Statistics of DNA capture by a solid-state nanopore

A solid-state nanopore can electrophoretically capture a DNA molecule and pull it through in a folded configuration. The resulting ionic current signal indicates where along its length the DNA was captured. A statistical study using an 8-nm-wide nanopore reveals a strong bias favoring the capture of molecules near their ends. A theoretical model shows that bias to be a consequence of configurational entropy rather than a search by the polymer for an energetically favorable configuration. We also quantified the fluctuations and length dependence of the speed of simultaneously translocating polymer segments from our study of folded DNA configurations.