Figure 1.

Schematic diagram of the experimental system and sample ion-current trace before and after addition of Ub molecules. (a) Solid-state NPs of ∼3.5 nm are used as single-molecule sensors for Ub and Ub chains (see inset for a typical TEM image). The passage of di-Ub molecules through the NP is illustrated. (b) NP current before (t < −5 s) and after (t > 0 s) addition of mono-Ub molecules to the cis chamber (V = 125 mV). (Inset) Enlargement of three translocation events, the open-pore (i_o) and the blocked-pore levels (i_b). Current traces were digitally low-pass filtered (50 kHz) for display purpose only. To see this figure in color, go online.