National Nano Device Laboratories, National Applied Research Laboratories, Tainan, Taiwan, ROC.
Analyst. 2013 Aug 21;138(16):4656-62. doi: 10.1039/c3an00190c.
Fluorescent labelling and chromogenic reactions that are commonly used in conventional immunoassays typically utilize diffusion dominated transport of analytes, which is limited by slow reaction rates and long detection times. By integrating alternating current (AC) electrokinetics and electrochemical impedance spectroscopy (EIS), we construct an immunochip for rapid, sensitive, and label-free detection. AC electroosmosis (ACEO) and positive dielectrophoresis (DEP), induced by a biased AC electric field, can rapidly convect and trap the analyte onto an EIS working electrode within a few minutes. This allows the change of electron-transfer resistance (ΔRet) caused by the antibody-antigen (IgG-protein A) binding to be measured and quantified in real time. The measured impedance change achieves a plateau after electrokinetic concentration for only 90 s, and the detection limit is able to reach 200 pg ml⁻¹. Compared to the conventional incubation method, the electrokinetics-enhanced method is approximately 100 times faster in its reaction time, and the detection limit is reduced by 30 times. The ΔRet of the positive response is two orders of magnitude higher than the negative control, demonstrating excellent specificity for practical applications.
荧光标记和显色反应通常用于传统免疫分析中，这些方法利用的是扩散主导的分析物传输，其传输速度受到缓慢的反应速率和较长的检测时间的限制。通过整合交流（AC）电泳和电化学阻抗谱（EIS），我们构建了一种用于快速、灵敏、无标记检测的免疫芯片。受偏置交流电场的影响，AC 电渗流（ACEO）和正介电泳（DEP）可以在几分钟内快速将分析物对流并捕获到 EIS 工作电极上。这使得可以实时测量和定量抗体-抗原（IgG-蛋白 A）结合引起的电子转移电阻（ΔRet）变化。在仅 90 s 的电泳浓缩后，测量的阻抗变化达到平台，检测限可达 200 pg ml⁻¹。与传统的孵育方法相比，动力学增强方法的反应时间快约 100 倍，检测限降低了 30 倍。阳性反应的 ΔRet 比阴性对照高两个数量级，表明其在实际应用中具有出色的特异性。
