A team of researchers at the California Institute of Technology developed DNA robots that could move molecules or deliver medicine in the body, according to a new study published in Science.

These cargo-sorting DNA robots are made from a single strand of DNA with three modules: one with a leg and two feet to walk, one with an arm and hand to grab and carry cargo and one to sense delivery points and alert the hand to release the cargo.

“Just like electromechanical robots are sent off to faraway places, like Mars, we would like to send molecular robots to minuscule places where humans can’t go, such as the bloodstream,” assistant professor of bioengineering and lab leader Lulu Qian said in a statement. “Our goal was to design and build a molecular robot that could perform a sophisticated nanomechanical task: cargo sorting.”

The design of the robots’ feet allows them to walk around on nano-sized pegboards made from DNA strands, but only one foot at a time is able to bind to the DNA surface so that the robot can move in a random direction with each step.

The researchers tested the robots with two dye molecules, requiring them to discover, pick up and then distribute the molecules throughout the surface. They also tested using multiple robots simultaneously on the same surface.

“Though we demonstrated a robot for this specific task, the same system design can be generalized to work with dozens of types of cargos at any arbitrary initial location on the surface,” former graduate student and research lead Anupama Thubagere said in the press release. “One could also have multiple robots performing diverse sorting tasks in parallel.”

The researchers though did not create the robots for any particular purpose, even though other DNA robots have already been developed in the past.

“We don’t develop DNA robots for any specific applications. Our lab focuses on discovering the engineering principles that enable the development of general-purpose DNA robots,” Qian said. “However, it is my hope that other researchers could use these principles for exciting applications, such as using a DNA robot for synthesizing a therapeutic chemical from its constituent parts in an artificial molecular factory, delivering a drug only when a specific signal is given in bloodstreams or cells, or sorting molecular components in trash for recycling.”