EN
The basic components of liposomes are typically amphiphilic phospholipids and cholesterol. Amphiphilic phospholipids form a bilayer structure, while cholesterol supports and maintains this bilayer structure. Commonly used phospholipids are sphingomyelin and glycerophospholipids, both of which have hydrophilic heads and hydrophobic tail regions. In an aqueous environment, phospholipid molecules spontaneously arrange into liposomes driven by hydrophobic interactions and other intermolecular forces. The role of cholesterol is to promote the stacking of lipid chains and the formation of the bilayer, reduce the fluidity of the bilayer, and decrease the transmembrane transport of water-soluble drugs. Moreover, cholesterol can reduce the interaction between liposomes and proteins in the body, reduce the loss of phospholipids, thereby enhancing the stability of liposomes.
Liposomes have a structure highly similar to cell membranes, which gives them excellent biocompatibility and biodegradability. As a result, liposomes can protect drugs from enzymatic degradation before they reach the target site.
Additionally, drugs can be physically encapsulated within the liposomes, which can enhance drug stability, reduce drug toxicity, increase the dosage of the drug, and achieve better therapeutic effects. The surface of the bilayer formed by amphiphilic phospholipids can be structurally modified with ligands or other functional groups through physical or chemical means, which endows liposomes with tissue targeting capabilities. This can extend the effective retention time of liposomes at the target site and even enable efficient targeted drug delivery. By altering the charge on the surface of the bilayer, liposomes can be used for the encapsulation and delivery of DNA and RNA drugs, such as cationic liposomes.
