The magnetic-bead-based electrochemical enzyme-linked immunoassay (MB-eElisa) represents an attractive approach to develop cost-effective systems that are suitable for sensing complex biological samples. Its sensitivity essentially depends on the transduction efficiency of enzyme catalytic reactions into electrochemical responses. Here, an ultrahigh signal-to-noise alkaline phosphatase (ALP)-based MB-eElisa system is developed with a renewable zinc oxide-reduced graphene oxide composite modified carbon paste electrode (ZnO@rGO/CPE). This biosensing system employs one antibody decorated MB (MB-Ab₁) to capture a model tumor marker—carcinoembryonic antigen (CEA)—from samples, while other antibody coated gold nanoparticles-ALP bioconjugates (Ab₂-AuNPs-ALP) convert 1-naphthyl phosphate (1-NPP) into electroactive 1-naphthol (1-NP). Benefitting from the unique electrochemical properties of a ZnO@rGO/CPE, including nearly zero background and significantly enhanced responses toward the hydrolyzed 1-NP in the presence of trace surfactants, the MB-eElisa system detects selectively CEA in a calibration range of 0.01–6.0 ng mL^–1 and with a detection limit of 4.0 pg mL^–1 (S/N = 3). Such a system was further applied to the detection of CEA in serum samples of cancer patients. The combination of MB-based ALP-linked immunoassay with a ZnO@rGO/CPE thus establishes a reusable and inexpensive electrochemical sensing platform for the rapid and sensitive detection of ultratrace biomarkers in complex biological samples.

中文翻译：

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碱性磷酸酶标记的磁珠修饰的ZnO @还原氧化石墨烯检测肿瘤标志物

基于磁珠的电化学酶联免疫测定（MB-eElisa）代表了一种有吸引力的方法，可开发出适用于感测复杂生物样品的经济高效的系统。它的敏感性主要取决于酶催化反应转化为电化学反应的效率。在这里，使用可再生氧化锌还原的氧化石墨烯复合改性碳糊电极（ZnO @ rGO / CPE）开发了基于超高信噪比的碱性磷酸酶（ALP）的MB-eElisa系统。该生物传感系统采用一种抗体修饰的MB（MB-Ab ₁）从样品中捕获模型肿瘤标记物-癌胚抗原（CEA），而另一种抗体包被的金纳米颗粒-ALP生物缀合物（Ab ₂-AuNPs-ALP）将1-萘磷酸酯（1-NPP）转化为电活性1-萘酚（1-NP）。得益于ZnO @ rGO / CPE的独特电化学性能，包括几乎零的本底和在存在痕量表面活性剂的情况下对水解的1-NP的显着增强的响应，MB-eElisa系统选择性地在0.01- 6.0 ng mL ^–1，检出限为4.0 pg mL ^–1（S / N = 3）。将该系统进一步应用于检测癌症患者血清样品中的CEA。因此，基于MB的ALP链接免疫测定与ZnO @ rGO / CPE的结合为快速，灵敏地检测复杂生物样品中的超痕量生物标志物建立了可重复使用且便宜的电化学传感平台。