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  • membrane fluidity  (2)
  • Chondroitin sulfate  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 274 (1996), S. 819-825 
    ISSN: 1435-1536
    Schlagwort(e): Chondroitin sulfate ; tetraalkylammonium counterion ; dilution enthalpy ; thermodynamic properties ; polyacrylate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The dilution enthalpies,Δ dil H, of tetraalkylammonium chondroitin 4-sulfate (R4NChSA) and polyacrylate (R4NPAA) having methyl (Me), ethyl (Et), propyl (Pr) and butyl (Bu) as alkyl groups (R) were measured to elucidate the effects of hydrophobic counterions. TheΔ dil H of R4NChS-A and R4NPAA were negative (exothermic) and decreased as the carbon number of tetraalkylammonium cation (R4N+) increased. These results were found to possess the same effects onΔ dil H as these of bromides. The non-electrostatic terms of dilution enthalpiesΔ dil H n of R4NChS and R4NPAA were evaluated by using the electrostatic terms ofΔ dil H obtained from Manning's theory. TheΔ dil H n of R4NChS-A and R4NPAA decreased, i.e., their exothermic tendencies increased as the carbon number of R4N+ increased, and the rate of decrease of the R4NPAA was more than that of the R4NChS-A. These results are discussed in relation to the increase of the hydrated water structure around R4N+ on dilution.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 274 (1996), S. 678-684 
    ISSN: 1435-1536
    Schlagwort(e): Cholesterol ; membrane fluidity ; muramyldipeptide ; phospholipid ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Application of the muramyldipeptide derivative B30-MDP to liposomal vaccines will aid in the development of improved high immunogenicity vaccines. To give full play to the effectiveness of B30-MDP as a liposomal vaccine, it is important to evaluate the effect of cholesterol, dimyristoylphosphatidylcholine (DMPC) or distearoylphosphatidylcholine (DSPC) incorporation on the chemical stability of B30-MDP and physicochemical properties of B30-MDP/lipid mixed vesicles from the view point of pharmaceutics. The observed degradation rate constants of B30-MDP by hydrolysis in B30-MDP/cholesterol mixed vesicles were increased with increasing concentration of cholesterol, however, those in B30-MDP/DMPC and B30-MDP/DSPC mixed vesicles were unchanged with increasing concentration of DMPC and DSPC. The degradation behavior of B30-MDP was then compared with physicochemical properties of B30-MDP/lipid mixed vesicles, such as membrane fluidity and particle size. It was apparent that the degradation of B30-MDP in B30-MDP/cholesterol mixed vesicles was influenced by the particle size, but not by the fluidity of the membranes. In the case of B30-MDP/phospholipid mixed vesicles, MDP/phospholipid mixed vesicles, the degradation of B30-MDP was not influenced by either the membranes' fluidity or the particle size of the mixed vesicles. It is considered that the degradation of B30-MDP in the mixed vesicles is dependent on the membrane state, and the addition of cholesterol to B30-MDP vesicle inhibits the mutual interaction of MDP regions, whereas the addition of phospholipids hardly influences the mutual interaction of MDP regions, possibly owing to phase separation between B30-MDP and phospholipids.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 274 (1996), S. 178-185 
    ISSN: 1435-1536
    Schlagwort(e): Cholesterol ; membrane fluidity ; muramyldipeptide ; phospholipid ; vesicle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Summary The muramyldipeptide derivative B30-MDP has immunoadjuvant activity and vesicleforming ability in aqueous solutions. To assist in the clinical application of B30-MDP to liposomal vaccine, we investigated the physicochemical properties including membrane fluidity, surface charge and particle size of B30-MDP vesicles containing cholesterol, dipalmitoylphosphatidyl-choline (DPPC) or dipalmitoylphosphatidylglycerol (DPPG). The membrane fluidity of B30-MDP/cholesterol vesicles was slightly influenced by cholesterol concentration and temperature. The membrane fluidity of B30-MDP/phospholipid vesicle was dependent on temperature. ESR spectra clearly showed the good miscibility of cholesterol with B30-MDP and the occurrence of phase separation between B30-MDP and phospholipid. The surface charge and particle size of B30-MDP/cholesterol vesicles were hardly influenced by cholesterol concentration in the membrane because the membrane surface was covered with the hydrophilic region of B30-MDP. The effect of this hydrophilic region of B30-MDP on the surface charge and particle size of B30-MDP/phospholipid vesicle was greater than that of phospholipid. This study showed that the membrane structure of B30-MDP/cholesterol vesicle differed from that of B30-MDP/phospholipid vesicle. Further, the hydrophilic region of B30-MDP is considered to play an important role in the physicochemical properties and formation of the vesicle.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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