Controlling the movement of micrometer-sized particles with light has attracted attention in the nanoscience field such as in the development of molecular robots. Inspired by bacteria that use actin filament formation for intracellular locomotion, we have developed a system to drive the movement of micrometer-sized particles by light-induced peptide nanofiber growth. First, we designed a DNA-peptide conjugate in which a nanofiber-forming peptide is linked to self-assembly inhibitory DNA moiety linked with a photodissociation amino acid. Although the DNA-peptide conjugate itself does not form nanofibers because self-assembly is inhibited, the peptide is released and forms nanofibers when irradiated with UV light. Thus, the conjugate can be used for spatiotemporal control of nanofiber formation. By introducing this conjugate into one side of phase-separated giant liposomes, we found that the movement of the liposomes is propelled by local nanofiber growth on the liposome surface upon UV light irradiation. In particular, the fast movement was observed when photodissociation amino acids with high photodissociation speed were used, indicating that the movement can be controlled by designing the photodissociation moiety. By using a self-assembled DNA microsphere (Nucleo-sphere) as a "car body" instead of giant liposomes, we have succeeded in controlling the direction of movement in response to the direction of light irradiation. In this system, the structure of Nucleo-sphere, whose interior is filled with DNA, is used to induce localized nanofiber formation on the light-irradiated side, thereby realizing a moving system with "negative phototaxis" that escapes from the direction of light irradiation. The propulsion of movement driven by these nanofiber formations is not only expected to lead to an understanding of natural moving systems, but also to applications as carriers for drug delivery and components for molecular robots.

Representative papers

• Chem. Commun., 51, 8020-8022 (2015). Inside Back Cover
• Sci. Rep., 8, 6243 (2018). Top 100 Chemistry Papers
• ACS Appl. Bio Mater., 4, 5425-5434 (2021). Supplementary Cover