Surfactant-free production of biomimetic giant unilamellar vesicles using PDMS-based microfluidics

Naresh Yandrapalli,Tom Robinson,Julien Petit,Oliver Bäumchen

doi:10.1038/s42004-021-00530-1

Abstract

Microfluidic production of giant lipid vesicles presents a paradigm-shift in the development of artificial cells. While production is high-throughput and the lipid vesicles are mono-disperse compared to bulk methods, current technologies rely heavily on the addition of additives such as surfactants, glycerol and even ethanol. Here we present a microfluidic method for producing biomimetic surfactant-free and additive-free giant unilamellar vesicles. The versatile design allows for the production of vesicle sizes ranging anywhere from ~10 to 130 µm with either neutral or charged lipids, and in physiological buffer conditions. Purity, functionality, and stability of the membranes are validated by lipid diffusion, protein incorporation, and leakage assays. Usability as artificial cells is demonstrated by increasing their complexity, i.e., by encapsulating plasmids, smaller liposomes, mammalian cells, and microspheres. This robust method capable of creating truly biomimetic artificial cells in high-throughput will prove valuable for bottom-up synthetic biology and the understanding of membrane function.

Highlights

Microfluidic production of giant lipid vesicles presents a paradigm-shift in the development of artificial cells
The microfluidic chip is fabricated using PDMS-based techniques and plasma bonded to a glass coverslip (Supplementary Fig. 1a)
Note that the coating process employed in this method takes ~5 min using a standard vacuum pump and at room temperature, making the entire fabrication and usage of the microfluidic chip simpler compared to other methodologies employed elsewhere which require higher temperatures, longer times, or multiple pumps[14,16,32,33,34]

Summary

Introduction

Microfluidic production of giant lipid vesicles presents a paradigm-shift in the development of artificial cells. A cell mimic should fulfill the basic requirements of being lipid-based, vesicular in structure, and encapsulating the desired biomolecules such as enzymes, DNA, and even smaller vesicles as artificial organelles[3]. The latter being an essential step in the emerging and accelerating field of bottom-up synthetic biology[4,5]. The copolymer works by incorporating itself, the poly(propylene) chains, into the hydrophobic region of the lipid membrane, altering the biophysical properties of the membrane[20,21,22,23] Additives such as glycerol and poly(vinyl alcohol) (PVA) used to improve the viscosity of the OA and IA phases for better manipulation of fluid flow, size control and emulsion stability, affect the membrane properties[14,24].

Methods

Results

Conclusion