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AB block copolymers with an amorphous polybutadiene block and a polypeptide block were prepared. The method of synthesis consists in the preparation of a polybutadiene block by anionic polymerization followed by a chemical modification of its living end introducing a primary amine group which is able to intiate the polymerization of the N-carboxy anhydride (NCA) of the chosen amino acid. By this way the'block copolymers polybutadiene/poly(y-benzyl L-glutamate) (14a) were prepared, in which the poly(y-benzyl-L-glutamate) block could be transformed into a poly(N 5-hydroxypropyl-~glutamine) block by reaction with 3-amino-1 -propano1 leading to the block copolymers polybutadiene/poly(N5-hydroxypropylglutamine) (14b). By using X-ray diffraction and electron microscopy it could be shown that the block copolymers 14a and 14b exhibit mesophases in different solvents and it was established that the structure of the mesophases is lamellar. Each sheet of the lamellar structure consists of the superposition of two layers: one formed by the polybutadiene chains in a more or less random coil conformation; the other formed by the polypeptide chains in an a-helix conformation, arranged in an hexagonal array and folded. ZUSAMMENFASSUNG:AB Blockcopolymere mit einem amorphen Polybutadienblock und einem Polypeptidblock wurden dargestellt. Die Synthesemethode besteht in der Herstellung eines Polybutadiens durch anionische Polymerisation und der Umwandlung des Jebenden" Endes in eine primare Aminogruppe, die die Polymerisation des N-Carboxyanhydrides (NCA) der gewahlten Aminosaure initiiert. Auf diese Weise wurden Polybutadien/Poly(y-benzyl-L-glutamat)-Blockcopolymere (14a) dargestellt. In diesen wurde durch Einwirkung von 3-Amino-1-propanol der Poly(y-benzyl-L-glutamat)-Block in einen Poly(N5-hydroxypropyl-L-glutamin)-Block umgewandelt, unter Bildung des Polybutadiene/Poly(N5-hydroxypropyl-L-glutamin)-Blockcopolymeren (14b). Mit Hilfe der Rontgenstreuung und der Elektronenmikroskopie wurde gezeigt, daD die Blockcopolymeren 14a und 14b in Gegenwart eines selektiven Losungsmittels geordnete Strukturen bilden, namlich eine lamellare Struktur. Jede Lamelle besteht aus zwei Schichten: in der einen liegen die Polybutadienketten als mehr oder weniger statistische Knauel vor, in der anderen sind die Polypeptidketten in Form einer @-Helix hexagonal angeordnet und gefaltet. *) Systematic nomenclature: poly{imino[3-(benzyloxycarbonyl)propylidene]carbony~};cf. " IUPAC, Information Bulletin No. 29, 1972.

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The thermotropic behavior and molecular properties of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-dihydrosterculoyl-sn-glycero-3-phosphoethanolamine (PDSPE) have been investigated by 2H NMR spectroscopy using samples selectively labeled at the 5'-, 9'-, 10'-, and 16'-positions of the sn-2 chains. Comparison with the corresponding phosphocholine analogues (POPC and PDSPC), obtained as intermediate synthetic products, was used to monitor the role of the polar head group. Replacement of the choline moiety by ethanolamine increased the gel to liquid-crystal transition temperature by 10-32 degrees C and led to a significantly higher ordering of the fatty acyl chains in the liquid-crystalline bilayer state. The lateral compression effect, due to the smaller area per polar head group in PE, results in a bilayer to hexagonal phase transition at elevated temperatures. The effects on both PC and PE due to replacement of the olefinic group by a cyclopropane unit are similar. A decrease in the temperature of the gel to liquid-crystal phase transition, Tc, is observed upon introduction of a cyclopropane ring; it goes from 26 degrees C in POPE to approximately 10 degrees C in PDSPE. In addition, a very significant broadening of the transition profile is observed. These observations are consistent with the poor packing ability of mixed saturated and cyclopropane-containing chains due to the bulky substituent effect. The temperature of the bilayer-hexagonal phase transition of PE samples was decreased by 15-20 degrees C on replacement of oleoyl chains by dihydrosterculoyl chains at the sn-2 position.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclodextrins are natural cyclic oligosaccharides widely used as "molecular cages" in the pharmaceutical, agrochemical, food and cosmetical industries. The optimization of their pharmacological properties has led to the synthesis of numerous analogues. Amphiphilic derivatives were designed to improve the cell targeting of the drug-containing cyclodextrin cavities through their transportation in the organism, within self-assembling systems. Amphiphilic cyclodextrins can self-assemble into water-soluble aggregates such as mono or polydisperse micelles, or insert in lipid membranes and liposomes. Polysubstituted amphiphilic cyclodextrins are briefly reviewed, and monosubstituted derivatives of native and methylated beta-cyclodextrins are presented in more details, with an emphasis on their self-organization within lipid membranes.

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