Towards electrospray-assisted production of lipid-based synthetic cell assemblies.

Lipid-based vesicles are widely used, minimalistic model containers for in vitro reconstitution of biological systems and engineering synthetic cells. These containers provide a micro-chassis to encapsulate biomolecules and study biochemical interactions. Liposomes are often the most sought-after vesicles owing to their cell-mimicking nature, and numerous bulk and on-chip methods exist for their production. However, exploring the scope of synthetic containers, both in terms of the alternative lipid assemblies as well as newer production methods is useful for expanding the toolbox for synthetic biology. In this paper, we report the development of an electrospray-based technique, which we term "ATPS-templated lipid assemblies via electrofusion of SUVs" (ATLAES), to form lipid-based vesicles. Using an aqueous two-phase system (ATPS), free of organic solvents, we demonstrate efficient formation of microscopic vesicles stabilized via interfacial lipid assembly. Interestingly, the formed vesicles exhibit a nebulous and disordered, but highly stable coating of lipids, and tend to form interconnected vesicle populations. Remarkably, the lipid assemblies can continue to rearrange and reconfigure over time, leading to spherical vesicles with ultra-thin and smooth lipid coating, suggestive of liposomes. Our work provides a new avenue, in the form of electrospray, to form various lipid-based assemblies using all-aqueous systems and we believe this platform can be further exploited for high-throughput vesicle production and higher-order assemblies.