Directional Propulsion of DNA Microspheres Based on Light-Induced Asymmetric Growth of Peptide Nanofibers.

Inspired by natural motors, synthetic motors powered by light have emerged as promising platforms for constructing artificial micro/nanorobots. As a concept of light-driven motors, we have previously reported propulsion of giant liposomes driven by light-induced peptide nanofiber growth on the surface, inspired by natural pathogens using external actin polymerization for their propulsion. However, their movement was nondirectional. Here, we used DNA microspheres (also known as nucleospheres) comprising DNA three-way junctions with self-complementary sticky ends as vehicles for directional propulsion by light-induced peptide nanofiber growth. By introducing a peptide-DNA conjugate connected by a photocleavage unit to the surface of nucleospheres, ultraviolet (UV) light irradiation induced the asymmetric peptide nanofiber growth on the surface. Nucleospheres exhibited directional movement away from the light source, showing negative phototaxis. This directional movement was maintained even after the light irradiation was ceased. Our phototactic system helps to better understand the mechanism of natural motors and construct bioinspired motors with controlled movement.