Surface polyfluorinated cationic vesicles

Three novel polyfluorinated cationic surfactants having a short perfluoroac yl group and double long alkyl chains, and three corresponding hydrocarbon analogues were synthesized. All of the surfactants formed small unilamellar vesicles in water upon sonication. The temperature conditions for the soni cation were carefully determined by confirming that the DSC curve had a rep roducible single phase transition peak. The TEM images indicated that the s ize of the polyfluorinated vesicles was in the range of 56-89 nm. The NMR r elaxation study upon the addition of paramagnetic Mn2+ ions to the bulk wat er phase showed that the terminal trifluoromethyl group of the short acylam ide chain in the surfactants faced directly to the bulk water phase; the ve sicle had a unique micro-structure with the perfluoroalkyl group extending its arm straightforwardly to the water phase. The vesicles were named "surf ace polyfluorinated vesicles''. The local oxygen concentrations surrounding each fluorine nucleus and proton of the surfactants within the vesicles we re estimated by observing the longitudinal relaxation time under nitrogen a nd oxygen atmospheres. Oxygen was enriched in the microenvironment surround ing the long alkyl chain and perfluoralkyl group, while the N-methyl group had a low oxygen concentration around it. The micro-distribution of water w ithin the vesicle was discussed by the estimated local concentration of oxy gen. The vesicles were thought to be stabilized by the channel-like water c onnecting the bulk water phase with the hydrated water of the N-methyl grou ps inside the vesicles. The surface polyfluorinated layer exhibited a subst antial protective effect against the oxidative attack of hydroxyl radical g enerated in the bulk phase water.