Beteiligte:
Warriner, Heidi E.;
Idziak, Stefan H. J.;
Slack, Nelle L.;
Davidson, Patrick;
Safinya, Cyrus R.
Erschienen:
American Association for the Advancement of Science (AAAS), 1996
Erschienen in:
Science, 271 (1996) 5251, Seite 969-973
Sprache:
Englisch
DOI:
10.1126/science.271.5251.969
ISSN:
0036-8075;
1095-9203
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>
A class of lamellar biological hydrogels comprised of fluid membranes of lipids and surfactants with small amounts of low molecular weight poly(ethylene glycol)-derived polymer lipids (PEG-lipids) were studied by x-ray diffraction, polarized light microscopy, and rheometry. In contrast to isotropic hydrogels of polymer networks, these membrane-based birefringent liquid crystalline biogels, labeled L
<jats:sub>α</jats:sub>
<jats:sub>,g</jats:sub>
, form the gel phase when water is added to the liquid-like lamellar L
<jats:sub>α</jats:sub>
phase, which reenters a liquid-like mixed phase upon further dilution. Furthermore, gels with larger water content require less PEG-lipid to remain stable. Although concentrated (∼50 weight percent) mixtures of free PEG (molecular weight, 5000) and water do not gel, gelation does occur in mixtures containing as little as 0.5 weight percent PEG-lipid. A defining signature of the L
<jats:sub>α</jats:sub>
<jats:sub>,g</jats:sub>
regime as it sets in from the fluid lamellar Lα phase is the proliferation of layer-dislocation-type defects, which are stabilized by the segregation of PEG-lipids to the defect regions of high membrane curvature that connect the membranes.
</jats:p>