噻唑聚合物膜修饰电极的制备及其在生物分析中的应用

【作者】 张莹；

【导师】 张雷；

【作者基本信息】 上海师范大学 ， 分析化学， 2015， 硕士

【摘要】 多巴胺(DA)是哺乳类动物中枢神经系统内重要的信息传递物质,它属于儿茶酚胺类药物,临床上广泛用于由心肌梗死、创伤、内毒素败血症、心脏手术、肾功能衰竭、充血性心力衰竭等引起的休克综合症的治疗。尿酸(UA)是核酸组成单位中嘌呤核苷酸分解代谢的产物,其在人体中含量的变化常常是一些疾病的征兆,如高血压、白血病、肺炎等。黄嘌呤(XN)是嘌呤核苷酸分解代谢的中间产物,并会在黄嘌呤氧化酶的作用下转换为尿酸,其在血浆和尿液中的浓度水平可以作为某些病理状态的敏感指标,特别是对黄嘌呤尿症。亚硝酸根(NO2-)作为一种致癌物质,对环境、食物和生物体系有着重大的影响,其含量的超标会导致血红蛋白氧化,而且它还能影响生物体内DA的传递。DA、UA和NO2-在传统电极上的氧化电位往往很接近且其氧化产物会污染电极。因此,传统电极难以对DA、UA、XN和NO2-难以进行选择性或同时测定。为了解决问题,各种各样的修饰电极已经被制备并应用于DA、UA、XN和NO2-的选择性或同时测定。由于噻唑类聚合物修饰电极有较强的选择性、较好的稳定性、较高的重现性以及在电极表面的厚度可控制等优点而始终在电化学分析领域占有不可替代的一席之地。本文主要包括以下三方面的工作:1.采用循环伏安法(CV)将2,6-二氨基-4,5,6,7-四氢苯并噻唑聚合修饰在玻碳电极(GCE)表面制备了聚2,6-二氨基-4,5,6,7-四氢苯并噻唑修饰的玻碳电极(PDTBT/GCE),并用于DA和UA的同时测定。PDTBT/GCE不仅能很好地改善DA和UA的电化学行为,而且能将其重叠的氧化峰分开成两个明显而尖锐的氧化峰,峰-峰电位差为0.14 V,故该修饰电极可用于对混合液中DA和UA的同时测定。在优化的实验条件下,DA和UA的氧化峰电流与其浓度分别在0.1~100μmol L-1和2~1000μmol L-1范围内呈良好的线性关系,相关系数分别为0.9984和0.9990,检出限(S/N=3)分别为0.05μmol L-1和0.20μmol L-1。在p H 7.0的磷酸缓冲溶液(PBS)中,PDTBT/GCE展现出了很好的电催化活性,电极表面的电化学反应过程是一个表面控制的电极过程,电荷转移速率常数(ks)为26.9 s-1,电荷转移系数(α)为0.52。该修饰电极重现性高、稳定性强,而且具有较好的选择性、和较宽的检测范围,将其应用于尿液中DA和UA的同时测定,结果满意。2.采用CV法将2-氨基苯并噻唑(ABT)和2,3-二巯基丁二酸(DMSA)共聚到玻碳电极表面制得ABT和DMSA共聚物修饰的玻碳电极(PABT-DMSA/GCE),并将其用于DA、UA和XN的同时测定。结果表明PABT-DMSA/GCE不仅能很好地改善DA、UA和XN的电化学行为,而且能将其重叠的氧化峰分开成三个明显而尖锐的氧化峰,DA-UA和UA-XN的峰间距分别为120 m V和410 m V,故该修饰电极可用于混合液中DA、UA和XN的同时测定。在优化的实验条件下,DA、UA和XN的氧化峰电流与其浓度分别在0.1~360μmol L-1,0.4~800μmol L-1,0.8~1500μmol L-1范围内呈良好的线性关系,相关系数分别为0.9965,0.9959和0.9965,检出限(S/N=3)分别为0.01μmol L-1和0.02μmol L-1和0.07μmol L-1。在p H 7.0的PBS中,PABT-DMSA/GCE展现出了很好的电催化活性,DA、UA和XN在不同扫速下的电化学氧化行为表明DA在PABT-DMSA/GCE上的电极过程是典型的吸附过程控制,而UA和XN的电极过程受扩散过程控制。该修饰电极重现性高、稳定性强,而且具有较好的选择性、较高的灵敏度和较宽的检测范围,将其应用于尿液和血清样本中DA、UA和XN的同时测定,获得了满意的结果。3.采用CV法将5-巯基-1H-四氮唑-1-乙酸(MTAA)修饰到GCE表面,制备聚5-巯基-1H-四氮唑-1-乙酸修饰的玻碳电极(PMTAA/GCE),并将其用于DA、UA和NO2-的同时测定。该修饰电极在p H 6.0的PBS中不仅对DA、UA和NO2-电化学氧化具有很好的电催化性能,而且能使其在修饰电极上进行很好的分离。在最优的条件下,DA、UA和NO2-的氧化峰电流与其浓度分别在0.2~110μmol L-1,1~600μmol L-1和8~1100μmol L-1范围内呈良好的线性关系,相关系数分别为0.9945,0.9932和0.9944,检出限(S/N=3)分别为0.03μmol L-1、0.2μmol L-1和0.5μmol L-1。DA、UA和NO2-在不同扫速下的电化学氧化行为表明DA在PMTAA/GCE修饰电极上的电极过程是典型的吸附过程控制,而UA和NO2-的电极过程受扩散过程控制。PMTAA/GCE可用于尿液样本中DA、UA和NO2-的同时测定,结果令人满意。更多还原

