Self-assembly of phosphate fluorosurfactants in carbon dioxide.

Anionic phosphodiester surfactants, possessing either two fluorinated chains (F/F) or one hydrocarbon chain and one fluorinated chain (H/F), were synthesized and evaluated for solubility and self-assembly in liquid and supercritical carbon dioxide. Several surfactants, of both F/F and H/F types and having varied counterions, were found to be capable of solubilizing water-in-CO2 (W/C), via the formation of microemulsions, expanding upon the family of phosphate fluorosurfactants already found to stabilize W/C microemulsions. Small-angle neutron scatteringwas used to directly characterize the microemulsion particles at varied temperatures, pressures, and water loadings, revealing behavior consistent with previous results on W/C microemulsions.

Depth-profiling with giant vesicle membranes.

A phospholipid fluorescent-labeled in one of three locations was paired with a phospholipid labeled with a quencher in one of three locations within a host phospholipid bilayer. The various combinations of quenching efficiencies allowed the location of the fluorescent labels to be determined. It was found that all three labels (including one attached to the chain terminus) position themselves at the bilayer surface.

New phosphate fluorosurfactants for carbon dioxide.

Anionic phosphate fluorosurfactants were shown to self-assemble into water-in-carbon dioxide microemulsions. The surfactants, having either two fluorinated chains or one fluorinated chain and one hydrocarbon chain, facilitated significant water uptake in CO2. Small angle neutron scattering (SANS) measurements of surfactant/water/CO2 solutions confirmed the presence of nanometer-scale aggregates, indicative of microemulsion formation.

Digitonin as a Chemical Trigger for the Selective Transformation of Giant Vesicles.

The rupture of cationic giant vesicles (see the picture) in the presence of anionic vesicles, or the reverse, on exposure to digitonin is dependent on the respective cholesterol levels (0-50 mol%). Thus a disparate giant vesicle population can be chemically induced to release the contents from only a portion of its members.