Liposomal Food Systems in Microfluidic Devices

Liposomes are self-organised systems constituting spherical vesicles of one or more concentric lipid bilayers that isolate one or several internal compartments from the external aqueous medium. Microfluidic production of liposomes is still strongly based on the use of planar hydrodynamic focusing devices, being conducted by introducing a dispersion of phospholipids in organic solvent into the central channel of the device, and subsequently constricting this central stream by one or more perpendicular aqueous streams. The focusing of the central current results in the controlled depletion of the organic solvent concentration through its diffusion into the aqueous phase, thereby triggering the self-organisation of phospholipids into bilayers and subsequently into liposomes. It has been shown that by hydrodynamic focusing microfluidics, unilamellar liposomes are formed with a size distribution that can be easily controlled by means of the ratio between the volume flow rates of the aqueous and organic streams. Thus, microfluidics is characterised as a simple and highly reproducible method for liposome production.