【作者】 肖春辉；

【导师】 陈金华；

【作者基本信息】 湖南大学 ， 化学工程与技术， 2012， 博士

【摘要】 电化学传感器因其构造简单，成本低廉，灵敏度高，选择性、稳定性和重现性好等优点，在化学传感领域得到十分广泛的应用。电极上的修饰材料与电化学传感器的性能具有密切联系，因此寻求适当的电极修饰材料以提高电化学传感器的性能一直是人们研究的主要方向之一。各种新型微/纳米碳材料（如活性碳、碳纳米管、硼氮掺杂碳、石墨烯等）因其良好的导电性、微观形貌可控及易功能化等物理化学特性，在电化学传感中得到广泛应用。另一方面,室温离子液体(RTILs)因为其良好的离子导电性能，极低的蒸汽压，宽的电化学窗口等特点，可以同时做为非水溶剂和电解质，在电化学传感研究领域具有广阔的应用前景。本论文基于新型碳材料和室温离子液体开展了一系列关于电化学传感器的研究工作，具体如下：（1）制备聚合型离子液体包裹的碳纳米管(PIL-CNTs)并应用于氧化还原型蛋白酶的固定、直接电化学和生物传感研究。通过透射电子显微镜(TEM)、热重分析(TGA)和傅里叶变换红外光谱(FT-IR)考察了PIL-CNTs的表面形貌及PIL的质量百分含量。相对于未修饰的CNTs，PIL-CNTs在水中具有更好的分散性以及表现出对O2和H2O2更优异的电催化氧化还原性能。另外将葡萄糖氧化酶(GOD)固定在PIL-CNTs修饰的玻碳电极(GC)电极上，GOD分子呈现出优异的直接电化学行为。同时，该电极(GOD/PIL-CNTs/GCE)对葡萄糖检测具有良好的电化学传感性能：宽线性范围（可达6mM）,高灵敏度(0.853μA mM-1)以及优良的稳定性和选择性。（2）利用CNTs和高锰酸钾之间的直接氧化还原反应，制备了一维毛虫状的二氧化锰-碳纳米复合材料(MnO2-C)。所制备的MnO2-C纳米复合材料主要由-MnO2纳米片组成，具有独特的微观结构，高比表面积(200m2/g)以及优良的导电性能。通过壳聚糖水凝胶电化学共沉积法制得MnO2-C复合材料修饰玻碳(MnO2-C/chit/GC)电极。该电极对L-半胱氨酸电化学氧化具有良好的特异性催化作用。同时，采用安培法研究了(MnO2-C/chit/GC)电极对L-半胱氨酸的电化学传感性能，在优化的实验条件下，响应快（7秒以内），线性范围宽(0.5-680μM)，检测限低(22nM)，稳定性高（在一个月之后响应信号仍然没有任何衰减），并且抗干扰能力强（对谷胱甘肽和其他可氧化氨基酸包括色氨酸，酪氨酸，L-赖氨酸和甲硫氨酸等的响应几乎可以忽略）。（3）采用模板法成功制备新型氮掺杂碳空心微球(HNCMs)，并且研究HNCMs修饰玻碳(HNCMs/GC)电极对尿酸(UA)、抗坏血酸(AA)和多巴胺(DA)三种有机小分子同时检测的传感性能。与裸GC和CNTs修饰GC(CNTs/GC)电极相比，HNCMs/GC电极对UA、AA和DA具有更高的催化氧化活性。而且HNCMs/GC电极上AA和DA、DA和UA的氧化峰电位差分别增至212mV和136mV，优于CNTs/GC电极上的峰电位差（168和114mV）。在UA、AA和DA共存体系中，UA、AA和DA的检测线性范围分别为5-30μM，100-1000μM和3-75μM，检测限(S/N=3)分别为0.04μM，0.91μM和0.02μM。此外，HNCMs/GC电极被证实可以检测人体尿液中的尿酸，并能有效检测超出正常浓度范围的AA或DA。为实际样品中UA、AA和DA的同时检测提供了一种潜在的应用材料。（4）首先采用高温裂解多巴胺聚合物法制备氮掺杂碳层修饰碳纳米管纳米复合材料(CNX-CNTs),并在该材料表面固载高分散、窄粒径分布的铂纳米颗粒(PtNPs)得到纳米复合材料Pt/CNX-CNTs，并研究了其在安培型葡萄糖酶传感器中的应用。分别采用透射电子显微镜(TEM)、循环伏安法(CV)和计时电流法(i-t)对该复合物的形貌特性及其电化学性质进行了表征。结果表明，碳纳米管表面被修饰了一层厚度约为9nm CNX层，并且在CNX-CNTs表面均匀地分散粒径为1.7±0.5nm的PtNPs。相比于未经处理的CNTs表面固载铂纳米颗粒的复合物(Pt/CNTs)，Pt/CNX-CNTs对过氧化氢的电化学氧化具有更优的催化活性。以Pt/CNX-CNTs为电极材料构建的葡萄糖酶生物传感器具有在不同pH条件下稳定、灵敏度高(66.51μA mM-1cm-2)、检测限低(0.4μM)、线性范围宽(0.01-6mM)和稳定性高的特点。（5）研究三硝基甲苯(TNT)和二硝基甲苯(DNT)在室温离子液体(RTILs)中的氧化还原动力学过程，并分别从以下几个因素进行评估：（1） RTILs阴阳离子结构的影响；（2） RTILs物理参数（如粘度、电导率、溶剂化作用等）的影响；（3）环境（温度和湿度）的影响。考察了TNT和DNT在RTILs电极体系中的电化学传感性能。对TNT和DNT的检测限分别达到190和230nM，线性范围可达100μM。此外，将TNT和DNT及其混合物(1:1)的电化学响应数据进行线性判别分析(LDA)，三种物质的分类精度达到100%。同时该体系在TNT和DNT浓度分别为0.27ppm (1.2nM)和2.05ppm (11.3nM)的气相中，也显示出较强的电化学响应，表明RTILs在气相传感器中可以作为理想的气体预富集材料从而提高灵敏度，并因其理化性质多样的特点，有望应用于电化学传感从而提高其响应灵敏度和选择性。（6）本章以石英晶体金电极作为工作电极，以离子液体为非水电解质溶液，采用实时的EQCM联用技术研究了离子液体中的氧气电化学还原过程，分析还原过程中产生QCM响应的原因，并研究离子液体的理化性质对EQCM响应的影响。EQCM的结果提供了其它方法不能提供的电化学过程中的动态信息，有利于研究循环伏安扫描及氧气还原对离子液体/电极界面变化的作用。并在该电极体系中考察氧气的电化学传感性能，结果表明，该体系对氧气的传感性能受阴阳离子结构的影响，对氧气电化学传感的检测限最低可达0.05vol.%，电化学响应与0%和20%之间的氧气浓度呈线性关系。电极体系在超过60天过后依然保留原有响应的98%，显示出该传感电极优越的实际操作性能。更多还原

【Abstract】 The electrochemical method has wide applications because of its easy preparation,low cost, high sensitivity, excellent selectivity, stability and reproducibility. Since thecharacteristics of the electrochemical biosensors greatly rely on the materials modifiedon the electrodes, in order to improve the performance of the biosensor, developingsuitable electrode materials is one of the most interesting projects. Novel carbonmaterials (such as active carbon, carbon nanotubes, B/N doped carbon, graphene et al.),due to unique physiochemical properties including excellent conductivity,morphology-controllable synthesis and easy functionalization, have been widely usedin electrochemical biosensor. On the other hand, room temperature ionic liquids(RTILs) can be used for both of solvent and electrolyte due to its intrinsic ionicconductivity, extremly low vapor potential, wide electrochemical window, which