Toluene/Butanol Binary Solvents Confined In Periodic Organosilicates
par Aicha Jani
The confinement of liquid mixtures in porous channels provides new insight into fluid ordering at the nanoscale. In this presentation, we address a phenomenon of microphase separation, which appears as a novel fascinating confinement effect for fully miscible binary liquids. This phenomenon was firstly investigated for tert butanol toluene mixtures confined in the straight and mono dispersed cylindrical nanochannels of MCM-41 and SBA-15 mesoporous silicates (D=3 6 nm and 8 3 nm). The present study aims at extending this approach to different fluid wall interactions. It shows that novel types of nanostructures can be generated using functionalized porous organosilicates with periodic alternating surface chemistry along the pore channel.
How do co-solvents affect Lanreotide self assembly ?
par Nadia Halzoun
Self-assembly is an ubiquitous process in nature. It governs the spontaneous supramolecular organisation of biological systems such as membranes, cytoskeleton, DNA double helix and protein folding through noncovalent interactions. Peptides are oligomers of amino acids linked by amide bond. They are versatile and simple building blocks to design self assembling nano architectures such as nanotubes, spheres, ribbons or fibers. In this presentation, a model of pharmaceutical peptide self assembly is discussed. Lanreotide is a dicationic octapeptide which forms more or less viscous gels in water. Its secondary β hairpin structure is cyclised by disulfide bridge 4. In pure water, Lanreotide (10% w/w) self assembles in nanotubes with a diameter of 24.4 nm, a wall thickness of 1.8 nm and few hundred micrometers length. The wall of the nanotubes forms a bi dimensional crystal. The self-assembly of Lanreotide is ruled by its amphiphilicity through hydrophobic and hydrophilic faces of the β hairpin. The nanostructures are stabilized by non covalent interactions : hydrophobic effect Hydrogen bond, aromatic interactions and electrostatic repulsions.