【作者】 张凤媛；

【导师】 王春明；

【作者基本信息】 兰州大学 ， 分析化学， 2012， 博士

【摘要】 本博士学位论文以石墨烯基复合材料修饰电极为研究手段,将其应用于几种生物分子的电化学行为研究,在此基础上建立了相关生物分子的电化学分析方法。研究内容包括：首先通过电聚合法和液相还原法制备了Pt/石墨烯、聚精氨酸/石墨烯、Cu2O/石墨烯、CuS/石墨烯四种石墨烯基复合纳米材料并将其修饰于电极表面；用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、红外光谱(FTIR)等分析手段对这些材料和相应的修饰电极进行表征；用所制备的修饰电极对多巴胺等数种生物分子进行了必要的电极行为、系统的分析条件、实际样品的分析验证和干扰试验等研究。简述如下：1.采用微波辅助法快速合成Pt/石墨烯纳米复合物,并用XRD, TEM和XPS对其进行表征。结果表明Pt纳米颗粒均匀的分散在石墨烯表面,其平均粒径为3.2nm。循环伏安实验的结果表明：Pt/石墨烯复合物修饰的玻碳电极对H2O2具有很好的电催化活性。安培测量结果表明Pt/石墨烯修饰电极对H2O2响应迅速,在4s内达到稳态,线性范围是2.5×10-6-6.65×10-mol·L-1,检测限为8×10-7mol·L-1。另外,在生理pH条件下,在多种干扰物质存在的情况下,该修饰电极对H2O2具有非常好的选择性。2.采用简单的一步电化学方法成功制备聚精氨酸/石墨烯复合膜修饰电极并将其用于尿酸、黄嘌呤和次黄嘌呤的同时检测。结果表明：该修饰电极对这三种物质具有很好的电催化活性。通过差示脉冲伏安实验得到尿酸、黄嘌呤和次黄嘌呤在聚精氨酸/石墨烯复合膜修饰电极上的线性范围分别为1.0×10-7-1.0×10-5mol·L-1,1.0×10-7-1.0×10-5mol·L-1和2.0×10-7-2.0×10-5mol·L-1,检测限分别为5×10-8mol·L-1,5×10-8mol·L-1和1×10-7mol·L-1(S/N=3)。此外,该修饰电极还具有良好的选择性和灵敏度,在同时测定尿样中尿酸、黄嘌呤和次黄嘌呤的实验中取得了满意的结果。3.通过乙二醇还原法制备氧化亚铜(Cu2O)和石墨烯的纳米复合材料,样品的形貌用XRD, XPS, TEM和SEM表征。采用循环伏安法评价Cu2O/石墨烯修饰电极对多巴胺的电化学性能。结果表明：与裸玻碳电极、Cu2O修饰电极和石墨烯修饰电极相比,Cu2O/石墨烯修饰电极对多巴胺具有很高的电催化活性,其检测限为1×10-8mol·L-1,线性范围是1.0×10-7-1.0×10-5mol·L-1,并且在伴有高浓度尿酸的情况下对多巴胺具有极好的选择性和灵敏性,在多巴胺实际样品的检测中也具有很好的结果。4.采用乙二醇还原法制备硫化铜(CuS)和石墨烯的纳米复合材料并将其用于检测七叶亭。结果表明,CuS/石墨烯修饰电极对七叶亭具有优异的电化学催化活性,在优化的实验条件下,该修饰电极可以实现七叶亭灵敏、简便和快速的检测并拥有较宽的线性范围及较低的检测限。更多还原

【Abstract】 In this paper, we studied the electrochemical behavior of several biological molecules on the graphene-based nanocomposites modified electrodes and established the electrochemical analysis of corresponding biomolecules. The major contents including:Pt/graphene, Cu2O/Graphene and CuS/Graphene were synthesized through liquid phase reduction method, poly (L-Arginine)/graphene composite film modified electrode was successfully prepared via a facile one-step electrochemical method. These nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and fourier transform infrared. Meanwhile, graphene-based nanocomposites modified electrodes were prepared and used to investigate the electrode behavior, the analytical conditions, the actual sample analysis and the interference tests of several kinds of biological molecules. The major contents are described as follows:1. Pt/graphene nanocomposites were rapidly synthesized via a one-step microwave-assisted method, and characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results exhibited that Pt nanoparticles (NPs) were well-dispersed on the graphene surface with the average diameter of about3.2nm. Cyclic voltammetry results demonstrated that the Pt/GN nanocomposites modified glassy carbon electrode exhibited excellent electrocatalytic activity to the reduction of H2O2. Amperometric response results indicated that the modified elelctrode displayed a fast response of less than4s with linear range of2.5×10-6-6.65mol·L-1and a relatively low detection limit of8×10-7mol·L-1(S/N=3). In addition, the Pt/GN/GCE showed good selectivity for H2O2detection in the presence of several interfering species under physiological pH condition.2. Poly (L-Arginine)/graphene composite film modified electrode was successfully prepared via a facile one-step electrochemical method and used for simultaneous determination of uric acid (UA), xanthine (XA) and hypoxanthine (HX). The electrochemical behaviors of UA, XA and HX at the modified electrode were studied by cyclic voltammetry and differential pulse voltammetry (DPV), and showed that the modified electrode exhibited excellent electrocatalytic activity towards the oxidation of the three compounds. The calibration curves for UA, XA and HX were obtained over the range of1.0×10-7-1.0×10-5mol·L-1,1.0×10-7-1.0×10-5mol·L-1and2.0×10-7-2.0×10-5mol·L-1by DPV, respectively and the detection limits for UA, XA and HX were5×10-8mol·L-1,5×10-8mol·L-1and1×10-7mol·L-1(S/N=3), respectively. With good selectivity and high sensitivity, the modified electrode has been applied to simultaneous determination of UA, XA and HX in human urine with satisfactory result.3. Cu2O/Graphene nanocomposites were synthesized via reduction of ethylene glycol. Its morphology was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Cyclic voltammetry was used to evaluate the electrochemical response of a glass carbon electrode (GCE) modified with the nanocomposite towards dopamine (DA). Compared to the bare GCE, the Cu2O nanoparticles modified electrode and the graphene modified electrode, the nanocomposites modified electrode displays high electrocatalytic activity in giving an oxidation peak current that is proportional to the concentration of DA in the range from1.0×10-7to1.0×10-5mol·L-1,with a detection limit of1×10-8mol·L-1(S/N=3). The modified electrode shows excellent selectivity and sensitivity even in the presence of high concentration of uric acid and can be applied to determine DA in real samples with satisfactory results.4. CuS/graphene nanocomposites were synthesized via reduction of ethylene glycol and used for determination of esculetin. Electrochemnical measurement indicates that CuS/graphene nanocomposites modified electrode exhibits an excellent electrochemical activity of esculetin. Under the optimized conditions, the modified electrode was successfully employed for the voltammetric determination of esculetin with a low detection limit, wide linear range.更多还原