128971-01-7Relevant academic research and scientific papers
A Hydrolytic Reporter of Cu(II) Availability in Artificial Liposomes
Ghirlanda, Giovanna,Scrimin, Paolo,Tecilla, Paolo,Tonellato, Umberto
, p. 3025 - 3029 (2007/10/02)
The dioctadecyl ammonium surfactant 1, functionalized with a p-nitrophenyl ester of picolinic acid has been synthesized and its hydrolysis in covesicular blends of nonfunctional surfactants dihexadecyldimethylammonium bromide, 3, dioctadecyldimethylammonium bromide, 4, and racemic 1,2-bis(palmitoyloxy)-3-(trimethylammonium)propyl bromide, 5, studied after addition of Cu(II) ions pH=5.0 and different temperatures.The cleavage of 1 gives the p-nitrophenoxide surfactant 2, which shows a strong absorption band at 400 nm.Clear biphasic kinetics were observed for all vesicular systems at a temperature below the gel-liquid crystal phase transition temperature (Tc) of the membrane; the first, faster process (ca. 60percent ester cleaved) was associated with the Cu(II)-catalyzed hydrolysis of the exovesicular ester; the slower one (the remaining ca. 40percent of the ester cleaved) was associated with the uncatalyzed hydrolysis of the endovesicular ester.Above Tc only a monoexponential process was observed.Variable temperature experiments allowed one to conclude that the cationic vesicles studied are totally impermeable to Cu(II) ions either below or above their Tc which controls the rate of the transbilayer movements of the lipids.
PROTON/HYDROXIDE PERMEATION ACROSS AMMONIUM ION BILAYER VESICLES DETECTED BY SELF-INDICATING HEAD GROUPS
Moss, Robert A.,Fujita, Tsunehisa
, p. 2377 - 2380 (2007/10/02)
p-Nitrophenol-functionalized vesicular surfactants (2) are sensitive, reversible and continuous reporters of local pH conditions at endovesicular and exovesicular surfaces.
