三种电活性小分子对映体的电流识别研究

发布时间：2018-09-05 14:02

【摘要】：手性又称为不对称性,是广泛应用于化学和医学领域中的专业术语,属于三维空间物体的基本属性。当一个物质与其镜像不能重合,就称其为手性物质。手性也是生物系统的基本特征,构成生物系统的许多分子都是有手性的,常见的包括:人体所需基本营养素如糖类和蛋白质,遗传信息载体DNA,氨基酸对映体分子,酶,激素及结构复杂的天然有机大分子等。手性对映体分子通常表现出不同的生理活性,尤其是手性药物。对生命体而言,手性识别是一种重要的生命现象。因此对手性分子的分析、识别与检测在现代药学、医学、生命科学、食品营养学、农药学以及其他领域意义重大。电化学手性识别是利用电化学测试方法对手性对映体分子进行识别的一种分析方法,与色谱法、荧光法、毛细管电泳法和紫外吸收光谱法等相比,电化学方法具有灵敏度高、响应迅速、选择性好、制备简易、可重复等优点。在电化学分析方法中,常常借助纳米材料构建手性表面,这些纳米材料导电性好、比表面大有利于提高手性分析的灵敏度。本文利用电化学聚合膜、碳纳米管、金属纳米粒子、DNA等材料构建了三种手性传感界面,并研究了传感界面与电活性小分子对映体的相互作用。主要研究内容包括以下三部分:1.研究了氧化型谷胱甘肽(GSSG)与L-赖氨酸多层电化学聚合膜形成的手性表面,对抗坏血酸(AA)和异抗坏血酸(IAA)的相互作用。实验采用循环伏安法将GSSG和L-赖氨酸分步聚合在玻碳电极表面,用扫描电子显微镜(SEM)观察了聚合膜的表面形貌,用电化学循环伏安技术(CV)与交流阻抗技术(EIS)探究不同修饰电极的电化学行为,利用差分脉冲伏安法(DPV)探讨了聚合膜与AA和IAA相互作用后的电流变化。实验结果表明:该手性表面与AA和IAA均能产生作用,但与AA的作用更强,产生的电流信大于IAA,具有选择性识别作用。2.实验首先在玻碳电极表面修饰碳纳米管(MWCNT),再用循环伏安法电聚合L-精氨酸(p-L-Arg),然后利用恒电位法沉积金纳米粒子(Au NPs),最后通过Au-S键结合手性选择剂N-异丁酰基-L-半胱氨酸(NILC),得到NILC修饰的传感界面。用扫描电子显微镜(SEM)观察修饰材料的形貌特征,用方波伏安法(SWV)探究了所得手性界面与酪氨酸(Tyr)对映体之间的选择性作用,实验结果表明:NILC修饰的手性界面对D-Tyr的作用比L-Tyr更强,D-Tyr与L-Tyr电流差异明显,由此实现了对酪氨酸对映体的安培识别。3.用碳纳米管与铂钯纳米合金复合材料(MWCNT/Pt-Pd NPs)修饰玻碳电极,再修饰上手性选择剂分子小牛胸腺DNA,得到手性传感器并研究该传感器与色氨酸对映体(Trp)的选择性作用。采用SEM和X射线能谱仪(EDX)观测材料的的表面形貌及组成元素,采用CV等方法探究了修饰材料的电化学性质,同时利用DPV探讨修饰界面与色氨酸对映体之间的选择性作用。实验结果表明,该传感界面对L-Trp的电流响应强于D-Trp。
[Abstract]:Chirality, also known as asymmetry, is a specialized term widely used in chemistry and medicine. It belongs to the basic properties of three-dimensional space objects. When a substance does not coincide with its mirror image, it is called a chiral substance. Chirality is also the basic characteristic of biological system. Many molecules that make up biological system are chiral. The common ones include basic nutrients such as carbohydrate and protein, DNA, amino acid enantiomer molecule, enzyme, etc. Hormones and complex structure of natural organic macromolecules and so on. Chiral enantiomers usually exhibit different physiological activities, especially chiral drugs. Chiral recognition is an important phenomenon of life. Therefore, the analysis, recognition and detection of chiral molecules are of great significance in modern pharmaceutical, medical, life sciences, food nutrition, pesticide and other fields. Electrochemical chiral recognition is an analytical method for the recognition of chiral enantiomers by electrochemical measurement. Compared with chromatography, fluorescence, capillary electrophoresis and ultraviolet absorption spectrometry, electrochemical method has high sensitivity. It has the advantages of quick response, good selectivity, easy preparation and repeatability. In electrochemical analysis methods, chiral surfaces are often constructed by means of nano-materials. These nanomaterials have good electrical conductivity, which is more favorable to improve the sensitivity of chiral analysis than the surface. In this paper, three chiral sensing interfaces were constructed by using electrochemical polymeric films, carbon nanotubes, metal nanoparticles and DNA. The interaction between the sensing interfaces and electroactive enantiomers of small molecules was studied. The main research contents include the following three parts: 1. The chiral surface of oxidized glutathione (GSSG) and L-lysine multilayer electrochemical polymerization film was studied. The interaction between ascorbic acid (AA) and isoascorbic acid (IAA) was studied. GSSG and L-lysine were polymerized on the surface of glassy carbon electrode by cyclic voltammetry. The morphology of the film was observed by scanning electron microscope (SEM). Electrochemical behavior of different modified electrodes was investigated by electrochemical cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The current changes of polymer films interacting with AA and IAA were investigated by differential pulse voltammetry (DPV). The experimental results show that the chiral surface can act on both AA and IAA, but more strongly with AA, and the resulting current signal is larger than that of IAA,. 2. In this experiment, carbon nanotubes (MWCNT),) were modified on the surface of glassy carbon electrode and then electropolymerized L-arginine (p-L-Arg) by cyclic voltammetry. Then the gold nanoparticles (Au NPs), were deposited by potentiostatic method. Finally, the Au-S bond was used to bind the chiral selector N- isobutylol-L-semi-N- isobutylol. The NILC modified sensing interface was obtained by cystine (NILC),. The morphology of the modified materials was observed by scanning electron microscopy (SEM). The selective interaction between the chiral interface and tyrosine (Tyr) enantiomers was investigated by square wave voltammetry (SWV). The experimental results show that the effect of the chiral interface modified by D-Tyr on D-Tyr is stronger than that on L-Tyr, and the difference between D-Tyr and L-Tyr current is obvious, thus realizing amperometric recognition of tyrosine enantiomers .3. The glassy carbon electrode was modified with carbon nanotubes and platinum-palladium nanoalloy composites (MWCNT/Pt-Pd NPs) and the chiral selective molecular calf thymus DNA, was modified to obtain the chiral sensor. The selective interaction between the sensor and tryptophan enantiomer (Trp) was studied. The surface morphology and component elements of the modified materials were observed by SEM and X-ray energy spectrometer (EDX). The electrochemical properties of the modified materials were investigated by CV and the selective interaction between the modified interface and tryptophan enantiomers was discussed by DPV. The experimental results show that the current response of the sensing interface to L-Trp is stronger than that of D-Trp.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.1

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