A new method for liposome preparation using a membrane contactor

In this article, we present a novel, scalable liposomal preparation technique suitable for the entrapment of pharmaceutical agents into liposomes. This new method is based on the ethanol-injection technique and uses a membrane contactor module, specifically designed for colloidal system preparation. In order to investigate the process, the influence of key parameters on liposome characteristics was studied. It has been established that vesicle-size distribution decreased with a decrease of the organic-phase pressure, an increase of the aqueous-phase flow rate, and a decrease of the phospholipid concentration. Additionally, special attention was paid on reproducibility and long-term stability of lipid vesicles, confirming the robustness of the membrane contactor-based technique. On the other hand, drug-loaded liposomes were prepared and filled with two hydrophobic drug models. High entrapment-efficiency values were successfully achieved for indomethacin (63%) and beclomethasone dipropionate (98%). Transmission electron microscopy images revealed nanometric quasispherical-shaped multilamellar vesicles (size ranging from 50 to 160 nm).