Turnstiles are often used to count the number of people going in or out of an area; a new device could perform the same function for DNA.
Researchers have created a "DNA reader" that is designed to count how many DNA molecules travel through a microscopic hole, an Ecole Polytechnique Fédérale de Lausanne news release reported.
The researchers diluted the DNA molecules in a solution containing "ions and are driven by an electric field through a membrane with a nanopore." When the molecule moves through the small hole it causes a slight disturbance in the electrical field, tipping off researchers to its movement.
The team has been working on the method for about 12 years, but previous models of the system had a number of glitches such as a regularly-clogged hole.
"We thought that we would be able to solve these problems by creating a membrane as thin as possible while maintaining the orifice's strength", Aleksandra Radenovic of the Laboratory of Nanoscale Biology at EPFL, said.
Radenovic came up with the idea to use graphene (a single layer of carbon molecules) in the system; which proved to be extremely strong and resilient. The "DNA turnstile" uses single strips of graphene dubbed "nanoribbons."
"Through an amazing coincidence the graphene layer's thickness measures 0.335 nm, which exactly fits the gap existing between two DNA bases, whereas in the materials used so far there was a 15 nm thickness," Radenovic said.
The thicker material did not allow researchers to individually analyze the DNA molecules, but the new nanoribbons are expected to allow for "exceptional precision" when monitoring their micro movement, which could even allow for genetic sequencing.
The system still needs some work. Since 50'000 DNA bases can pop through the pores in onle five milliseconds the electrical signal must be clearer in order for the researchers to "read" the live sequence of the DNA molecule's passage.
"The possibility of detecting the passage of DNA with graphene nanoribbons is a breakthrough as well as a significant opportunity," Radenovic said.
