Compared with conventional methods, single-molecule real-time (SMRT) DNA sequencing exhibits longer read lengths than conventional methods, less GC bias, and the ability to read DNA base modifications. However, reading DNA sequence from sub-nanogram quantities is impractical owing to inefficient delivery of DNA molecules into the confines of zero-mode waveguides—zeptolitre optical cavities in which DNA sequencing proceeds. Here, we show that the efficiency of voltage-induced DNA loading into waveguides equipped with nanopores at their floors is five orders of magnitude greater than existing methods. In addition, we find that DNA loading is nearly length-independent, unlike diffusive loading, which is biased towards shorter fragments. We demonstrate here loading and proof-of-principle four-colour sequence readout of a polymerase-bound 20,000-base-pair-long DNA template within seconds from a sub-nanogram input quantity, a step towards low-input DNA sequencing and mammalian epigenomic mapping of native DNA samples.

与常规方法相比，单分子实时（SMRT）DNA测序比常规方法具有更长的读取长度，更小的GC偏倚和读取DNA碱基修饰的能力。但是，由于无法将DNA分子有效地传递到零模波导（在其中进行DNA测序的Zeptolitre光学腔）的限制内，因此无法从亚纳米级的量读取DNA序列是不切实际的。在这里，我们表明，电压诱导的DNA加载到在其底部装有纳米孔的波导中的效率比现有方法高五个数量级。此外，我们发现DNA负载几乎与长度无关，这与扩散负载不同，后者倾向于较短的片段。我们在这里展示了聚合酶结合的20的加载和原理证明四色序列读数，