Vesicle Generating An Oscillatory Shape Change Under a pH Gradient

Living matter exhibits autonomous and oscillatory motion in response to the surrounding environment. Some biological functions are maintained by proteins operating under pH gradient that is formed by an active transport of proton. The pH is also an important quantity of chemical reactions in an aqueous medium. Thus, the design of autonomously moving molecular assembly with sustainable motions similar to biological systems is interesting for biomimetic applications of a molecular assembly. In this presentation, a vesicle generating an oscillatory shape change is reported. The vesicle is oleic–acid based and exhibits a sustainable oscillatory shape change under pH gradient that is formed by a diffusion of basic aqueous solution. The vesicle was apparently double spherical, and its size was almost constant during the structural change. This vesicle continuously generates mechanical work from a pH gradient. In this presentation, we reported experimental results of this vesicle dynamics in detail and proposed a mechanism of vesicle dynamics that converts pH gradient to work.