Effect of lipid composition on the characteristics of liposomes prepared using the polyol dilution method

Abstract

Polyol dilution (PD) is a liposome preparation method suitable for mass production in the cosmetics industry. For PD-liposomes, lecithin is the primary material of choice because of its cost advantage. However, despite the importance of understanding the effect of lipid composition on the physicochemical properties of PD-liposomes in terms of formulation design, this has not yet been elucidated. In this study, PD-liposomes were prepared using hydrogenated egg yolk lecithin (EL) and its main components, 1,2-distearoyl-glycero-3-phosphocholine (DSPC), 1,2-dipalmitoyl-glycero-3-phosphocholine (DPPC), and 1,2-distearoyl-glycero-3-phosphoethanolamine (DSPE). The compound 1,3-butylene glycol (BG), which is widely used in the cosmetics industry, was used as a representative polyol. Herein, we aimed to clarify the effect of lipid composition on PD-liposomes. The results showed that the particle size, dispersion stability, shape, and phase state of the lipid bilayer in PD-liposomes could be controlled by changing the composition of the hydrophilic and hydrophobic groups of the lipids. In particular, when PE was added to a system consisting of PC molecules, a significant decrease in particle size, improvement in dispersion stability, and shape changes were observed, indicating a significant effect on the physicochemical properties of the PD-liposomes. In addition, adding BG induced the formation of an interdigitated structure in the lipid bilayer when PC was the only hydrophilic group component; adding even a small amount of PE suppressed the formation of this structure. Furthermore, we confirmed that premixing BG and lipids enhanced the miscibility of different types of lipid molecules. The findings of this study are expected to contribute to the design of highly functional PD-liposomes by enabling the selection and design of appropriate lipid compositions for practical applications.