1: Biochim Biophys Acta. 2008 Oct;1778(10):2058-68. Epub 2008 Apr 11.

Nanoscale membrane activity of surfactins: influence of geometry, charge and

Francius G, Dufour S, Deleu M, Paquot M, Mingeot-Leclercq MP, Dufrêne YF.

Unité de chimie des interfaces, Université catholique de Louvain, Croix du Sud
2/18, B-1348 Louvain-la-Neuve, Belgique.

We used real-time atomic force microscopy (AFM) to visualize the interactions
between supported lipid membranes and well-defined surfactin analogs, with the
aim to understand the influence of geometry, charge and hydrophobicity. AFM
images of mixed dioleoylphosphatidylcholine/dipalmitoylphosphatidylcholine
(DOPC/DPPC) bilayers recorded after injection of cyclic surfactin at 1 mM, i.e.
well-above the critical micelle concentration, revealed a complete solubilization
of the bilayers within 30 min. A linear analog having the same charge and acyl
chains was able to solubilize DOPC, but not DPPC, and to promote redeposition
leading eventually to a new bilayer. Increasing the charge of the polar head or
the length of the acyl chains of the analogs lead to the complete solubilization 
of both DOPC and DPPC, thus to a stronger membrane activity. Lastly, we found
that at low surfactin concentrations (40 microM), DPPC domains were always
resistant to solubilization. These data demonstrate the crucial role played by
geometry, charge and hydrophobicity in modulating the membrane activity
(solubilization, redeposition) of surfactin. Also, this study suggests that
synthetic analogs are excellent candidates for developing new surfactants with
tunable, well-defined properties for medical and biotechnological applications.

PMID: 18455997 [PubMed - indexed for MEDLINE]

Related Links

    Solubilization of supported lipid membranes by octyl glucoside observed by
time-lapse atomic force microscopy. [Colloids Surf B Biointerfaces. 2007]

    Membrane resistance to Triton X-100 explored by real-time atomic force
microscopy. [Langmuir. 2006] PMID:16768509

    The biologically important surfactin lipopeptide induces nanoripples in supported
lipid bilayers. [Langmuir. 2007] PMID:17696376

    Penetration of surfactin into phospholipid monolayers: nanoscale interfacial
organization. [Langmuir. 2006] PMID:17154623

    Effect of membrane composition on surface states of ganglioside
GM1/dipalmitoylphosphatidylcholine/dioleoylphosphatidylcholine monolayers.
[Colloids Surf B Biointerfaces. 2004] PMID:15261092