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Pandur Ž, Penič S, Iglič A, Kralj-Iglič V, Stopar D, Drab M. Surfactin molecules with a cone-like structure promote the formation of membrane domains with negative spontaneous curvature and induce membrane invaginations. J Colloid Interface Sci 2023; 650:1193-1200. [PMID: 37478736 DOI: 10.1016/j.jcis.2023.07.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 06/22/2023] [Accepted: 07/09/2023] [Indexed: 07/23/2023]
Abstract
Surfactin uniquely influences lipid bilayer structure by initially inducing membrane invaginations before solubilization. In this study, we exposed DOPC giant vesicles to various surfactin concentrations at different temperatures and observed surfactin-induced membrane invaginations by using differential interference contrast and confocal laser fluorescence microscopy. These invaginations were stable at room temperature but not at higher temperatures. Surfactin molecules induce membrane nanodomains with negative spontaneous curvature and membrane invaginations despite their intrinsic conical shape and intrinsic positive curvature. Considering the experimentally observed capacity of surfactin to fluidize lipid acyl chains and induce partial dehydration of lipid headgroups, we propose that the resulting surfactin-lipid complexes exhibit a net negative spontaneous curvature. We further conducted 3D numerical Monte Carlo (MC) simulations to investigate the behaviour of vesicles containing negative curvature nanodomains within their membrane at varying temperatures. MC simulations demonstrated strong agreement with experimental results, revealing that invaginations are preferentially formed at low temperatures, while being less pronounced at elevated temperatures. Our findings go beyond the expectations of the Israelachvili molecular shape and packing concepts analysis. These concepts do not take into account the influence of specific interactions between neighboring molecules on the inherent shapes of molecules and their arrangement within curved membrane nanodomains. Our work contributes to a more comprehensive understanding of the complex factors governing vesicle morphology and membrane organization and provides insight into the role of detergent-lipid interactions in modulating vesicle morphology.
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Affiliation(s)
- Žiga Pandur
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Samo Penič
- Laboratory of Bioelectromagnetics, Faculty of Electrical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Veronika Kralj-Iglič
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - David Stopar
- Department of Microbiology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Mitja Drab
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia.
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2
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Altunayar-Unsalan C, Unsalan O, Mavromoustakos T. Molecular interactions of hesperidin with DMPC/cholesterol bilayers. Chem Biol Interact 2022; 366:110131. [PMID: 36037876 DOI: 10.1016/j.cbi.2022.110131] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 08/05/2022] [Accepted: 08/20/2022] [Indexed: 11/03/2022]
Abstract
Since cell membranes are complex systems, the use of model lipid bilayers is quite important for the study of their interactions with bioactive molecules. Mammalian cell membranes require cholesterol (CHOL) for their structure and function. For this reason, the mixtures of phospholipid and cholesterol are necessary to use in model membrane studies to better simulate the real systems. In the present study, we investigated the effect of the incorporation of hesperidin in model membranes consisting of dimyristoylphosphatidylcholine (DMPC) and CHOL by using differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and atomic force microscopy (AFM). ATR-FTIR results demonstrated that hesperidin increases the fluidity of the DMPC/CHOL binary system. DSC findings indicated that the presence of 5 mol% hesperidin induces a broadening of the main phase transition consisting of three overlapping components. AFM experiments showed that hesperidin increases the thickness of DMPC/CHOL lipid bilayer model membranes. In addition to experimental results, molecular docking studies were conducted with hesperidin and human lanosterol synthase (LS), which is an enzyme found in the final step of cholesterol synthesis, to characterize hesperidin's interactions with its surrounding via its hydroxyl and oxygen groups. Then, hesperidin's ADME/Tox (absorption, distribution, metabolism, excretion and toxicity) profile was computed to see the potential impact on living system. In conclusion, considering the data obtained from experimental studies, this work ensures molecular insights in the interaction between a flavonoid, as an antioxidant drug model, and lipids mimicking those found in mammalian membranes. Moreover, computational studies demonstrated that hesperidin may be a great potential for use as a therapeutic agent for hypercholesterolemia due to its antioxidant property.
