What Schneider and coworkers did was to fabricate a nanometer-scale hole called a nanopore in the graphene membrane, which represents the ideal recorder. They demonstrated that single molecules of DNA in water can be pulled through such a graphene nanopore and, importantly, that each DNA molecule can be detected as it passes through the pore. The detection technique is very simple: upon applying an electrical voltage across the nanopore, ions in the solution start to flow through the hole and a current is detected. This current gets smaller whenever a DNA molecule enters the nanopore and partly blocks the flow of ions. Each single DNA molecule that slides through the pore is thus detected by a drop in the current.
The DNA moves base per base through the nanopore. With the atomically thin graphene nanopore one in principle has the potential for reading off the DNA sequence, base per base. A number of groups worldwide have been trying to realize graphene nanopores. Schneider et al are the first to report their results this week.
DNA translocation through nanopores has been developed before by the Dekker lab and others, for example using SiN membranes. Graphene nanopores offer new opportunities many more than sequencing. Since graphene, unlike SiN, is an excellent conductor, an obvious next step is using the intrinsic conductive properties of graphene. Nanopores offer a range of opportunities of sensors for science and applications.
|Contact: Prof. Cees Dekker|
Delft University of Technology