聚合物膜修饰电极的电化学法制备及其在氨基酸检测中的应用

发布时间：2018-06-24 05:35

本文选题：聚对氨基苯磺酸 + 聚邻巯基苯胺　；参考：《广东工业大学》2011年硕士论文

【摘要】：氨基酸是蛋白质的基本结构单位,是动物体合成蛋白质的原料来源,属食品、饲料的营养成分,也可作为营养型化妆品的有效成分及表面活性剂、其他工业产品的化工原料。因此,氨基酸分析是工业、农业生产及生命科学研究中最重要的技术之一。芳香族氨基酸包括苯丙氨酸、酪氨酸和色氨酸等。芳香族氨基酸的代谢情况在肝、肾、神经精神疾病等疾病诊断中有重大意义。因此定量分析血液中的芳香族氨基酸不仅在蛋白质化学和评价病人的营养状况方面十分重要,而且在多种疾病的诊断治疗和病因学研究上十分关键。目前,临床测定芳香族氨基酸的方法有许多,包括高效液相色谱法、毛细管电泳法、荧光法、紫外分光光度法、质谱法等等。其中HPLC是分析芳香族氨基酸的常用方法,但是样品处理复杂,需梯度洗脱,衍生产物不稳定。也有研究人员利用芳香族氨基酸在一定的激发光照射下能产生自然荧光的特性来测定,获得了较好的结果,但是由于它们荧光光谱严重重叠,荧光特性不一致而不能在同一波长下同时进行3种氨基酸的测定,因此不能满足某些疾病的临床诊断与监测需要。色氨酸、酪氨酸和苯丙氨酸都是在紫外区有吸收的常见氨基酸,用紫外分光光度法测定时,因其吸收光谱严重重叠,需要采用一定的数学方法。这些方法中所用仪器较贵,且三种氨基酸往往相互干扰。电分析化学是根据物质在溶液中的电化学性质及其变化建立的一类分析方法,特别是现代仪器分析与计算机联用实现了分析工作的自动化。目前,在工业农业、食品检验、环境保护和医学检验等各领域获得广泛的应用。氨基酸的电化学分析因简单、灵敏、无放射、无污染与各种现代化的分离方法相结合可以大大简化操作过程,节约分析时间,且灵敏度及准确度都很高,选择性好。氨基酸的电化学分析可分为直接电化学分析和间接电化学分析。直接电化学分析检测要求被测物质具有一定的电化学活性。在三种芳香烃氨基酸中,色氨酸(Trp)和酪氨酸(Tyr)都是电活性物质,是人和动物必需的氨基酸,Trp又是限制性氨基酸,对其测定具有重要意义。采用电分析方法直接检测是较理想的选择。化学修饰电极是通过化学修饰的方法在电极表面进行分子设计,将具有优良化学性质的分子、离子、聚合物固定在电极表面,造成某种微结构,利用微结构所提供的多种能利用的势场,使待测物进行有效的分离富集,并借控制电极电位,进一步提高选择性。把电化学测定方法的灵敏性和修饰剂化学反应的的选择性相结合,成为分离、富集和选择性三者合而为一的理想体系,广泛应用于选择性富集与分离、电催化、选择性渗透、媒介作用和化学传感器。本论文聚合物膜修饰电极的电化学法制备及其应用从以下两个方面进行了探讨,一方面电化学聚合法制备了对氨基苯磺酸聚合膜修饰玻碳电极(P-p-ABSA/GCE),系统而详细地研究了色氨酸和酪氨酸在P-p-ABSA/GCE修饰电极上的电化学行为；另一方面对金电极上电化学法聚合邻巯基苯胺进行了初探。主要内容包括： 1,采用循环伏安法在玻碳电极表面修饰聚对氨基苯磺酸,随着循环扫描周数的增加,伏安图上相应蜂电流不断增长证明聚合物的形成。该制备方法简便、快捷,所制得的修饰膜均一稳定,具有良好的重现性。 2,研究了L-色氨酸(L-Trp)在该电极上的电化学行为,以及支持电解质、溶液pH、扫描速率等对L-Trp电化学行为的影响。该修饰电极明显提高了L-Trp的氧化峰电流,参与电极反应的质子数和电子数相等,电极过程为吸附控制过程。在pH 3.0的NaH2PO4-Na2HPO4缓冲溶液中,氧化峰电流与浓度在5.0×10-8～2.0×10-5 mol/L范围内呈良好的线性关系,检出限为1.5×10-8mol/L。连续测定5×10-6mol/L的L-Trp标准溶液,电流值的相对标准偏差(RSD)为3.13%(n=5),重现性良好。一些常见物质对测定无干扰。 3,研究了L-酪氨酸(L-Tyr)在该电极上的电化学行为,并优化了测定条件。该修饰电极明显提高了L-Tyr的氧化峰电流,参与电极反应的质子数和电子数相等,电极过程为吸附控制过程。在0.2 mol/L H3PO4溶液中,氧化峰电流与浓度在2×10-7～2×10-5mol/L范围内呈良好的线性关系,检出限为1.0×10-7 mol/L。连续测定5×10-6mol/L的L-Tyr标准溶液,电流值的相对标准偏差(RSD)为4.95%(n=5),具有较好的重现性。 4,色氨酸和酪氨酸在一般电极上完全不能分开,但在P-p-ABSA/GCE修饰电极上,采用差分脉冲伏安法,在2.0mol/L H2SO4溶液中,色氨酸和酪氨酸的氧化峰电位分别为0.912 V和1.016 V,可以完全分离,实现了色氨酸和酪氨酸共存时的选择性测定。且该法用于医院营养输液常用的复合氨基酸注射液中色氨酸和酪氨酸的同时测定,取得了满意的结果。 5,另一方面,在对金电极上电化学法聚合邻巯基苯胺的研究上,本论文采用恒电位法在金电极上电解合成了聚邻巯基苯胺(PATP)膜。该聚合物兼有聚苯胺的导电性和-SH基团的氧化还原性能,在巯代苯胺聚合物电极材料的研究与开发中具有重要前景,也可能在电池正极材料上得到应用,如一次锂电池的正极材料。另外,-SH基团能与金形成稳定Au-S键,可以作为用于石英晶体微天平分析时的分子印迹聚合物,用于分离手性氨基酸,在电化学传感器方面得到应用。初步探讨了邻巯基苯胺的电化学聚合过程及PATP的氧化还原机理。结果表明,邻巯基苯胺的聚合反应是通过阳离子自由基中间体进行的,且用恒电位法合成PATP膜时,电位应控制在1.38V～1.43V之间。在此基础上用循环伏安法对PATP膜的电化学性质进行表征,研究了聚合电位、盐酸浓度、聚合时间对PATP电化学行为的影响。
[Abstract]:Amino acid is the basic structural unit of protein. It is the source of raw material for protein synthesis in animal body. It belongs to food, feed nutrition, and can also be used as an effective component and surfactant of nutritional cosmetics and chemical raw materials for other industrial products. Therefore, amino acid analysis is the most important technology in industry, agricultural production and life science research. Aromatic