"We used two fluorescent dyes, one is yellow and another is pink, as two types of molecular cargo", Qian said. How rapidly each zipping and unzipping event happens and how much energy it consumes can be predicted for any specified DNA sequence, allowing researchers to regulate how fast the robot travels and how much energy it consumes to do a task.
The robots were then programmed to do three very specific tasks: walk along a platform which had been set up, find a molecule cargo (a two-dimensional origami self-folding DNA test platform), and then deliver this cargo to a specified location.
"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", said Lulu Qian, Assistant Professor at the California Institute of Technology or Caltech.
What is a DNA robot?They did this to show that the DNA robot was able to differentiate between these two. Incidentally, the robots-each built from a DNA molecule of the single-strand variety which consisted of only 53 nucleotides- stood at an unfathomably small height of just 20 nanometers and each step covered a distance of only six nanometers. It includes two "foot" domains joined by a leg strand and a "hand" domain at the end of an arm strand.
While many similar robots have been invented by scientists on a molecular level, these particular robots can execute a lot of tasks from their simple structure. A single strand of DNA is composed of four different molecules called nucleotides-abbreviated A, G, C, and T-and arranged in a string known as a sequence.
Are these the first DNA robots?
A new "robot" made of a single strand of DNA, can autonomously "walk" around a surface, pick up certain molecules and drop them off in designated locations.
While the idea of DNA robots is not a new one, a recent breakthrough in the development of this technology could one day be groundbreaking in the field of medicine. "It is one of the first steps towards developing general-purpose DNA robots", says Qian. Scientists are not at the stage yet where they can program robots of this size to have built-in memory, so instead, the robots were created to "match" their cargo.
The researchers designed the goal strand to automatically snatch the cargo from the robot. (A sheet of paper, by comparison, is about 100,000 nanometers thick.) As the robots roam the pegboard, they grab molecules tethered to the pegs, then drop them off when they receive a chemical signature at a different peg.
The researchers estimate that each DNA robot took around 300 steps to complete its task, or roughly 10 times more than in previous efforts. However, at the moment, scientists were only able to design the DNA robot and its way of functioning. This task is no easy one, since molecular cargos are a little harder to manipulate.
What can they be used for?
"If someone gets a tumour, you can have small robotics, small robots walking to that location doing small scale surgery", he said.
Nanobots are devices made from DNA that are so small they can be injected into the human bloodstream.
"When you deliver them into the human body, it could potentially create risk if that genetic coding integrates into the genome information", he said.
We don't develop DNA robots for any specific applications.
"Many of the potential applications are still science fiction, and there are many practical difficulties that need to be overcome", Qian said.
These robots have been programmed to recognize and transport molecules from one point to another.