Figure 3.

Synchronized nanopore–FET of 10 kbp DNA. Salt-concentration-dependent translocations for 1 M, 100 mM, and 50 mM KCl are shown in (A)–(C) for both the nanopore (upper) and gate (lower) channels. At lower KCl concentrations, the amplitude of biphasic peaks on the gate (I_gate) was more pronounced relative to blockade current from the nanopore (I_pore). Asymmetric salt concentrations were also used across the nanopore (D–F) to tune the Debye screening length. For asymmetric concentrations ([cis] = 100 mM for all cases), both blockade current and peak amplitude on the gate were shown to decrease with a greater dilution of KCl in the bath. More importantly, the ratio between I_gate and I_pore was increased. I_gate was extracted by summing up the absolute values of negative amplitude with positive amplitude. Experimental conditions: 400 pM 10 kbp ds DNA was added into the nanopore and translocated from the inside (cis) of the open barrel to the outside (trans); in all cases, V_pore = −700 mV, V_gate = 0 mV.