Liposomes or phospholipid vesicles are one of the most versatile nanoparticles used to convey drugs, vaccines, genes, enzymes, or other substances to target cells and as a model to mimic biological membranes. To fulfil their roles in drug delivery and biotechnology, the physical and chemical properties of liposomes, such as size, shape, chemical composition, lamellarity, encapsulation efficiency of cargo molecules, and the density of proteins reconstituted in the membrane, need to be characterized to ensure reproducible preparation of the vesicles. Compared to bulk analysis, techniques focusing on the individual analysis of liposomes can reveal heterogeneity that is otherwise masked by ensemble averaging. Herein, we review the recent advances in techniques for single-liposome characterization.
