Analytical methods for physicochemical properties of lipid membrane nanovesicles

Abstract

Lipids are major components of biomembranes. Therefore, artificial lipid-based particles composed of amphipathic phospholipids are used as a model of biomembranes for life sciences. Furthermore, they are applied to a variety of fields, such as foods, cosmetics, and medical products. In order to produce functionalized lipid membrane vesicles based on the intended use, the control of lipid compositions and the physicochemical properties of the vesicles are important. We have developed an analytical method for the physicochemical properties of membrane vesicles, mainly used for medical applications. Concerning the size analysis of nano-sized membrane vesicles, we developed a size separation method using monolithic capillary columns. Furthermore, by using dynamic light scattering for detection, we used an on-line system that enables both the size separation and determination of analyzed nanoparticles. We have also developed the system for observing lipid membrane vesicles in an aqueous medium using atomic force microscopy. This system has enabled determining the stiffness of a lipid membrane. We elucidated the relationship between the stiffness of the lipid membrane of the nanovesicles and the product performance, such as in vitro release, cell uptake and cell spheroids penetration of the vesicles. These show that the analytical systems introduced here would contribute to the development of lipid membrane nanovesicles for medical applications.