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Affiliation(s)
- Cisem Altunayar-Unsalan
- Ege University Central Research Testing and Analysis Laboratory Research and Application Center, 35100, Bornova, Izmir, Turkey.
| | - Ozan Unsalan
- Ege University, Faculty of Science, Department of Physics, 35100, Bornova, Izmir, Turkey.
| | - Thomas Mavromoustakos
- Section of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece.
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3
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Goussous S, Fellows A, Casford M, Davies P. A time domain study of surfactin penetrating a phospholipid monolayer at the air-water interface investigated using sum frequency generation spectroscopy, infrared reflection absorption spectroscopy, and AFM-nano infrared microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1568-1578. [DOI: 10.1016/j.bbamem.2019.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 05/13/2019] [Accepted: 06/07/2019] [Indexed: 01/06/2023]
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Bueno OVM, Benítez JJ, San-Miguel MA. Understanding segregation processes in SAMs formed by mixtures of hydroxylated and non-hydroxylated fatty acids. RSC Adv 2019; 9:39252-39263. [PMID: 35540662 PMCID: PMC9076118 DOI: 10.1039/c9ra06799j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/02/2019] [Indexed: 11/21/2022] Open
Abstract
In this paper, we focus on the segregation processes emerging when preparing mixtures with different compositions of aleuritic (9,10,16 trihydroxyhexadecanoic) (ALE) and palmitic (hexadecanoic) (PAL) acids. The combination of atomic force microscopy (AFM) and molecular dynamics (MD) simulations enabled us to prove the role of the functional groups in the formation of self-assembled monolayers (SAMs) on muscovite mica surfaces. MD simulations indicate that segregation processes are favored in high ALE composition mixtures in agreement with the experimental evidence, whereas low ALE compositions promote the co-existence between segregated and dispersed systems. The secondary hydroxyl groups play a central role in the self-assembling mechanism because they control the formation of hydrogen bonding networks guarantying system stability. Segregation processes emerging when preparing self-assembled layers from mixtures with different compositions of aleuritic (9,10,16 trihydroxyhexadecanoic) (ALE) and palmitic (hexadecanoic) (PAL) acids.![]()
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Affiliation(s)
- Otto V. M. Bueno
- Department of Physical Chemistry
- Institute of Chemistry
- University of Campinas – UNICAMP
- 13083-970 Campinas
- Brazil
| | - J. J. Benítez
- Instituto de Ciencias de Materiales de Sevilla
- Centro Mixto CSIC-Universidad de Sevilla
- 49 (41092)-Sevilla
- Spain
| | - Miguel A. San-Miguel
- Department of Physical Chemistry
- Institute of Chemistry
- University of Campinas – UNICAMP
- 13083-970 Campinas
- Brazil
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5
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De Oliveira DWF, Cara AB, Lechuga-Villena M, García-Román M, Melo VMM, Gonçalves LRB, Vaz DA. Aquatic toxicity and biodegradability of a surfactant produced by Bacillus subtilis ICA56. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2017; 52:174-181. [PMID: 27791474 DOI: 10.1080/10934529.2016.1240491] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, the environmental compatibility of a biosurfactant produced by a Bacillus subtilis strain isolated from the soil of a Brazilian mangrove was investigated. The biosurfactant, identified as surfactin, is able to reduce surface tension (ST) to 31.5 ± 0.1 mN m-1 and exhibits a lowcritical micelle concentration (CMC) value (0.015 ± 0.003 g L-1). The highest crude biosurfactant concentration (224.3 ± 1.9 mg L-1) was reached at 72 h of fermentation. Acute toxicity tests, carried out with Daphnia magna, Vibrio fischeri and Selenastrum capricornutum indicated that the toxicity of the biosurfactant is lower than that of its chemically derived counterparts. The results of the biodegradability tests demonstrated that the crude surfactin extract was degraded by both Pseudomonas putida and a mixed population from a sewage-treatment plant, in both cases the biodegradation efficiency being dependent on the initial concentration of the biosurfactant. Finally, as the biodegradation percentages obtained fall within the acceptance limits established by the Organization for Economic Co-operation and Development (Guidelines for Testing of Chemicals, OECD 301E), crude surfactin can be classified as a "readily" biodegradable compound.
