Liposomi kao nosači lijekova: strukturna svojstva i klasifikacija

Liposomes are colloidal particles in which a phosholipid bilayer membrane, composed from self-assembled amphiphlic molecules encapsulates pare of the aqueous phase in which they are dispersed. Since their discovery in the mid-1960s, they were first used to study biological membranes. Due to their biodegradability and biocompatibility, today, liposomes are useful system for the delivery or targeting of drugs to specific sites in the body. Liposomes are characterized by their phospholipid composition, particle size, number of lamellae, and inner/outer aqueous phases, all of which dictate their stability and inceraction characteristics. They are able to incorporate almost any drug regardless of solubility, or to carry on their surface cell-specific ligands. Therefore, liposomes have the potential to be tailored in a variety of ways to ensure the production of formulations that are optimal far clinical use. Morphologically, we distinguish between small, medium-sized, large and giant unilamellar, oligoor multi-lamellar, as well as multivesicular liposomes. With respect to inceraction properties there are several types of liposomes: conventional liposomes which are characterized by a nonspecific reactivity of the milieu, sterically stabilized liposomes that are relatively inert and therefore nonreactive to the environment, immunoliposomes and polymorphic liposomes which are very reactive towards specific agents