Characteristic time for the end monomers of a spherically confined polymer to find a nano-pore

Translocation of a polymer through a nano-pore is relevant in a variety of contexts such as passage of RNAs through a nuclear pore and transportation of proteins across a membrane. An essential step in polymer translocation is for the end monomers to search the pore. This process requires a characteristic time, referred to as the attempt time in this work. Here, we study the attempt time tau of a confined polymer inside a spherical surface by combining a scaling approach and Langevin dynamics simulations. For a moderately to strongly confined polymer, our results suggest that tau similar to R-3.(67) for R > P and tau similar to R-2.(67) for R < P, where R is the radius of the spherical surface and P is the persistence length of the polymer. All simulation data obtained for an intermediate range of the volume fraction of monomers phi(less than or similar to 0.2) tend to collapse onto each other. This implies that tau does not explicitly depend on phi, in agreement with the theoretical predictions. These results will be useful for interpreting translocation as a two-step process: the initial attempt to find the pore and eventual pore crossing. Published under license by AIP Publishing.

Automated summary

This study investigates the attempt time of a confined polymer inside a spherical surface using a scaling approach and Langevin dynamics simulations. Results suggest that the attempt time does not explicitly depend on the volume fraction of monomers within a certain range.