An immunosensor for label-free electrochemical detection of MiniChromosome Maintenance Protein 5, MCM5, a protein overexpressed in cervical cancer, based on a gold electrode is reported. The electrode was first modified with a submonolayer (capture layer) of 11-mercaptoundecanoic acid (11-MUA) and then activated with N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to immobilize the capture antibody. The change in electrode surface properties (wettability) during the formation of the 11-MUA layers was determined using the static water contact angle (WCA). The binding of MCM5 antigens to the capture antibody was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using 5 mM [Fe(CN)⁶]^3−/4− in 0.1 M LiClO₄(aq) as an electroactive probe. AC Impedance was used to measure charge transfer resistance (R_ct), which reflects impeded electron transfer when the antigen is bound to the antibody functionalized surface. After exposing the antibody-functionalized surface to MCM5 antigens, R_ct increases linearly with the logarithmic value of MCM5 antigen concentration, with a linear dynamic range of 10⁻⁶ to 10⁻¹¹ g/mL, a correlation coefficient of 0.99, and a detection limit of 2.9 pM (10⁻¹¹ g/mL). This excellent sensitivity was achieved with simple preparation steps and minimal reagent consumption, without the need for complicated procedures such as enzymatic amplification, fluorescent labeling, or nanoparticle modification.

报道了一种基于金电极的免疫传感器，用于无标记电化学检测 MiniChromosome Maintenance Protein 5，MCM5，一种在宫颈癌中过表达的蛋白质。电极首先用 11-巯基十一烷酸 (11-MUA) 的亚单层（捕获层）改性，然后用N- (3-二甲基氨基丙基) -N-乙基碳二亚胺盐酸盐 (EDC) 和N-羟基琥珀酰亚胺 (NHS) 用于固定捕获抗体。使用静态水接触角 (WCA) 确定 11-MUA 层形成期间电极表面性质（润湿性）的变化。^{使用 5 mM [Fe(CN) 6} ] ^3-/4-在 0.1 M LiClO ₄ (aq) 作为电活性物质，通过循环伏安法 (CV) 和电化学阻抗谱 (EIS) 监测 MCM5 抗原与捕获抗体的结合探测。交流阻抗用于测量电荷转移电阻 (R _ct )，它反映了当抗原与抗体功能化表面结合时受阻的电子转移。将抗体功能化表面暴露于 MCM5 抗原后，R _ct随MCM5抗原浓度的对数值呈线性增加，线性动态范围为10 ^-6至10 ^-11  g/mL，相关系数为0.99，检测限为2.9 pM（10 ^-11  g/mL）。这种出色的灵敏度是通过简单的制备步骤和最少的试剂消耗实现的，无需复杂的程序，如酶促扩增、荧光标记或纳米粒子修饰。