Fig. 2.

‘Read Until’ strategy for selective sequencing of dsDNA molecules. The ionic current profile obtained during translocation of a DNA strand through the nanopore is compared in real time to the ionic current profile of a target sequence. a As sequencing of the template strand of DNA proceeds (during step iv), the measured current is compared to the reference current profile. If there is a match, sequencing of that strand continues to completion (steps v–vii). A new strand can now be captured. b Alternatively, if the measured current does not match the reference current profile, the membrane potential is reversed, sequencing of that strand stops, and the strand is ejected (at stage v). A new strand can now be captured. (Image based on the strategy of Loose et al. [43])