Surfactant dependent morphology of polymeric capsules of perfluorooctyl bromide: influence of polymer adsorption at the dichloromethane-water interface.

In a strategy to develop more stable ultrasound contrast agents (UCAs), we have designed a process to obtain nano/microcapsules with a single core of liquid perfluorocarbon within a biodegradable polymeric shell of homogeneous thickness. During the optimization of perfluorooctyl bromide (PFOB) encapsulation by solvent emulsion-evaporation, a marked influence of surfactants has been observed. While sodium cholate leads to spherical capsules of homogeneous thickness, sodium taurocholate induces to the formation of "acorn"-particles with one hemisphere of PFOB and another one of PLGA, and polyvinyl alcohol is responsible for the coexistence of both morphologies. Whereas the theoretical model proposed by Torza and Mason [J. Colloid Interface Sci. 33 (1970) 67] fails to predict the observed morphologies, microscopic observations of the evaporation and interfacial tension measurements provide an insight into the mechanism of formation of these structures. Most probably, there is a competition between PLGA and the surfactant stabilizing the emulsion at the dichloromethane-water interface. If PLGA is able to adsorb at the interface, the core-shell morphology is obtained, otherwise the acorn morphology is preferentially formed. When the surfactant rearrangement at the interface is long (>30 min), a coexistence of morphologies can be obtained.

[Nursing practices about preparation and administration of oral solutions in psychiatry]. / Pratiques infirmières de préparation et d'administration des solutions buvables en psychiatrie.

Oral liquid drugs have many advantages in psychiatry (compliance, facility of administration) but they may be origin of medicinal iatrogenics (dose error). Since 2001, chemistry of Paul Guiraud's hospital (Villejuif) has developed recommendations about this galenic form and measured every two years practices evolution and respect of recommendations. In 2005, we analysed 601 prescriptions (100%) and collected 215 questionnaires (60% of answers). This study confirms the large prescription of oral liquid forms and the necessity to improve recommendations diffusion. The chemistry in collaboration with the cares department has produced a booklet of drugs administration, a poster and has set up information meetings with medical and nursery teams. The aim of this study is to evaluate nurse practices about preparation and administration of oral liquid drugs. It is part of a global process to accredit and secure the drug use process.

New self-assembled nanogels based on host-guest interactions: characterization and drug loading.

We show here, for the first time, that two neutral polymers may completely associate together in water to spontaneously form supramolecular nanoassemblies (nanogels) of spherical shape. The cohesion of these stable structures of about 200 nm is based upon a "lock and key" mechanism: inclusion complexes are formed between the hydrophobic alkyl chains grafted on a polysaccharide (dextran) and the molecular cavities contained in a poly-cyclodextrin polymer. Production yields reached 95%. It was established that all the alkyl chains were included within the cyclodextrins' cavities in these nanoassemblies. The multivalent character of the interactions between the two polymers ensures the stability of the nanoassemblies. Moreover, empty cyclodextrin units remained accessible for the inclusion of compounds of interest such as benzophenon or tamoxifen.