Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Anal Chem. 2010 Apr 1;82(7):2989-95. doi: 10.1021/ac100036p.
A novel electrochemical immunosensor for sensitive detection of cancer biomarker alpha-fetoprotein (AFP) is described that uses a graphene sheet sensor platform and functionalized carbon nanospheres (CNSs) labeled with horseradish peroxidase-secondary antibodies (HRP-Ab2). Greatly enhanced sensitivity for the cancer biomarker is based on a dual signal amplification strategy: first, the synthesized CNSs yielded a homogeneous and narrow size distribution, which allowed several binding events of HRP-Ab2 on each nanosphere. Enhanced sensitivity was achieved by introducing the multibioconjugates of HRP-Ab2-CNSs onto the electrode surface through "sandwich" immunoreactions. Second, functionalized graphene sheets used for the biosensor platform increased the surface area to capture a large amount of primary antibodies (Ab1), thus amplifying the detection response. On the basis of the dual signal amplification strategy of graphene sheets and the multienzyme labeling, the developed immunosensor showed a 7-fold increase in detection signal compared to the immunosensor without graphene modification and CNSs labeling. The proposed method could respond to 0.02 ng mL(-1) AFP with a linear calibration range from 0.05 to 6 ng mL(-1). This amplification strategy is a promising platform for clinical screening of cancer biomarkers and point-of-care diagnostics.
一种新型电化学免疫传感器，用于灵敏检测癌症生物标志物甲胎蛋白（AFP），使用石墨烯片传感器平台和功能化的碳纳米球（CNSs）标记辣根过氧化物酶-二抗（HRP-Ab2）。该癌症生物标志物的灵敏度大大提高基于双重信号放大策略：首先，合成的 CNSs 产生均匀且窄的尺寸分布，允许 HRP-Ab2 在每个纳米球上发生多个结合事件。通过“三明治”免疫反应将 HRP-Ab2-CNSs 的多生物结合物引入电极表面，从而实现了增强的灵敏度。其次，用于生物传感器平台的功能化石墨烯片增加了表面积，以捕获大量的一抗（Ab1），从而放大了检测响应。基于石墨烯片和多酶标记的双重信号放大策略，与没有石墨烯修饰和 CNSs 标记的免疫传感器相比，所开发的免疫传感器的检测信号增加了 7 倍。该方法可以对 0.02ng mL（-1）的 AFP 做出响应，线性校准范围从 0.05 到 6ng mL（-1）。该放大策略为癌症生物标志物的临床筛选和即时诊断提供了一个有前途的平台。
