We report the electrochemical detection of 20 nm silver nanoparticles at a chip-based microelectrode array (MEA) without the need for a conventional reference electrode. This is possible due to the system’s open-circuit potential allowing the oxidation of silver nanoparticles in the presence of phosphate-buffered saline (PBS). The hypothesis is confirmed by modulating the open-circuit potential via addition of ascorbic acid in solution, effectively inhibiting the detection of silver nanoparticle events. Employing the reference-free detection concept, we observe a linear relationship between the nanoparticle impact frequency at the microelectrodes and the nanoparticle concentration. This allows for viable quantification of silver nanoparticle concentrations in situ. The presented concept is ideal for the development of simple lab-on-a-chip or point-of-use systems enabling fast and low-cost screening of nanoparticles.

中文翻译：

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无参比电极的银纳米颗粒的片内随机检测

我们报告了在基于芯片的微电极阵列（MEA）上对20 nm银纳米颗粒的电化学检测，而无需常规参考电极。由于系统的开路电势允许存在磷酸盐缓冲液（PBS）的情况下氧化银纳米颗粒，因此这是可能的。通过在溶液中添加抗坏血酸来调节开路电位，从而有效地抑制了对银纳米粒子事件的检测，从而证实了这一假设。采用无参考检测的概念，我们观察到纳米粒子在微电极上的撞击频率与纳米粒子浓度之间的线性关系。这使得银纳米粒子的浓度可行的量化原位。提出的概念非常适合开发简单的单芯片实验室或使用点系统，从而可以快速，低成本地筛选纳米颗粒。