Characterization of lipid composition and diffusivity in OLA generated vesicles

Michael Schaich,Diana Sobota,Hannah Sleath,Jehangir Cama,Ulrich F Keyser

doi:10.1016/j.bbamem.2020.183359

Michael Schaich, Diana Sobota + Show 3 more

Open Access

https://doi.org/10.1016/j.bbamem.2020.183359

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Abstract

Giant Unilamellar Vesicles (GUVs) are a versatile tool in many branches of science, including biophysics and synthetic biology. Octanol-Assisted Liposome Assembly (OLA), a recently developed microfluidic technique enables the production and testing of GUVs within a single device under highly controlled experimental conditions. It is therefore gaining significant interest as a platform for use in drug discovery, the production of artificial cells and more generally for controlled studies of the properties of lipid membranes. In this work, we expand the capabilities of the OLA technique by forming GUVs of tunable binary lipid mixtures of DOPC, DOPG and DOPE. Using fluorescence recovery after photobleaching we investigated the lateral diffusion coefficients of lipids in OLA liposomes and found the expected values in the range of 1 μm2/s for the lipid systems tested. We studied the OLA derived GUVs under a range of conditions and compared the results with electroformed vesicles. Overall, we found the lateral diffusion coefficients of lipids in vesicles obtained with OLA to be quantitatively similar to those in vesicles obtained via traditional electroformation. Our results provide a quantitative biophysical validation of the quality of OLA derived GUVs, which will facilitate the wider use of this versatile platform.

Highlights

Liposomes, small aqueous compartments encapsulated by a lipid bilayer, have come a long way since their first description by Bangham and Horne in 1964 [1,2]
We investigated the lipid composition of Giant Unilamellar Vesicles (GUVs) formed using the Octanol-Assisted Liposome Assembly (OLA) system by performing a mean fluorescence intensity analysis on PGPE, PGPC and PCPE binary lipid mixtures
We showed that the lipid composition of vesicles formed with the novel OctanolAssisted Liposome Assembly (OLA) technique matches the composition of the lipid in the LO phase input during the vesicle formation process

Summary

Introduction

Small aqueous compartments encapsulated by a lipid bilayer, have come a long way since their first description by Bangham and Horne in 1964 [1,2]. Known as lipid vesicles, are a widely used tool in many branches of science and industry, including the pharmaceutical and cosmetics industries [3]. Unilamellar liposomes of several microns in diameter, termed Giant Unilamellar Vesicles (GUVs), are especially widespread in the fields of biophysics and synthetic biology, where they are used in the bottom up construction of synthetic cells [4,5]. GUVs have been used as model membranes for drug transport studies across lipids [6,7] and for studying antibiotic transport facilitated by bacterial porins [8]. Others have used GUVs as micro containers for chemical reactions [9]

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