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Affiliation(s)
- Darlane W F De Oliveira
- a Departamento de Engenharia Química , Universidade Federal do Ceará , Fortaleza , CE , Brazil
| | - Alejandro B Cara
- b Department of Chemical Engineering , Faculty of Sciences, University of Granada , Granada , Spain
| | - Manuela Lechuga-Villena
- b Department of Chemical Engineering , Faculty of Sciences, University of Granada , Granada , Spain
| | - Miguel García-Román
- b Department of Chemical Engineering , Faculty of Sciences, University of Granada , Granada , Spain
| | - Vania M M Melo
- c Departamento de Biologia , LemBiotech, Laboratório de Ecologia Microbiana e Biotecnologia, Universidade Federal do Ceará , Fortaleza , CE , Brazil
| | - Luciana R B Gonçalves
- a Departamento de Engenharia Química , Universidade Federal do Ceará , Fortaleza , CE , Brazil
| | - Deisi A Vaz
- b Department of Chemical Engineering , Faculty of Sciences, University of Granada , Granada , Spain
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Assemblies of pore-forming toxins visualized by atomic force microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:500-11. [PMID: 26577274 DOI: 10.1016/j.bbamem.2015.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 10/23/2015] [Accepted: 11/09/2015] [Indexed: 02/05/2023]
Abstract
A number of pore-forming toxins (PFTs) can assemble on lipid membranes through their specific interactions with lipids. The oligomeric assemblies of some PFTs have been successfully revealed either by electron microscopy (EM) and/or atomic force microscopy (AFM). Unlike EM, AFM imaging can be performed under physiological conditions, enabling the real-time visualization of PFT assembly and the transition from the prepore state, in which the toxin does not span the membrane, to the pore state. In addition to characterizing PFT oligomers, AFM has also been used to examine toxin-induced alterations in membrane organization. In this review, we summarize the contributions of AFM to the understanding of both PFT assembly and PFT-induced membrane reorganization. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
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7
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Meraz IM, Melendez B, Gu J, Wong STC, Liu X, Andersson HA, Serda RE. Activation of the inflammasome and enhanced migration of microparticle-stimulated dendritic cells to the draining lymph node. Mol Pharm 2012; 9:2049-62. [PMID: 22680980 DOI: 10.1021/mp3001292] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Porous silicon microparticles presenting pathogen-associated molecular patterns mimic pathogens, enhancing internalization of the microparticles and activation of antigen presenting dendritic cells. We demonstrate abundant uptake of microparticles bound by the TLR-4 ligands LPS and MPL by murine bone marrow-derived dendritic cells (BMDC). Labeled microparticles induce concentration-dependent production of IL-1β, with inhibition by the caspase inhibitor Z-VAD-FMK supporting activation of the NLRP3-dependent inflammasome. Inoculation of BALB/c mice with ligand-bound microparticles induces a significant increase in circulating levels of IL-1β, TNF-α, and IL-6. Stimulation of BMDC with ligand-bound microparticles increases surface expression of costimulatory and MHC molecules, and enhances migration of BMDC to the draining lymph node. LPS-microparticles stimulate in vivo C57BL/6 BMDC and OT-1 transgenic T cell interactions in the presence of OVA SIINFEKL peptide in lymph nodes, with intact nodes imaged using two-photon microscopy. Formation of in vivo and in vitro immunological synapses between BMDC, loaded with OVA peptide and LPS-microparticles, and OT-1 T cells are presented, as well as elevated intracellular interferon gamma levels in CD8(+) T cells stimulated by BMDC carrying peptide-loaded microparticles. In short, ligand-bound microparticles enhance (1) phagocytosis of microparticles; (2) BMDC inflammasome activation and upregulation of costimulatory and MHC molecules; (3) cellular migration of BMDC to lymphatic tissue; and (4) cellular interactions leading to T cell activation in the presence of antigen.
