References of "Deleu, Magali"
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See detailLa chimie au service de la biomasse
Deleu, Magali ULg

Scientific conference (2007)

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See detailMolecular organization of surfactin-phospholipid monolayers: Effect of phospholipid chain length and polar head
Bouffioux, O.; Berquand, A.; Eeman, M. et al

in Biochimica et Biophysica Acta - Biomembranes (2007), 1768(7), 1758-1768

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 ... [more ▼]

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. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailThe Biologically Important Surfactin Lipopeptide Induces Nanoripples In Supported Lipid Bilayers
Brasseur, Robert ULg; Braun, N.; El Kirat, K. et al

in Langmuir (2007), 23(19), 9769-72

Under specific conditions, lipid membranes form ripple phases with intriguing nanoscale undulations. Here, we show using in situ atomic force microscopy (AFM) that the biologically important surfactin ... [more ▼]

Under specific conditions, lipid membranes form ripple phases with intriguing nanoscale undulations. Here, we show using in situ atomic force microscopy (AFM) that the biologically important surfactin lipopeptide induces nanoripples of 30 nm periodicity in dipalmitoyl phosphatidylcholine (DPPC) bilayers at 25 degrees (i.e. well below the pretransition temperature of DPPC). Whereas most undulations formed the classical straight orientation with characteristic angle changes of 120 degrees , some of them also displayed unusual circular orientations. Strikingly, ripple structures were formed at 15% surfactin but were rarely or never observed at 5 and 30% surfactin, emphasizing the important role played by the surfactin concentration. Theoretical simulations corroborated the AFM data by revealing the formation of stable surfactin/lipid assemblies with positive curvature. [less ▲]

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See detailCharacterization at nanometric scale of the interaction between fluoroquinolones (ciprofloxacin) and membrane lipids
Bensikaddour, Helmet; Fa, Nathalie; Deleu, Magali ULg et al

Poster (2006)

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See detailInvestigation of interactions between phospholipids, cholesterol and surfactin by atomic force microscopy and differential scanning calorimetry
Eeman, Marc; Nylander, Tommy; Dufrêne, Yves et al

Poster (2006)

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See detailEffects of lipopeptidesonmodel membranes
Deleu, Magali ULg

in 6th annual surface and colloid symposium: lipid-peptide interactions and biological function (2006)

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See detailPenetration of surfactin into phospholipid monolayers: Nanoscale interfacial organization
Eeman, M.; Berquand, A.; Dufrene, Y. F. et al

in Langmuir (2006), 22(26), 11337-11345

Atomic force microscopy (AFM) combined with surface pressure-area isotherms were used to probe the interfacial behavior of phospholipid monolayers following penetration of surfactin, a cyclic lipopeptide ... [more ▼]

Atomic force microscopy (AFM) combined with surface pressure-area isotherms were used to probe the interfacial behavior of phospholipid monolayers following penetration of surfactin, a cyclic lipopeptide produced by Bacillus subtilis strains. Prior to penetration experiments, interfacial behavior of different surfactin molecules (cyclic surfactins with three different aliphatic chain lengths-S13, S14, and S15-and a linear surfactin obtained by chemical cleavage of the cycle of the surfactin S15) has been investigated. A more hydrophobic aliphatic chain induces greater surface-active properties of the lipopeptide. The opening of the peptide ring reduces the surface activity. The effect of phospholipid acyl chain length (dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine- (DPPC), and distearoylphosphatidylcholine) and phospholipid polar head (DPPC, dipalmitoylphosphatidylethanolamine and dipalmitoylphosphatidylserine) on monolayer penetration properties of the surfactin S15 has been explored. Results showed that while the lipid monolayer thickness and the presence of electrostatic repulsions from the interfacial film do not significantly influence surfactin insertion, these parameters strongly modulate the ability of the surfactin to alter the nanoscale organization of the lipid films. We also probed the effect of surfactin structure (influence of the aliphatic chain length and of the cyclic structure of the peptide ring) on the behavior of DPPC monolayers. AFM images and isotherms showed that surfactin penetration is promoted by longer lipopeptide chain length and a cyclic polar head. This indicates that hydrophobic interactions are of main importance for the penetration power of surfactin molecules. [less ▲]

