A novel electrochemical immunosensor was developed for label-free detection of carcinoembryonic antigen (CEA) as a cancer biomarker. The designed immunosensor was based on CEA antibody (anti-CEA) anchored with core shell Fe3O4@Au nanoparticles which were immobilized on a screen-printed carbon electrode modified with manganese dioxide decorating on graphene nanoplatelets (SPCE/GNP-MnO2/Fe3O4@Au-antiCEA). The SPCE was placed onto a home-made electrode holder for easy handling. The approach was based on direct binding of CEA to a fixed amount of anti-CEA on the modified electrode for the specific detection using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) monitored in a solution containing 5 mM [Fe(CN)63-/4-] prepared in 0.1 M phosphate buffer at pH 7.4. The difference in signal response owing to the redox reaction of [Fe(CN)6]3-/4- before and after interaction with CEA was regarded as the immunosensor response corresponding directly to the CEA concentration. Under optimized conditions, the linear range of 0.001-100 ng/mL, and the detection limits of 0.10 pg/mL (LSV) and 0.30 pg/mL (EIS) were evaluated. The applicability of the immunosensor was verified by well-corresponding determination of CEA in diluted human serum samples by electrochemiluminescence (ECL) immunoassay. Therefore, the proposed immunosensor could be suitable enough for a real sample analysis of CEA.

中文翻译：

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基于二氧化锰-石墨烯纳米片和核壳Fe3O4 @ Au纳米粒子的超灵敏免疫传感器，用于无标记的癌胚抗原检测。

开发了一种新型的电化学免疫传感器，用于无标记地检测癌胚抗原（CEA）作为癌症的生物标志物。设计的免疫传感器基于CEA抗体（抗CEA），该抗体锚固在核壳Fe3O4 @ Au纳米颗粒上，该纳米颗粒被固定在用二氧化锰修饰的丝网印刷碳电极上，修饰在石墨烯纳米血小板上（SPCE / GNP-MnO2 / Fe3O4 @ Au- antiCEA）。将SPCE放置在自制的电极支架上，以便于操作。该方法基于修饰电极上CEA与固定量抗CEA的直接结合，用于使用线性扫描伏安法（LSV）和电化学阻抗谱（EIS）在含5 mM [Fe（CN在pH 7.4的0.1 M磷酸盐缓冲液中制备的[63- [4-]]。与CEA相互作用之前和之后，由于[Fe（CN）6] 3- / 4-的氧化还原反应导致的信号响应差异被视为直接对应于CEA浓度的免疫传感器响应。在优化的条件下，评估的线性范围为0.001-100 ng / mL，检出限为0.10 pg / mL（LSV）和0.30 pg / mL（EIS）。通过电化学发光（ECL）免疫测定法很好地确定了稀释的人血清样品中的CEA，从而验证了免疫传感器的适用性。因此，提出的免疫传感器可能足够适合于CEA的真实样品分析。检出限分别为0.10 pg / mL（LSV）和0.30 pg / mL（EIS）。通过电化学发光（ECL）免疫测定法很好地确定了稀释的人血清样品中的CEA，从而验证了免疫传感器的适用性。因此，提出的免疫传感器可能足够适合于CEA的真实样品分析。检出限分别为0.10 pg / mL（LSV）和0.30 pg / mL（EIS）。通过电化学发光（ECL）免疫测定法很好地确定了稀释的人血清样品中的CEA，从而验证了免疫传感器的适用性。因此，提出的免疫传感器可能足够适合于CEA的真实样品分析。