基于环糊精和核酸适体的持久性有机污染物电化学传感研究

发布时间：2018-03-01 05:31

  本文关键词： 持久性有机污染物 电化学传感器 环糊精 核酸适体 纳米材料 石墨烯 碳纳米管 金纳米颗粒　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：持久性有机污染物(Persistent organic pollutants,POPs)是一类具有高毒、持久、生物积累性、远距离迁移性,严重危害人类健康和环境的人工合成的有机污染物。POPs大多具有致癌、致畸、致突变效应和遗传毒性,能干扰人体内分泌系统,并且广泛存在于全球范围内各种环境介质以及动植物组织器官和人体中,已经成为一个新的全球性问题。因此,发展高灵敏、高选择性的传感器痕量检测POPs刻不容缓。β-环糊精(β-cyclodextrin,β-CD)是由环糊精葡萄糖残基酶作用于葡萄糖聚合物形成的寡聚葡萄糖,由7个D-吡喃葡萄糖基以α-1,4葡萄糖苷键连接而成。β-环糊精可依据范德华力、疏水相互作用力、主客体分子间的匹配作用与许多无机、有机分子、无机离子结合成主客体包合物。核酸适体(简称“适体”,aptamer)是能特异结合蛋白质或其他小分子物质的寡聚核苷酸片段。适体作为一种新的识别分子,适体对靶分子有高度亲和力和严格特异性识别能力,因而适体生物传感器往往具有好的灵敏度和高选择性。利用环糊精或核酸适体特异性结合环境中痕量的污染物,并协同纳米材料(石墨烯、碳纳米管、多孔碳材料、金纳米颗粒)优异的物理、化学性能,本文制备了一系列电化学传感器,用于超灵敏检测POPs:(1)采用六亚甲基二异氰酸酯(HMDI)作为交联剂聚合β-CD,制备了β-CD-HMDI聚合物非共价功能化多壁碳纳米管(MWCNTs/Poly(β-CD-HMDI)复合材料,并采用傅里叶红外、X射线衍射法、扫描电镜、热重分析和电化学方法对其表征。基于MWCNTs/Poly(β-CD-HMDI)复合材料,成功地制备了一种新型电化学传感器,用于检测非电活性4,4’-二氯联苯(DPCB)。研究中以中性红(NR)做探针,由于主客体包合作用,NR进入环糊精空腔,在MWCNTs/Poly(β-CD-HMDI)/GC电极上出现明显的NR峰电流。由于环糊精对探针分子和目标分子的包合作用存在竞争关系,当DPCB存在时,DPCB分子取代NR分子,从而导致NR的峰电流下降。利用NR的峰信号变化,实现对DPCB的间接电化学检测。所制备的MWCNTs/Poly(β-CD-HMDI)/GCE电化学传感器具有好的灵敏度、重现性和稳定性,检测线性范围为2 nM～80 uM,检测限为0.4 nM(S/N=3)。(2)基于探针分子罗丹明B(Rh B)和目标分子双酚A(BPA)与电聚合β-环糊精/电还原石墨烯(Pβ-CD/EG)的主客体竞争包合作用,建立了一种新型电流比电化学传感器用于高灵敏检测双酚A。Rh B进入β-CD疏水内腔,在Pβ-CD/EG修饰玻碳电极上出现明显的氧化峰电流。双酚A存在时,与Rh B相比,BPA与β-CD的主客体结合能力更强,Rh B被BPA取代。因此,Rh B峰电流(IRh B)下降,BPA峰电流(I_(BPA))相应增加。在1～6000 nM浓度范围内,电流比I_(BPA)/IRh B与BPA浓度呈线性关系,检测限为52 pM(S/N=3)。本方案用于高灵敏度检测BPA,有望在实际环境样中检测有机污染物。(3)基于适体与目标分子BPA的特异性结合作用,制备了一种新型双信号电化学生物传感器,实现对BPA的高选择性、超灵敏检测。首先,在电极表面电沉金纳米颗粒(Au NPs),然后将适体DNA(DNA1)和与之互补的DNA链(c DNA)杂交的双链DNA自组装到电极表面,c DNA上标记有亚甲基蓝(MB),因而在电极上出现较强的MB电信号。当存在BPA目标分子时,适体与BPA结合,修饰有MB的c DNA会从双链DNA中解离出来,导致MB的电信号减弱,与此同时电极上出现BPA的电信号。本方案用于高灵敏度、高选择性检测BPA,在1 pM～100 nM浓度范围内,I_(BPA)/I_(MB)与BPA浓度呈线性关系,检测限为0.09 pM(S/N=3),有望用于实际环境样中有机污染物的检测。
[Abstract]:Persistent organic pollutants (Persistent organic, pollutants, POPs) is a kind of high toxicity, persistence, bioaccumulation, long-range transport of organic pollutants,.POPs synthetic serious harm to human health and the environment are carcinogenic, teratogenic, mutagenic effects and genetic toxicity, can interfere with the body's endocrine system, and widely exists in the various environmental media worldwide and the tissues of plants and animals and humans, has become a new global problem. Therefore, the development of high sensitive, high selective sensor POPs trace detection delay. B-cyclodextrin (beta beta -cyclodextrin, -CD) is formed by cyclodextrin glucosyl residues of enzymes in glucose polymer oligomeric glucose by 7 D- glycosyl to alpha -1,4 glucoside linkages and beta cyclodextrin. On the basis of Fan Dehua force, hydrophobic interaction, host guest molecule The match between many inorganic, organic molecules, inorganic ions to form host guest inclusion complexes. The aptamer (referred to as "aptamer", aptamer) is the specific binding to proteins or other small molecules oligonucleotides aptamer. As a new kind of molecular recognition, the aptamer with high affinity strict and specific recognition ability to the target molecule, so the aptamer biosensor has good sensitivity and high selectivity. The use of cyclodextrin or aptamer binding specificity of trace contaminants in the environment, and the coordination of nano materials (graphite, carbon nanotubes, porous carbon materials, gold nanoparticles) excellent physical and the chemical properties, a series of electrochemical sensors were prepared for ultrasensitive detection of POPs: (1) with six methylene diisocyanate (HMDI) as crosslinking agent was prepared by polymerization of beta -CD and beta -CD-HMDI polymer non covalently functionalized multi walled carbon Nanotubes (MWCNTs/Poly (beta -CD-HMDI) composite materials, and using Fourier transform infrared, X ray diffraction, scanning electron microscopy, thermogravimetric analysis and electrochemical method for its characterization. Based on the MWCNTs/Poly (beta -CD-HMDI) composites were successfully prepared by a novel electrochemical sensor, for the detection of non electric activity of 4,4 '- two chlorodiphenyl (DPCB). In order to study the neutral red (NR) as probe, the host guest inclusion, NR into the cavity of cyclodextrin, MWCNTs/Poly (beta -CD-HMDI) NR peak current appeared on /GC electrode. Because there is competition between the cyclodextrin and the probe molecule target molecule inclusion, when DPCB when DPCB molecules replace NR molecules, resulting in the peak current of NR decreased. The change peak signal of NR, realize the indirect electrochemical detection for DPCB expression. The prepared MWCNTs/Poly (beta -CD-HMDI) /GCE electrochemical sensor has good sensitivity and reproducibility. 绋冲畾鎬，

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