壳聚糖电沉积法构筑基于三维大孔石墨烯电极的电化学传感新体系

Electrode material and architecture play critical roles in bioanalysis for simple, sensitive and stable detection. Three dimensional (3D) macroscopic electrodes are highly desirable since they can improve the performance of electrochemical biosensors. Therefore，development of novel electrochemical biosensing platform based on 3D macroscopic electrodes is of great significance. Monolithic and macroscopic graphene foam grown by chemical vapor deposition (CVD) could serve as the electrode scaffold. Compared with the conventional 2D (planar) electrochemical electrodes, such 3D macroscopic graphene electrodes are attractive for the construction of biosensors due to the unique advantages of macroscopic scaffold, large active surface area, unhindered substance diffusion, high conductivity and stability. More importantly, 3D graphene electrodes provide potential for cheap and large-scale preparation with high reproducibility. However, the surface of 3D macroscopic graphene is highly hydrophobic and has no functional group. The modification of 3D macroscopic graphene using biofunctinal substrates is the key to expand its application in bioanalysis. As a biocompatible polymer, chitosan (CS) remains a focus of study in recent years due to its hydrophilicity, excellent film-forming ability and remarkable biocompatibility. Electrochemical deposition has been reported recently as a simple method to obtain film with controllable thickness under moderate conditions. Biocomposite film could be conveniently prepared by effective incorporation of functional substrates in electrodeposition solution. The project will give metholodoly for the development of novel electrochemical bioassay platform on 3D macroscopic graphene electrodes using CS deposition as a simple and universal way. The unique characteristics of both 3D macroscopic graphene and chitosan are combined. Three type of biosensing platforms inculding enzyme biosensor, aptamer biosensor and immunosensor will be fabricated and used for sensitive detection of glucose, thrombin, cancer cells and tumor biomarker, respectively. Brief research is given as follow. Enzyme will be immobilized on 3D macroscopic graphene electrodes through entrappment in one-step CS electrodeposition. Direct electrochemistry and electrocatalysis will be achieved. Using ferrocene grafted CS, biocomposite film containing immobilized redox mediator will be prepared. Using electrostatic or Au-SH assembly, two probe aptamers will be immobilized for sensitive detection of thrombin and selective detection of tumor cells. By modification of amino groups of CS, antibody coulb be covalently immobilized to develop immunoelectrode and the model tumor biomarker-carcinoembryonic antigen could be determinated. The project will provide new starategy for the application of 3D macroscopic graphene in bioanalysis.

利用三维大孔石墨烯(3D-G)电极有效构建生物传感新体系具有重要理论意义和实际应用价值。本项目拟利用壳聚糖(CS)电沉积法构建基于3D-G电极的电化学传感新体系。利用化学气相沉积法生长的3D-G材料，制备3D-G基底碳电极；将其高比表面积、优越的电子传导性能与CS的生物相容性、易衍生化特性相结合；以CS电沉积法为普适方法，可控制备多功能性CS复合膜修饰三维大孔电极，实现三类传感分析新体系(第三代酶传感器、适配子传感器、免疫传感器)的有效制备和高灵敏电化学检测。具体为：3D-G电极上一步电沉积含酶复合膜，实现酶的直接电化学和电催化；利用二茂铁接枝CS，电沉积含电化学探针的复合膜，通过组装法固载相关适配子，实现对凝血酶的高灵敏检测及人宫颈癌细胞的选择性检测；对CS的氨基衍生化后共价固定抗体，实现对肿瘤标志物癌胚抗原的免疫检测。项目可为三维石墨烯大孔电极在生物电化学领域的应用提供新思路。

项目开展了基于三维大孔石墨烯(3D-G)电极构建电化学生物传感新体系的研究。具体研究工作为：利用一步壳聚糖电沉积对3D-G进行改性，在其表面通过沉积壳聚糖膜同步固载葡萄糖氧化酶及导电增强材料单壁碳管，构筑酶传感界面，制备了高灵敏的三维酶电化学传感器，可实现实际生物样品中葡萄糖的灵敏检测；研究了三维免疫传感界面的构筑方法，通过聚多巴胺衍生化法对3D-G进行修饰，引入二次反应活性，共价固定植物凝集素ConA，以ConA与糖蛋白辣根过氧化物酶HRP间的亲和作用为驱动力，定向固定HRP标记的癌胚抗原抗体，构建了三维电化学免疫传感器，实现了实际生物样品中肿瘤标志物癌胚抗原的灵敏电化学检测；采用自组装结合聚多巴胺修饰法功能化3D-G开发了三维酶电化学传感界面的构筑方法。3D-G电极表面自组装修饰碳管-亚甲基蓝复合物，进一步修饰聚多巴胺覆盖层稳定电子介体并引入二次反应活性共价固定HRP，实现酶与电子介体在3D-G电极上的共固定化，构建了无试剂三维电化学传感器，可用于过氧化氢的无试剂高灵敏检测；项目还研究了电沉积结合聚多巴胺修饰法在3D-G电极固载功能性金纳米粒子构建非酶电化学传感器。这些传感器的成功制备为开发三维石墨烯材料发展新型三维电化学传感体系提供了新思路。