Study of giant charge reconstruction on lipid vesicles using optical bottle technique

Abstract

Lipid vesicles are self-assembled structures composed of lipid bilayers that surround water or cellular cytoplasm. The electric double layers around lipid vesicles play crucial roles in various fields, such as artificial cells and drug delivery systems. While previous studies have reported the controllable adsorption of ions onto the membrane surfaces depending on the lipid composition, systematic researches on the overall structure of the electric double layer, including ion distributions and effective surface charges, have been lacking. In this dissertation, we measure the second virial coefficient (B$_2$) of lipid vesicles using optical bottle technique and subsequently profile the characteristics of the electric double layer, including charge reconstruction factors and Debye length. In particular, we demonstrate that the involvement of water-derived H$^+$ ions is a significant factor influencing charge regulation, and the presence of DOPC around DOPG can induce giant charge reconstruction of the lipid vesicles by altering the topological structure of the stabilization shell for adsorbed cations.