The transport of polymers across nanoscale pores underpins many biological processes, such as the ejection of bacteriophage DNA into a host cell and the transfer of genes between bacteria. The movement of polymers into and out of confinement is also the basis for a wide range of sensing technologies used for single-molecule detection and sequencing. Acquiring an accurate understanding of the translocation dynamics is an essential step in the quantitative analysis of polymer structure, including the localization of binding sites or sequences. Here we use synthetic nanopores and nanostructured DNA molecules to directly measure the velocity profile of driven polymer translocation through synthetic nanopores. Our results reveal a two-stage behaviour in which the translocation initially slows with time before accelerating close to the end of the process. We also find distinct local velocity correlations as the DNA polymer chain passes through the nanopore. Brownian dynamics simulations show that the two-stage behaviour is associated with tension propagation, with correlations arising from the random-walk conformation in which the DNA begins.

聚合物穿过纳米级孔隙的运输支撑着许多生物过程，例如噬菌体 DNA 喷射到宿主细胞中以及细菌之间的基因转移。聚合物进出限制的运动也是用于单分子检测和测序的各种传感技术的基础。准确了解易位动力学是定量分析聚合物结构的重要步骤，包括结合位点或序列的定位。在这里，我们使用合成纳米孔和纳米结构 DNA 分子直接测量驱动聚合物通过合成纳米孔易位的速度分布。我们的结果揭示了一个两阶段的行为，其中易位最初随着时间的推移而减慢，然后在接近过程结束时加速。当 DNA 聚合物链通过纳米孔时，我们还发现了明显的局部速度相关性。布朗动力学模拟表明，两阶段行为与张力传播有关，相关性源于 DNA 开始的随机游走构象。