Formation of nano-sized lipid vesicles with asymmetric lipid components using a pulsed-jet flow method

Abstract Nano-sized lipid vesicles (50–300 nm in diameter) are widely used in drug delivery systems and cosmetics. Recently, exosomes have been shown to be important as the carriers of biomolecules. The membrane structures of exosomes exhibit the same asymmetric lipid distributions as those of the plasma membranes of eukaryotic cells. The asymmetric lipid distributions of the exosome membranes play a key role in the interactions with and recognition of living cells. The asymmetric lipid distributions of nano-sized lipid vesicles facilitate delivery in advanced drug delivery systems, which emulate the cellular transportation systems of exosomes. In this study, we generate nano-sized asymmetric lipid vesicles using a pulsed-jet method for cell-sized asymmetric lipid vesicle formation. They were generated from an asymmetric planar lipid bilayer by applying pulsed-jet flows of longer duration and higher pressure than those used in the formation of micro-sized lipid vesicles. Using a transmission electron microscope, nano-sized lipid vesicles with thicknesses of approximately 5–6 nm (approximately 70% of the generated sample), unilamellarity, and asymmetry were observed to be produced by this method. The nano-sized asymmetric lipid vesicles using this method have the potential to be useful as carriers in drug delivery systems.