Application of an Improved RESS Process for Atractylodes Macrocephala Koidz Volatile Oil Liposomes Production

To improve the bioavailability and targeting effect to hepatic cells of volatile oil from Atractylodes macrocephala Koidz, the volatile oil was incorporated into liposomes by a improved process of rapid expansion of supercritical solutions (RESS). In this process, the liposomal materials and the volatile oil were dissolved in the mixture of supercritical carbon dioxide (SC-CO₂)/ethanol and then the solution was sparyed into a buffer solution through a coaxial nozzle to form liposomes suspension.The physicochemical properties of the liposomes including structure, size of particle, entrapment ratio and loading efficiency were measured. The encapsulating performance of liposomes could be controlled by changing expansion process conditions such as pressure, temperature of SC-CO₂ and the amount of cosolvent in SC-CO₂ [x (CH₃CH₂OH)]. Under the optimum conditions of 30MPa, 338K and x (CH₃CH₂OH)=15 %, the entrapment efficiency, drug loading, and average particle size of liposomes were found to be 82.18 %, 5.18 % and 173 nm respectively, which were complied with the standards of Chinese pharmacopoeia. The results indicate the improved RESS technique provide an innovative way for formation of liposomes loading multi-components extracted from Chinese traditional medicines.