【作者】 李娜；

【导师】 崔华；

【作者基本信息】 中国科学技术大学 ， 分析化学， 2010， 博士

【摘要】 论文首先综述了化学发光、金属纳米材料的性质和常用的表征方法,以及金属纳米材料参与的化学发光及其分析应用的研究现状。虽然化学发光的基础理论和分析应用已经有多年的研究历史,但是有关化学发光的研究一直局限于分子和离子水平。最近,金属纳米粒子直接或者间接参与的化学发光拓展了化学发光理论和应用研究范畴。已经发现金属纳米粒子能够作为催化剂、还原剂、微尺度反应平台和能量接受体参与化学发光。但是,纳米化学发光体系依然十分有限,而且一些体系发光量子产率较低,很难应用于分析测定。进一步开发纳米化学发光体系不但有利于化学发光和纳米材料的基础研究而且为化学发光的分析应用提供了新方法和新思路。此外,有关化学发光反应中纳米粒子功能控制的研究鲜见报道。基于此,本论文以纳米银钯合金和纳米银为研究对象,利用胶体pH和纳米粒子表面吸附剂两种途径,设计了两个纳米化学发光新体系,实现了纳米化学发光体系的控制,探索了这些体系的化学发光行为、规律和机理。同时,利用高效液相色谱与纳米化学发光体系联用发展了一种高灵敏度的分析新方法。主要研究内容如下：1.利用化学还原法合成了一种银钯双金属纳米粒子,借助扫描电子显微镜、透射电子显微镜、X射线能谱分布、X射线衍射等仪器分析手段,详细研究了粒子的尺寸,形貌,化学组成和结构等。将酸性的银钯双金属胶体与鲁米诺溶液混合伴随着“闪光型”的化学发光现象。该化学发光的特点是调节胶体溶液的pH值能够可逆地调控这个化学发光的强度。当胶体溶液在酸性条件下,化学发光处于“开”的状态；当胶体溶液在碱性条件下,化学发光则处于“关”的状态。另外,研究发现酸化已经发生过化学发光反应的胶体溶液,再重复注入鲁米诺工作溶液,化学发光能够再生。而且通过这样的再生方法,胶体至少能够重复使用30次。借助化学发光光谱和紫外可见光谱：等仪器手段我们进一步深入研究了化学发光依赖于胶体溶液pH值的原因,提出了银钯纳米粒子pH依赖的催化作用机理。银钯纳米粒子在酸性条件下能够与溶解氧反应生成过氧化钯的中间体,该中间体氧化鲁米诺能够产生化学发光。由于氢离子是生成过氧化钯中间体的必备条件。所以调节银钯胶体的pH值能够控制该化学发光“开”或“关”。最后,我们研究了银原子在银钯胶体参与的化学发光中的作用,结果表明银能够催化并增强该化学发光。本章工作发现没有任何功能分子参与的简单银钯合金纳米粒子在化学发光反应中的催化活性完全受控于其所在溶液的pH值。由于pH控制的催化作用不但能够用于化学发光反应而且也能够应用于那些众多的依赖于酸碱协同催化的有机化学反应中,本章工作为将简单纳米粒子设计成为拥有pH控制的催化作用的智能纳米材料提供了一个新的思路。2.银纳米粒子在吸附剂(溴离子)和硫酸铜的存在下能够与鲁米诺溶液发生化学发光反应。试剂加入的顺序是该化学发光体系的关键。只有鲁米诺溶液最后加入反应体系,才能产生光发射。通过紫外吸收光谱、X射线衍射和X光电子能谱等方法确认了与化学发光密切相关的关键中间产物Cu(I)配合物,提出了化学发光的机理。在溴离子存在下,银纳米粒子还原硫酸铜获得Cu(I)的配合物,部分Cu(I)的配合物能够与溶解氧反应产生超氧基阴离子。超氧基阴离子与鲁米诺反应产生化学发光。溴离子在该化学发光体系中有两个重要的作用。一方面它是作为吸附剂增强胶体银的还原性,协助还原反应生成Cu(I)。另外一方面溴离子与Cu(I)配合防止Cu(I)在水中歧化。根据这个发光机理我们推测其它具有以上两种功能的亲核试剂如碘离子、氯离子和硫代硫酸钠也能够诱导该化学发光反应。在合理调整实验条件后我们观察到这些亲核试剂也能够成功地引发该化学发光。本章工作利用吸附剂增强纳米粒子的还原性能,构建了吸附剂存在下纳米粒子诱导的鲁米诺化学发光新体系。3.基于鲁米诺—硝酸银—纳米金化学发光体系,建立了一种高效液相色谱与纳米化学发光联用同时分析鼠脑透析液中单胺类神经递质及其代谢物的分析新方法。将一些与生命活动相关的还原性物质引入鲁米诺—硝酸银—纳米金化学发光体系,包括单胺类神经递质及其代谢物、尿酸和谷胱甘肽等。结果发现这些物质对该化学发光体系有明显的抑制作用。其中,单胺类神经递质及其代谢物的抑制作用非常强。以多巴胺为例,我们利用紫外光谱和停留动力学实验研究了抑制作用的机理。接着,考虑到目前还没有液相色谱和化学发光联用法能够解决儿茶酚胺类和吲哚胺类化合物的同时测定,我们基于化学发光抑制作用,发展了一种化学发光与液相色谱联用新方法同时测定单胺类神经递质及其代谢物(包括肾上腺素、去甲肾上腺素、多巴胺、5-羟色胺、3,4-二羟基苯乙酸、香草酸和5-羟基吲哚乙酸),并且成功应用于鼠脑透析液的分析检测中。该方法具有操作简便、分析时间短、选择性好等优点。本方法是首次将纳米金参与的化学发光用于液相色谱柱后检测。4.将碳纳米管修饰的玻碳电极用于研究在循环伏安扫描过程中鲁米诺的阴极电致化学发光。通过与裸玻碳电极比较,碳纳米管在电极表面能够使鲁米诺阴极电致化学发光的电位向正电位移动而且能够极大地增强该电致化学发光的强度。基于碳纳米管浓度、鲁米诺浓度和工作溶液pH等因素对鲁米诺的阴极电致化学发光的影响研究,发现碳纳米管对该电致化学发光的影响都来源于其对氧气还原的催化作用。氧气在碳纳米管的催化下被电还原生成过氧化氢阴离子,过氧化氢阴离子能够与鲁米诺反应产生化学发光。更多还原

【Abstract】 In this dissertation, the state of arts in the field of chemiluminescence (CL), the properties and characterization methods of metal nano-materials and their applications in CL were reviewed. Although the theory and the application of CL have been investigated for many years, the study of CL was limited to molecular and ion systems. Recently, metal nanoparticle-involved CL became one of the most attractive developments in these fields, in which metal nanoparticles can participate in CL reactions as catalyst, reductant, naonosized platform and energy acceptor. However, most of the reported nanoparticles-involved CL systems were not of high quantum yield for many applications in analysis. The design of new nanoparticles-involved CL were valuable not only to gain a better understanding