【作者】 邹翠娥；

【导师】 杜玉扣；

【作者基本信息】 苏州大学 ， 分析化学， 2018， 博士

【摘要】 抗坏血酸（AA）、尿酸（UA）和多巴胺（DA）是人类和一些动物体内不可或缺的生物小分子,对生物体的生命健康具有非常重要的作用。亚硝酸钠（NaNO₂）通常作为食品添加剂和腐蚀抑制剂出现在我们的日常生活中,也被认为是环境的重要污染物之一。芦丁（RT）则是治疗高血压和脑出血等疾病的一类有效药物。这些生物小分子在人体内含量的异常通常会影响人体健康,例如,人体内尿酸浓度的异常会引起如痛风、关节炎、痛风性肾病、高尿酸血症和贫血等一系列疾病;而人体内亚硝酸盐的超标,不仅会使血红蛋白中的亚铁离子氧化成三价铁离子而导致人体中毒,更会在特定条件下形成亚硝胺,亚硝胺是肝癌和高血压等疾病的高致病化学物质之一。基于以上这些原因,开发高效、快速检测这些生物小分子的测试方法具有非常重要的意义。由于AA、DA、UA、NaNO₂和RT均具有一定的电化学活性,且电化学检测技术因其灵敏度高、操作简便、成本低和响应迅速等优点,在对生物小分子的检测中受到越来越多的关注,然而由于裸玻碳电极（GCE）电子传输效率低,在对AA、DA、UA、NaNO₂和RT的电化学检测中,其很难获得令人满意的结果,因此制备出具有高灵敏度和选择性的检测电极已经成为传感器研究的重中之重。近年来,科研工作者做了大量对石墨烯-贵金属纳米复合材料在生物传感器中的应用研究。石墨烯（GE）自发现以来,由于其具有独特的比表面积、特殊的电子性能、优良的物理化学特性以及较高的化学稳定性和热稳定性,已经引起研究人员的广泛关注。而贵金属纳米粒子也因其优秀的催化性能、较小的尺寸和较高的比表面积在电化学生物传感器方面扮演着越来越重要的角色。在石墨烯与贵金属纳米粒子独特性能的基础上,将贵金属纳米粒子与二维碳材料石墨烯进行复合得到的纳米材料可能会在生物传感器中具有更好的应用价值。在本论文工作中,我们将石墨烯-贵金属纳米粒子复合的纳米材料应用于AA、DA、UA、NaNO₂和RT的检测中,主要研究内容包括以下四个方面:（1）通过电沉积方法将球状金纳米粒子修饰的三维花状石墨烯（f-GE）纳米复合物成功地制备在玻碳电极的表面,并将Au/f-GE/GCE电极用于亚硝酸盐的电化学检测。我们通过扫描电子显微镜（SEM）、X射线能谱仪（EDX）、X射线衍射分析（XRD）对沉积的金纳米粒子及石墨烯的形貌和结构进行了表征,循环伏安法（CV）和差分脉冲伏安法（DPV）则用于不同修饰电极对亚硝酸钠的电化学检测。结果发现,与电极f-GE/GCE和Au/GCE相比,Au/f-GE/GCE在0.78 V处具有更加明显和尖锐的氧化峰,而且亚硝酸根离子的浓度与其对应的氧化峰电流具有优良的线性关系,其线性范围为0.13-20375.98μM,最低检测限为0.01μM（S/N=3）。另外,实验结果还证明了Au/f-GE/GCE具有较好的重现性、稳定性和抗干扰性,同时对亚硝酸盐的实样检测中该电极具有良好的回收率。（2）氮掺杂石墨烯（NG）负载的金银纳米环复合材料修饰的玻碳电极（Au-Ag/NG/GCE）作为一种新型电极对芦丁进行电化学检测。通过透射电子显微镜（TEM）、X射线能谱仪（EDX）及X射线光电子能谱（XPS）对合成的纳米复合材料的形貌和结构特征进行了表征。与其它电极相比（Au/NG/GCE、Ag/NG/GCE、NG/GCE）,氮掺杂石墨烯负载的金银纳米环复合材料在对芦丁的电化学检测中具有更好的电化学响应,这可能是由于金属金、银与氮掺杂石墨烯之间的协同效应导致的。在最佳实验条件下,该制备电极对芦丁的检测线性范围为0.05μM-241.20μM,最低检测限为0.01μM（S/N=3）。此外,实验结果证明该制备电极具有优良的重复性、稳定性及抗干扰性,并在芦丁的实样检测中表现出潜在的应用价值。（3）以钯纳米立方体作为结构导向核心,利用简单的方法成功合成了钯金核壳结构的纳米粒子,并将其与石墨烯充分混合后修饰玻碳电极,应用于抗坏血酸、尿酸和多巴胺的同时检测。由于金属钯、金和石墨烯之间的协同效应,Pd@Au/RGO/GCE在抗坏血酸、尿酸和多巴胺的同时检测中表现出优良的电化学活性、较强的电子传递能力、较好的选择性和灵敏度。循环伏安法和差分脉冲伏安法用于对三种物质检测的电化学表征,结果发现,被检测物质的浓度与氧化峰电流之间存在良好的线性关系,AA、DA和UA的检测范围分别为50.00-2856.63μM、1.00-400.56μM、5.00-680.76μM。从各物质的差分脉冲伏安曲线可以得到三种物质的最低检测限分别为24.88μM、0.20μM和1.25μM。（4）利用简单的方法合成了石墨烯负载的钯金纳米粒子复合材料,通过将合成的复合材料修饰的玻碳电极应用于AA、DA、UA和RT的电化学检测。通过TEM、EDX、XRD等手段对纳米材料的结构进行表征,结果表明金钯纳米粒子是合金结构,且金钯纳米粒子均匀地分散在石墨烯的表面。利用差分脉冲伏安法和循环伏安法对被测溶液中的AA、DA、UA和RT进行电化学检测,其检测范围分别为12.50-700.00μM（AA）、1.25-73.75μM（DA）、2.50-66.25μM（UA）和0.025-5.63μM（RT）,最低检测限分别为12.50μM、0.75μM、2.50μM和0.025μM。此外,该制备电极在AA、DA、UA及RT的实样检测中也表现出较好的检测性能并得到了较高的回收率。更多还原

【Abstract】 Ascorbic acid（AA）,uric acid（UA）and dopamine（DA）are indispensable small biomolecules,which play an important role in human and animal health.Nitrite（NaNO₂）,widely applied in our daily life as a corrosion inhibitor and an additive in food industry,has been recognized as an alarming pollutant to the environment.Rutin（RT）is one of the effective components in drugs for the treatment of high blood pressure and cerebral hemorrhage.For these biomolecules,abnormal content in human body will influence our health.For instance,irregular UA content in blood may lead to some diseases such as gout,arthritis,gouty nephropathy,hyperuricemia and anemia.An excessive nitrite level in human