DataSheet_1_A sandwich-like configuration with a signal amplification strategy using a methylene blue/aptamer complex on a heterojunction 2D MoSe2/2D WSe2 electrode: Toward a portable and sensitive electrochemical alpha-fetoprotein immunoassay.docx

Liver cancer is one of the most common global health problems that features a high mortality rate. Alpha-fetoprotein (AFP) is a potential liver cancer biomarker for the diagnosis of liver cancer. The quantitative detection of AFP at an ultratrace level has important medical significance. Using the reaction of the antibody–antigen pair in an immunosensor enables the sensitive and selective AFP assay. Finding a strategy in signal generation and amplification is challenging to fabricate new sensitive electrochemical immunosensors for AFP detection. This study demonstrates the construction of a simple, reliable, and label-free immunosensor for the detection of AFP on a smart phone. Exfoliated two-dimensional (2D) molybdenum diselenide (MoSe2) and 2D tungsten diselenide (WSe2) were employed to modify the disposable screen-printed carbon electrode (SPCE) to use as the electrochemical platform, which is affixed to a small potentiostat connected to a smart phone. The modified electrode offers antibody immobilization and allows detection of AFP via an immunocomplex forming a sandwich-like configuration with the AFP-corresponding aptamer. A heterojunction 2D MoSe2/2D WSe2 composite improves the SPCE’s reactivity and provides a large surface area and good adsorption capacity for the immobilizing antibodies. The signal generation for the immunosensor is from the electrochemical response of methylene blue (MB) intercalating into the aptamer bound on the electrode. The response for the proposed sandwich-like immunosensor is proportional to the AFP concentration (1.0–50,000 pg ml-1). The biosensor has potential for the development of a simple and robust point-of-care diagnostic platform for the clinical diagnosis of liver cancer, achieving a low limit of detection (0.85 pg ml-1), high sensitivity, high selectivity, good stability, and excellent reproducibility.

肝癌是全球最常见的公共健康问题之一，其致死率居高不下。甲胎蛋白（Alpha-fetoprotein，AFP）是用于肝癌诊断的潜在生物标志物，对超痕量水平的AFP进行定量检测具有重要医学价值。利用免疫传感器中抗原-抗体对的反应可实现灵敏且具有选择性的AFP检测，但开发用于信号生成与放大的策略，以制备新型高灵敏度电化学免疫传感器用于AFP检测，仍颇具挑战。本研究构建了一款可依托智能手机实现AFP检测的简单、可靠且无标记型免疫传感器。将剥离制备的二维二硒化钼（exfoliated two-dimensional molybdenum diselenide，MoSe₂）与二维二硒化钨（2D tungsten diselenide，WSe₂）用于修饰一次性丝网印刷碳电极（disposable screen-printed carbon electrode，SPCE），以此作为电化学传感平台，并将其连接至配套小型恒电位仪，进而与智能手机对接。该修饰电极可实现抗体固定，并通过与AFP对应适配体结合形成类三明治构型的免疫复合物，完成AFP检测。二维MoSe₂/二维WSe₂异质结复合材料可提升SPCE的反应活性，同时提供较大比表面积与良好吸附能力，用于固定抗体。该免疫传感器的信号生成源于亚甲基蓝（methylene blue，MB）嵌入电极表面结合的适配体所产生的电化学响应。所提出的类三明治型免疫传感器的响应信号与AFP浓度（1.0~50000 pg·ml⁻¹）呈正相关。该生物传感器有望开发为一款简便耐用的即时诊断（point-of-care，POC）平台，用于肝癌的临床诊断，其检出限低至0.85 pg·ml⁻¹，同时具备高灵敏度、高选择性、良好稳定性与优异重现性。