Ali M, Schiedt B, Healy K, Neumann R, Ensinger W
Department of Materials Science, Darmstadt University of Technology, Petersenstraße 23, D-64287 Darmstadt, Germany.
Nanotechnology. 2008 Feb 27;19(8):085713. doi: 10.1088/0957-4484/19/8/085713. Epub 2008 Feb 4.
Chemical modification of nanopore surfaces is of great interest as it means that the surface composition is no longer fixed by the choice of substrate material, even to the point where large biomolecules can be attached to the pore walls. Controlling nanopore transport characteristics is one important application of surface modification which is very relevant given the significant interest in sensors based on the transport of ions and molecules through nanopores. Reported here is a method to change the surface charge polarity of single track-etched conical nanopores in polyimide, which also has the potential to attach more complex molecules to the carboxyl groups on the nanopore walls. These carboxyl groups were converted into terminal amino groups, first by activation with N-(3-dimethylaminopropyl)-N-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) followed by the covalent coupling of ethylenediamine. This results in a changed surface charge polarity. Regeneration of a carboxyl-terminated surface was also possible, by reaction of the amino groups with succinic anhydride. The success of these reactions was confirmed by measurements of the pore's pH sensitive current-voltage (I-V) characteristics before and after the chemical modification, which depend on surface charge. The permselectivity of the pores also changed accordingly with the modification.
纳米孔表面的化学修饰备受关注，因为这意味着表面组成不再由基底材料的选择来固定，甚至可以将大生物分子附着到孔壁上。控制纳米孔传输特性是表面修饰的一个重要应用，鉴于对基于离子和分子通过纳米孔传输的传感器有极大兴趣，这一应用非常相关。本文报道了一种改变聚酰亚胺中单个径迹蚀刻锥形纳米孔表面电荷极性的方法，该方法还有可能将更复杂的分子附着到纳米孔壁上的羧基上。这些羧基首先通过用N-(3-二甲基氨基丙基)-N-乙基碳二亚胺（EDC）和N-羟基琥珀酰亚胺（NHS）活化，然后通过乙二胺的共价偶联转化为末端氨基。这导致表面电荷极性发生变化。通过使氨基与琥珀酸酐反应，也可以使羧基末端表面再生。化学修饰前后对孔的pH敏感电流-电压（I-V）特性进行测量，证实了这些反应的成功，该特性取决于表面电荷。孔的渗透选择性也随修饰而相应改变。