havebeen attracted wide consideration in electrochemical sensors. In this t hesis, a fewelectrochemical sensors based on carbon materials and RTILs have been developed, ofwhich the main points are summarized as follows:(1) Polymerized ionic liquid-wrapped carbon nanotubes (PIL-CNTs) were firstlydesigned for direct electrochemistry and biosensing of redox proteins. The CNTs werecoated successfully with polymerized ionic liquid (PIL) layer, as verified bytransmission electron microscopy (TEM), thermogravimetric analysis (TGA) andFourier transform infrared (FT-IR) spectroscopy. The PIL-CNTs were dispersed betterin water and showed superior electrocatalysis toward O2and H2O2comparing topristine CNTs and the mixture of IL monomer and CNTs. With glucose oxidase (GOD)as a protein model, the direct electrochemistry of the redox protein was investigated onthe PIL-CNTs modified glassy carbon (GC) electrode and excellent directelectrochemical performance of GOD molecules was observed. The proposedbiosensor (GOD/PIL-CNTs/GC electrode) displayed good analytical performance forglucose with linear response up to6mM, response sensitivity of0.853μA mM-1, goodstability and selectivity.(2) A novel one-dimensional (1-D) caterpillar-like manganese dioxide-carbon(MnO2-C) nanocomposite has been synthesized by a direct redox reaction betweencarbon nanotubes and permanganate ions for the first time. The as-preparednanostructured MnO2-C composite mainly consisting of-MnO2nanoflakes had a unique microstructure, high specific surface area (200m2/g) and favourableconductivity. The MnO2-C composite, added as a modification to the glassy carbon(GC) electrode via a direct electrochemical co-deposition process with a chitosanhydrogel, was found to exhibit excellent catalytic activity toward L-cysteineelectro-oxidation because the specific interaction between the-SH group of L-cysteineand solid MnO2occurred to form surface complexes. A determination of L-cysteine atthe MnO2-C/chitosan/GC electrode was carried out by amperometric measurement.Under the optimum experimental conditions, the detection response for L-cysteine wasfast (within7s). The logarithm of catalytic currents shows a good linear relationshipwith that of the L-cysteine concentration in the range of0.5-680mM, with a lowdetection limit of22nM. The MnO2–C/Chit/GC electrode exhibited excellent stability(without any decrease of the response signal after1month) and admirable resistanceagainst interference like glutathione and other oxidizable amino acids (tryptophan,tyrosine, L-lysine and methionine).(3) Hollow nitrogen-doped carbon microspheres (HNCMs) as a novel carbonmaterial have been prepared and the catalytic activities of HNCMs-modified glassycarbon (GC) electrode towards the electrooxidation of uric acid (UA), ascorbic acid(AA) and dopamine (DA) have also been investigated. Comparing with the bare GCand carbon nanotubes (CNTs) modified GC (CNTs/GC) electrodes, the HNCMsmodified GC (HNCMs/GC) electrode has higher catalytic activities towards theoxidation of UA, AA and DA. Moreover, the peak separations between AA and DA,and DA and UA at the HNCMs/GC electrode are up to212and136mV, respectively,which are superior to those at the CNTs/GC electrode (168and114mV). Thus thesimultaneous determination of UA, AA and DA was carried out successfully. In theco-existence system of UA, AA and DA, the linear response range for UA, AA and DAare5-30μM,100-1000μM and3-75μM, respectively and the detection limits (S/N=3)are0.04μM,0.91μM and0.02μM, respectively. Meanwhile, the HNCMs/GCelectrode can be applied to measure uric acid in human urine, and may be useful formeasuring abnormally high concentration of AA or DA. The attractive features ofHNCMSprovide potential applications in the simultaneous determination of UA, AAand DA.