Encapsulation of Hydrophilic and Lipophilic Compounds in Nanosomes Produced with a Supercritical Based Process

Abstract

Liposomes are created when phospholipids self-assemble in an aqueous medium creating spherical closed structures. These vesicles can be loaded with hydrophilic active principles (AP) into the aqueous inner core or with lipophilic compounds in the lipidic double layer. In this work a new supercritical based process for the one-step continuous production of nanosomes is proposed for the encapsulation of hydrophilic and lipophilic compounds. This process is called Supercritical Assisted Liposome Formation (SuperLip). The innovation of this process consists in the inversion of the traditional phases of production of liposomes: water droplets are created by a spray atomization in a high pressure vessel, and then a double layer of phospholipids fast surrounds them. A systematic study on liposome size, morphology, encapsulation efficiency has been performed for several different hydrophilic AP (ampicillin, ofloxacin, bovine serum albumin, fluorescein, eugenol and theophylline). Some operative parameters were also optimized to achieve the production of nanometric liposomes with high encapsulation efficiencies. Operating in this way nanometric and monodispersed liposome suspensions were produced with EE up to 99%. To complete the study, other lipidic compounds were entrapped in the double lipidic layer, obtaining high entrapment efficiencies (TE), also in this case, up to 84.9%.