the properties of metal nanoparticles and the fundamental studies of CL but also to extend the analytical applications of CL. Meanwhile, the investigation of nanoparticle-controlled CL system has been rarely reported. Therefore, in the present dissertation, the pH-dependent catalysis of Pd-Ag nanoparticles and adsorbate-enhanced reducibility of Ag nanoparticles were employed to design new CL systems. The CL behaviors, rules and mechanisms of these new CL systems were investigated. Moreover, a novel method for simultaneous determination of monoamine neurotransmitters and their metabolites was developed by coupling high-performance liquid chromatography (HPLC) with nanoparticles-involved CL. The main results are as follows:1. Pd-Ag colloid was synthesized by chemical reduction method in a solution. The morphology, chemical composition and structure of the Pd-Ag nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray diffraction patterns (XRD). It was found that the acidic Pd-Ag colloid could react with luminol to produce an unusual chemiluminescence, which could be reversibly switchable by modulating the pH of Pd-Ag colloid. When the Pd-Ag colloid was in acidic conditions, the CL was "on"; when the Pd-Ag colloid was in neutral and basic conditions, the CL was "off. Moreover, after the CL reaction, the CL emission could be regenerated by the acidification of the reacted mixture and the repetitious injection of luminol. The CL mechanism was investigated by CL spectra, UV-visible spectra, the effect of N2 and O2 on the CL reaction, and the oxidation reaction between acidic Pd-Ag colloid and 2,2’-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid). It is proposed that acidic Pd-Ag colloid reacted with the dissolved oxygen to yield Pd hydroperoxide, a key intermediate, which oxidized luminol under Ag catalysis to produce light emission. Because H+is necessary for the formation of Pd hydroperoxide, the luminol CL emission could be controlled by the pH of Pd-Ag colloid. pH-switchable chemiluminescence was successfully obtained for the first time by using simple Pd-Ag nanoparticles without coating any smart polymers or functional molecules. Pd-Ag nanoparticles as catalysts in the aerobic oxidation of luminol are very stable and could be reused for at least 30 cycles without obvious losing in their virgin catalytic activity, which is also a promising catalyst for the aerobic oxidation of other organic compounds.2. In the presence of adsorbates (Br-) and Cu2+, Ag nanoparticles could initiate luminol CL. To yield the CL emission, the luminol must be the last reagent added into the system. UV-visible absorption spectra showed that silver nanoparticles in the presence of NaBr could react with CUSO4 before injection of luminol. The X-ray diffraction patterns and X-ray photoelectron spectra demonstrated that Cu (Ⅰ) complex was a key reaction product in AgNPs-NaBr-CUSO4 system. Besides, it was also found that superoxide dismutase could inhibit the CL, revealing that a superoxide anion was involved in the CL reaction. On this basis, it