Poly(ethylene glycol)-modification of the phospholipid vesicles by using the spontaneous incorporation of poly(ethylene glycol)-lipid into the vesicles

被引:124
作者
Sou, K [1 ]
Endo, T [1 ]
Takeoka, S [1 ]
Tsuchida, E [1 ]
机构
[1] Waseda Univ, Adv Res Inst Sci & Engn, Dept Polymer Chem, Tokyo 1698555, Japan
关键词
D O I
10.1021/bc990135y
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
The critical micelle concentrations of 1,2-dipalmitoyl-sn-glycero-3-phosphoethaanolamine-N-[monomethoxy poly(ethyleneglycol) (5000)] (PEG-DPPE) and its distearoyl analogue (PEG-DSPE) were 70 and 9 mu M, respectively, in buffer solutions ([Tris] = 20 mM, [NaCl] = 140 mM, pH 7.4) at 37 degrees C. When these PEG-Lipid micelle dispersions were mixed with the dispersions of phospholipid vesicles comprised of a C16 membrane, of which the carbon number is 16, or a C18 membrane, the PEG-lipid micelles were dissociated into monomers and then spontaneously incorporated into the surface of the preformed vesicles. The incorporation rates and the enthalpy changes during incorporation were measured with an isothermal titration microcalorimeter. The incorporation rate of PEG-DPPE was faster than that of PEG-DSPE, because the dissociation rate of the PEG-DPPE micelles was faster than that of PEG-DSPE micelles. The incorporation equilibrium constant of PEG-DSPE was larger than that of PEG;DPPE due to its slow dissociation rate from the membrane, caused by the stronger hydrophobic interaction. The combination of PEG-DSPE and the C18 membrane was the most thermodynamically stabilized pair. Furthermore, the dispersion stability of the surface-modified vesicles prepared by this spontaneous incorporation was analyzed by using the critical molecular weight of the polymer for the aggregation of vesicles. The aggregation of the vesicles was successfully supressed with an increase in the molecular weight of the PEG in the PEG-lipid and its incorporation ratio.
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页码:372 / 379
页数:8
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