Fig. 2.

Sequencing DNA with a nanopore sensor. An external electrical field drives DNA through the nanopore, transiently blocking the ionic current. By analysis of these current blockades, the DNA sequence can be discerned, in principle. (a) A strand of DNA (lime) threading the transmembrane pore of the α-hemolysin channel (maroon) shown in the cross section normal to the phospholipid membrane (green). The spheres represent the phosphate atoms; water and ions are not shown. The DNA strand has been pulled into the pore by all-atom steered MD (18). (b) Driven by an external electrical field, double-stranded DNA (orange and mauve) enters the artificial nanopore in a silicon nitride membrane (lime). The image is a snapshot from an all-atom MD simulation; water and ions are not shown.