Membrane functionalisation using modified cyclodextrins (M. Bauer)
Cyclodextrins are cyclic oligoglucosides with a truncated cone shape. Being able
to form inclusion complexes with many molecules and being readily modified due
to their large number of hydroxyl groups, cyclodextrins are valuable scaolds for
supramolecular chemistry and amphiphilic compound construction.
This work focuses on the ability of modified amphiphilic cyclodextrins to form
monolayers and to insert into DPPC model membranes. The investigated compounds
are permethylated - and - cyclodextrin derivatives to which one or two
lipophilic cholesterol units are attached. Langmuir monolayers of the pure amphiphiles,
as well as mixtures with DPPC, are studied. In order to find out about
the phase behavior, Langmuir isotherms are recorded and simultanously imaged
by Brewster Angle Microscopy. To be able to obtain more quantitative information,
x-ray and neutron reflectivity measurements are carried out. Atomic Force
Microscopy of Langmuir Blodgett films on hydrophilic silicon wafers is used to
get a detailed structure of the monolayers.
This research is embedded in the Slidtetherlig project, having been started in the
beginning of 2008 in collaboration with the ICS in Strasbourg. Goal of this project
is to construct functionalised vesicles by incorporation of the amphiphilic cyclodextrins
into its membrane, so that rotaxanes can be formed with functionalised
polyethylene glycol polymers threaded through the cyclodextrin cavities (Fig. 1).
These nanodevices might be of use for directed liposomal drug delivery, construction
of soft nano-interfaces and measurement of forces between membranes.
Système modèle de biominéralisation (N. Chevalier)
J'exposerai dans un premier temps le résultat de mes recherches sur la croissance de carbonate de calcium sous des monocouches - peptidiques notamment - et leurs implications pour notre compréhension de la biominéralisation. Je parlerai ensuite du comportement bizarre d'une monocouche d'acide gras observée par AFM liquide.