Detection beyond the Debye Screening Length in a High-Frequency Nanoelectronic Biosensor
Detection beyond the Debye Screening Length in a High-Frequency Nanoelectronic Biosensor
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DOI：
10.1021/nl203666a
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发表时间：
2012-02-01
期刊：
影响因子：
10.8
通讯作者：
Zhong, Zhaohui
中科院分区：
文献类型：
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作者：
Kulkarni, Girish S.;Zhong, Zhaohui
基于纳米管和纳米线独特的电子特性的纳米传感器具有高灵敏度，并有可能彻底改变医疗诊断领域。直流（dc）检测的广泛阵列的有机和无机分子已经证明了这些设备。然而，基于测量直流电导变化的传感机制在高背景盐浓度下失效，其中器件的灵敏度受到溶液中存在的移动离子的离子筛选的影响。在这里，我们成功地证明了单壁碳纳米管场效应晶体管作为高频生物传感器可以减轻基本离子筛选效应。交流激励场与分子偶极子场之间的非线性混合可以产生对表面结合的生物分子敏感的混合电流。在超过1 MHz的频率下实现了100 mM缓冲溶液中单层链亲和素与生物素结合的电检测。理论模型证实，通过降低离子筛选效应，在高频下提高了灵敏度。该结果有望为POC检测提供一个新的生物传感平台，其中生物传感器可以直接在生理相关条件下起作用。
Nanosensors based on the unique electronic properties of nanotubes and nanowires offer high sensitivity and have the potential to revolutionize the field of Point-of-Care (POC) medical diagnosis. The direct current (dc) detection of a wide array of organic and inorganic molecules has been demonstrated on these devices. However, sensing mechanism based on measuring changes in dc conductance fails at high background salt concentrations, where the sensitivity of the devices suffers from the ionic screening due to mobile ions present in the solution. Here, we successfully demonstrate that the fundamental ionic screening effect can be mitigated by operating single-walled carbon nanotube field effect transistor as a high-frequency biosensor. The nonlinear mixing between the alternating current excitation field and the molecular dipole field can generate mixing current sensitive to the surface-bound biomolecules. Electrical detection of monolayer streptavidin binding to biotin in 100 mM buffer solution is achieved at a frequency beyond 1 MHz. Theoretical modeling confirms improved sensitivity at high frequency through mitigation of the ionic screening effect. The results should promise a new biosensing platform for POC detection, where biosensors functioning directly in physiologically relevant condition are desired.