amino acids include phenylalanine, tyrosine and tryptophan. The metabolism of aromatic amino acids is of great significance in the diagnosis of liver, kidney, and neuropsychiatric diseases. Therefore, the quantitative analysis of aromatic amino acids in the blood is important not only in protein chemistry and in evaluating the nutritional status of patients, but also in the evaluation of the nutritional status of the patients. At present, there are many methods for the clinical determination of aromatic amino acids, including high performance liquid chromatography, capillary electrophoresis, fluorescence, UV spectrophotometry, mass spectrometry and so on. HPLC is a common method for the analysis of aromatic aminoacids, but the sample treatment is complex and needs gradient. Elution, derivatives are unstable, and some researchers have obtained good results by using aromatic amino acids to produce natural fluorescence properties under certain excitation light, but they have obtained good results. But because of their serious overlapping of fluorescence spectra and the inconsistency of fluorescence characteristics, the determination of 3 kinds of amino acids can not be carried out simultaneously under the same wavelength. The clinical diagnosis and monitoring needs of certain diseases are not satisfied. Tryptophan, tyrosine and phenylalanine are common amino acids that are absorbed in the ultraviolet region. When the absorption spectra are seriously overlapped by ultraviolet spectrophotometry, some mathematical methods are needed. The instruments used in these methods are more expensive, and the three kinds of amino acids are often reciprocal. Interference.
Electroanalytical chemistry is a kind of analytical method based on the electrochemical properties and changes of substances in solutions, especially the automation of analytical work in conjunction with modern instrument analysis and computer. The electrochemistry of amino acids has been widely used in various fields, such as industrial agriculture, food inspection, environmental protection and medical inspection. The analysis of simple, sensitive, no radiation, no pollution and various modern separation methods can greatly simplify the operation process, save the analysis time, and the sensitivity and accuracy are high and the selectivity is good. The electrochemical analysis of amino acids can be divided into direct electrochemical analysis and indirect electrochemical analysis. Direct electrochemical analysis and detection requirements are required. In the three aromatic hydrocarbon amino acids, tryptophan (Trp) and tyrosine (Tyr) are both electroactive substances, which are essential amino acids for human and animal, and Trp is a restrictive amino acid. It is of great significance for the determination of the substance. Direct detection by electroanalysis is an ideal choice.
