Nano Lett. 12, 512–517 (2012)

Nanoscale pores in a synthetic or biological material can be used to sense single molecules in solution and could potentially allow DNA to be sequenced quickly and at low cost. In a typical experiment, a single strand of DNA is threaded through a nanopore under an applied potential and modulations in the ionic current passing through the pore are used to identify the molecule. Synthetic solid-state nanopores offer certain advantages over biological pores, such as robustness and versatility, although controlling the exact shape of such nanopores is difficult. Ulrich Keyser, Tim Liedl and colleagues at the University of Cambridge and Ludwig-Maximilians-University Munich have now created hybrid nanopores by inserting precise DNA origami nanostructures into solid-state nanopores.

DNA origami is a technique in which a long single strand of DNA is folded into a predesigned shape using a number of shorter 'stapling' strands, and the researchers used the approach to build hollow three-dimensional structures with four overlapping skirts and a square base. One end of the origami nanostructure has an outer edge length of 27.5 nm, whilst the other end has an edge length of 12.5 nm. This geometry allows the origami nanopores to fit in solid-state nanopores (which have a conical shape) with a range of diameters.

The Cambridge-Munich team show that DNA origami nanopores can be repeatedly inserted and ejected from solid-state nanopores by reversing the applied potential. They also show that the hybrid nanopores can be used to detect γ-DNA strands.