2. Preparation of Drug Liposomes by Thin-Film Hydration and Homogenization

Among the methods for liposome preparation, thin-film hydration is one of the most commonly used methods, which will produce heterogeneous multilamellar vesicles (MLVs). Depending on this process, two types of model molecules, including lipophilic drugs and hydrophilic cargoes, have been mainly reported to be incorporated into liposome. The former can be dissolved together with the lipids prior to the formation of thin film, and the latter, such as oligonucleotide-based hydrophilic ingredients, can be dissolved in the hydration mediums, and then passively incorporated into liposomes via hydration procedure. Following the operation of thin-film hydration, two homogenization methods, sonication and extrusion, have been most usually applied to generate liposomes with optimal size and polydispersity, large unilamellar vesicles (LUVs) or small unilamellar vesicles (SUVs). Here, we initially introduce the thin-film hydration and homogenization, and describe the preparation methods for liposomal products entrapping two types of various cargoes above.