PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9330200

Polyhedral non-ionic surfactant vesicles.

I F Uchegbu·A Schätzlein·G Vanlerberghe·N Morgatini·A T Florence
View original source ↗Export metadata ↓

Abstract

Large polyhedral (2-10 microns) non-ionic surfactant vesicles (niosomes) formed from mixtures of a hexadecyl diglycerol ether (C16G2), a cholesteryl poly-24-oxyethylene ether (solulan C24) and a low level of cholesterol are being investigated as slow-release systems for ophthalmic, subcutaneous or intramuscular administration. The phase-diagram of this three-component system has been constructed and these polyhedral vesicles are found to be in the gel (L beta) phase. Confocal laser-scanning microscopy was used to confirm the complex morphology of these vesicles. The thermo-responsive nature of release of entrapped carboxyfluorescein and nicotinamide adenine dinucleotide has been studied; release is increased with increase in temperature (37 degrees C) even though the polyhedral vesicles still maintain their polyhedral shape at this temperature. The results indicate that the thermo-responsive features of the niosomes are a result of reversible changes in bi-layer permeability caused by temperature-mediated alteration in the membrane-packing characteristics of the polyethoxylated cholesterol ether.

Explore related subjects

CholesterolEthersMicroscopy, ConfocalSurface-Active AgentsJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

I F Uchegbu, A Schätzlein, G Vanlerberghe, N Morgatini, A T Florence. 1997. Polyhedral non-ionic surfactant vesicles.. https://doi.org/10.1111/j.2042-7158.1997.tb06853.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2001

Preeclampsia and Na,K-ATPase activity of red blood cell ghosts from neonatal and maternal blood.

We determined Na,K-ATPase activity and cholesterol/phospholipid ratio of maternal and cord red blood cell ghosts from either normotensive or preeclamptic pregnant women. The Na,K-ATPase activity of the red cell ghosts from neonatal blood is significantly lower (25-32%) as compared with the ATPase activity of the maternal red cell ghosts, regardless of the presence or not of preeclampsia. This diminution in Na,K-ATPase activity of the neonatal red blood cell ghosts could be due to an increase in the cholesterol/phospholipid molar ratio of the membrane. The Na,K-ATPase activity of the red blood cell ghosts from pregnant women was unaffected by preeclampsia; however, fetal red blood cell ghosts from infants of preeclamptic mothers showed a significantly lower ATPase activity (20%) than fetal red blood cell ghosts from infants of normotensive mothers. A low Na,K-ATPase activity in the neonatal red blood cells from mothers with preeclampsia could be an indication of an important modification of the physiological role of this enzyme.

Cholesterol↗
PubMed2000

Infrared spectroscopic characterization of the interaction of cationic lipids with plasmid DNA.

Fourier transform infrared spectroscopy was used to characterize the interaction of the cationic lipids 1,2-dioleoyl-3-trimethylammonium-propane and dioctadecyldimethylammonium bromide with plasmid DNA. The effect of incorporating the neutral colipids cholesterol and dioleoylphosphatidylethanolamine on this interaction was also examined. Additionally, dynamic and phase analysis light scattering were used to monitor the size and zeta potential of the resulting complexes under conditions similar to the Fourier transform infrared measurements. Results suggest that upon interaction of cationic lipids with DNA, the DNA remains in the B form. Distinct changes in the frequency of several infrared bands arising from the DNA bases, however, suggest perturbation of their hydration upon interaction with cationic lipids. A direct interaction of the lipid ammonium headgroup with and dehydration of the DNA phosphate is observed when DNA is complexed with these lipids. Changes in the apolar regions of the lipid bilayer are minimal, whereas the interfacial regions of the membrane show changes in hydration or molecular packing. Incorporation of helper lipids into the cationic membranes results in increased conformational disorder of the apolar region and further dehydration of the interfacial region. Changes in the hydration of the DNA bases were also observed as the molar ratio of helper lipid in the membranes was increased.

Cholesterol↗