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  • Chemistry  (40)
  • 2000-2004
  • 1985-1989  (40)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Interaction of amphiphilic polymers with model membranes (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 166 (1989), S. 71-80 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lipid bilayers of cell membranes are usually connected to two types of biopolymers: the cytoskeleton and the glycocalix. These structures are not only responsible for the stabilization of the lipid bilayer, they also alter the surface properties of the cells. Among the various attempts to mimick membrane properties using polymeric systems(1), one method is the fixation of amphiphilic polymers via hydrophobic anchor groups to lipid bilayers. In the experiments reported here the influence of amphiphilic polymers on the morphology of giant unilamellar liposomes has been investigated. Therefore a series of amphiphilic polyvinylpyrrolidone and dextran derivatives has been synthesized. The fixation of these polymers to the liposomal membranes could be shown with a fluorescence-labelled derivative by using epifluorescence microscopy. The polymer-membrane interaction caused by the insertion of the anchor groups leads to drastic morphological changes in this model membrane system. The exclusive interaction with the outer membrane of multilamellar liposomes could be demonstrated by freeze fracture electron microscopy. In addition, the anchoring of a natural capsular polysaccharide in liposomes has been proven by immunofluorescence. In these experiments, also a clustering (patching) of the antigen caused by the binding of the antibody could be observed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051660105
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  • 2
    Electronic Resource
    Electronic Resource
    Photodimerization and photopolymerization of amphiphilic cinnamic acid derivatives in oriented monolayers, vesicles and solution (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1843-1853 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cinnamic acid moieties were incorporated into amphiphilic compounds containing one and two alkyl chains. These lipid-like compounds with photoreactive units undergo self-organization to form monolayers at the gas-water interface and bilayer structures (vesicles) in aqueous solutions. The photoreaction of the cinnamic acid moiety induced by 254 nm UV light was investigated in the crystalline state, in monolayers, in vesicles and in solution in organic solvents. The single-chain amphiphiles undergo dimerization to yield photoproducts with twice the molecular weight of the corresponding monomers in organized systems. The photoreaction of amphiphiles containing two cinnamic acid groups occurs via two mechanisms: The intramolecular dimerization produces bicycles, with retention of the molecular weight of the corresponding monomer. The intermolecular reaction leads to oligomeric and polymeric photoproducts. In contrast to the single-chain amphiphiles, photodimerization processes of lipoids containing two cinnamic acid moieties also occur in solution in organic solvents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870804
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  • 3
    Electronic Resource
    Electronic Resource
    Dielectric properties of a combined main-chain/side-chain liquid-crystalline polymer (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1501-1509 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric relaxation properties of a combined main-chain/side-chain liquid-crystalline polymer were investigated. It was found that the rotation of the side chain about the main chain (δ-process) is not as strongly restricted as in side-chain liquid-crystalline polymers. This is attributed to the facts that the side chain is attached to the flexible spacer within the chain backbone and that the concentration of the side chains is comparatively small. Two low-temperature relaxation processes were observed to occur in the glassy smectic and the crystalline state. They are attributed to intramolecular motions with in the mesogenic groups.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880624
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation and characterization of unsymmetrical “liposomes in a net” (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 299-315 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Negatively charged lipid molecules were converted into polymerizable lipids by introduction of polymerizable mono- or bifunctional counterions. As an attempt to mimic the cytoskeleton of biomembranes, unsymmetrical polymeric vesicles were prepared, where the polyelectrolyte is attached either only to the inner or to the outer bilayer surfaces. Polymerizable cations were introduced to the outer surface of preformed small unilamellar vesicles via ion-exchange. The outer counterions of vesicles bearing polymerizable counterions at both sides of the membrane were replaced by Na+. Polymerization of these systems leads to unsymmetrical vesicles. The introduction, separation and polymerization of the organic counterions was monitored by UV-spectroscopy. Due to polymerization of the counterions, the phase transition temperature of the membranes is shifted remarkably to higher temperatures. For a comparison of ionically attached and covalently bound polymers, two cationic lipids were synthesized, which have a bifunctional polymerizable headgroup. In contrast to the lipids with “ionic” spacers, the polymerization of the covalently bound methacrylic units resulted in a decrease of the phase transition temperature. Thus, by application of ionically bound polymerizable units, unsymmetrical polymerized vesicle membranes are readily available. These systems may serve as models for mimicking the cytoskeleton of living cells.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890206
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  • 5
    Electronic Resource
    Electronic Resource
