Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Nano Lett. 2013 Feb 13;13(2):658-63. doi: 10.1021/nl3042678. Epub 2013 Jan 29.
Measurements on protein translocation through solid-state nanopores reveal anomalous (non-Smoluchowski) transport behavior, as evidenced by extremely low detected event rates; that is, the capture rates are orders of magnitude smaller than what is theoretically expected. Systematic experimental measurements of the event rate dependence on the diffusion constant are performed by translocating proteins ranging in size from 6 to 660 kDa. The discrepancy is observed to be significantly larger for smaller proteins, which move faster and have a lower signal-to-noise ratio. This is further confirmed by measuring the event rate dependence on the pore size and concentration for a large 540 kDa protein and a small 37 kDa protein, where only the large protein follows the expected behavior. We dismiss various possible causes for this phenomenon and conclude that it is due to a combination of the limited temporal resolution and low signal-to-noise ratio. A one-dimensional first-passage time-distribution model supports this and suggests that the bulk of the proteins translocate on time scales faster than can be detected. We discuss the implications for protein characterization using solid-state nanopores and highlight several possible routes to address this problem.
通过固态纳米孔进行的蛋白质转运测量显示出异常（非斯莫鲁霍夫斯基）的传输行为，这可以从极低的检测事件率得到证明；也就是说，捕获率比理论上预期的要小几个数量级。通过转运大小在 6 到 660 kDa 之间的蛋白质，系统地进行了事件率对扩散常数的依赖性的实验测量。对于较小的蛋白质，差异被观察到显著更大，因为它们移动得更快，并且信噪比更低。通过测量对于一个大的 540 kDa 蛋白质和一个小的 37 kDa 蛋白质的孔尺寸和浓度对事件率的依赖性，进一步证实了这一点，其中只有大蛋白质遵循预期的行为。我们排除了这种现象的各种可能原因，并得出结论，这是由于有限的时间分辨率和低信噪比的组合。一维首次通过时间分布模型支持这一点，并表明大部分蛋白质在比可检测时间更快的时间尺度上转运。我们讨论了使用固态纳米孔进行蛋白质表征的影响，并强调了几种可能解决此问题的途径。