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See detailEffect Of The Antibiotic Azithromycin On Thermotropic Behavior Of Dopc Or Dppc Bilayers
Fa, N.; Ronkart, Sébastien ULg; Schanck, A. et al

in Chemistry and Physics of Lipids (2006), 144(1),

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See detailFengycin Interaction With Lipid Monolayers At The Air-Aqueous Interface - Implications For The Effect Of Fengycin On Biological Membranes
Deleu, Magali ULg; Paquot, Michel ULg; Nylander, T.

in Journal of Colloid and Interface Science (2005), 283(2), 358-365

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See detailHemolytic activity of new linear surfactin analogs in relation to their physico-chemical properties
Dufour, Samuel; Deleu, Magali ULg; Nott, Katherine ULg et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1726

New linear analogs of surfactin have been synthesized. Their physico-chemical parameters were determined. The results indicate that these linear products show surface activities although they are lowered ... [more ▼]

New linear analogs of surfactin have been synthesized. Their physico-chemical parameters were determined. The results indicate that these linear products show surface activities although they are lowered compared to those of cyclic compounds. The hemolytic activities have also been assayed. In contrast with cyclic surfactins, no significant hemolysis occurs for the linear products in the range of concentrations tested. Moreover, a protective effect against Triton X-100 induced hemolysis has been highlighted for linear surfactins. The concentration at which this protective effect happens is correlated directly to the CMC, and inversely to the acyl chain length of the product. In a hypotonic medium, analogs having a long acyl chain tend to increase the hemolysis, meanwhile the product with the shortest chain tends to decrease it. [less ▲]

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See detailProbing fluoroquinoone-biomembrane interactions on the nanoscale
Fa, Nathalie; Burton, Ingrid; Deleu, Magali ULg et al

Poster (2005)

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See detailEffect of potential drugs on model membranes - An AFM study
Eeman, Marc; Deleu, Magali ULg; Paquot, Michel ULg et al

Poster (2005)

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See detailHemolytic activity of new linear surfactin analogs
Dufour, Samuel; Deleu, Magali ULg; Wathelet, Bernard ULg et al

Poster (2005)

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See detailEffects of bioactive amphiphiles on model cell membranes
Deleu, Magali ULg

in 11th W. Mejbaum-Katzenellenbogen's Molecular Biology Seminar: amphiphiles and their aggregates in basic and applied science (2005)

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See detailNanoscale Properties Of Mixed Fengycin/Ceramide Monolayers Explored Using Atomic Force Microscopy
Eeman, M.; Deleu, Magali ULg; Paquot, Michel ULg et al

in Langmuir (2005), 21(6),

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 ... [more ▼]

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 °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 adhesionAFMimages 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 °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)andfengycin concentration influence the molecular organization of mixed fengycin/ceramide monolayers.Webelieve 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. [less ▲]

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See detailNovel use of lipopeptide preparations
Deleu, Magali ULg; Brans, Alain; Brasseur, Robert ULg et al

Patent (2004)

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See detailFrom renewable vegetables resources to microorganisms: new trends in surfactants
Deleu, Magali ULg; Paquot, Michel ULg

in Comptes Rendus Chimie (2004), 7(6-7), 641-646

Surfactants are an important class of chemical products in view of the volumes sold and of their great variety of applications. Biosurfactants produced by microorganisms, and surfactants derived from ... [more ▼]

Surfactants are an important class of chemical products in view of the volumes sold and of their great variety of applications. Biosurfactants produced by microorganisms, and surfactants derived from renewable raw materials are coming progressively onto the market. Considering their many properties and large field of applications, their development needs extensive cooperation across disciplines (chemists, physicochemists, biologists, product developers, formulators...) in order to fully characterize them (chemical structure, surface activity, self assembly properties...) and identify their potential uses. New value adding opportunities will result from the identification of specific activities of biosurfactants, especially in relation with their biological effects (antibiotic, antifungal, insecticide, antiviral and antitumoral agent, immunomodulator or specific toxins and enzyme inhibitors). (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved. [less ▲]

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