Generation of liposomes using a supercritical carbon dioxide eductor vacuum system: Optimization of process variables

Supercritical CO2 (SC-CO2) was used to produce liposomes without the aid of any organic solvent. The rapid expansion of supercritical solvent (RESS) strategy and Bernoulli's principle was utilized to introduce cargo solution into a eductor nozzle system to generate liposomes. The pressure of SC-CO2 and cargo flow rate in the ranges of 12.4 MPa (1800 psig)-17.2 MPa (2500 psig) and 2.2 mL/s(-5) mL/s, respectively, were used and the nozzle was positioned at three different levels in the eductor, to investigate their effects on the characteristics of liposomes. The liposomes' sizes became uniform when the pressure was increased from 12.4 MPa to 17.2 MPa. The maximum encapsulation efficiency (EE) was 44% when the nozzle was positioned at the vena contracta right before the beginning of cargo introduction point in the eductor, with cargo solution flow rate of 2.2 mL/s, and the pressure and temperature of 17.2 MPa and 60 degrees C, respectively. Mixing of the two fluid streams in the eductor nozzle was simulated using Finite Volume Method (FVM). It was found that the mixing was most efficient when the nozzle was positioned right before the beginning of cargo introduction point. The developed system offers an attractive alternative for green generation and use of liposomes in food and biomedical applications.