Solid-state nanopores are proving to be invaluable tools for probing biology at the single-molecule level.
Graphene nanopore devices developed by the Penn team work in a simple manner. The pore divides two chambers of electrolyte solution and researchers apply voltage, which drives ions through the pores. Ion transport is measured as a current flowing from the voltage source. DNA molecules, inserted into the electrolyte, can be driven single file through such nanopores.
As the molecules translocate, they block the flow of ions and are detected as a drop in the measured current. Because the four DNA bases block the current differently, graphene nanopores with sub-nanometer thickness may provide a way to distinguish among bases, realizing a low-cost, high-throughput DNA sequencing technique.
In addition, to increase the robustness of graphene nanopore devices, Penn researchers also deposited an ultrathin layer, only a few atomic layers thick, of titanium oxide on the membrane which further generated a cleaner, more easily wettable surface that allows the DNA to go through it more easily. Although graphene-only nanopores can be used for translocating DNA, coating the graphene membranes with a layer of oxide consistently reduced the nanopore noise level and at the same time improved the robustness of the device.
Because of the ultrathin nature of the graphene pores, researchers were able to detect an increase in the magnitude of the translocation signals relative to previous solid state nanopores made in silicon nitride, for similar applied voltages.
The Penn team is now working on improving the overall reliability of these devices and on utilizing the conductivity of the graphene sheet to create devices with transverse electri
|Contact: Jordan Reese|
University of Pennsylvania