A living cell is an ultimate highly functional molecular robot. The high functionality results from not only its various functional molecules but also its “micrometer-sized” body that has enough space to possess the molecules. However, the sizes of already-developed molecular nanomachines are too small to include many functional molecules. Toward the construction of highly functional molecular machines and molecular robots, it is required to construct molecular robots with large (i.e., micrometer-sized) bodies. Here, we propose an autonomous micrometer-sized molecular robot “DNA ciliate”.

“DNA ciliate”is an autonomous micrometer-sized molecular robot that has three independent functional modes.

DNA ciliate

“DNA ciliate” is an autonomous micrometer-sized molecular robot, which is inspired by water microorganisms, ciliates. A natural ciliate has a micrometer-sized body with cilia and achieves various functions such as autonomous motion with the cilia, phototaxis, etc. Similarly, the DNA ciliate has a micrometer-sized body with many DNAs as cilia, and it can switch three different modes in response to its external environment: the free moving mode, the track walking mode, and the light-irradiated gathering mode. (See below)

The DNA ciliate can move around in a broad range of space using the free moving mode. This mode utilizes the Brownian motion of the DNA ciliate.
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In the track walking mode, the DNA ciliate walk directionally along a single-stranded DNA track on a plate using the cleaving activity of deoxyribozymes attached on the body of the DNA ciliate. The deoxyribozymes cleave substrate DNA strands arrayed as the track, and help the DNA ciliate move to the region of uncleaved substrate DNA step-by-step.
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The DNA ciliates gather at a specific area where an ultraviolet (UV) light is irradiated; this is the light-irradiated gathering mode. To achieve this mode, a UV-switching DNA system based on the cis-trans isomerization of azobenzenes was designed.
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