Solvent-Mediated Dewetting Principles for Cell-Sized Liposome Formation.

Reconstitution of synthetic cells holds potential to advance synthetic biology, biomanufacturing, and therapeutics. Microfluidic generation of cell-sized liposomes via double emulsion templating offers precise control over composition and formation process, yet the principles underlying solvent-mediated dewetting remain poorly understood. Using a solvent combination of hexanol and paraffin oil, we demonstrate that solvent-mediated dewetting liposome generation entails both solvent removal and the application of mechanical stimuli. Solvent removal suffices to induce the morphological transition from double emulsions to partially dewetted liposomes exhibiting low and high budding angles of the residual oil pockets. This transition is driven by relaxation of monolayer and membrane tensions, arising from the increased lipid packing density at the liposome interfaces during solvent depletion. While dewetting kinetics and intermediate stages are governed by solvent removal rate, complete dewetting is not spontaneous. Using optical tweezers, we identify tethering between the liposome and oil pocket and characterize the mechanical force required for liposome detachment. By integrating these principles, a predictive, high-throughput approach for generating biocompatible, surfactant-free liposomes is provided. These findings establish a mechanistic framework for liposome dewetting and, through similarities to lipid droplet morphogenesis, offer a protocell platform that could further the understanding of biological budding processes.