body,not only can lead to the irreversible oxidation of hemoglobin to methemoglobin,but also can react with dietary components to form a nitrosamine,resulting in cancer and hypertension.Accordingly,it is of great significance to develop efficient methods to detect these small biomolecules.Owing to the electrochemical activity of AA,DA,UA,NaNO₂ and RT,electrochemical techniques have attracted great attention due to their high sensitivity,ease of handling and electrode fabrication,low cost and short response time.However,it’s hard to get satisfying result to determine AA,DA,UA,NaNO₂ and RT electrochemically on bare glassy carbon electrode（GCE）since bare GCE has poor electron transfer ability.Hence,it is extremely important to prepare an electrode with higher selectivity and sensitivity for the reliable detection of AA,DA,UA,NaNO₂and RT.Recently there have been many studies on graphene–noble metal nanocomposites acting as electrochemical biosensors.Graphene（GE）has attracted particular attention due to its large specific surface area,unique electronic properties,excellent physicochemical properties,high chemical and thermal stability.In addition,noble metal nanostructures have been playing an important role in electrochemical biosensors due to their excellent catalytic capability,unique dimension property and high effective surface area.To this end,the combination of noble metal-based NPs and the special 2D carbon-based material GE at the nanoscale dimension offers great promise for improved applications.In our work,graphene-noble metal nanocomposites are used to determine AA,DA,UA,NaNO₂ and RT electrochemically.The research is presented in the four sections described below:（1）The spherical Au nanoparticles and 3D flower-like structure graphene were successively deposited on glassy carbon electrode to obtain Au/f-GE/GCE via a two-step electrodeposition method for the detection of NaNO₂.The morphology and elemental compositions as well as crystal structures were confirmed by scanning electron microscopy（SEM）,energy dispersive X-ray spectroscopy（EDX）and X-ray diffraction measurements（XRD）.Electrochemical measurements including cyclic voltammetry（CV）and differential pulse voltammetry（DPV）were used to evaluate the electrochemical behaviors of NaNO₂on the as-prepared electrode.Compared with f-GE/GCE and Au/GCE,Au/f-GE/GCE showed a sharper and more obvious oxidation peak at 0.78 V.The oxidation peak current of NaNO₂ on Au/f-GE/GCE was linearly proportional to its concentration in the range from 0.13 to 20375.98μM,with a detection limit of 0.01μM（at S/N=3）.Furthermore,it also demonstrated that the as-prepared electrode exhibited excellent reproducibility and long-term stability,as well as good recovery when applied to the determination of NaNO₂in pickled pork samples.