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B Hupfer

Publications and source records attributed to B Hupfer.

3 recordsLinked to original sources
PubMed1983

Liposomes from polymerizable phospholipids.

The synthesis and characterization of a great variety of single and double chain phospholipids containing the diacetylene and butadiene moiety is described. These substances can be dispersed in water by ultrasonication and the resulting vesicles can be photopolymerized with the retention of their original structure. Absorption spectra of the polymerized diacetylenic lipids show significant differences depending on the molecular structure of the monomers. By the polymerization reaction, the gel to liquid crystalline phase transition is suppressed, which does not correspond to the properties of biological membranes. Evidence for enhanced stability of polymerized vesicles is given by treatment with ethanol and detergents showing that trapped markers are released to a much smaller extent than in the case of unpolymerized vesicles. Diacetylenic lipids show a pronounced hysteresis of the phase transition. If the membrane of supercooled vesicles crystallizes, all trapped marker is released within seconds. Possibilities for overcoming this extreme rigidity of the membranes are discussed.

Biopolymers↗
PubMed1983

Spreading and polymerization behavior of diacetylenic phospholipids at the gas-water interface.

A variety of polymerizable lipids derived from hexacosa-10,12-diynoic acid and hexacosa-10,12-diyne-1-ol have been synthesized and spread at the gas/water interface. The measured surface pressure/area isotherms indicate that head group charge and bulkiness have strong influences on the area occupied per molecule. In the case of zwitterionic phospholipids additional area changes are brought about by alkaline and acidic subphases, which is probably due to an alteration of head group conformation. Condensed state diacetylenic lipid monolayers in a nitrogen atmosphere are polymerizable by UV irradiation. The polymerization reaction was monitored at the gas/water interface by the area change at constant surface pressure and the change of optical density in the visible region. As already observed for vesicle polymerization, single chain amphiphiles exhibit a different absorption behavior than asymmetric double chain amphiphiles of the phosphoglycerol type. The polymerized monolayers were more densely packed and more stable than their monomeric counterparts as indicated by the smaller areas and higher pressures reached before the collapse points.

Alkynes↗