【作者】 谢青；

【导师】 杨文胜；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2011， 博士

【摘要】 关于氧化还原蛋白质直接电化学的研究在环境科学、生命科学、能源科学和分析化学等领域引起越来越多科学家的关注。直接电化学的研究对于研究生物系统中各种酶之间电子相互传递以及开发新型的第三代电化学生物传感器具有重要的意义。纳米技术的发展为蛋白质直接电化学的研究提供了新思路，纳米材料所具有的比表面积大，催化活性高、特殊的物理化学性质在促进蛋白质直接电化学以及提高生物传感器性能方面有广阔的应用前景。本论文设计合成了不同维度的纳米材料，固定氧化还原蛋白质构造生物传感器，研究蛋白质的直接电化学性质及其催化特性，探索纳米材料形貌结构和传感器性能之间的内在联系。具体内容如下：1.以一维纳米材料（MnO₂纳米棒）-阳离子纤维素（QY）纳米复合材料为固定化载体固定肌红蛋白（Mb），利用X-射线衍射（XRD）和扫描电镜（SEM）对纳米棒的结构形貌进行表征，傅立叶红外光谱（FTIR）结果表明Mb在复合薄膜中保持了原有的天然结构，并实现了直接电子转移，电子转移速率ks为7.81s^-1。相对于Mb-MnO₂/GC电极和Mb-QY/GC电极，Mb-MnO₂-QY/GC电极构建的H₂O₂传感器表现出更优良的性能，线性范围是0.5-120μmol·L^-1，检测限为0.3μmol·L^-1，同时制备电极具有良好的稳定性，抗干扰性和重现性。2.以二维纳米材料——无机纳米片为组装基元，采用带相反电荷的TiO₂纳米片和Mb层层组装，制备了（Mb/TiO₂）_n多层复合生物敏感膜。利用电化学交流阻抗（EIS）和紫外吸收光谱（UV-Vis）检测了层层组装的过程。扫描电镜照片（SEM）和原子力显微镜（AFM）考察了薄膜的微观形貌。Mb在薄膜中实现了快速直接电子转移，该薄膜修饰电极对底物H₂O₂催化表现出较高的灵敏度0.616A·mol^-1·L·cm^-2。在MnO₂纳米片和Mb的基础上，加入聚合物Nafion，依然可以通过静电吸引力成功实现层层组装，制备（Mb/Nafion/Mb/MnO₂）_n多层复合薄膜，Mb在该薄膜中仍然实现了快速有效的直接电子转移。3.采用二维纳米材料石墨纳米片KS6和Nafion复合固定血红蛋白（Hb）。FTIR和UV-Vis结果表明Hb在复合材料中保持了原有的天然结构，Hb在KS6-Nafion薄膜中实现了快速的电子转移，Hb-KS6-Nafion修饰玻碳（GC）电极制备的NaNO₂传感器表现出较宽的检测范围8⁴60μmol·L^-1和460²300μmol·L^-1，优良的稳定性和抗干扰性。4.采用水热-焙烧的方法设计合成了一种基于纳米片的核壳中空三维结构TiO₂微球。利用XRD、SEM和透射电镜（TEM）对微球形貌进行表征并推测微球生长机理。通过低温氮吸附法（BET）、UV-Vis和电化学测试证明基于纳米片的核壳中空结构TiO₂微球有利于固定生物分子辣根过氧化物酶（HRP），利用其固定HRP构造的H₂O₂传感器表现出优良的性能，在拥有较低检测限0.05μmol·L^-1的同时，拥有较宽的检测范围0.4¹40μmol·L^-1。5.采用恒电流电沉积的方法一步合成了纳米片交叉的Co（OH）₂三维多孔薄膜，用于固定Hb修饰电极制备生物传感器。利用SEM表征了Co（OH）₂薄膜的形貌，通过UV-Vis光谱证明Hb在薄膜中保持了天然的结构，实现了快速的电子转移，电子转移速率Ks为8.34s^-1。基于Co（OH）₂三维多孔薄膜固定Hb制备的传感器对底物H₂O₂催化拥有的灵敏度为743.67μA mM^-1cm^-2，检测范围从0.4到200μmol·L^-1。更多还原

