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  • 1
    Electronic Resource
    Electronic Resource
    Cyclodextrins lessen the membrane damaging effect of nonionic tensides (1987)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 5 (1987), S. 433-437 
    Details
    ISSN: 1573-1111
    Keywords: Liposomes ; permeability ; tenside cyclodextrin complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nonylphenyl-ethyleneoxide polymers containing 5, 9 and 30 ethyleneoxide groups per molecule build into the hydrophobic fatty acid chains of the cell membrane phospholipid dipalmitoyl-phosphatidylcholine (DPPC) resulting in a decreased main transition temperature, a decreased enthalpy of the main transition and in enhanced potassium permeability of DPPC liposomes. The α-, β- and γ-cyclodextrins form inclusion complexes with the tenzides lowering their free concentration. The complex formation lessens or sometimes totally prevents the membrane damaging effect of tensides. The effectivity order of cyclodextrins is βCD〉γCD〉αCD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00664099
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Stabilization of small unilamellar DMPC-liposomes by uncharged polymers (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 66-71 
    Details
    ISSN: 1435-1536
    Keywords: Keywords DMPC-liposomes ; size distribution ; uncharged polymers ; kinetic stability ; photon correlation spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Polymer-free and polymer-bearing small unilamellar (SUV) liposomes from dimyristoyl-phosphatidylcholine (DMPC) were prepared under standardized conditions. Polymer-bearing liposomes were formed by incorporating an uncharged polymer [hydrolyzed poly(vinyl alcohol) (PVA), poly(vinyl alcohol-co-vinylacetal) (PVA-Al), poly(vinyl alcohol-co-vinyl propional) (PVA-Prol) poly(vinyl alcohol-co-vinyl butiral) (PVA-Bul) copolymer or poly(vinyl pyrrolidone) (PVP)] into the membrane bilayer of vesicles. The kinetic (long-term) stability of the liposome dispersions stored in distilled water, in physiological NaCl solution and at various pH values, respectively, were studied. The physical stability of vesicles was tested by measuring the size and the zeta potential of liposomes by means of a Malvern Zetasizer 4 apparatus. It was shown that most of these polymers are effective steric stabilizers for the DMPC-liposomes. Among the polymers, the PVA-Bul and PVA-Prol copolymers and the PVP of high molecular mass exhibited the most efficient stabilizing effect at each pH studied, indicating that the formation of a relatively thick polymer layer around the lipid bilayers ensures an enhanced and prolonged physical stability of liposomes. Also, the butiral or propional side chain in the PVA-based copolymers presumably promotes the anchoring of macromolecules to the vesicles. Using these macromolecules, the colloidal interactions between vesicles can be modified and so the physical stability of liposomes and the kinetic stability of liposome dispersions can also be controlled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050210
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Lipophilicity determination of some new crown ethers by reversed-phase thin-layer chromatography (1985)
    Springer
    Chromatographia 20 (1985), S. 253-260 
    Details
    ISSN: 1612-1112
    Keywords: Reversed-phase TLC ; Crown ether derivatives ; Quantitative-Structure-Activity Relationship ; Lipophilicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The lipophilicity of 28 modified crown ether derivatives was determined by reversed-phase thin-layer chromatography (RPTLC) using various organic phases and supports. The lipophilicity values determined in different RPTLC systems showed good correlations, however the quality of the organic phase (methanol, acetone, acetonitrile) and the support characteristics influenced to a small extent the determination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259698
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of the lipophilicity of some aniline derivatives by reversed-phase thin-layer chromatography. The effect of salts (1986)
    Springer
    Chromatographia 21 (1986), S. 312-316 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Aniline derivatives ; Effect of metallic salts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The lipophilicity of aniline and 36 ring-substituted aniline derivatives was determined by reversed-phase thin-layer chromatography using NaCl, KCl, MgCl2, CaCl2, AlCl3 and tetramethyl-ammoniumhydroxide, either adsorbed on the silica surface before impregnation or added to the eluent. In most cases the salts decreased the retention power of silica resulting in enhanced mobility of the aniline derivatives. The monovalent cations had the lowest, while AlCl3 and tetramethylammoniumhydroxide had the highest impact on selectivity. This phenomenon can be explained by the different ion charges. The correlation between the RM values and the partition coefficient between n-octanol: water were in all cases inferior to those obtained in salt-free systems this means that the presence of salts modifies differently the lipophilicity of aniline derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311601
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  • 5
    Electronic Resource
    Electronic Resource
    Nonionic tensides modify papain structure and proteolytic activity (1990)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 10 (1990), S. 85-92 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of 33 polyethoxylated nonionic tensides with various hydrophobic moieties was studied on the proteolytic activity and phase transition behaviour of papain. Tensides with longer ethyleneoxide chain markedly increased the phase transition temperatures of papain indicating possible hydrogen bond formation between the hydrophilic ethyleneoxide chain and the polar substructures of papain. The character of lipophilic moiety of tensides influences also each physicochemical parameter of papain suggesting the existence of hydrophobic interactions too. The significant positive linear correlations between the activity increasing and structure stabilizing effects of tensides make probably that the structure modification of papain accounts for its enchanced proteolytic activity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370100122
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    Paper (German National Licenses)
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