Optimization of electrochemical aptamer-based sensors via optimization of probe packing density and surface chemistry.
Optimization of electrochemical aptamer-based sensors via optimization of probe packing density and surface chemistry.
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DOI：
10.1021/la800801v
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发表时间：
2008-09-16
期刊：
影响因子：
--
通讯作者：
Plaxco KW
中科院分区：
文献类型：
--
作者：
White RJ;Phares N;Lubin AA;Xiao Y;Plaxco KW
电化学适配体（E-AB）传感器是一种新型的生物传感器平台，它是由表面固定的氧化还原标记的DNA适配体修饰的电极组成。为了进一步改进该技术，我们系统地研究了探针（适体）填充密度、用于询问传感器的AC频率以及用于钝化电极的自组装单层（SAM）的性质对针对小分子可卡因和蛋白质凝血酶的代表性E-AB传感器的性能的影响。我们发现，通过控制在传感器制造过程中采用的适配体的浓度，我们可以控制在一个数量级的范围内的电极表面上的探针DNA分子的密度。在这个范围内，可卡因传感器的增益从60%到200%不等，最大增益观察到附近的最低探针密度。相比之下，在类似的范围内，凝血酶传感器的信号变化从16%到42%不等，并且在中间密度下观察到最佳信号传导。在低赫兹频率的截止值以上，两个传感器都没有显示出对它们的询问中所采用的交变电势的频率的任何显著依赖性。最后，我们发现E-AB信号增益对用于钝化询问电极的烷乙氧基SAM的性质敏感;而更薄的SAM导致更高的绝对传感器电流，将SAM的长度从6个碳减少到2个碳使我们的可卡因传感器的观察到的信号增益减少了10倍。我们证明，制造和操作参数可以变化，以实现最佳的传感器性能，这些可以作为未来传感器制造的基本轮廓。
Electrochemical, aptamer-based (E-AB) sensors, which are comprised of an electrode modified with surface immobilized, redox-tagged DNA aptamers, have emerged as a promising new biosensor platform. In order to further improve this technology we have systematically studied the effects of probe (aptamer) packing density, the AC frequency used to interrogate the sensor, and the nature of the self-assembled monolayer (SAM) used to passivate the electrode on the performance of representative E-AB sensors directed against the small molecule cocaine and the protein thrombin. We find that, by controlling the concentration of aptamer employed during sensor fabrication, we can control the density of probe DNA molecules on the electrode surface over an order of magnitude range. Over this range, the gain of the cocaine sensor varies from 60% to 200%, with maximum gain observed near the lowest probe densities. In contrast, over a similar range, the signal change of the thrombin sensor varies from 16% to 42% and optimal signaling is observed at intermediate densities. Above cut-offs at low hertz frequencies, neither sensor displays any significant dependence on the frequency of the alternating potential employed in their interrogation. Finally, we find that E-AB signal gain is sensitive to the nature of the alkanethiol SAM employed to passivate the interrogating electrode; while thinner SAMs lead to higher absolute sensor currents, reducing the length of the SAM from 6-carbons to 2-carbons reduces the observed signal gain of our cocaine sensor 10-fold. We demonstrate that fabrication and operational parameters can be varied to achieve optimal sensor performance and that these can serve as a basic outline for future sensor fabrication.
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