Chemically modified electrodes are chemically modified to carry out molecular design on the surface of the electrode. The molecules, ions and polymers with excellent chemical properties are fixed on the surface of the electrode to cause some micro structure, and a variety of potential fields provided by the microstructures are used to effectively separate and enrich the measured objects, and to control the potential of the electrode. One step to improve selectivity.
The sensitivity of electrochemical determination method and the selectivity of the modifier chemical reaction are combined to become an ideal system for separation, enrichment and selectivity, which are widely used in selective enrichment and separation, electrocatalysis, selective osmosis, media action and chemical sensing devices.
In this paper, the electrochemical preparation of polymer film modified electrode and its application are discussed in the following two aspects. On the one hand, the electrochemical polymerization of p-aminophenylsulfonic acid polymerized membrane modified glassy carbon electrode (P-p-ABSA/GCE) has been prepared, and the electrochemical behavior of tryptophan and tyrosine on the P-p-ABSA/GCE modified electrode has been studied in detail. On the other hand, the electrochemical polymerization of O - mercapto aniline on gold electrode was studied.
1, polyp-aminophene sulfonic acid was modified by cyclic voltammetry at the surface of glassy carbon electrode. With the increase of cycle scanning weeks, the corresponding bee current on the voltammetry proved the formation of polymer. The preparation method was simple and fast, and the modified membranes were stable and good reproducibility.
2, the electrochemical behavior of L- tryptophan (L-Trp) on this electrode and the effect of supporting electrolyte, solution pH, scanning rate on the electrochemical behavior of L-Trp were investigated. The modified electrode obviously improved the oxidation peak current of L-Trp, the number of protons and the electron number phase in the electrode reaction, and the electrode process as the adsorption control process. In the NaH2PO4- of pH 3 NaH2PO4- In the Na2HPO4 buffer solution, the peak current and concentration of oxidation peak are linear in the range of 5 x 10-8 to 2 x 10-5 mol/L. The detection limit is 1.5 x 10-8mol/L. for 5 x 10-6mol/L L-Trp standard solution. The relative standard deviation of current value (RSD) is 3.13% (n=5), and the reproducibility is good. Some common substances have no interference to the determination.
3, the electrochemical behavior of L- tyrosine (L-Tyr) on this electrode was studied and the determination conditions were optimized. The modified electrode improved the oxidation peak current of L-Tyr obviously, the number of protons and the number of electrons in the electrode reaction were equal, the electrode process was the adsorption control process. The peak current and concentration of oxidation peak in 0.2 mol/L H3PO4 solution were 2 x 10-7 ~ 2 x 10-5mo. There is a good linear relationship in the range of l/L. The detection limit is 1 x 10-7 mol/L. for the continuous determination of 5 x 10-6mol/L L-Tyr standard solution, the relative standard deviation of current value (RSD) is 4.95% (n=5), and it has good reproducibility.
4, tryptophan and tyrosine can not be separated completely on the general electrode, but on the P-p-ABSA/GCE modified electrode, the peak potential of tryptophan and tyrosine is 0.912 V and 1.016 V in 2.0mol/L H2SO4 solution, and the selective determination of tryptophan and tyrosine in the coexistence of tryptophan and tyrosine can be completely separated and the selective determination of tryptophan and tyrosine is achieved. The method has been applied to the simultaneous determination of tryptophan and tyrosine in compound Amino Acid Injection commonly used in hospital nutrition infusion. Satisfactory results have been obtained.
5, on the other hand, in the study of the electrochemical polymerization of O mercapto aniline on gold electrodes, the polyaniline (PATP) film was synthesized by electrolysis on gold electrode by potentiostatic method. The polymer has both the conductivity of Polyaniline and the redox property of the -SH group. It has been developed in the research and development of the polymer electrode material of thiol substituted aniline. In addition, the -SH group can form a stable Au-S bond with gold, which can be used as a molecularly imprinted polymer used in the analysis of quartz crystal microbalance, and is used to separate chiral amino acids and be applied in electrochemical sensors. The electrochemical polymerization process of O mercapto aniline and the oxidation reduction mechanism of PATP show that the polymerization of O mercapto aniline is carried out through the cationic radical intermediate, and the potential should be controlled between 1.38V and 1.43V when the PATP film is synthesized by constant potential method. On this basis, the electrochemical properties of the PATP membrane are carried out by cyclic voltammetry. The effects of polymerization potential, concentration of hydrochloric acid and polymerization time on Electrochemical Behavior of PATP were characterized.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：O646.5;O629.7

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