Quasi-Phototaxis in Slime-Type Molecular Robots

Abstract

Light-responsive molecular robots that are capable of phototaxis are expected to be utilized in various applications, from biomedical to materials and to environmental fields. However, implementation of such reactive paradigm in molecular robots is still in its infancy. As a critical step towards achieving phototactic behavior, here we introduce 3-Cyanovinylcarbazole nucleoside (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${ }^{\text{CNV}}$</tex> K), a reversible photocrosslinker, as a light-induced trigger for the dynamic structure generation mechanism of artificial metabolism in slimetype molecular robots. Quasi-phototactic behavior is demonstrated through pre-irradiation of UV light with specific wavelengths to the generation mix of slime-type molecular robots. The reaction results in directional locomotion within Y-shaped microfluidic device towards the channel with the generationtriggered side, representing an analogy to Braitenberg vehicle 2a motion based on the molecular-level control of the metabolic pathway. Further development is anticipated to yield more dynamic and complex behaviors, paving the way for molecular cybernetics, and ultimately, the realization of active, intelligent, and adaptive synthetic matter.