Single-Vesicle Assays Using Liposomes and Cell-Derived Vesicles: From Modeling Complex Membrane Processes to Synthetic Biology and Biomedical Applications

Abstract

The plasma membrane is of central importance for defining the closed volume of cells in contradistinction to the extracellular environment. The plasma membrane not only serves as a boundary, but it also mediates the exchange of physical and chemical information between the cell and its environment in order to maintain intra- and intercellular functions. Artificial lipid- and cell-derived membrane vesicles have been used as closed-volume containers, representing the simplest cell model systems to study transmembrane processes and intracellular biochemistry. Classical examples are studies of membrane translocation processes in plasma membrane vesicles and proteoliposomes mediated by transport proteins and ion channels. Liposomes and native membrane vesicles are widely used as model membranes for investigating the binding and bilayer insertion of proteins, the structure and function of membrane proteins, the intramembrane composition and distribution of lipids and proteins, and the intermembrane interactions during exo- and endocytosis. In addition, natural cell-released microvesicles have gained importance for early detection of diseases and for their use as nanoreactors and minimal protocells. Yet, in most studies, ensembles of vesicles have been employed. More recently, new micro- and nanotechnological tools as well as novel developments in both optical and electron microscopy have allowed the isolation and investigation of individual (sub)micrometer-sized vesicles. Such single-vesicle experiments have revealed large heterogeneities in the structure and function of membrane components of single vesicles, which were hidden in ensemble studies. These results have opened enormous possibilities for bioanalysis and biotechnological applications involving unprecedented miniaturization at the nanometer and attoliter range. This review will cover important developments toward single-vesicle analysis and the central discoveries made in this exciting field of research.

Lipid-Based Antimicrobial Delivery-Systems for the Treatment of Bacterial Infections

“…Liposome preparation method is an important factor affecting the structure and size of liposomes. Although liposome preparation methods have been well-established, a short but comprehensive summary of the most used methods will be given to allow better understanding by a multi-disciplinary readership (Figure 3; Pick et al, 2018). In situ lipid synthesis and formation of liposomes by self-assembly into bilayered lipid structures yields liposomes of widely varying size.…”

Recent advances in metallopolymer-based drug delivery systems

“…[7][8][9] Thus, a variety of inorganic materials were used, including carbon (nanotube, nanodiamond, graphene), 10,11 magnetic nanoparticles (NPs) of iron oxide, 12,13 mesoporous silica nanoparticles (MSNPs), 14,15 gold (gold nanorod, nanocage, and NP), 16,17 and rare earth upconversion nanoparticles. 18,19 Among DDSs based on organic materials, we note liposomes 20,21 and lipid particles. 22,23 Although some of these DDSs showed promising results and a number of formulations were approved for use in the clinic, the problem remains unresolved.…”

Microfluidics for Biosynthesizing: from Droplets and Vesicles to Artificial Cells

“…For example, the asymmetrical lipid vesicles exhibit better endocytosis rate and endosomal escape ability compared with the symmetrical counterparts . Furthermore, the asymmetry property of vesicles is also necessary for replication and quantitative analysis . To model realistic cell membranes, asymmetry structure must be incorporated.…”