【Abstract】 Dopamine(DA) is one of the important catecholamine neurotransmitters in the mammalian central nervous system, and it is widely applied to the treatment of circulatory collapse syndrome caused by the myocardial infarction, trauma, endotoxin sepsis, cardiac surgery or congestive cardiac failure. Uric acid(UA), a primary end product of purine metabolism, its abnormal level is commonly a symptom of some diseases, like hyperpiesia, leukemia and pneumonia. Xanthine(XN) is a purine nucleotide catabolism of intermediates, and will be converted to uric acid in the role of xanthine oxidase. XN levels in plasma and urine concentrations can be used as a sensitive indicator of some pathological conditions, especially for xanthine aciduria. Nitrite(NO2-), a precursor to carcinogenic nitrosamines, is important within environmental, food and physiological systems, and its excessive level in blood will result in haemoglobin oxidation. Moreover, it could enhance or inhibit the release of DA. It is nearly impossible to determine DA, UA, XN and NO2- selectively or simultaneously at bare electrodes due to the weak and overlapped oxidation waves and the electrode fouling caused by the adsorption of their oxidation products, which can lead to the poor sensitivity and selectivity. Hence, the development of sensitive and selective biosensors for their selective or simultaneous detection is highly desirable for analytical applications and also diagnostic researches.To solve these problems, various modified electrodes have been constructed and used to selectively or simultaneously determine DA, UA, XN and NO2-. Conjugated polymers always have irreplaceable position in the electrochemical academic circles due to their numerous advantages, such as strong selective, good stability, high repeatability, and the thickness of the electrode surface can be controlled. Recently, thiazole-based polymers also gradually got people’s attention due to their unexceptionable selectivity and sensitivity. This paper includes three aspects as followed:1. A Poly(2,6-diamino-4,5,6,7-tetrahydrobenzothiazole)(PDTBT) modified glassy carbon electrode(GCE)(PDTBT/GCE) had been fabricated by electropolymerization of DTBT and used for the simultaneous detection of DA and UA in 0.1 mol L-1 phosphate buffer solution(PBS, p H 7.0). The results were showed that the PDTBT modified GCE not only exhibited excellent electrocatalytic activity toward the electrooxidations of DA and UA, but also resolved the weak and overlapped voltammetric responses of DA and UA into two sensitive and well-defined oxidation peaks with a large peak potential separation of 0.14 V, which can be applied for the selective and simultaneous determinations of DA and UA in a mixture. Under the optimum conditions, the anodic peak currents of DA and UA were linearly dependent on the concentrations of DA and UA in the ranges of 0.1–100 and 2.0–1000 μmol L-1 with the correlation coefficients of 0.9984 and 0.9990, respectively. The detection limits were 0.05 μmol L-1 and 0.20 μmol L-1(S/N=3). In 0.1 mol L-1 PBS p H 7.0, the PDTBT film exhibited good electrochemical