References of "Deleu, Magali"
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See detailEffect of Fengycin, a Lipopeptide Produced by Bacillus Subtilis, on Model Biomembranes
Deleu, Magali ULg; Paquot, Michel ULg; Nylander, T.

in Biophysical Journal (2008), 94(7), 2667-2679

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See detailFunctional properties of phospholipids and proteins from rapeseed as native tensioactives
Vaca Medina, Guadalupe; Mouloungui, Zéphirin; Deleu, Magali ULg et al

Poster (2008)

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See detailInfluence of environmental conditions on the interfacial organisation of fengycin, a bioactive lipopeptide produced by Bacillus subtilis
Eeman, Marc; Pegado, Luis; Dufrêne, Yves et al

Poster (2008)

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See detailAtomic force microscopy of supported lipid bilayers.
Mingeot-Leclercq, Marie*-Paule; Deleu, Magali ULg; Brasseur, Robert ULg et al

in Nature Protocols (2008), 3(10), 1654-9

Supported lipid bilayers (SLBs) are widely used in biophysical research to investigate the properties of biological membranes and offer exciting prospects in nanobiotechnology. Atomic force microscopy ... [more ▼]

Supported lipid bilayers (SLBs) are widely used in biophysical research to investigate the properties of biological membranes and offer exciting prospects in nanobiotechnology. Atomic force microscopy (AFM) has become a well-established technique for imaging SLBs at nanometer resolution. A unique feature of AFM is its ability to monitor dynamic processes, such as the interaction of bilayers with proteins and drugs. Here, we present protocols for preparing dioleoylphosphatidylcholine/dipalmitoylphosphatidylcholine (DOPC/DPPC) bilayers supported on mica using small unilamellar vesicles and for imaging their nanoscale interaction with the antibiotic azithromycin using AFM. The entire protocol can be completed in 10 h. [less ▲]

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See detailNanoscale membrane activity of surfactins: Influence of geometry, charge and hydrophobicity
Francius, Gregory; Dufour, Samuel; Deleu, Magali ULg et al

in Biochimica et Biophysica Acta - Biomembranes (2008), 1778

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See detailCharacterization of the interactions between fluoroquinolone antibiotics and lipids: a multitechnique approach.
Bensikaddour, Hayet; Fa, Nathalie; Burton, Ingrid et al

in Biophysical Journal (2008), 94(8), 3035-46

Probing drug/lipid interactions at the molecular level represents an important challenge in pharmaceutical research and membrane biophysics. Previous studies showed differences in accumulation and ... [more ▼]

Probing drug/lipid interactions at the molecular level represents an important challenge in pharmaceutical research and membrane biophysics. Previous studies showed differences in accumulation and intracellular activity between two fluoroquinolones, ciprofloxacin and moxifloxacin, that may actually result from their differential susceptibility to efflux by the ciprofloxacin transporter. In view of the critical role of lipids for the drug cellular uptake and differences observed for the two closely related fluoroquinolones, we investigated the interactions of these two antibiotics with lipids, using an array of complementary techniques. Moxifloxacin induced, to a greater extent than ciprofloxacin, an erosion of the DPPC domains in the DOPC fluid phase (atomic force microscopy) and a shift of the surface pressure-area isotherms of DOPC/DPPC/fluoroquinolone monolayer toward lower area per molecule (Langmuir studies). These effects are related to a lower propensity of moxifloxacin to be released from lipid to aqueous phase (determined by phase transfer studies and conformational analysis) and a marked decrease of all-trans conformation of acyl-lipid chains of DPPC (determined by ATR-FTIR) without increase of lipid disorder and change in the tilt between the normal and the germanium surface (also determined by ATR-FTIR). All together, differences of ciprofloxacin as compared to moxifloxacin in their interactions with lipids could explain differences in their cellular accumulation and susceptibility to efflux transporters. [less ▲]

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See detailProbing Peptide-Membrane Interactions Using Afm
Brasseur, Robert ULg; Deleu, Magali ULg; Mingeot-Leclercq, Mp. et al

in Surface and Interface Analysis [=SIA] (2008), 40(3-4), 151-156

Atomic force microscopy (AFM) has become a powerful addition to the range of instruments available to probe the organization of lipid monolayers and bilayers. Currently, AFM is the only tool that can ... [more ▼]

Atomic force microscopy (AFM) has become a powerful addition to the range of instruments available to probe the organization of lipid monolayers and bilayers. Currently, AFM is the only tool that can provide nanoscale topographic images of supported lipid membranes under physiological conditions, enabling researchers to resolve their detailed structure and to monitor their interaction with drugs, peptides and proteins. Here, we survey recent data obtained by our research groups that demonstrate the power of the technique for exploring peptide–membrane interactions, with an emphasis on microbial lipopeptides and on tilted peptides. [less ▲]

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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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