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Affiliation(s)
- Ismail M Meraz
- Department of Nanomedicine and §Department of Systems Medicine and Bioengineering, The Methodist Hospital Research Institute , 6670 Bertner Avenue, Houston, Texas 77030, United States
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Shen HH, Thomas RK, Penfold J, Fragneto G. Destruction and solubilization of supported phospholipid bilayers on silica by the biosurfactant surfactin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7334-7342. [PMID: 20112935 DOI: 10.1021/la904212x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The lipopeptide surfactin from Bacillus subtilis strains exhibits strong surface and biological activity, the latter probably because of its interaction with biological membranes. We have investigated the interaction of aqueous solutions of surfactin with supported bilayers of diphosphatidylcholine (DPPC) on silica using neutron reflectometry. We have also used small-angle neutron scattering (SANS) to study the solubilized aggregates formed as a result of the destruction of the supported membrane by surfactin. Although surfactin on its own does not attach to the silica supporting surface, it is taken up from solution by the membrane, confirming that there is an attractive interaction between DPPC and surfactin. The surfactin concentration in the layer can reach up to about 20 mol % relative to DPPC. The membrane is stable provided that the surfactin concentration is below its critical micelle concentration (cmc, 5 x 10(-5) M). Above the cmc, however, the membrane is solubilized and removed from the surface, though not always completely, over a period of hours. There are signs that there is an induction period while the surfactin concentration builds up in the membrane. This would be consistent with the need for a threshold concentration of surfactin in the bilayer. The presence of a surfactin correlation peak in the SANS showed that in the bulk solution, at the same concentrations as used for the deposition, surfactin forms aggregates that must be localized in the DPPC multilamellar vesicles at a separation of about 160 A. The structure could be fitted with an approximate model where the surfactin has an aggregation number of 50 +/- 10 with a radius of about 27 A. Given the very small water thicknesses in the DPPC lamellar aggregates, the surfactin must exist as aggregates in the phospholipid bilayer, and these structures are responsible for solubilizing the DPPC.
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Affiliation(s)
- Hsin-Hui Shen
- Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, UK.
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10
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Boettcher C, Kell H, Holzwarth JF, Vater J. Flexible loops of thread-like micelles are formed upon interaction of L-alpha-dimyristoyl-phosphatidylcholine with the biosurfactant surfactin as revealed by cryo-electron tomography. Biophys Chem 2010; 149:22-7. [PMID: 20406718 DOI: 10.1016/j.bpc.2010.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/08/2010] [Accepted: 03/10/2010] [Indexed: 10/19/2022]
Abstract
Vesicles of L-alpha-dimyristoyl-phosphatidylcholine (DMPC) are known to disintegrate upon treatment with surfactin, a lipoheptapeptide biosurfactant from Bacillus subtilis OKB 105, as was observed by static light scattering (SLS) and cryo-transmission electron microscopy (cryo-TEM) recently. The lysis of DMPC bilayers occurs strongly dependent on the surfactin concentration according to a three-stage model. Unilamellar DMPC vesicles are disrupted to form sheet-like lamellar intermediates at a moderate surfactant concentration, but undergo a transition towards smaller particles of unknown structure at a higher surfactant concentration according to earlier neutron scattering experiments. Here we present direct structural evidence from cryo-electron tomography data that thread-like micelles with a uniform diameter of 6.5 nm are organized into loops of different sizes at a surfactin concentration of > 15 mol%.
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Affiliation(s)
- Christoph Boettcher
- Forschungszentrum für Elektronenmikroskopie, Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstr. 36a, D-14195 Berlin, Germany.
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11
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Shen HH, Thomas RK, Taylor P. The location of the biosurfactant surfactin in phospholipid bilayers supported on silica using neutron reflectometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:320-327. [PMID: 19902970 DOI: 10.1021/la9034936] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have investigated the formation of supported surfactin-phospholipid mixed bilayers using neutron reflectometry. Micellar mixtures of phospholipid (diphosphatidyl choline, DPPC), surfactin, and beta-d-dodecyl maltoside were used to make the deposition. When the surfactin concentration is at its critical micelle concentration (CMC = 6 x 10(-6) M) in the bulk solution, there is no adsorption at all on the silica. When the surfactin concentration is lowered below the CMC, a mixed bilayer of surfactin and DPPC is formed. Since surfactin does not adsorb on silica from solutions of surfactin alone, this shows that there is a strong attraction between surfactin and DPPC. The variation of adsorbed amount, composition, and structure of the adsorbed layer are consistent with the attractive interaction between surfactin and DPPC and with their respective negative and positive affinities for the silica surface. Three phospholipid isotopic contrasts were measured and used to define the composition and structure of the surfactin-phospholipid bilayer. The maximum amount of surfactin in the bilayer reaches a mole fraction of about 0.2 and this is located in the outer leaflet of the bilayer within the headgroup and part of the adjacent chain region.
