黄素辅酶在氧化锌纳米棒光电极上的光致电化学响应及其应用的研究

发布时间：2018-12-27 10:21

【摘要】：黄素辅酶,包括黄素单核苷酸(FMN)和黄素腺嘌呤二核苷酸(FAD)以及它们的前体核黄素(RF),是黄素蛋白(主要为氧化还原酶)的辅基,它可以接受2个氢而还原为FMNH2或FADH2,参与人体内多种氧化还原反应,促进糖、氨基酸、脂和蛋白质的代谢。因此,黄素辅酶及其相关蛋白质的测定具有重要的意义。如果黄素辅酶能作为电子给体,与光敏纳米材料组成一种新的光致电化学(PEC)反应系统,借助于这个PEC分析的平台,就能建立测定黄素辅酶的新方法,是非常有意义的工作。本文利用四电极双通道电化学系统,在电化学还原黄素辅酶后,使其与光激发下的氧化锌纳米棒光电极(ZnONRP)发生PEC反应,构建了一种纳米界面光电极与黄素辅酶的PEC反应通道,通过光电流的测量实现了对黄素辅酶的直接检测。本文主要做了以下三个方面的研究:1.用电化学沉积法制备了ZnONRP,优化了制备方法,并通过扫描电镜(SEM)和X射线衍射谱(XRD)对电极的修饰结果进行了表征。以制备的ZnONRP作为光敏界面,由第二工作电极还原RF为RFH2,使其与ZnONRP发生PEC反应,建立了以RF为电子供体,ZnONRP为电子受体的PEC反应系统。基于ZnONRP对RF的光致电化学响应,通过检测光电流实现了对RF的定量分析。文中讨论了光电化学敏感界面对RF的响应机理,讨论了偏压、电解液pH值、光照强度以及工作电极与第二工作电极之间的距离对PEC反应和测定RF的影响。在优化的实验条件下,光电流强度与1.00?10-11?1.00?10-6 mol/L RF浓度的对数值成正比,检测限为6.0?10-12 mol/L(S/N=3),灵敏度为195.6 nA/logC(μmol/L)。对实际样品测定的相对标准偏差(RSD)小于6.25%,回收率为99.0%?104%,常见生化物质对RF的光电流响应无干扰。2.用FMN和FAD代替RF,利用黄素辅酶在ZnONRP上的PEC反应,创建了黄素辅酶的PEC分析法。在优化的实验条件下,光电流强度与FMN或FAD浓度对数成正比,在1.00?10-11?1.00?10-6 mol/L的浓度范围内,光电流强度与FMN和FAD浓度的对数值成正比,线性相关系数R2分别为0.996和0.998,检出限分别为8.00?10-12和5.00?10-12 mol/L(S/N=3)。3.FAD是葡萄糖氧化酶(GOD)的辅酶,葡萄糖是GOD的底物,用葡萄糖还原GOD中的FAD,再利用壳聚糖的电荷传递功能,通过直接电子转移和ZnONRP-FAD光致电化学系统,建立了葡萄糖的PEC分析法。在优化了壳聚糖的浓度、GOD负载量和电解液pH后,光电流强度与葡萄糖浓度在0.60~2.80mmol/L浓度范围内呈指数关系,相关系数R2=0.991,检出限为0.20 mmol/L。将该方法用于对人血清中葡萄糖含量的检测,RSD为0.86%,回收率为98.5%~103.3%。
[Abstract]:Flavin coenzymes, including Flavin mononucleotide (FMN) and Flavin adenine dinucleotide (FAD), as well as their precursor riboflavin (RF), are the counits of the Flavin protein (mainly redox enzyme). It can accept two hydrogen and reduce to FMNH2 or FADH2, in human body to participate in a variety of redox reactions, promoting the metabolism of sugar, amino acids, lipids and proteins. Therefore, the determination of Flavin coenzyme and its related proteins is of great significance. If Flavin coenzyme can be used as electron donor to form a new photochemical (PEC) reaction system with Guang Min nanomaterials, with the help of this PEC analysis platform, a new method for the determination of Flavin coenzyme can be established, which is of great significance. In this paper, a four-electrode two-channel electrochemical system was used to make PEC reaction with photoinduced photoelectrode (ZnONRP) of zinc oxide nanorods after electrochemical reduction of Flavin coenzyme. A PEC reaction channel between photoelectrode and Flavin coenzyme was constructed, and the direct detection of Flavin coenzyme was realized by photocurrent measurement. This paper mainly does the following three aspects of research: 1. The preparation method of ZnONRP, was optimized by electrochemical deposition. The modified results of the electrode were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Using the prepared ZnONRP as Guang Min interface, the second working electrode was used to reduce RF to RFH2, to induce PEC reaction with ZnONRP. A PEC reaction system with RF as electron donor and ZnONRP as electron receptor was established. Based on the photochemical response of ZnONRP to RF, the quantitative analysis of RF is realized by detecting photocurrent. The response mechanism of photochemically sensitive interface to RF is discussed. The effects of bias voltage, pH value of electrolyte, illumination intensity and the distance between the working electrode and the second working electrode on the PEC reaction and the determination of RF are discussed. Under the optimized experimental conditions, the photocurrent intensity is proportional to the logarithmic value of the concentration of 1.00 ~ (-11) ~ (-1) ~ (-1) ~ (10 ~ (-6) mol/L RF, and the detection limit is 6.0 ~ 10 ~ (-12) mol/L (S/N=3). The sensitivity is 195.6 nA/logC (渭 mol/L). The relative standard deviation (RSD) for the actual samples was less than 6.25, the recovery was 99.0 and 104, and the common biochemical substances had no interference with the photocurrent response of RF. 2. Using FMN and FAD instead of RF, the PEC analysis method of Flavin coenzyme was established by using PEC reaction of Flavin coenzyme on ZnONRP. Under the optimized experimental conditions, the photocurrent intensity is in direct proportion to the logarithm of FMN or FAD concentration. In the range of 1.00 ~ (-11) ~ (-1) ~ (-1) ~ (-6) mol/L, the optical current intensity is directly proportional to the logarithmic values of FMN and FAD concentrations. The linear correlation coefficient R2 was 0.996 and 0.998, and the detection limits were 8.00 ~ (-12) and 5.00 ~ (-12) mol/L (S/N=3), respectively. 3.FAD was the coenzyme of glucose oxidase (GOD), and glucose was the substrate of GOD. The FAD, in GOD was reduced with glucose and the charge transfer function of chitosan was utilized. The PEC analysis of glucose was established by direct electron transfer and ZnONRP-FAD photochemical system. When the concentration of chitosan, GOD loading and electrolyte pH were optimized, there was an exponential relationship between the photocurrent intensity and glucose concentration in the range of 0.60~2.80mmol/L concentration, the correlation coefficient was R2N 0.991and the detection limit was 0.20 mmol/L.. The method was applied to the determination of glucose in human serum. The RSD was 0.86 and the recovery rate was 98.5 and 103.3%.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.1

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