(4) CNTs wrapped with nitrogen-doped carbon (CNx) layer (CNx-CNTs) werepyrolyzed from Polydopamine-CNTs composite (PDA-CNTs). Using CNx-CNTs assupport, PtNPs with high dispersion and small particle size were successfully anchoredon CNT surface and as-prepared Pt/CNX-CNTs nanohybrids were fabricated in amperometirc enyzme sensor for glucose detection. The micrographs of Pt/CNX-CNTsnanohybrids were characterized by TEM. The result shows that the CNTs surface wasuniformly coated with a CNXlayer with a thickness of ca.9nm. Pt NPs with anaverage diameter of ca.1.7±0.5nm were highly dispersed on CNX-CNTs surface.Comparing Pt/CNTs, Pt/CNX-CNTs nanocomposite shows much better electrocatalyticactivity toward H2O2electrooxidation. Based on these results, we succeed inconstructing a glucose amperometric biosensor with admirable pH tolerant, highsensitivity (66.51μA mM-1cm-2), low detection limit (0.4μM) and excelent stability.(5) The full spectrum of properties associated with RTILs is exploited to assess theviability of this platform, thus revealing the correlation between the redox propertiesand the physiochemical parameters of the species involved. This includes theevaluation of (1) the variation of redox responses toward analytes with similarmolecular structures or functionalities of RTILs;(2) the influence in terms of physicalcriteria of the system such as viscosity and conductivity as well as chemical structureof RTILs;(3) the sustainability in harsh conditions (high temperature or humidity) andinterferences. The principle is exemplified via trinitrotoluene (TNT) and dinitrotoluene(DNT) with inherent redox activity as analytes and IL membranes as solvents andelectrolytes using glassy carbon (GC) electrodes. A discrete response pattern isgenerated that is analyzed through linear discriminant analysis (LDA) leading to100%classification accuracy even for the mixture of analytes. Quantitative analysis throughsquare wave voltammetry (SWV) gave rise to the detection limits in liquid phase of190and230nM for TNT and DNT, respectively, with a linear range up to100μM.Gas-phase analysis shows strong redox signals for the estimated concentrations of0.27(1.2nM) and2.05ppm (11.3nM) in the gas phase for TNT and DNT, respectively,highlighting that RTILs adopt a role as a preconcentrator to add on sensitivity withenhanced selectivity coming from their physiochemical diversity, thus addressing themajor concerns usually referred to most sensor systems.(6) A simple online electrochemical cell design, consisting of Au quartz crystalworking electrode and incorporating ionic liquids (RTILs) as electrolytes, has beensuccessfully applied for the amperometric sensing of oxygen. In addtion, the ionicliquid electrochemical system has also been investigated by the real time EQCMintergrated technique, which provides sensitive measure of interfacial dynamicprocesses that other techniques can not. The obtained analytical parameters were foundto be strongly dependent on the choice of cation and anion. A limit of detection foroxygen as low as0.05vol.%, linearity over an oxygen partial pressure between0%and 20%, with a stable practical analytical response shown over the examined period of60days with no obvious fouling of the electrode surface.更多还原