Buoyancy‐Driven Flotation and Magnetotaxis of Vesicle‐Based Prototissue Fibers Induced by Oxygen Bubbles under Enzymatic Reactions

Abstract Creation of tissue‐like materials termed prototissues has recently been garnering attention in the field of systems chemistry as a step towards bioinspired complex chemical systems mimicking multicellular organisms. Aiming at such life‐like chemical systems, motility is one of the key properties. Although recent research has focused on inducing motility of individual protocells, motility of prototissues remained to be difficult because it is challenging to induce driving forces which are sufficient for motility of huge prototissues at a millimeter‐/centimeter‐scale. In this study, we demonstrate new strategies to induce motility of vesicle‐based prototissue fibers by generating oxygen bubbles. Since enzyme catalase was incorporated into vesicles, the prototissue fibers composed of multiple vesicles exhibited enzymatic reactions where hydrogen peroxide was decomposed to generate oxygen. After supersaturation of the oxygen, heterogeneous nucleation occurred at the surface of the prototissue fibers to form oxygen bubbles. The buoyancy due to the oxygen bubbles induced flotation of the prototissue fibers, realizing directional motion. Additionally, since oxygen has a paramagnetic property, the prototissue fibers with oxygen bubbles exhibited magnetotaxis where they moved toward magnets. This study provides a potential for prototissues to be applied as smart soft robots with fine‐tuned motility in response to chemicals and magnets.