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Affiliation(s)
- Hsin-Hui Shen
- Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, United Kingdom.
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12
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Wu G, Lee KYC. Effects of poloxamer 188 on phospholipid monolayer morphology: an atomic force microscopy study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:2133-2139. [PMID: 19140701 DOI: 10.1021/la802908x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
P188, a triblock copolymer of the form poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) is known as an effective membrane sealant. Using a dipalmitoylphosphatidylcholine monolayer at the air-water interface to mimic the outer leaflet of the cell membrane, we have examined the interaction between P188 and a phospholipid film. Atomic force microscopy (AFM) was used to investigate the morphological changes in the lipid monolayer induced by P188 insertion upon transferring the lipid/polymer film from the air-water interface onto a solid substrate. Our AFM results confirm that lipid packing regulates poloxamer insertion such that P188 only changes the morphology of a lipid monolayer when the lipid packing density is below that of the insertion threshold. By combining phase imaging and different driving forces in tapping mode AFM, our results further help reveal the distribution of poloxamers in the lipid monolayer with nanometer resolution.
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Affiliation(s)
- Guohui Wu
- Department of Chemistry, the Institute for Biophysical Dynamics & the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
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13
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Bouffioux O, Berquand A, Eeman M, Paquot M, Dufrêne YF, Brasseur R, Deleu M. Molecular organization of surfactin–phospholipid monolayers: Effect of phospholipid chain length and polar head. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1758-68. [PMID: 17532292 DOI: 10.1016/j.bbamem.2007.04.015] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 04/19/2007] [Accepted: 04/20/2007] [Indexed: 11/26/2022]
Abstract
Mixed monolayers of the surface-active lipopeptide surfactin-C(15) and various lipids differing by their chain length (DMPC, DPPC, DSPC) and polar headgroup (DPPC, DPPE, DPPS) were investigated by atomic force microscopy (AFM) in combination with molecular modeling (Hypermatrix procedure) and surface pressure-area isotherms. In the presence of surfactin, AFM topographic images showed phase separation for each surfactin-phospholipid system except for surfactin-DMPC, which was in good agreement with compression isotherms. On the basis of domain shape and line tension theory, we conclude that the miscibility between surfactin and phospholipids is higher for shorter chain lengths (DMPC>DPPC>DSPC) and that the polar headgroup of phospholipids influences the miscibility of surfactin in the order DPPC>DPPE>DPPS. Molecular modeling data show that mixing surfactin and DPPC has a destabilizing effect on DPPC monolayer while it has a stabilizing effect towards DPPE and DPPS molecular interactions. Our results provide valuable information on the activity mechanism of surfactin and may be useful for the design of surfactin delivery systems.
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Affiliation(s)
- O Bouffioux
- Centre de Biophysique Moléculaire Numérique, Faculté Universitaire des Sciences Agronomiques de Gembloux, Passage des Déportés, 2, B-5030 Gembloux, Belgium
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14
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Yang H, Wang Y, Lai S, An H, Li Y, Chen F. Application of Atomic Force Microscopy as a Nanotechnology Tool in Food Science. J Food Sci 2007; 72:R65-75. [DOI: 10.1111/j.1750-3841.2007.00346.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Kell H, Holzwarth JF, Boettcher C, Heenan RK, Vater J. Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of L-alpha-dimyristoyl phosphatidylcholine. Biophys Chem 2007; 128:114-24. [PMID: 17383076 DOI: 10.1016/j.bpc.2007.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2006] [Revised: 03/04/2007] [Accepted: 03/06/2007] [Indexed: 10/23/2022]
Abstract
To understand the biological action of surfactin from Bacillus subtilis we investigated its effects on the phase transition of L-alpha-dimyristoyl phosphatidylcholine (DMPC)-vesicles from the crystalline to the fluid state using differential scanning calorimetry; light scattering; small angle neutron scattering and cryo-electron microscopy. DSC-thermograms revealed two phase transition peaks. Light scattering profiles showed two branches with characteristic hysteresis phenomena. With both techniques the same values of the phase transition temperatures T(m1) and T(m2) of 23.5 and 23 degrees C were obtained indicating two forms of DMPC-surfactin aggregates which could be visualized by cryo-electron microscopy. Until 4 mol% surfactin the vesicular form predominated, but was accompanied by bilayered membrane fragments by increasing the biosurfactant concentrations. At surfactin concentrations higher than 15 mol% smaller DMPC-surfactin micelles of ellipsoidal conformation were formed, as demonstrated by small angle neutron scattering. In addition, by "Poor Man's" temperature-jump-relaxation spectroscopy slow transients in the phase transition of vesicular DMPC-surfactin aggregates with relaxation times of 20-30 s were detected which presumably indicate the slow dissipation of intermediate lipid-and surfactin domains formed after the main phase transition on the way to the fluid state. This process is accelerated by surfactin.
