We report a dramatic improvement in the detection sensitivity of electrochemical immunosensors through the use of a magnetic nanoparticle for immunoassay reactions and an ITO working electrode for measurement of the electrochemical enzymatic reaction signals. In general, electrochemical sensors developed for immunoassay require the immobilization of capture antibodies on the surface of the working electrode. Under these circumstances, the working electrode comes into direct contact with various biological samples, and unwanted non-specific binding inevitably interferes with the detection signal. Moreover, chemical surface treatment of the working electrode to immobilize capture antibodies degrades the quality of the electrochemical signals during target determination. Here, we address these issues by immobilizing capture antibodies on the surface of magnetic nanoparticles and separating the surface for measurement of electrochemical signals from the immune reactions. By avoiding direct contact with biological materials, the surface of the working electrode could not be contaminated and could be maintained clean. We also provide experimental evidence that these novel immunoassay platforms benefit from a reduction in the noise signal. Indeed, the signal-to-noise ratio, an essential characteristic of quantitative detection, could be improved by approximately 11.8-fold compared with the electrochemical immunoassay of conventional surface modification approach, while retaining an excellent coefficient of variation (≤ 18%). The method was applied to the practical immunosensing for matrix met-alloproteinase-9 (MMP-9), the bladder cancer marker in the urine, and exhibited excellent performance.

我们报告了通过使用磁性纳米粒子进行免疫测定反应和使用ITO工作电极测量电化学酶反应信号，电化学免疫传感器的检测灵敏度有了显着提高。通常，为免疫测定而开发的电化学传感器需要将捕获抗体固定在工作电极的表面上。在这种情况下，工作电极直接与各种生物样品接触，并且不必要的非特异性结合不可避免地会干扰检测信号。而且，为了固定捕获抗体而对工作电极进行化学表面处理会降低目标确定过程中电化学信号的质量。这里，我们通过将捕获抗体固定在磁性纳米颗粒的表面上并将表面分开以测量来自免疫反应的电化学信号来解决这些问题。通过避免与生物材料直接接触，工作电极的表面不会被污染，并且可以保持清洁。我们还提供实验证据，这些新型免疫测定平台受益于噪音信号的减少。实际上，与常规表面修饰方法的电化学免疫测定相比，定量检测的基本特征信噪比可提高约11.8倍，同时保留出色的变异系数（≤18％）。该方法应用于基质金属蛋白酶9（MMP-9）的实际免疫检测，