Determination of the thickness of the fixed aqueous layer around polyethyleneglycol-coated liposomes.
The zeta potentials of adriamycin-encapsulating liposomes containing 1-(monomethoxy polyethyleneglycol)-2,3-dimyristoylglycerol (PEG-DMG) were measured in an isotonic solution of 10mM lactate buffer (pH 4.0) with sodium chloride and sucrose. The negativity of the zeta potentials of adriamycin-encapsulating liposomes containing PEG-DMG decreased with increases in NaCl concentration more steeply than that of adriamycin-encapsulating liposomes without PEG coating. From this observation, the electrical potential distributions near the membrane surfaces were shown to be different between adriamycin-encapsulating liposomes with and without PEG coating. Based on these zeta potential data, the thickness of the fixed aqueous layer around PEG-DMG-containing adriamycin liposomes was determined from the slope of 1n zeta potential versus Debye-Hückel parameter plot. As a result, a correlation was indicated to exist between the circulation time of liposomes and the thickness of the aqueous layer around the liposomes.
Shimada
K
K
School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Miyagishima
A
A
Sadzuka
Y
Y
Nozawa
Y
Y
Mochizuki
Y
Y
Ohshima
H
H
Hirota
S
S
D002626:Chemistry, Pharmaceutical; D004317:Doxorubicin / Q000008:administration & dosage / Q000737:chemistry; D004563:Electrochemistry; D008081:Liposomes / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*
D008081:Liposomes; D011092:Polyethylene Glycols; D004317:Doxorubicin