An. Nikolova et Mn. Jones, EFFECT OF GRAFTED PEG-2000 ON THE SIZE AND PERMEABILITY OF VESICLES, Biochimica et biophysica acta, L. Lipids and lipid metabolism, 1304(2), 1996, pp. 120-128
The permeability of PEG-derivatized vesicles produced by the extrusion
technique (VETs) to encapsulated D-glucose has been studied. Vesicles
were prepared from mixtures of dipalmitoylphosphatidylcholine (DPPC),
phosphatidylinositol (PI) and dipalmitoylphosphatidylethanolamine wit
h covalently attached poly(ethylene glycol) of molecular weight 2000 (
DPPE-PEG2000). The occurrence of an irreversible temperature-induced s
ize transition of the PEG-derivatized VETs was detected close to the t
emperature of the main phase transition of the predominant phospholipi
d component by photon correlation spectroscopy. The permeability of th
e vesicles towards radioactive D-glucose was studied by a method simil
ar to the one proposed by Johnson and Bangham at 25, 37 and 50 degrees
C for VETs with DPPE-PEG content from 0 to 9 mol%. A complex effect o
f the PEG-coverage was found with a maximum leakage in the range of th
e transition of the polymer from the mushroom to the brush conformatio
n.