Department of Electrical Engineering, Columbia University, New York, New York 10027, United States.
Nano Lett. 2011 Sep 14;11(9):3739-43. doi: 10.1021/nl201781q. Epub 2011 Aug 1.
Point-functionalized carbon nanotube field-effect transistors can serve as highly sensitive detectors for biomolecules. With a probe molecule covalently bound to a defect in the nanotube sidewall, two-level random telegraph noise (RTN) in the conductance of the device is observed as a result of a charged target biomolecule binding and unbinding at the defect site. Charge in proximity to the defect modulates the potential (and transmission) of the conductance-limiting barrier created by the defect. In this Letter, we study how these single-molecule electronic sensors are affected by ionic screening. Both charge in proximity to the defect site and buffer concentration are found to affect RTN amplitude in a manner that follows from simple Debye length considerations. RTN amplitude is also dependent on the potential of the electrolyte gate as applied to the reference electrode; at high enough gate potentials, the target DNA is completely repelled and RTN is suppressed.
功能化点碳纳米管场效应晶体管可作为生物分子的高灵敏度探测器。当探针分子通过共价键与纳米管侧壁的缺陷结合时，在器件的电导中观察到双能级随机电报噪声（RTN），这是由于带电靶生物分子在缺陷处结合和脱附引起的。靠近缺陷的电荷调制由缺陷产生的电导限制势垒的势（和传输）。在这封信中，我们研究了这些单分子电子传感器如何受到离子屏蔽的影响。靠近缺陷位点的电荷和缓冲浓度都以符合简单德拜长度考虑的方式影响 RTN 幅度。RTN 幅度还取决于施加到参考电极的电解质门的电势；在足够高的门电势下，靶 DNA 完全被排斥，RTN 被抑制。
