The journey of a single polymer chain to a nanopore

The delivery of a polymer chain from the chamber of origin to the destination through a nano-scale pore (nanopore) is called polymer translocation. This process has a crucial role in many biological processes, for example, virus injection and drug delivery, and it has been studied for more than three decades. However, before the chain can travel through the pore, it must first find the entrance of the nanopore and insert. This process is called polymer capture and has a significant impact on the conformation of the translocation. It has been observed that during the capture process, the polymer can form folded shapes called hairpins. From our molecular dynamics-lattice Boltzmann simulations, we observed that the presence of hydrodynamic flow not only facilitates the finding process but also can result in the extension of the chain and unravelling of the hairpins. This phenomenon, which we call the pulley effect, stems from the different velocity of different strands of the folded chain.