Sterically stabilized liposome preparation

In this chapter we will provide information about the basic characteristics of liposomes staring from their building blocks, that is, phospholipids. After this, liposome structure, physicochemical properties, and stability, which are most important for their in vivo performance, will be discussed as well as methods used for liposome preparation, characterization, and stabilization. Following this first part which is more technological, we will move into the biological part and talk about the fate of conventional liposomes and sterically stabilized liposomes, as well as liposomal drugs, after in vivo administration by different routes [mainly intravenous (i.v.), intraperitoneal (i.p.), or subcutaneous (s.c.)] and also give some information about other possible routes for in vivo administration of liposomes. Finally, specific applications of liposomes in therapeutics will be presented, some in more detail, mainly for the therapy of different types of cancer. 

Weight calculation is based on molar ratio DOPEiCHEMs (3 2) (24). For the preparation of 2 ml of sterically stabilized liposomal suspensions with total phospholipids concentration 3 mM and copolymers at various contents from 2.5 to 10 mol % (with respect to total lipid content) mix in glass tubes 0.0036 mmol DOPE (268 pi of DOPE stock solution (10 mg/ml)), 0.0024 mmol CHEMs (233 pi of CHEMs... 

Serum-stable formulations with minimal leakage at physiological pH and rapid drug release at pH 5.0-5.5 can be easily prepared by inserting a hydrophobicaUy modified iV isopropylacrylamide/ methacrylic acid copolymer (poly(NIPAM-co-MAA)) in the Hpid bilayer of sterically stabilized liposomes. The present chapter describes polymer synthesis, as well as the preparation, and characterization of large unilamelar pH-sensitive vesicles. 

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