Bilayer composition

Prolonged presence of the drug at the site of injection is the aim of liposome encapsulation of drugs, which are injected in the vitreous body. Both amphotericin and gentamicin in liposome formulations were cleared from the injection site significantly more slowly than the free drug residence times depended on liposome size and, in some cases, on bilayer composition (Tremblay et al., 1985 Barza et al., 1985, 1987 Fishman et al., 1986). 

A. (1986a). Preparation of liposomes via detergent removal from mixed micelles by dilution. The effect of bilayer composition and process parameters on liposome characteristics, Pharm. Weekbl. 

Kersten, G. F. A., Van de Put, A., Teerlink, T., Beuvery, E. C., and Crommelin, D. J. A. (1988a). Immunogenicity of liposomes and iscoms containing the major outer membrane protein of Neisseria gonorrhoeae -Influence of protein content and liposomal bilayer composition. Inf. Immun., 56. 1661-1664. 

Levitsky IA, Kanelos PT, Woodbury DS, Euler WB (2006). Photoactuation from a carbon nano-tube-nafion bilayer composite. J. Phys. Chem. B. 110 9421-9425. 

Fig. 69. SEM of a cross-section of a three-layered film (bar = (0 pm) CA layer (a) PVA-bilayer composite layer (6). The vertical shades are artifacts [429]...

Bilayer composition can be almost infinitely varied by choice of the constituent lipids. Phosphatidylcholine (PC), a neutral phospholipid, has emerged as the major lipid component used in the preparation of pharmaceutical liposomes. Phosphatidylglycerol and phosphatidylethanolamine are also widely used. Liposomal bilayers may also accommodate sterols, glycolipids, organic acids and bases, hydrophilic polymers, antibodies and other agents, depending on the type of vesicle required. 

DaunoXome liposomes are also long circulating liposomes, in this case encapsulating the cytostatic daunorubicin. Although a non-stealth system, long circulation times are attained by using a particularly rigid bilayer composition, in combination with a relatively small liposome size. 

D. Yoo, S.S. Shiratori, M.R Rubner, Controlling Bilayer Composition and Surface Wettability of Sequentially Adsorbed Multilayers of Weak Polyelectrolytes , Macromolecules, 31, 4309 (1998)... 

A bilayered composite skin equivalent has been developed with a viable dermis and epidermis. The epidermis is composed from cornified differentiated keratinocytes and a dermal matrix composed of a collagen lattice containing viable fibroblasts. Its cellular components assist with wound closure through stimulation of the wound bed. The outer layer of the differentiated bilayered skin equivalent, the stratum corneum, acts as a specialized vapor permeable membrane and protective outer barrier.f ... 

Foged C, Arigita C, Simdblad A, Jiskoot W, Storm G, Frokjaer S (2004) Interaction of dendritic cells with antigen-containing liposomes effect of bilayer composition. Vaccine 22 1903-1913... 

Hristova K, Kenworthy A, McIntosh TJ (1995) Effect of bilayer composition on the phase behavior of liposomal suspension... 

The photopolymerizable composition can be used both as liquids to coat a substrate with light sensitive films and as dry photoresist films. In the latter case, the photoresist is a trilayer pie consisting of a top layer made of poly (ethylene terephthalate), a middle layer being the photopolymerizable composition, and an underlayer made of polyethylene. The underlayer is removed before exposure and the remained bilayer composite is laminated onto a clean substrate. The article is prebake to anneal a polymer layer and to enhance adhesion to the substrate. The selective exposure by the UV light through the top layer hardens the exposed areas of the photoresist. After exposure, the top layer is removed and the photoresist layer... 

In order to understand the complex behavior of cellular membranes and their response to external perturbations Uke electric flelds, one has to elucidate the basic mechanical properties of the lipid bilayer. The signiflcant expansion in recent years of the field of membrane raft-hke domain formation [11, 132, 133] imposes the compelling need for understanding the effect of hpid bilayer composition on membrane properties. Cholesterol, a ubiquitous species in eukaryotic membranes, is an important component in raft-hke domains in cells and in vesicles, which mohvates studies aimed at understanding its influence on the mechanical properties and stability of membranes. 

Digestion of the membranes with PL ase A results in the formation of lysophosphol-ipids and free fatty acids. These products affect the fluidity and surface charge of the bilayer, and could result in loss of the ability of the membrane to sustain a potential. The disappearance of the electrochromic response could be related to these changes. In this study, effects of digestion on bilayer composition were determined and correlated to the spectral change. It was shown further that the electrochromic carotenoids lose their ability to sense the field. 

Y. Yang and A. J. Heeger, Polyanihne bilayer composite electrode for efficient polymer light emitting diodes. Mol. Cryst. Liq. Cryst. 256, 537—542 (1994). 

B.-S. Liu, C.-H. Yao, S.-S. Fang, Evaluation of a non-woven fabric coated with a chitosan bilayer composite for wound dressing. Macromol. Biosci. 8(5), 432-440 (2008)... 

However, this is not the case. At these concentrations of the additives the L -phases are already unstable. The assumed n-value of 1.455 is probably too high for the bilayer composition, because the bilayer contains water from the solvated ethylenoxide groups. With 30% water, we obtain an average value of 1.425. With this value the stability of the La-phases agrees with the composition of the solvent. 

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