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Affiliation(s)
- Henny Kell
- Fritz-Haber-Institut, Max-Planck-Society, Faradayweg 4-6, D-14195 Berlin, Germany
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16
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Chiantia S, Ries J, Kahya N, Schwille P. Combined AFM and Two-Focus SFCS Study of Raft-Exhibiting Model Membranes. Chemphyschem 2006; 7:2409-18. [PMID: 17051578 DOI: 10.1002/cphc.200600464] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Dioleoylphosphatidylcholine/sphingomyelin/cholesterol (DOPC/SM/cholesterol) model membranes exhibit liquid-liquid phase separation and therefore provide a physical model for the putative liquid-ordered domains present in cells. Here we present a combination of atomic force microscopy (AFM) imaging, force measurements, confocal fluorescence imaging and two-focus scanning fluorescence correlation spectroscopy (two-focus SFCS) to obtain structural and dynamical information about this model membrane system. Partition coefficients and diffusion coefficients in the different phases were measured with two-focus SFCS for numerous fluorescent lipid analogues and proteins, while being directly related to the lateral organization of the membrane and its mechanical properties probed by AFM. Moreover we show how the combination of these different approaches is effective in reducing artifacts resulting from the use of a single technique.
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Affiliation(s)
- Salvatore Chiantia
- Biotechnologisches Zentrum, Technical University of Dresden, Tatzberg 47-51, 01307 Dresden, Germany
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17
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Lee TH, Aguilar MI. Trends in the development and application of functional biomembrane surfaces. BIOTECHNOLOGY ANNUAL REVIEW 2006; 12:85-136. [PMID: 17045193 DOI: 10.1016/s1387-2656(06)12004-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- Tzong-Hsien Lee
- Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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18
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Ng ML, Lee JWM, Leong MLN, Ling AE, Tan HC, Ooi EE. Topographic changes in SARS coronavirus-infected cells at late stages of infection. Emerg Infect Dis 2005; 10:1907-14. [PMID: 15550199 PMCID: PMC3328989 DOI: 10.3201/eid1011.040195] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Scanning electron and atomic force microscopy was used for the first time to view the maturation of SARS-CoV at the cell surface. Scanning electron and atomic force microscopy was used for the first time to view the maturation of the severe acute respiratory syndrome–associated coronavirus at the cell surface. The surface form of the cells at advanced infection displayed prolific pseudopodia that, in addition to the rest of the plasma membrane, were also active sites of virus release. High magnification of the maturing virus particles showed a rosette appearance with short knoblike spikes under both the scanning electron and atomic force microscopes. The final expulsion step of the maturing virus particles seemed to result in some disruptions to the plasma membrane. The cytoskeletal network along the edge of the infected cells was enhanced and could be involved in transporting and expelling the progeny virus particles. Thickening of the actin filaments at the cell edge provided the bending force to extrude the virus particles.
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Affiliation(s)
- M L Ng
- Department of Microbiology, National University of Singapore, Singapore.
