Liposomer

Liposomer, also commonly referred to as a liposome, is a nanoscale or microscale vesicle formed when amphiphilic lipids assemble into closed bilayers in an aqueous environment. The structure consists of one or more phospholipid bilayers that enclose an aqueous core, enabling encapsulation of hydrophilic substances in the interior and incorporation of lipophilic compounds within the bilayer itself. Liposomers range in size from about 20 nanometers to several micrometers and are categorized as small unilamellar vesicles, large unilamellar vesicles, or multilamellar vesicles based on lamellarity.

Preparation methods include thin-film hydration, reverse-phase evaporation, ethanol or isopropanol injection, detergent dialysis, and microfluidic assembly. Cargo loading can be passive during formation or active using transmembrane gradients (remote loading). Surface modification, such as polyethylene glycol (PEG) grafting or attachment of targeting ligands, can improve stability, circulation time, and tissue specificity.

Applications are broad in biomedicine and cosmetics. In drug delivery, liposomers can improve solubility, protect labile agents, alter pharmacokinetics, and reduce systemic toxicity. They are used for anticancer, antifungal, and antimicrobial therapies, as well as vaccines and genetic material delivery. Several liposomal drugs are approved, including liposomal doxorubicin and liposomal amphotericin B.

Challenges include physical instability (leakage, fusion), oxidation of lipids, storage requirements, batch variability, and occasional immune recognition. Large-scale production and reproducibility remain active research areas. Safety profiles depend on lipid composition, cargo, and administration route, and regulatory evaluation is essential for each formulation.

See also: liposome, lipid nanoparticle, nanomedicine.