cholesterol is observed. The investigated stratum corneum mixtures exhibit a rich polymorphism from crystalline domains with heterogeneous lipid composition to a "fluid" homogeneous phase. Thus, a single gel phase is not evident for the presented stratum corneum model systems. The study shows, that under skin physiological conditions (pH 5.5, hydrated, 30-35 degrees C) ternary systems composed of an equimolar ratio of ceramides, free palmitic acid and cholesterol may form gel-like domains delimitated by a liquid-crystalline phase boundary. The presented results support the microstructural arrangement of the stratum corneum lipids as suggested by the domain mosaic model.
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