ABSTRACT
Liposomes are vesicular colloidal particles composed of self-assembled amphiphilic molecules. Amphiphiles are molecules that contain two groups with different solubility. The hydrophilic group, often referred to as the polar head, is “water loving,” while the hydrophobic part, the so-called nonpolar tail, is “water hating.” The structure of lipid systems can be approximated by taking into account the geometric properties of these amphiphiles. In the case when the polar part is larger than the nonpolar tail, the molecules tend to pack into structures with high radii of curvature. Positively charged lipids, with the exceptions of sphingosine and some lipids in primitive life forms, practically do not exist in nature. Before the explosion in lipid synthesis in the early 1990s several cationic detergents were used for preparation of liposomes with positive charge. There are several very important parameters describing properties of detergents and lipids.
