Simulation Study On The Translocation Of A Partially Charged Polymer Through A Nanopore

The phenomenon of translocation of biopolymers through membranes is ubiquitous in biosystems. Polymers can across membranes through nano-pores or nano-channels. Figuring out the rules that control the dynamics of the polymer is not only helpful for better understanding of the life process, but also important for medicine, physics, chemical industry and biotechnology, etc. With the development of the nanotechnology, scientists can fabricate nano-pores and biopolymers, which are very helpful for people discovering the dynamical process of the translocation of polymers. Experimental studies, theoretical researches and computer simulations have paid extensive attention on the process of the translocation, and many interesting results have been reported. In this dissertation we report our main work as follows:The translocation of a partially charged polymer through a neutral nano-pore under external electrical field is studied by using dynamic Monte Carlo method on a simple cubic lattice. One monomer in the polymer is charged which suffers a driving force when it locates inside the pore. Two time scales, mean first passage timeτFp with the first monomer restricted to never draw back into cis side and translocation timeτfor polymer continuously warming through nano-pore, are calculated. The first passage timeτFp decreases with the increase in the driving force f,and the dependence ofτFP on the position of charged monomer M is in agreement with the theoretical results using Fokker-Planck equation. But the dependence of the translocation timeτon the position of charged monomer shows a different behavior. It increases with f for M< N/2, where N is polymer length. The novel behavior of r is explained qualitatively from dynamics of polymer during the translocation process and from the free energy landscape.