Sterically Stabilized Liposomes: Physical and Biological Properties
作者:
WoodleMartin C.,
NewmanMary S.,
CohenJoel A.,
期刊:
Journal of Drug Targeting
(Taylor Available online 1994)
卷期:
Volume 2,
issue 5
页码: 397-403
ISSN:1061-186X
年代: 1994
DOI:10.3109/10611869408996815
出版商: Taylor&Francis
关键词: liposome;PEG;zeta potential;drug delivery;pharmacokinetics
数据来源: Taylor
摘要:
AbstractAdvanced liposomal therapeutics has been attained by liposome surface modification, initially with specific glycolipids and subsequently with surface-grafted PEG, reducingin vivorapid recognition and uptake, giving prolonged blood circulation, and providing selective localization in tumors and other pathological sites, as described in recent reviews. The result is improved efficacy of encapsulated agents. The surface PEG may produce a steric barrier, as described for colloids. Reducedin vivouptake may result from inhibition of plasma-protein adsorption, or opsonization, by the steric coating. Several physical studies support this mechanism, including electrophoretic mobility (zeta potential). Our previous results for 2000-dalton PEG indicated a coating thickness about 5 nm, in agreement with independent measurements. We report here results for 750 to 5000-dalton PEGs. The calculated coating thickness increases with molecular weight in a nonlinear fashion. The dependence of blood circulation and tissue distribution on PEG molecular weight correlates with zeta-potential estimates of PEG-coating thickness. Effects on tissue distribution are reported for liver and spleen, the major phagocytic organs. The biological properties of these liposomes depend on the surface polymer rather than the lipid bilayer, yielding important advantages for lipid-mediated control of drug interaction and release without affecting the biodistribution.
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