Factors Affecting Polymer Translocation Through a Nanopore in a Membrane

Monte Carlo simulations were used to study the translocation of a flexible polymer through a pore in a membrane, assuming an attractive interaction between the monomers and the membrane on the trans side of the membrane and no interaction on the cis side. For the case T〈Tc （the temperature corresponding to the minimum in the translocation time τ）, the value of τdecreases with increasing temperature, whereas for T〉Tc, τ increases with increasing temperature. The translocation time depends on the absorbed energy uo in a nontrivial way. The value of τ increases initially upon increasing uo before it begins to decrease. The variation of the translocation time with respect to the solvent quality was also studied. It showed that there is a transition, as the solvent quality improves from ＂poor＂ to ＂good＂： when εAB〈εc （the interaction energy corresponding to the minimum in τ）, τdecreases with increasing the value of εAB; when εAB〉εc, τincreases with increasing εAB- When the chain length was changed, it was found that when the absorbed energy uo was greater than uc,τ was proportional to N1.602; for uo〈uc, τ∝N2.248. As the solvent quality improved from ＂poor＂ to ＂good,＂ the translocation probability increased initially before becoming stable.