An ultrasensitive sandwich-type electrochemical immunosensor was developed for quantitative monitoring of Alpha fetoprotein (AFP). To achieve this objective, an incorporated signal amplification strategy of platinum nanoparticles anchored on cobalt oxide/graphene nanosheets (Pt NPs/Co3O4/graphene) was proposed by acting as the label of secondary antibodies. The prepared label not only empowered by advantages of each component but exhibited better electrochemical performance than single Pt NPs, Co3O4 and graphene, which has shown large specific surface area and good catalytic activity towards the reduction of H2O2. Meanwhile, the nanocomposite of gold nanoparticles adhered on 3-mercaptopropyltriethoxysilane functionalized graphene sheets (Au@MPTES-GS) was used as matrix to accelerate electron transfer and immobilize primary antibodies in this system. The signal amplification mechanism of the matrix and the label were explored successfully. Under optimal conditions, the electrochemical immunosensor exhibited a wide linear range from 0.1 pg mL-1 to 60 ng mL-1 with a low detection limit of 0.029 pg mL-1for AFP. The proposed immunosensor may have promising application in the clinical diagnosis of AFP and other tumor markers.

中文翻译：

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基于固定在氧化钴/石墨烯纳米片上的铂纳米颗粒用于信号放大的用于甲胎蛋白检测的超灵敏电化学免疫传感器

开发了一种超灵敏夹心型电化学免疫传感器，用于定量监测甲胎蛋白 (AFP)。为了实现这一目标，通过充当二抗的标记，提出了锚定在氧化钴/石墨烯纳米片（Pt NPs/Co3O4/石墨烯）上的铂纳米颗粒的结合信号放大策略。所制备的标签不仅具有各组分的优势，而且表现出比单一 Pt NPs、Co3O4 和石墨烯更好的电化学性能，表现出较大的比表面积和良好的还原 H2O2 的催化活性。同时，粘附在 3-巯基丙基三乙氧基硅烷功能化石墨烯片 (Au@MPTES-GS) 上的金纳米颗粒的纳米复合材料用作基质以加速电子转移并在该系统中固定一抗。成功探索了基质和标记物的信号放大机制。在最佳条件下，电化学免疫传感器表现出从 0.1 pg mL-1 到 60 ng mL-1 的宽线性范围，对 AFP 的检测限低至 0.029 pg mL-1。所提出的免疫传感器可能在 AFP 和其他肿瘤标志物的临床诊断中具有广阔的应用前景。AFP 为 029 pg mL-1。所提出的免疫传感器可能在 AFP 和其他肿瘤标志物的临床诊断中具有广阔的应用前景。AFP 为 029 pg mL-1。所提出的免疫传感器可能在 AFP 和其他肿瘤标志物的临床诊断中具有广阔的应用前景。