Study on the polymer translocation induced blockade ionic current inside a nanopore by Langevin dynamics simulation

摘要

The blockade ionic current inside a nanopore due to polymer translocation is studied using a three-dimensional Langevin dynamics method. The blockade current I_B is dependent on the polymer length N, polymer configuration, polymer-pore interaction, and charge of the polymer. The behavior of I_B can be explained using four factors: (1) the volume vacancy fraction f_V inside the pore; (2) the conformation of the polymer; (3) the location of the polymer inside the pore; and (4) the total charge Z _(tot) inside the pore. We find that I_B increases with f _V but decreases with increasing |Z_(tot|). The influence of the polymer's conformation is complex, dependent on the size of polymer R _G and the cross-sectional size of the pore s. A compact conformation can decrease I_B when R_G > s but increase I_B when R_G < s. For the latter case, the conformation of the polymer is too small to block the pore, thus providing a broad passage for the ions. At the same f_V, monomers will locate close to the surface with a large polymer-pore attraction, which also provides a large I_B.