Long-circulating sterically protected liposomes
 PEGylated liposome
Liposomes are used for many years as a vehicle for drug delivery and targeting. However typical liposome compositions have a major problem: They rapidly exit the blood stream and accumulate in spleen macrophages and Kupffer cells in the liver. Various approaches and methods to overcome this problem were tested and investigated. The real break through was achieved with the discovery of polymer modified long circulating liposomes. Among all the polymers that were designed for long circulating liposomes linear poly(ethylene glycol) or PEG is the most popular one. The reasons for the long circulation of the PEG liposomes are followings:
- Surface charge of the PEGylated liposomes
- The repulsive interaction between PEG-grafted liposomes and other particles
- The hydrophilicity of the PEGylated liposomes
- The decrease rate of the absorption of the plasma protein on the surface of the PEGylated liposome
Incorporation of PEG (poly(ethylene glycol) into the liposomal membrane
A hydrophobic derivative of PEG such as PEG-PE with molecular weight of 1-10 kDa can be incorporated into the liposomes. In this method the PEG-PE must be added to the lipid mixture before the liposome formation.
Attachment of PEG to the surface of previously prepared liposomes
A single end reactive derivative of PEG can be coupled with certain reactive groups on the liposomal surface such as maleimide. This method is usually called the post-coating PEGylation technique. This method is suitable for attaching PEG to the surface of the preformed immunoliposomes.
Encapsula NanoSciences provides various formulations PEGylated liposomes. For more information send us an email at info@encapsula.com
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