采用Fe3O4(核)/ZrO2(壳)纳米磁珠(ZMPs)标记待测物识别抗体,并用HRP酶封闭和DNA链接,建立了一类新型的“珠链状”一维磁性纳米探针制备方法.将甲胎蛋白(AFP)一抗固定于纳米金修饰的玻碳电极表面,构建了免疫电极(GCE ｜ AFP Ab1).基于该电极和上述合成探针,通过双抗体夹心法测定免疫产物上HRP酶对过氧化脲(CP)氧化对苯二酚反应的催化电流,研制了一类基于一维纳米结构组装的夹心型安培免疫传感器.研究表明:此一维纳米结构探针不仅大大增加了酶在电极表面的富集量,成倍扩增了催化电流,显著提高了传感器的灵敏度,而且易于通过外磁场与背景液可控分离,简化了分析步骤,并提高了结果的重复性.此传感器对AFP检测的线性范围为0.01～25tg/L;检出限达4 ng/L(3σ),并被用于人血清中痕量AFP的测定,结果满意.%A new type of one-dimensional magnetic nanoprobes was fabricated based on a DNA chain fixed with a number of Fe3O4 (core)/ZrO2 (shell) nano-magnetic beads (ZMPs) labeled with secondary antibody. The a-fetoprotein (AFP) was analyzed by using probes DNA/(ZMPs-HRP-AFP Ab2)n and immobilizing a-fetoprotein antibody (AFP Ab,) onto the glassy carbon electrode modified by nano-gold. The sandwich-type immunocomplex could be formed between the immobilized AFP Abi on the GCE and the probes DNA/( ZMPs-HRP-AFP Ab2) n and the carried HRP could catalyze the electrochemical reduction of carbamide peroxide (CP) with the help of hydroquinone (HQ). The novel one-dimensional nano structure assemble and sandwich-type amperometric immunosensor was developed. Enhanced sensitivity was achieved by introducing more HRP-AFP Ab2 onto the electrode surface through the pearl chain structure. Under optimal conditions, the proposed method could respond to 4 ng/L AFP with a linear calibration range from 0.01 to 25 ug/L. The immunosensor was employed to determine AFP in serum samples and the results were satisfactory. The proposed amperometric immunosensor was sensitive, quick, magnetic field controllable. This study provided a platform technology for developing a one-dimensional assembly and highly sensitive immunosensor, which was suitable for screen determination of tumors in serums of normal patients.
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