【作者】 周艳丽；

【导师】 只金芳；

【作者基本信息】 中国科学院研究生院（理化技术研究所） ， 物理化学， 2008， 博士

【摘要】 硼掺杂的金刚石(boron-doped diamond, BDD)薄膜电极除了具有金刚石的优异性能如高的物理、化学稳定性和良好的生物兼容性外,还拥有一系列突出的电化学特性:宽电化学视窗、低背景电流、高电化学稳定性和强抗电极表面玷污能力。但是,sp3碳的高稳定性也使得其电极表面难于功能化。本论文通过各种化学修饰的手段,在其表面引入活性基团,进一步制作了生物传感器并研究了相应的性能。本文还研究了金刚石表面纳米结构的构建及立方氮化硼(cubic boron nitride, cBN)表面的修饰和功能化,并开展了其应用研究。得到的主要结论如下:1.首先是利用光化学的方法,即使用带有保护基的烯丙胺在紫外光照的条件下通过自由基反应的机理键合到BDD表面,脱去保护基团得到烷烃链基氨修饰的表面;其次是利用重氮盐化学及后续的电化学还原,在BDD表面得到苯胺基的单分子层。利用此两种活化的BDD电极表面进行了酪氨酸酶的固定,所制备的酪氨酸酶传感器在水体中酚类污染物的检测方面均得到了宽的检测范围、高的灵敏度、低的检测限(0.1μM)和高的稳定性。相比较来说,由于苯胺基比烷烃链基氨终端的电极具有较可逆的电化学性质,重氮盐修饰制得的生物传感器的检测灵敏度要优于光化学的方法。2.硼掺杂的纳米金刚石薄膜(BDND)与微米级的薄膜相比,具有更平整的表面,且sp2碳的引入在电化学过程中起到了电子传递的媒介体的作用,从而提高了金刚石电极的电化学性能。在BDND电极表面通过光化学的手段进行了羧基功能化,进一步细胞色素c通过共价键合法固定其上。细胞色素c与电极之间发生了准可逆的直接电化学行为,并有较快的电子传递速率(5.2±0.6 s-1)。此修饰电极对H2O2表现了良好的电催化性能。可以说,功能化的BDND电极是第三代生物传感器的理想基底材料。3.利用偏压辅助的微波等离子体技术将BDND薄膜进行了刻蚀处理,得到了纳米级、高密度和均匀的金刚石椎和柱的二维阵列。将金刚石纳米椎进行表面修饰和功能化,形成了不同尺度金纳米粒子(gold nanoparticles, AuNPs)修饰的单层。进一步研究了AuNPs修饰的金刚石椎在表面增强Raman光谱方面的应用,结果表明AuNPs (50 nm)修饰的金刚石椎是Raman活性的良好的基底材料。此金刚石表面纳米结构的构建扩展了金刚石薄膜材料的可应用领域。4. cBN是人工合成的又一超硬材料,它具有可比拟于甚至超越于金刚石材料的性能。本文探索了cBN表面的修饰和功能化,氢终端的cBN表面在紫外光照的条件下与含有C=C双键的烯丙胺化合物发生反应,从而得到氨基终端的表面。在氨基化的cBN表面进行了DNA生物传感器的设计与制作,初步的结果显示功能化的cBN表面是好的生物传感器的基底材料。另外,将AuNPs自组装到氨基终端的cBN表面,固定的AuNPs催化形成了银纳米片的结构,此银纳米片修饰的cBN薄膜在表面增强Raman光谱方面的应用结果表明有很好的Raman活性和很高的稳定性。此cBN表面的功能化虽然只是初步的结果,但确实也是为cBN薄膜在生物传感和分析领域的应用奠定了基础。更多还原

【Abstract】 Conducting boron-doped diamond (BDD) thin films have emerged as attractive new electrode materials because, in addition to having good electrochemical properties including: wide electrochemical potential window, very low double-layer capacitance, extreme electrochemical stability and high resistance to deactivation by fouling, it is widely considered to be biocompatible. Thus, the BDD electrodes are of interest for a variety of electrically based chemical and biological sensing applications. In this paper, the major efforts in BDD electrodes used in biosensors essentially involve elaborate surface modification steps to impart chemical functional groups for covalent coupling of biomolecules. In addition, the construction of nano-structures on diamond films, the modification of cubic boron nitride (cBN) and their applications were investigated. The main conclusions are listed as follows:1. Firstly, the hydrogen-terminated BDD surface was first functionalized by photochemically linking vinyl groups of allylamine, producing covalently linked aminoalkyl-terminated surface; Sencondly, combined chemical and electrochemical modifications of the BDD film with nitrobenzenediazonium, an aminophenyl- modified surface was produced. Then amperometric biosensors based on immobilization of tyrosinase on the above two active amine-terminated BDD surfaces were developed. The resulted enzyme electrodes exhibit a good performance in terms of dynamic range of detection, sensitivity, detection limit (0.1μM) and long-term stability to the detection of phenolic compounds. By comparison, the sensitivity of the enzyme electrode prepared via diazonium method is higher than that of the electrode constructed by photochemical method, which probably because, the aryl ring is more conductive than alkyl chain.2. Compared with microcrystalline BDD, boron-doped nanocrystalline diamond (BDND) thin-film electrodes have a smoother surface while maintaining the intact diamond properties. Importantly, in addition to boron doping, the sp2-bonded carbon phase on grain boundaries of BDND films can provide charge carriers, which lead to better reversible properties for redox systems. Cytochrome c (Cyt c) was covalently immobilized on a carboxyl-terminated BDND electrode constructed by photochemical surface modification. The Cyt c on BDND electrode exhibited a direct electrochemistry with a pair of quasi-reversible, well-defined redox peaks and a high electron transfer constant of 5.2±0.6 s-1. The prepared Cyt c-modified BDND electrode showed excellent electrocatalytic performance in terms of fast response, low detection limit and high stability towards the reduction of H2O2. In a word, BDND thin-film is an ideal substrate as a third-generation biosensor support.3. High-density, uniform diamond nanocone and nanopillar arrays were fabricated by employing bias-assisted reactive ion etching in a H/Ar-plasma. Different sizes of gold nanoparticles (AuNPs) were self-assembled on the diamond nancones surface functionalized by photochemical method and AuNPs monolayer was formed. The application of the AuNPs–modified diamond nanocones film in the surface-enhanced Raman spectroscopy (SERS) was investigated and a high Raman activity was obtained. The above reslults reflect a genuine breakthrough in developing new potential applications of the diamond nanostructures films.4. cBN is of significant interest due to its unique set of properties that are comparable or even superior to diamond. Surface functionalization and modification scheme of cBN films was demonstrated. A homogeneous layer of amino groups was bonded covalently on the B and/or N atoms of cBN surface via a photochemical reaction with allylamine. Modification of amine-terminated cBN films with amine-modified DNA probes presents an example of applications as DNA biosensors. AuNPs self-assembled on the amine-terminated cBN surface initiate the silver deposition and homogenous, cross-linked silver nano-sheets were formed. The silver nanosheets-modified cBN film demonstrated a high activity and a long-term stability for SERS. Our work is an initial but important step towards the practical sensing applications of cBN-based devices in chem- and bio-sensing technology.更多还原