(1) Monolayer liposomes: When liposomes contain a single-layer double-layer lipid membrane, they are called monolayer liposomes. Single layer liposomes with a size less than 100nm are called small monolayers, while monolayer liposomes with a size greater than 100nm are called large monolayer liposomes;
(2) Multilayer liposomes: When liposomes contain many concentric bilayer lipid membranes, they are called multilayer liposomes. When liposomes contain several non concentric liposomes encapsulated within a single bilayer lipid membrane, they are called polycystic liposomes;
(3) Immunoliposomes: Immunoliposomes are primarily used for actively targeting drugs in the body;
(4) Invisible liposomes: liposomes that can avoid phagocytosis and circulate in the systemic circulation for a long time. Invisible liposomes are achieved by covering the surface of the carrier with hydrophilic chains such as polyethylene glycol (PEG);
(5) Lipid vesicle gel: When phospholipids are dispersed in aqueous medium with high concentration, they form semi-solid vesicles, called lipid vesicle gel. Lipid vesicle gel is usually prepared by high-pressure homogenization method, which contains high concentration of phospholipids. Lipid vesicle gel is mainly used as non gastrointestinal storage preparation. They can also be used as intermediates for liposome dispersions to prevent drug leakage and improve storage stability; (6) Lipid roll: Liposome roll is a stable small liposome carrier, mainly composed of negatively charged lipids such as phosphatidylserine and divalent cations such as Ca2+. Usually, their form resembles a multi-layer cigar;
(7) Nanoliposomes: Compared to micrometer scale carriers, they have many advantages: they can avoid being recognized by small phagocytic cells, resulting in longer circulation time in the blood; Can penetrate deep into tissues through capillaries and biofilms. In addition, they are easily absorbed by cells, thereby improving the therapeutic effect of the target site and prolonging the pharmacological effect time in the required area, even up to several weeks. It has greatly improved the controlled release encapsulated drugs and achieved precise targeting.
