Conical nanopore membranes: Controlling the nanopore shape
Conical nanopore membranes: Controlling the nanopore shape
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DOI：
10.1002/smll.200500196
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发表时间：
2006-02-01
期刊：
影响因子：
13.3
通讯作者：
Martin, CR
中科院分区：
文献类型：
--
作者：
Harrell, CC;Siwy, ZS;Martin, CR
在生物传感器中使用纳米孔作为传感元件的兴趣越来越大。[1-6]通常使用α-溶血素蛋白质纳米孔，并且该传感器由嵌入脂质双层膜内的单个蛋白质纳米孔组成。[1-3]离子电流通过纳米孔，并且分析物物种被检测为与分析物通过孔的移位相关的该电流中的瞬时块;这被称为随机或连续脉冲感测。[1-3]虽然这是一个非常有前途的传感范例，但消除脆弱的脂质双层膜并可能用非生物等效物代替生物纳米孔将是有利的。[7-16]各种方法已被用于制备连续脉冲传感的非生物纳米孔，包括聚焦离子束蚀刻，[7，8，11]软光刻，[10]碳纳米管的膜嵌入，[4]和跟踪蚀刻方法。[5，6，13-17]圆锥形纳米孔[13-17]对于传感应用特别有利。[6，18]这是因为Lee等人已经表明，当离子电流通过圆锥形纳米孔时，所得跨膜电压降的大部分集中在纳米孔的小直径开口（尖端开口）中和附近的电解质溶液。[5]因此，在尖端开口中和附近存在用于分析物种类的“感测区”。[5，6]如果用于控制锥形纳米孔的锥角的手段是可用的，则该感测区的长度和区内的场强可以系统地变化。我们最近发现，通过重离子追踪[19]聚合物膜的各向异性蚀刻[5，6，13-17]制备的锥形纳米孔的锥角可以通过改变孔蚀刻期间施加的跨膜电势差而系统地改变。这种改变锥角的能力通过电子显微镜和通过蚀刻后流过纳米孔的离子电流的电化学研究来证明。这些调查的结果在这里描述。
There is increasing interest in using nanopores as the sensing elements in biosensors.[1–6] The α-hemolysin protein nanopore is typically used, and this sensor consists of a single protein nanopore embedded within a lipid bilayer membrane.[1–3] An ionic current is passed through the nanopore, and analyte species are detected as transient blocks in this current associated with translocation of the analyte through the pore; this is known as stochastic or resistivepulse sensing.[1–3] While this is a very promising sensing paradigm, it would be advantageous to eliminate the fragile lipid bilayer membrane and perhaps to replace the biological nanopore with an abiotic equivalent.[7–16] A variety of approaches have been used to prepare abiotic nanopores for resistive-pulse sensing, including focused-ion-beam etching,[7, 8, 11] soft lithography,[10] film embedding of carbon nanotubes,[4] and the track-etch method.[5, 6, 13–17] Conically shaped nanopores [13–17] are especially advantageous for sensing applications.[6, 18] This is because Lee et al. have shown that when an ion current is passed through a conical nanopore, the majority of the resulting transmembrane voltage drop is focused to the electrolyte solution in and near the small-diameter opening (tip opening) of the nanopore.[5] As a result, there is a “sensing zone” for analyte species in and near the tip opening.[5, 6] If a means for controlling the cone angle of the conical nanopore were available, the length of this sensing zone, and the field strength within the zone, could be systematically varied. This would allow for tailoring of the nanopore to suit any desired sensing application.We have recently discovered that the cone angle of conical nanopores prepared by anisotropic etching [5, 6, 13–17] of heavy-ion-tracked [19] polymer films can be systematically varied by varying the transmembrane potential difference applied during pore etching. This ability to vary the cone angle was proven by electron microscopy and through electrochemical investigations of the ion current flowing through the nanopore after etching. The results of these investigations are described here.