On the contrary, large number of biological molecule translocations result in the statistical superposition effect in the modulation in the base current, which is embodied in the decrease in the background current. Figures 4 GM6001 mw and 5 show the ionic current changes induced by IgG translocation only through nanopore arrays. In Figure 4, the black and red lines stand for the detected background ionic current curve and the modulated ionic current curve, respectively (the driven voltage

is 1.0 V, and KCl concentration is 0.1 mol/L). The background ionic current value is stable at 680 nA, which corresponds to spot A in Figure 5. When the biomolecules are added, their translocations result in the decline of the current; so, the modulated ionic current value is stable at 110 nA, which corresponds to spot B in Figure 5. Figure 4 Ionic current modulated by IgG translocation through nanopore arrays. The black line and red line stands for the detected background ionic current curve and modulated ionic current curve, respectively (the driven voltage is 1.0 V, and KCl concentration is 0.1 mol/L). Figure 5 The recorded ionic current

versus the variation of IgG concentration in 0.1 mol/L KCl solution. The applied voltage is 1 V. The diameter of the nanopore arrays is 50 nm. The inset in the top right corner shows the differences between the background currents and the recorded currents at find more 40 ng/mL Lck of IgG for different KCl concentrations. Figure 5 shows the detected current changing, with IgG concentration increasing at the driven voltage of 1.0 V. The differences between the background currents and the modulated currents versus KCl concentrations (IgG concentration is 40 ng/mL) are plotted, as shown in the inset of Figure 5, which reflects the influence

on the ionic current caused by the concentration of electrolyte solution. If KCl concentration continues to increase, the ion density in the solution becomes higher and higher. Then, the lost amounts in K+ and Cl− due to the physical place-holding effect are rather bigger. On the other hand, the obtained results about the current changing tendency with IgG concentration indicate that the detected ionic current decreases with IgG concentration increase when it is lower than 40 ng/mL. Obviously, the entry of the IgG molecules results in the partial occupations of nanopore arrays, which prevents K+ and Cl− from passing through the PC membrane. Within a certain concentration, the translocation probability of IgG increases with its increasing concentration. As we have known, the volume of IgG is much larger than that of K+ or Cl−, so the charge density is rather lower in the occupied channel space, which results in the decrease in the detected ionic current.