activity, showing a surface-controlled electrode process with the apparent heterogeneous electron transfer rate constant(ks) of 25.9 s-1 and the charge–transfer coefficient(α) of 0.49, and thus displayed the features of an electrocatalyst.The practical use of the modified electrode had been used for the simultaneous detections of DA and UA in urine samples by using standard adding method with satisfactory results.2. A thiazole-based copolymer(PABT-DMSA) had been synthesized by electrochemical copolymerization of 2-aminobenzothiazole(ABT) and 2,3-dimercaptosuccinic acid(DMSA) on glassy carbon electrode(GCE), and it was used for the simultaneous detection of DA and UA. The performance of the PABT-DMSA/GCE towards the electrooxidation of DA, UA and XN had been investigated by CV and DPV methods. The results displayed that the modi?ed electrode not only exhibited excellent electrocatalytic activity toward the electrooxidations of DA, UA and XN in PBS(p H 7.0), but also could separate the weak oxidation waves of these species at bare GCE into three well-defined and strong oxidation peaks. The peak potential separations are 120 m V for DA–UA and 410 m V for UA–NO2- using DPV, which are large enough for the simultaneous determinations of DA, UA and XN. The linear concentration dependences of the DPV responses for DA, UA and XN are in the ranges of 0.1~360 μmol L-1,0.4~800 μmol L-1,0.8~1500 μmol L-1 with correlation coefficients of 0.9965, 0.9959 and 0.9965, respectively. The detection limits are 0.01 μmol L-1, 0.02 μmol L-1 and 0.07 μmol L-1 for DA, UA and XN, respectively(S/N=3). The modified electrode had been used for the simultaneous determinations of DA, UA and XN in human urine and serum samples by using standard adding method with satisfactory results.3. Poly(5-mercapto-1H-tetrazole-1-acetic acid)(PMTAA) film modified glassy carbon electrode(GCE) has been fabricated and used for selective and simultaneous detections of DA, UA and NO2- in 0.1 mol L-1 PBS(p H 6.0). The poly(5-mercapto-1H-tetrazole-1-acetic acid) film(PMTAA) modified GCE(PMTAA/ GCE) not only exhibits electro-catalytic effects towards the oxidations of DA, UA and NO2- with negatively shifted oxidation potentials and enhanced peak current responses, but also resolves the weak and overlapped voltammetric responses of DA, UA and NO2- into three strong and well-de?ned voltammetric peaks with both CV and DPV echniques, which can be employed for the selective and simultaneous determinations of DA, UA and NO2- in their mixture. Under the optimum conditions, the linear concentration dependences of the DPV current responses are observed for DA, UA and NO2- in the concentration ranges of 0.2~110 μmol L-1,1~600 μmol L-1 and 8~1100 μmol L-1, with the correlation coefficients of 0.9945, 0.9932 and 0.9944, respectively. The detection limits are 0.03 μmol L-1, 0.2 μmol L-1 and 0.5 μmol L-1 for DA, UA and NO2-, respectively(S/N=3). The practical application of the modified electrode has been investigated by the simultaneous determinations of DA, UA and NO2- in human urine samples by using standard adding method with satisfactory results.更多还原