（2）A hybrid nanostructure of Au-Ag nanorings decorated by N-doped graphene（NG）was utilized as an electrocatalyst to construct a novel electrochemical sensor.Transmission electron microscopy（TEM）,Energy dispersive X-ray spectroscopy（EDX）and X-ray photoelectron spectroscopy（XPS）were used to characterize the as-prepared composites.The Au-Ag nanorings/NG modified electrode exhibited a much better electrochemical response for rutin than the Au/NG,Ag/NG and NG electrodes due to the synergestic catalytic effect between the Au-Ag nanorings and NG.Under optimal conditions,the electrochemical sensor of the Au-Ag nanorings/NG exhibited a wide linear range from0.05μM to 241.20μM with a low detection limit of 0.01μM（S/N=3）.In addition,the proposed sensor also displayed good repeatability and long-term stability,all of which are essential for applications in bioassay analysis.（3）Using Pd nanocubes as the structure-directing cores,a facile method for the fabrication of PdAu core-shell（PdAu）heterostructures has been successfully developed.The as-prepared Pd@Au was further modified by reduced graphene oxide（RGO）to obtain Pd@Au/RGO.The glassy carbon electrode fabricated by Pd@Au/RGO was employed to detect ascorbic acid,dopamine and uric acid simultaneously.Owing to the synergistic effect among Au,Pd and RGO,the Pd@Au/RGO/GCE demonstrates excellent electrocatalytic activity,electron transfer capability,selectivity and sensitivity in the analysis of AA,DA and UA.CV and DPV were used to evaluate the electrochemical behaviors of AA,UA and DA on the as-fabricated electrode.Good linear calibration plots for AA,DA and UA were established by simultaneously increasing the concentration of AA,DA and AA in the ranges of 50.00-2856.63μM,1.00-400.56μM and 5.00-680.76μM,respectively.The individual DPVs for AA,DA and UA were also investigated and the detection limits were found to be 24.88μM,0.20μM and 1.25μM,respectively.（4）A facile method was employed to develop PdAu bimetallic nanocomposite（PdAu）successfully.The synthesized PdAu nanoparticles were further modified by reduced graphene oxide to obtain PdAu/RGO.The glassy carbon electrode fabricated by the as-prepared PdAu/RGO was utilized to determine ascorbic acid,dopamine,uric acid and rutin electrochemically.The synthesized PdAu/RGO nanoparticles were characterized by TEM,EDX and XRD,which revealed that the Au and Pd were alloyed and distributed evenly on the thin structured reduced graphene oxide.CV and DPV were utilized to evaluate the electrochemical performances toward AA,UA,DA and RT on the as-fabricated electrode.The individual DPV for AA,DA,UA and RT were studied and good linear relationship was observed for all the four materials in the ranges of12.50-700.00μM,1.25-73.75μM,2.50-66.25μM and 0.025-5.63μM,respectively,with individual detection limits of 12.50μM,0.75μM,2.50μM and 0.025μM,respectively.AA,DA and UA were determined simultaneously via CV and DPV.The simultaneous analysis of AA,DA and RT was also investigated using CV and DPV.Additionally,the modified electrode has fairly good performance when used in the analysis of real samples to determine the content of AA,DA,UA and RT.更多还原