【Abstract】 Direct electrochemistry of redox proteins has attracted considerablerecent attention since it provides fundamental knowledge of redox behavior ofproteins or enzymes in a biological system and serves as a model system to aidin the understanding of electrontransfer mechanisms, and also provides afoundation for the construction of third-generation biosensors.Nanotechnology provides a new way to construct the third-generationbiosensor. Nanomaterials have unique optical, electrical and catalyticproperties and large surface area, good biocompatibility, which can greatlyenhance the direct electron transfer of proteins and promote the biosensorperformance. The object of this dissertation is to explore different dimernsionsnanomaterials for fabrication the third-generation biosensors. More details aresummarized below:1.1-D nanomaterial, MnO₂nanorods, was prepared and shown to be apromising matrix with biocompatible polyquaternium （QY） for Mb immobilization. The structure and morphology of the MnO₂nanorods werecharacterized by X-ray diffraction （XRD） and scanning electron microscopy（SEM）. Fourier transform infrared （FTIR） spectra revealed that Mbimmobilized in the MnO₂-QY nanocomposite film retained its native structure.Compared with Mb-MnO₂/GC electrode, the prepared Mb-MnO₂-QY/GCelectrode displayed wider linear range0.5-120μmol·L^-1, a lower detectionlimit of0.3μmol·L^-1, better stability, interference immunity andreproducibility.2.2-D nanomaterial, TiO₂nanosheets, was applied to assemble（Mb/TiO₂）nfilms by layer-by-layer technology. Electrochemical impedancespectroscopy （EIS） and UV-Vis spectra were used to monitor thelayer-by-layer process. The morphology of films was characterized by SEMand Atomic force microscope （AFM）. The thickness of film was much smallerthan the films assembled by other nanomaterials. The prepared electrodeexhibited high catalytic efficiency to H₂O₂. On the basis of MnO₂nanosheetsand Mb, Nafion was added to successfully assemble the（Mb/Nafion/Mb/MnO₂）nmultilayer films. The composite film not onlyprovided a favorable microenvironment for Mb but also kept the stability dueto the rigid structure of nanosheet.3.2-D nanomaterial, commercial conductive graphite nanosheet KS6,was designed for the immobilization of Hb to construct biosensors for thedetection of NaNO₂. The FTIR and UV-Vis spectra revealed that Hb retained its native secondary structure in the KS6-based composite film. TheHb-KS6-Nafion/GC electrode exhibited fast direct electron transfer andshowed a good electrocatalytic performance to NaNO₂with wide linear rangeof8-460μmol·L^-1and460-2300μmol·L^-1, stability and interference immunity.4.3-D nanomaterial, nanosheet-based TiO₂microspheres with a hollowcore-shell structure, have been synthesized and employed to immobilize HRPin order to fabricate a mediator-free biosensor. The morphology and structureof the TiO₂microspheres were characterized by XRD, SEM and TEM. Apossible growth mechanism has been proposed. Spectroscopic andelectrochemical measurements revealed that the TiO₂microspheres are animmobilization support with biocompatibility for enzymes, affording goodenzyme stability and bioactivity. Due to the nanosheet-based hollow core-shellstructure of the TiO₂microspheres, the direct electron transfer of HRP isfacilitated and the resulting biosensor displayed good performance for thedetection of H₂O₂, with both a low detection limit of0.05μmol·L^-1and a widelinear range from0.4to140μmol·L^-1.5.3-D nanomaterial, interlaced nanosheet-based Co（OH）₂porous film, havebeen successfully fabricated by one-step cathodic electrodeposition method.Hb was successfully immobilized on a GC electrode modified by interlacednanosheet-based3-D acroporous Co（OH）₂films. The nanosheet-likemorphologies of Co（OH）₂were observed by SEM. UV-Vis spectra reveal thatHb immobilized on the Co（OH）₂film almost retains its native structure. A fast direct electron transfer is achieved between Hb and underlying electrode withan average electron transfer rate of8.34s1. The resulting biosensor exhibitsgood performance for the detection of H₂O₂, with a wide linear range from0.4to200μM，low detection limit of0.2μM, high sensitivity of743.67μA mM-1cm-2, excellent stability and reproducibility.更多还原