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19
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Liu X, Huang W, Wang E. An electrochemical study on the interaction of surfactin with a supported bilayer lipid membrane on a glassy carbon electrode. J Electroanal Chem (Lausanne) 2005. [DOI: 10.1016/j.jelechem.2004.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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20
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Eeman M, Deleu M, Paquot M, Thonart P, Dufrêne YF. Nanoscale properties of mixed fengycin/ceramide monolayers explored using atomic force microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:2505-2511. [PMID: 15752046 DOI: 10.1021/la0475775] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To gain insight into the interactions between fengycin and skin membrane lipids, mixed fengycin/ceramide monolayers were investigated using atomic force microscopy (AFM) (monolayers supported on mica) and surface pressure-area isotherms (monolayers at the air-water interface). AFM topographic images revealed phase separation in mixed monolayers prepared at 20 degrees C/pH 2 and composed of 0.25 and 0.5 fengycin molar ratios, in the form of two-dimensional (2-D) hexagonal crystalline domains of ceramide surrounded by a fengycin-enriched fluid phase. Surface pressure-area isotherms as well as friction and adhesion AFM images confirmed that the two phases had different molecular orientations: while ceramide formed a highly ordered phase with crystalline chain packing, fengycin exhibited a disordered fluid phase with the peptide ring lying horizontally on the substrate. Increasing the temperature and pH to values corresponding to the skin parameters, i.e., 37 degrees C/pH 5, was found to dramatically affect the film organization. At low fengycin molar ratio (0.25), the hexagonal ceramide domains transformed into round domains, while at higher ratio (0.5) these were shown to melt into a continuous fengycin/ceramide fluid phase. These observations were directly supported by the thermodynamic analysis (deviation from the additivity rule, excess of free energy) of the monolayer properties at the air-water interface. Accordingly, this study demonstrates that both the environmental conditions (temperature, pH) and fengycin concentration influence the molecular organization of mixed fengycin/ceramide monolayers. We believe that the ability to modulate the formation of 2-D domains in the skin membrane may be an important biological function of fengycin, which should be increasingly investigated in future pharmacological research.
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Affiliation(s)
- M Eeman
- Unité de Chimie Biologique Industrielle and Unité de Bio-industries, Faculté Universitaire des Sciences Agronomiques de Gembloux, Passage des Déportés, 2, B-5030 Gembloux, Belgium
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21
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Santos NC, Castanho MARB. An overview of the biophysical applications of atomic force microscopy. Biophys Chem 2004; 107:133-49. [PMID: 14962595 DOI: 10.1016/j.bpc.2003.09.001] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2002] [Revised: 07/30/2003] [Accepted: 09/04/2003] [Indexed: 11/27/2022]
Abstract
The potentialities of the atomic force microscopy (AFM) make it a tool of undeniable value for the study of biologically relevant samples. AFM is progressively becoming a usual benchtop technique. In average, more than one paper is published every day on AFM biological applications. This figure overcomes materials science applications, showing that 17 years after its invention, AFM has completely crossed the limits of its traditional areas of application. Its potential to image the structure of biomolecules or bio-surfaces with molecular or even sub-molecular resolution, study samples under physiological conditions (which allows to follow in situ the real time dynamics of some biological events), measure local chemical, physical and mechanical properties of a sample and manipulate single molecules should be emphasized.
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Affiliation(s)
- Nuno C Santos
- Instituto de Bioquímica/Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal.
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Greene ME, Kinser CR, Kramer DE, Pingree LSC, Hersam MC. Application of scanning probe microscopy to the characterization and fabrication of hybrid nanomaterials. Microsc Res Tech 2004; 64:415-34. [PMID: 15549695 DOI: 10.1002/jemt.20100] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Scanning probe microscopy (SPM) is a widely used experimental technique for characterizing and fabricating nanostructures on surfaces. In particular, due to its ability to spatially map variations in materials properties with nanometer spatial resolution, SPM is particularly well suited to probe the subcomponents and interfaces of hybrid nanomaterials, i.e., materials that are made up of distinct nanometer scale components with distinguishable properties. In addition, the interaction of the SPM tip with materials can be intentionally tuned such that local surface modification is achieved. In this manner, hybrid nanostructures can also be fabricated on solid substrates using SPM. This report reviews recent developments in the characterization and fabrication of hybrid nanomaterials with SPM. Specific attention is given to nanomaterials that consist of both organic and inorganic components including individual biomolecules mounted on inorganic substrates. SPM techniques that are particularly well suited for characterizing the mechanical and electrical properties of such hybrid systems in atmospheric pressure environments are highlighted, and specific illustrative examples are provided. This review concludes with a brief discussion of the remaining challenges and promising future prospects for this field.
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Affiliation(s)
- Mark E Greene
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, USA
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