Figure 2.
Typical conductance blockade events and corresponding histograms from 3.5 kbp long DNA molecules interacting with a 2.5 ± 0.4 nm diameter nanopore. (a) Representative conductance traces of individual events. Events I–III are single-level events, i.e., they reach a single blockade level and return to the baseline after a while. There are also a smaller number of multilevel events, such as events IV and V. The different blockade levels are labeled 0, H, and L, and are discussed in the main text. (b) Histogram of the conductance traces of all the events (black solid line). The change in conductance is plotted with respect to the open pore conductance. Each event contributes multiple counts to this histogram. A number of peaks can be distinguished, fitted by Gaussian curves and denoted by different colors. The brown solid line is the sum of these fitted Gaussians. (c) 2D histogram of the same set of events, showing the dwell time and relative current blockade IB for each event. The events cluster into distinct populations (denoted by squares; see Materials and Methods) that correspond to the peaks in the histogram in b.