Microfluidic generation of cell-sized liposomes using a budding strategy

Cell-sized liposomes have emerged as valuable tools in biological applications, such as artificial cells and synthetic biology. The microfluidic production of liposomes using polydimethylsiloxane (PDMS) microfluidic devices offers superior reproducibility and precise control over liposome properties. However, the hydrophobicity of PDMS hinders the formation of liposome precursors, water-in-oil-in-water (W/O/W) double-emulsion droplets, which requires hydrophilic surface treatment of the channels. In this study, we present a microfluidics-based strategy called ”Budding” to prepare cell-sized, monodisperse, unilamellar liposomes rapidly, bypassing the W/O/W double-emulsion droplet formation step and eliminating the impact of hydrophobic channels on liposome preparation. The resulting liposomes were monodispersed (coefficient of variation = 2.9-7.5%) with precise size control (14.4-55.5 μm) achieved by adjusting the flow rate. The unilamellar and water permeability of the liposomes were confirmed through α-hemolysin insertion assays and osmotic swelling assays, respectively. Additionally, the ability to create multi-compartment liposomes was demonstrated, highlighting their potential as versatile tools in various biological applications.