Fig. 2: Event properties of DNA under low ionic strength and asymmetric salt conditions.

a Typical event structures observed with λ-DNA translocation experiments under low salt, symmetric conditions at −600 mV. The three events correspond to linear, partially folded, and fully folded λ-DNA from left to right (current traces in black overlaid with red lines). The corresponding blue lines show an example of each DNA configuration. The schematic on the right displays the salt conditions as well as the voltage applied to either side (denoted by positive or negative signs) and how λ-DNA enters via EOF (anti-EPF) from the capture zone located at the outer walls of the nanopore. b Observation of CEs in asymmetric salt conditions when λ-DNA + 1 M KCl was added into the pipette and 4 M KCl was outside at −600 mV. To the right, EPF is used to repel λ-DNA away from the negatively applied voltage and exit the pore into the bath solution. Red inset: DNA exiting the pore produces CEs containing a tail before returning back to baseline. c Current traces of REs in asymmetric salt conditions when λ-DNA + 4 M KCl was added into the bath and the pore contained 1 M KCl. Located to the right is a schematic showing how DNA is electrophoretically attracted to translocate into the pore when +600 mV is applied. All buffers were prepared at pH 7.4. Blue inset: DNA entering the pore yields REs that look similar to square pulses. d Event decay to equilibrium for the case experiments shown in b. DNA is exiting the pore and thus should immediately leave the sensing zone of the pore as opposed to the reverse translocation direction.