Direct force measurements on DNA in a solid-state nanopore
Direct force measurements on DNA in a solid-state nanopore
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DOI：
10.1038/nphys344
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发表时间：
2006-07-01
期刊：
影响因子：
19.6
通讯作者：
Dekker, Cees
中科院分区：
文献类型：
--
作者：
Keyser, Ulrich F.;Koeleman, Bernard N.;Dekker, Cees
在纳米孔在生物学中的各种作用中，一个重要的作用是使聚合物能够转运，例如在细菌之间的基因转移（1）和RNA通过核膜的转运（2）。最近，这激发了使用蛋白质（3-5）和固态（6-10）纳米孔作为单分子传感器，用于通过电压驱动的易位检测和结构分析DNA和RNA。所涉及的力的大小对于理解和利用这种移位机制至关重要，但到目前为止，它仍然是未知的。在这里，我们展示了通过将光镊（11）与离子电流检测相结合来首次测量固态纳米孔中单个DNA分子上的力。光镊施加的反作用力可以用来减缓甚至阻止DNA分子的移位。我们得到的值为0.24 +/- 0.02 pN mV（-1）的单一DNA分子上的力，盐浓度从0.02到1 MKCl无关。该力对应于每碱基对0.50 +/-0.05电子的有效电荷，相当于裸DNA电荷减少75%。
Among the variety of roles for nanopores in biology, an important one is enabling polymer transport, for example in gene transfer between bacteria(1) and transport of RNA through the nuclear membrane(2). Recently, this has inspired the use of protein(3-5) and solid-state(6-10) nanopores as single-molecule sensors for the detection and structural analysis of DNA and RNA by voltage-driven translocation. The magnitude of the force involved is of fundamental importance in understanding and exploiting this translocation mechanism, yet so far it has remained unknown. Here, we demonstrate the first measurements of the force on a single DNA molecule in a solid-state nanopore by combining optical tweezers(11) with ionic-current detection. The opposing force exerted by the optical tweezers can be used to slow down and even arrest the translocation of the DNA molecules. We obtain a value of 0.24 +/- 0.02 pN mV(-1) for the force on a single DNA molecule, independent of salt concentration from 0.02 to 1MKCl. This force corresponds to an effective charge of 0.50 +/- 0.05 electrons per base pair equivalent to a 75% reduction of the bare DNA charge.