Lipid multilayers

Sujak, A., Mazurek, P., Gruszecki, W.I., 2002. Xanthophyll pigments lutein and zeaxanthin in lipid multilayers formed with dimyristoylphosphatidylcholine. J Photochem Photobiol B. 68, 39-44. 

When hydrated phospholipids (containing about 50% water) are squeezed between two flat quartz plates, one can frequently obtain highly ordered, uniaxial, parallel arrays of about 100 to 10,000 bilayers (see, for example, Ref. 33). These lipid multilayers are ideal for a number of spectroscopic studies of phospholipids. Most of the membrane work described in the present work has been carried out using liposomes and oriented multilayers. 

Electrical Properties of Lipid Multilayers. By the Langmuir-Blod-gett technique (39, 40), it is possible to obtain well ordered multilayers... 

The second diffusion problem, desorption from oil-water multilaminates, is considered as a model for (a) controlled release from liposomes and lipid multilayers and (b) for transport through biological laminates such as stratum corneum. In contrast to nonsteady-state transport across multilaminates, desorption from laminates depends only on the outermost layers. 

Desorption from an oil-water multilaminate should be an accurate model for controlled release from liposomes and lipid multilayers and may be helpful to understand transport through naturally occurring biological laminates such as stratum corneum. Asymptotic solutions based upon simple assumptions about the concentration profile may also be used to understand the desorption properties. 

The limitations of this simplified model have been immediately recognized, and the first criticism [3] even preceded the full development of the DLVO theory. Since then many improvements of the theory have been proposed, to account for the finite size of the ions [4], image forces [5], dielectric corrections [6], ion correlations [7], ion-dispersion [8] and ion-hydration forces [9], to name only a few. Despite the many corrections brought to the traditional DLVO theory, there are some experiments, such as those regarding the stability of neutral lipid multilayers, which could still not be explained within this framework. It is therefore commonly accepted that an additional repulsion occurs when two surfaces approach each other at a distance shorter than a few nanometers. Because this force was initially related to the structuring of water near surfaces, it is commonly named hydration force [10]. 

The lipid multilayers with a homogeneous composition generally show a transition of gel-liquid crystal. When the temperature is raised to 42 °C, which is higher than the phase transition of 41.4 °C, the released amount of 5-FU increased, while the amount of drug delivered decreased at 37 °C, which is lower... 

Figure 6.20 Lipid multilayers in cast films may be doped with water-soluble or amphiphilic porphyrins. The hydrophobic macrocycle of protoporphyrin derivatives (—) with one hydrophilic edge integrates into the hydrophobic membrane, but their orientation is not fixed. Water-soluble porphyrins with four sulfo-nated phenyl rings at the methine bridges are oriented parallel to the film surface. The ordering of the hydrophobic bilayer can also be controlled by azo-dyes which are covalently bound to the hydrophobic chains of the lipids, hereC,H,r-C6H4-N=N—C6H4-C,oH2o—N(CHs)sBr.

In an effort to mimic the conditions encountered in in vivo irradiation in the epidermis, the irradiation of 7-dehydrocholesterol (157) in various ordered lipid multilayers has been studied. The results (Table 4 and Scheme 13) clearly show... 

Photochemistry of Olefins, Acetylenes, and Related Compounds Table 4 Products from irradiation of (157) in lipid multilayers... 

I. Lundstrom and M. Stenberg, Charge Injection and Charge Storage in Lipid Multilayers, Chem. Phys. Lipids 12, 287-302 (1974). 

Lipid bilayers, 321,322,329,335,383 Lipid dermatoarthritis, 548 Lipid extraction, Bligh and Dyer, 272 Lipid film, spreading pressure, 338 Lipid monolayers, 338 Lipid multilayers, 341 Lipid polymers, 284 Lipid-protein interactions, 382-84 Lipid proteinosis, 548 Lipid structure, 322 see also Chain packing Lipid-water properties, 327-32, 356,... 

Vogel H, Jahnig F. The stnictute of melinin in membranes. Biofdiys J 1986r, 50 573-582. Smith R. Separovic F, Bennett FC, Cornell BA. Melittin-induced changes in lipid multilayers A solid-state NMR study. Biophys J 1992 63 469-474. 

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