    Deuteron NMR study of molecular order and motion of the mesogenic side groups in liquid-crystalline polymers (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 2711-2723 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular order and mobility of two liquid-crystalline polyacrylates with phenyl benzoate moieties as mesogenic side groups and (CH2)m spacers (m = 2 and m = 6) were investigated by pulsed 2H NMR. The mesogenic side groups were isotopically labelled at the terminal phenylene ring. In the glassy state the orientational distribution function was characterized from the angular dependence of the 2H NMR line shape of samples macroscopically ordered in their nematic phase by the 8,4 T magnetic field of an NMR spectrometer. It was found to be Gaussian with widths of ± 18,5° and ± 10,5° for the m = 2 frozen nematic and m = 6 frozen smectic system, respectively. The phenylene rings undergo 180° jumps about their local C2-axes in the glassy state. The time-scale of this process, however, was found not to be uniform. Instead, the analysis of 2H NMR line shapes and their intensities as a function of temperature yielded a log-Gaussian distribution with correlation times characteristic of amorphous solids, 2,2 versus 2,5 decades in width and mean activation energy ĒA = 42 versus 47 kJ/mol for the m = 2 and m = 6 system, respectively. The correlation times for the centre of the distribution agree with those obtained by dielectric relaxation measurements of the same systems, suggesting that reorientation of the whole mesogenic group is detected via the phenylene rings.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021871121
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis, structure, and phase behaviour of liquid-crystalline rigid-rod polyesters and polyamides with disc-like mesogens in the main chain (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1431-1445 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aromatic polyesters and polyamides with disc-like mesogens in the main chain were prepared from tetra-substituted hydroquinones and derivatives of 1,4-phenylenediamine. Depending on the atomatic acids (terephthalic acid, 2,5-dialkoxyterephthalic acid) used in the condensation reaction, the repeating units of these polymers carried 4 or 6 lateral substitutents. All polymers are highly soluble in several organic solvents, e.g. CHCl3, toluene, acetone. The phase behaviour of the polymers was studied by means of differential scanning calorimetry and optical polarizing microscopy. Depending on the number of lateral substitutents the polyesters and polyamides show crystalline and thermotropic liquid-crystalline phases. X-ray investigations showed a board-like Packing of the rigid-rod polymers which we have termed as a “sanidic” (meaning board-like) phase.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880619
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  • 7
    Electronic Resource
    Electronic Resource
    Micelle-forming block copolymers: Pinocytosis by macrophages and interaction with model membranes (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 725-733 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A block copolymer (6) with both hydrophilic and hydrophobic regions was synthesized, in order to examine its interaction with model membranes and its uptake by living cells. The copolymer comprised poly(ethylene oxide) and poly(L-lysine) with 50 mol-% substitution of the ε-amino groups with palmitoyl groups. To permit 125I-labelling, p-methoxyphenyl residues (1-4 mol-%) were incorporated into the block copolymer and into a poly(ethylene oxide) used for comparison. Sudan Red 7 B solubilization studies indicated that the block copolymer, but not the homopolymer, forms micelles. Differential scanning calorimetry of dipalmitoyl-phosphatidylcholine liposomes indicated that the block copolymer interacts with and probably penetrates lipid membranes. Both poly(ethylene oxide) and the block copolymer were captured by rat peritoneal macrophages in vitro, and inhibitor studies indicated that uptake of both polymers was by pinocytosis. Rates of uptake were indicative of adsorptive pinocytosis, and it is concluded that both poly(ethylene oxide) and the block copolymer present a largely hydrophilic aspect which interacts positively with the cell surface.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860406
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  • 8
    Electronic Resource
    Electronic Resource
    Bis(2-chloroethyl)amine bound to copolymers of N-(2-hydroxypropyl)methacrylamide and methacryloylated oligopeptides via biodegradable bonds (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 257-264 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Drug carriers were prepared by combining oligopeptidic sequences with synthetic polymeric chains. Soluble copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA) were synthesized containing oligopeptidic side chains terminating in a drug model (p-nitroaniline). The susceptibility of these oligopeptidic sequences to degradation on incubation with lysosomal enzymes and human serum was evaluated by monitoring the p-nitroaniline liberation. It was shown that the drug model can be attached to the polymer carrier by means of an oligopeptidic spacer stable in blood serum and degradable after the polymer has been in contact with intracellular lysosomal enzymes. The studied polymer carriers were used for binding an anticancer drug, bis(2-chloroethyl)amine.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880203
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of liquid-crystalline copolymers with dichroic dyes and mesogens as side groups (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1355-1366 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Liquid-crystalline copolymers with covalently attached dichroic dyes were synthesized and characterized. Copolymers with high anthraquinone and trisazo-dye content were obtained by copolymerization of dye monomers with 4-cyanophenyl 4-(6-acryloyloxyhexyloxy)benzoate (1) and 6-acryloyloxyhexyl 4-(trans-4-propylcyclohexyl)benzoate (2). Particular attention is given to the influence of the dye content and the dye structure on the liquid-crystalline behavior of the copolymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880611
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  • 10
    Electronic Resource
    Electronic Resource
    Ordered and disordered glasses: A comparison of thermodynamical and dynamical properties (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1345-1351 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characteristic dynamical properties of the glassy state were studied for side-chain polymers in which either an isotropic glassy state or a nematic glassy state could be induced at will. The dynamical properties of such ordered and disordered glasses were found to be identical. This may indicate that the decrease of the volume taking place at the isotropic-nematic transition leaves the free volume unchanged. It was furthermore observed that the glassy state is able to stabilize a given structure both with respect to a first- and second-order phase transition for kinetic reasons.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890612
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