Asymmetric Hybrid Polymer–Lipid Giant Vesicles as Cell Membrane Mimics

Abstract

Lipid membrane asymmetry plays an important role in cell function and activity, being for instance a relevant signal of its integrity. The development of artificial asymmetric membranes thus represents a key challenge. In this context, an emulsion‐centrifugation method is developed to prepare giant vesicles with an asymmetric membrane composed of an inner monolayer of poly(butadiene)‐b‐poly(ethylene oxide) (PBut‐b‐PEO) and outer monolayer of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC). The formation of a complete membrane asymmetry is demonstrated and its stability with time is followed by measuring lipid transverse diffusion. From fluorescence spectroscopy measurements, the lipid half‐life is estimated to be 7.5 h. Using fluorescence recovery after photobleaching technique, the diffusion coefficient of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐(lissamine rhodamine B sulfonyl) (DOPE‐rhod, inserted into the POPC leaflet) is determined to be about D = 1.8 ± 0.50 μm2 s−1 at 25 °C and D = 2.3 ± 0.7 μm2 s−1 at 37 °C, between the characteristic values of pure POPC and pure polymer giant vesicles and in good agreement with the diffusion of lipids in a variety of biological membranes. These results demonstrate the ability to prepare a cell‐like model system that displays an asymmetric membrane with transverse and translational diffusion properties similar to that of biological cells.

Switchable Lipid Provides pH-Sensitive Properties to Lipid and Hybrid Polymer/Lipid Membranes

“…Hybrid lipid/polymer vesicles have been designed with the idea of overcoming the drawbacks of each component (leakage and mechanical instability for liposomes, low permeability for polymersomes) and combining the benefits of each component (biocompatibility and permeability of liposomes, toughness of polymersomes) [5,26]. Some studies comment about their potential use [27], as nano/micro reactors [28] and/or as drug delivery agents [29] where membrane permeability is of prime importance. Without stimuli-responsive properties, payload release is only achieved by passive diffusion.…”

Microfluidics for Biosynthesizing: from Droplets and Vesicles to Artificial Cells

“…Asymmetrical vesicles indicate the inner and outer of the vesicles contain different types of molecules . The asymmetrical structure plays a key role in realize vesicles' potential applications . For example, the asymmetrical lipid vesicles exhibit better endocytosis rate and endosomal escape ability compared with the symmetrical counterparts .…”

“…[161,162] The asymmetrical structure plays a key role in realize vesicles' potential applications. [163] For example, the asymmetrical lipid vesicles exhibit better endocytosis rate and endosomal escape ability compared with the symmetrical counterparts. [164] Furthermore, the asymmetry property of vesicles is also necessary for replication and quantitative analysis.…”

Light-Driven Biocatalysis in Liposomes and Polymersomes: Where Are We Now?

“…Many research groups were inspired to embed different photosynthetic systems into the membrane of liposomes to convert light energy into ATP and to employ liposomes for light-driven biocatalysis [12][13][14][15][16][17][18][19][20]. In those studies, different phospholipids were used to mimic the transversal heterogeneity of a natural asymmetric membrane, which is composed of an outer layer (with the lipids phosphatidylcholine and sphingomyelin) and an inner layer (with the lipids phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol) [21,22]. Subsequently, an asymmetric charge distribution occurs across the bilayer, with higher negative charge in the inner layer typically due to phosphatidylserine.…”