Electrokinetic principles such as streaming current and streaming potential are extensively used for surface characterization. Recently, they have also been used in biosensors, resulting in enhanced sensitivity and simpler device architecture. Theoretical models regarding streaming current/potential studies of particle-covered surfaces have identified features such as the particle size, shape and surface charge to influence the electrokinetic signals and consequently, the sensitivity and effective operational regime of the biosensor. By using a set of well-characterized proteins with varying size and net surface charge, this article experimentally verifies the theoretical predictions about their influence on the sensor signal. Increasing protein size was shown to enhance the signal when their net surface charge was either opposite to that of the sensor surface, or close to zero, in agreement with the theoretical predictions. However, the effect gradually saturated as the protein size exceeded the coulomb screening length of the electrolyte. In contrast, the proteins containing the same type of charge as the surface showed little or no difference, except that the signal inverted. The magnitude of the surface charge was also shown to influence the signal. The sensitivity of the technique for protein detection varied over two orders of magnitude, depending upon the size and surface charge. Furthermore, the capacity of the electrokinetic method for direct electrical detection of various proteins, including those carrying little or no net electric charges, is demonstrated.

中文翻译：

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分子大小和Zeta电位对电动生物传感的影响。

诸如流动电流和流动电位之类的电动原理被广泛用于表面表征。最近，它们也已用于生物传感器，从而提高了灵敏度并简化了设备架构。关于流过电流/对被颗粒覆盖的表面进行电势研究的理论模型已经确定了诸如粒径，形状和表面电荷之类的特征，这些特征会影响电动信号，从而影响生物传感器的灵敏度和有效的操作方式。通过使用一组大小各异且表面净电荷各不相同的蛋白质，本文通过实验验证了有关它们对传感器信号影响的理论预测。与理论预测一致，当蛋白质的净表面电荷与传感器表面的净电荷相反或接近零时，增加蛋白质大小可增强信号。但是，随着蛋白质大小超过电解质的库仑筛选长度，其效果逐渐饱和。相反，与表面含有相同电荷类型的蛋白质几乎没有差异，只有信号相反。还显示了表面电荷的大小会影响信号。蛋白质检测技术的灵敏度在两个数量级上变化，这取决于大小和表面电荷。此外，证明了用于直接电检测各种蛋白质的电动方法的能力，包括几乎不携带或不携带净电荷的蛋白质。