免疫反应诱导的电活性MOFs界面“离子屏障效应”及其免标记电化学生物传感应用

Electrode interface solvation and electric double-layer induced “ion-barrier effect” (IBE) in combination with bioreaction can be utilized for the construction of label-free electrochemical biosensors, which presents the advantages of low background interference and without need of signal molecule labeling. But this type of biosensor still has some drawbacks such as low sensitivity caused by the limited electroactive site, few application in biosensing and seldom discussion in mechanism. Against this background, a new electrochemical sensing strategy for cardiac biomarkers is planned to be established based on the combining of in-situ modification electroactive MOFs on electrode and the immune reaction induced IBE. The main research concepts include: (1) Using different approaches such as (electro-)deposition and layer-layer coordination assembly to the in-situ fabricate MOFs modified electrode surface and then use it as the antibody probe immobilization layer, from which the rich electroactive site in the MOFs will greatly enhance the signal output as well as the analytical sensitivity; (2) The immuno reaction induced IBE of MOFs matrix is ingeniously used for electrochemical immunosensor, from which the type of non-label IBE-based electrochemical biosensor is enriched and its application is broadened.(3) Discuss working principle of immuno bioreaction caused solvation and electric double-layer effect, and further elucidate the working principle of IBE-based biosensor.

将电极界面溶剂化和双电层作用引起的“离子屏障效应”(IBE)与生物反应相结合可用于构建免标记型电化学生物传感器，其具有背景干扰小、无需信号分子标记等优点，但目前该类传感器还存在电活性位点有限、传感应用不广泛、机理探讨不够深入等问题。基于此，本项目拟以心脏标志物为靶标模型，将免疫反应诱导IBE与MOFs现场制备技术相结合，构建一类新型的免标记免疫电化学传感器。主要研究思路包括：(1)采用(电)化学沉积、层层配位组装等方式现场制备MOFs修饰电极，并利用MOFs丰富的电活性位点提高传感器的信号输出强度及分析灵敏度；(2)巧妙利用免疫反应诱导的MOFs基底层IBE，丰富IBE基免标记电化学传感器类型并拓展其应用领域；(3)探讨免疫生物反应引起的电极界面溶剂化和双电层作用机理，进一步阐释IBE基传感器工作原理。

本项目通过设计和筛选合适的金属离子(Fe3+、Cu2+、Zr2+等)和桥联配体对苯二甲酸(H2BDC)，2,5-二羟基对苯二甲酸(DHTPA)、单宁酸(TA)等，采用共价耦合、电化学沉积法、金属离子溶出结合化学沉积等方法在基底电极表面组装了电活性的MIL-101(Fe)、Cu-MOF-74、 Cu-TA和UiO-66等MOFs材料。采用SEM、AFM、FTIR、Raman、XPS等现代测试技术对合成的MOFs材料进行了形貌、组成、结构等表征。将构建的传感界面与生物免疫反应相结合构建了一系列新型的免标记型电化学传感器，将传感器与目标分子进行特异性反应，得到抗原-抗体结合层，从引起电化学活性修饰层 “电子转移扰动”，使输出的电化学信号规律性变化。基于所合成的MOFs良好的电化学活性、大的比表面积、特殊的孔结构等特征，所构建的电化学传感器可用于心脏损伤指示蛋白（肌钙蛋白，cTnI）的快速、灵敏、准确免标记检测。将免疫传感元件肌钙蛋白抗体替换为核酸或核酸适配体探针，该传感界面可同样用于生物毒素赭曲霉毒素A（OTA）、肝癌特异标志物miRNA-122等目标物的免标记传感检测，表明该传感策略具有良好的通用性。. 在本项目基金资助下，课题负责人以第一作者或通讯作者发表论文9篇，其中Analytical Chemistry 1篇，Biosensors and Bioelectronics 1篇，Chinese Chemical Letters 2篇，以第一发明人获得授权发明专利2项，参加学术会议2次。指导或协助指导硕士研究生7人，其中2020年毕业（协助指导）1人，2021年毕业2人，在校生4人）。

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