was suggested that the luminol CL induced by silver nanoparticles in the presence of NaBr and Cu2+derived from Cu(I) complex formed via the reduction of CuSO4 by AgNPs by the aid of NaBr, which reacted with the dissolved oxygen to generate the superoxide anion; then the superoxide anion reacted with luminol to produce CL. Br- as an adsorbate was considered to decrease the oxidation potential of silver nanoparticles so that Cu(II) is readily reduced to Cu(I) and to bind to Cu(I) preventing Cu(I) from dismutation in water. As expected, other adsorbates such as Cl-, I-and thiosulfate, which were also efficient to decrease the oxidation potential of AgNPs and bind to Cu (I), could also induce the luminol CL.3. Based on the luminol-AgNO3-Au colloid CL system, a novel method for simultaneous determination of monoamine neurotransmitters and their metabolites was developed by coupling high-performance liquid chromatography with nanoparticle-involved CL reaction. Our previous work showed that gold nanoparticles could trigger chemiluminescence (CL) between luminol and AgNO3. In the present work, the effect of some biologically important reductive compounds, including monoamine neurotransmitters and their metabolites, reductive amino acids, ascorbic acid, uric acid, and glutathione, on the novel CL reaction were investigated for analytical purpose. It was found that all of them could inhibit the CL from the luminol-AgNO3-Au colloid system. Among them, monoamine neurotransmitters and their metabolites exhibited strong inhibition effect. Taking dopamine as a model compound, the CL mechanism was studied by measuring absorption spectra during the CL reaction and the reaction kinetics via stopped-flow technique. The CL inhibition mechanism is proposed to be due to that these tested compounds competed with luminol for AgNO3 to inhibit the formation of luminal radicals and to accelerate deposition of Ag atoms on surface of gold nanoparticles, leading to a decrease in CL intensity. Based on the inhibited CL, a novel method for simultaneous determination of monoamine neurotransmitters and their metabolites was developed by coupling high-performance liquid chromatography with this CL reaction. The new method was successfully applied to determine the compounds in a mouse brain microdialysate. Compared with the reported HPLC-CL methods, the proposed method is simple, fast, and could simultaneously determine catcholamine and indoleamine and their metabolites.4. The electrochemiluminescent (ECL) behavior of luminol on a carbon nanotube (CNT)-modified glass carbon electrode (GCE) during cathodic scanning was investigated. Compared with a bare glass carbon electrode, the CNT-modified GCE promoted a positive shift in ECL potential and an increase in the ECL signal. The effects of CNTs concentration, luminol concentration, and pH on the cathodic ECL of luminol were studied, and the possible cathodic ECL mechanism was proposed. CNTs could catalyze electronic reduction of dissolved oxygen to produce HO2-, which reacted with luminol to give ECL signal.更多还原