A liposome is an artificially-prepared vesicle made up of a concentric bilayer of amphiphilic phospholipid molecules. When encapsulating drugs inside it, degradation of drugs can be avoided, distribution in vivo is changed, the accumulation at target organs is increased, drug efficacy is enhanced and side-toxicity is reduced. However, liposome can be easily cleaned out by the monocyte/macrophage system, which greatly limits its application as drug carrier. Thanks to the appearance of pegylated liposomes, this problem is successfully resolved.

A typical molecular structure of the poly(ethylene glycol) phospholipid conjugate is shown as follows:

The liposome modified with poly(ethylene glycol), also named “long-circulating liposome”, is formed by mixing a certain amount of pegylated phospholipid molecules such as DSPE-PEG with unpegylated phospholipid molecules. It not only inherits the advantages of liposome, but also inhibits the absorption of plasma proteins onto its surface, prolongs the circulation time in blood, enables escape more smoothly from the capture by monocyte/macrophage system in order to arrive at the disease site more effectively, a process also called “passive targeting”, and reveals a dosage dependence in pharmacokinetics.

Drug molecules can be encapsulated into liposome to develop liposomal delivery system.

The active targeting long circulating liposome bearing targeting moieties on its surface can facilitate binding via a specific expression on the targeted drug delivery site. The targeting moiety can be attached to the one end of the PEG chain extending out of the liposome.

Note: Long-circulating Liposome series can be customized according to the structure and molecular weight of poly(ethylene glycol) as well as the type of phospholipids.

SINOPEG is a dynamic science company dedicated to developing and manufacturing of poly(ethylene glycol) derivatives (PEGs) for drug pegylation, drug delivery, medical devices, bio-engineering, diagnostic assay development, polymer engineering, and broad uses in nanotechnology.