A Novel Single Step Method of Synthesizing Large Unilamellar Liposomes for Biomedical Applications

S.M. Phapal, P. Sunthar
Indian Institute of Technology Bombay, IN

Keywords: liposomes, drug delivery, coacervation, diffusion, encapsulation


We have investigated various coacervation techniques for liposome synthesis. The aim is to study various local mixing conditions and their effect on the size of liposomes formed. To control the extent of mixing, four different methods were employed. This includes a novel device and a method where the mixing of lipidic phase with aqueous phase is achieved purely by diffusion. The liposomes formed by this new stationary interface diffusion method are monodisprese (DLS: PDI<0.2 and confocal microscopy) and large unilamellar vesicles as indicated by HRTEM studies. The method is highly reproducible and unlike other methods mentioned in literature, the liposome size is unaffected by ratios of phospholipid-ethanol-water . Extensive study of various synthesis conditions/parameters and their effect on physicochemical properties of liposomes provides useful information that will help to understand liposome formation mechanism by coacervation techniques. We conclude that the presence of convection severly hampers the maximum size the liposomes can achieve. Also as the method is single step and produces monodispersed liposomes, no further post processing (sizing) required, thus the encapsulation efficiency is higher. It is also free from harsh chemical and mechanical environments, and therefore suitable for encapsulation of susceptible drugs and genetic materials.