Capture and Translocation of Nucleic Acids into Sub-5 nm Solid-State Nanopores - Nanopores: Sensing and Fundamental Biological Interactions - page 239

Fig. 10.9 Ion-current traces showing PEG entry into a 4 nm solid-state pore at varying voltage V
applied to the trans chamber ( top ). Entry rate as a function of voltage ( bottom ). Reproduced with
permission from Wanunu et al. [ 50 ], Copyright Nature Publishing Group

drag during translocation, which is associated with cation flow in the opposite
direction to DNA movement, slows the DNA and increases the translocation time.
Experiments using the uncharged polymer polyethylene glycol (PEG) were
performed in order to verify that the direction of electroosmotic flow (EOF) in
SiN nanopores is governed by the cations, and therefore is directed towards the
negatively biased electrode [ 50 ]. In Fig. 10.9 , we show a set of ion current traces
after PEG (MW ¼ 12,000) was added to the cis chamber at a final concentration

of 415 m M (small enough to avoid creating an appreciable osmotic flow), under