Translocation of a stiff polymer in a microchannel

The voltage-driven dynamics of a stiff polymer through a nanopore are treated with a bend elastic model. In contrast to flexible polymers described by a stretch elasticity, bend elastic chains can be oriented in an external field, here the anchoring field created by the pore atoms. The trajectory of the chain is calculated using the Langevin equation of motion. The dynamical equation is solved by a normal mode analysis of the elastic curve with free ends. Interaction with the pore walls acts to align the chain, and with the electric field induced inside the pore controls the translocation time. Application of a force proportional to the distance of the exit from the end of the pore such as an optical trap slows down the motion, and reduces the chain response to the wall potential and the extension along the pore axis. DNA is a well-known semirigid polymer, and a comparison is made to the molecular dynamics simulation of translocation of DNA through a synthetic nanopore.