Shrinking nanopores shows potential for applications in DNA sequencing and detection

Graphene nanopores have emerged as an efficient alternative to biological nanopores and other solid-state nanopores due to potential applications in DNA sequencing and detection. Because the thickness of a nanopore affects the molecule detection accuracy of the nanopore, scientists look to ultra-thin graphene nanopores for solutions.

While previous studies have examined the shrinking of graphene nanopores, authors Ma et al. were the first to study such shrinking in relation to nanopore thickness.

The authors used a method to produce nanopores on graphene membranes with adjustable size. Their process involves two steps. First, they sputter a large nanopore using a conventional, focused ion beam. Then, they shrink the nanopore to under 5 nm using the electron beam from a scanning electron microscope.

Using this process, they discovered that shrinking the diameter of a nanopore also increases its thickness, which will need to be taken into consideration during fabrication.

“Our fabrication process is completely controllable so we can prepare nanopores of any size. As well, we have greatly reduced the noise of graphene nanopore using deionized water at trans side,” author Jian Ma said.

Putting their nanopores to the test, the researchers were able to use the new graphene nanopores to detect nucleotide “C” and nucleotide “G” homopolymer DNA strands based on differences in dimensions.

The authors plan to further reduce the size of nanopores and intend on expanding their approach to produce high-density nanopores on graphene membranes with adjustable size under a nanometer.

Source: “Detection of DNA homopolymer with graphene nanopore,” by Lei Zhou, Kun Li, Zhongwu Li, Pinyao He, Kabin Lin, Jingwen Mo, and Jian Ma, Journal of Vacuum Sciences and Technology (2019). The article can be accessed at https://doi.org/10.1116/1.5116295 .