Science Magazine

sciencemag.org SCIENCE G R A P H IC : C . B IC K E L / S C IE N C E as well as an arm and hand domain used for picking up and dropping off cargos. Each robot can perform three modular operations: a random walk step to one of its neighbors, a pickup of a cargo strand, and the drop off of a cargo strand. The study’s design is simple and elegant. It has four key features. First, the design allows for a natural parallelism; each robot executes individual sorting tasks largely independent of the other robots, except that a random walk step cannot move into the location of another robot, and two robots cannot simultaneously pickup or drop off the same identical cargo strand at the same time. Second, any given robot can be reused for multiple cargo-sorting tasks, because a random walk step by a robot to each of its four possible neighbors requires no energy expenditure. Third, the pickup and subsequent drop off of a cargo strand do not depend on the type of cargo, and the same robot can therefore be used to transport either of the two types of cargo strands, simplifying the protocol design. Finally, since all the cargo and robots remain attached to the same DNA origami, each cargo-sorting task is localized to an individual DNA origami. The authors demonstrate that multiple distinct cargo-sorting tasks can be executed simultaneously in a single test tube, each on a distinct DNA origami. The major advance in Thubagere et al.’s study is their methodology for designing simple DNA devices that work in parallel to solve nontrivial tasks. Similar systems should be able to perform more complex tasks, such as executing chemical synthesis in parallel. Many exciting emerging applications, for example in nanomedicine, may make use of parallel executing DNA devices. j