Entropy of Insertion, Not Pore Jamming, Controls Polycatenane Translocation Dynamics

Catenanes are a mechanically interlocked molecular architecture consisting of two or more consecutively interlocked macrocycles. They play an important role in applications that range from molecular machines and switches to catalysis and drug delivery underpinned by their unique topological structure. Polymer translocation applications have also been widely studied, such that the phenomenon of polycatenane translocation can be applied to various tasks such as low-cost characterization, controlled drug delivery, and rapid DNA sequencing. This talk will discuss the translocation dynamics of a polycatenane passing through a small nanopore under an external driving force using Langevin dynamics simulations. The simulations reveal the translocation dynamics are controlled by the entropy of insertion into the pore, rather than simple pore jamming. In addition, the size of the pore radius greatly affects the mean translocation time especially in the small pore limit. We observe a huge jump in the translocation time at a critical pore radius. No power law-type behavior (which is typically deduced from studies of translocation in larger pore sizes) can account for this highly non-linear pore size dependent behavior. We explain this abnormality by thorough statistical analysis of the translocation of the polycatenane knots, and the orientation of the polycatenane during the translocation process.