Nation-离子液体-碳纳米管复合膜修饰电极的制备及用于抗坏血酸、多巴胺及尿酸的同时测定

制备了一种新颖的Nation-离子液体一多壁碳纳米管复合膜修饰电极,并研究了抗坏血酸（AA）、多巴胺（DA）和尿酸（uA）在该修饰电极上的电化学行为．该修饰电极结合了多壁碳纳米管良好的导电性、离子液体优良的催化性能及Nation的高选择性等优点,对AA、DA和UA的氧化具有很好的催化和分离效果,实现了AA、DA和UA的同时测定．在三者共存体系中,AA和DA、DA和UA的氧化峰电位差分别为148和167mV．对AA、DA和UA的同时检测,线性范围分别为5-3200、1～1100和1-300gmol／L,检出限分别为1．66、0．33和0．33gmol／L．该修饰电极选择性好、稳定性高、重现性好,有望用于实际样品中AA、DA和UA的同时检测．     

金纳米粒子/聚多巴胺/碳纳米管修饰玻碳电极对核黄素的测定

采用原位还原法制备金纳米粒子/聚多巴胺/碳纳米管（Au-PDA-MWNTs）复合材料,并将其用于建立高灵敏检测核黄素的电化学方法.采用紫外–可见光谱、扫描电镜、x-射线能谱对Au-PDA-MWNTs复合材料进行表征,采用循环伏安法和差示脉冲伏安法探讨核黄素（RF）在Au-PDA-MWNTs修饰的玻碳电极上的电化学行为,并对RF含量进行测定.该方法对核黄素的检测在5×10^-9 mol·L^-1～1×10^-5 mol·L^-1的范围内呈良好的线性关系（R=0.9906）,检测限为1.7×10^-9 mol·L^-1.本方法操作简便、抗干扰能力强,方法可行,因此该方法成功实现了维生素药片中RF含量的测定.     

聚吡咯／多壁碳纳米管修饰电极对多巴胺的测定

制备了聚吡咯/多壁碳纳米管(PPy/MWNT)复合膜修饰电极。研究了神经递质多巴胺(DA)在该修饰电极上的电化学行为。实验表明,PPy/MWNT复合膜修饰电极对DA的电催化作用优于PPy修饰电极。在pH=4.10的0.2mol/L醋酸-醋酸钠缓冲溶液中,DA在该修饰电极上的CV曲线于0.31V和0.28V处出现一对灵敏的氧化还原峰,峰电位差△Ep比裸玻碳电极降低58mV,比PPy修饰电极降低28mV,峰电流显著增加。氧化峰电流ipa与DA浓度在1.0×10-4~7.8×10-8mol/L范围内呈良好的线性关系,线性回归方程为ip(μA)=0.2512 1.2300C(×10-5mol/L),相关系数r=0.9992,检出限为3.9×10-8mol/L。常见物质对DA的检测无干扰,DA注射液样品检测回收率为94%~104%。     

基于碳纳米管和离子液体复合物修饰电极的免疫传感器检测莱克多巴胺

建立了一种新的电化学免疫传感器方法, 将多壁碳纳米管(MWCNTs)和室温离子液体1-丁基-3-甲基咪唑四氟硼酸盐([BMIM]BF₄)复合物, 和偶联了牛血清蛋白(BSA)的莱克多巴胺抗原, 使用Nafion固定在电极上, 利用莱克多巴胺抗体和抗原之间特定反应的竞争模式, 以K₃Fe(CN)₆为探针, 通过循环伏安法和差分脉冲伏安法监测免疫反应, 对溶液中莱克多巴胺的浓度进行检测. 线性范围宽(1～1500 ng/mL), 检测限可低至0.3 ng/mL. 同时, 我们对猪饲料实际样品进行测定, 回收率令人满意.     

壳聚糖-碳纳米管修饰电极的电催化作用研究

报道了一种新型的壳聚糖-碳纳米管修饰电极(MC/GCE)的电化学特性.此修饰电极对神经递质去甲肾上腺素(NE)表现出很强的电催化效应,在pH 5.5的磷酸盐缓冲溶液中,NE的峰电流与浓度在5.0×10-6～1.0×10-4 mol/L范围内呈线性关系.此外,其它生物分子如多巴胺(DA)、尿酸(UA)在MC/GCE上也有很好的电化学响应.修饰电极表现出很好的稳定性和选择性.     

聚合离子液体-多壁碳纳米管化学修饰电极同时测定多巴胺、抗坏血酸与尿酸

以1-乙烯基咪唑(1-Vinylimidazole)和1-溴乙烷(1-Bromoethane)为原料设计合成了溴化1-乙烯基-3-乙基咪唑功能化离子液体(1-Vinyl-3-ethylimidazolium bromide),以偶氮二异丁腈(Azobis(2-methylpropionitrile))为引发剂,制备了聚1-乙烯-3-乙基咪唑溴代盐聚合离子液体(Poly(ViEtIm~+Br~-))。在此基础上,利用Poly(ViEtIm~+Br~-)中咪唑基团与多壁碳纳米管之间的强π-π相互作用,在温和条件下,使用非共轭方法制备了聚合离子液体-多壁碳纳米管复合物修饰电极(Poly(ViEtIm~+Br~-)/MWCNTs/GCE),并成功应用于多巴胺(DA)、抗坏血酸(UA)和尿酸(UA)的同时测定。结果表明,在DA、AA、UA 3者的同时存在下,Poly(ViEtIm~+Br~-)/MWCNTs对3者的检测范围分别为2～180μmol/L、50～5 000μmol/L、4～50μmol/L,对应检出限分别为0.4、22.2、0.9μmol/L。将该电极用于维生素C注射剂中抗坏血酸浓度的检测以及盐酸多巴胺注射剂中多巴胺浓度的检测,回收率为98.8%～101%,检测效果良好。     

离子液体/多壁碳纳米管/壳聚糖修饰电极同时检测多巴胺、抗坏血酸及尿酸的研究

将水溶性离子液体([ BMIM] N(CN)2)、多壁碳纳米管(MWCNTs)和壳聚糖(CS)三者结合,修饰在玻碳电极上制备MWCNTs - IL - CS修饰玻碳电极,并研究了多巴胺(DA)、抗坏血酸(AA)、尿酸(UA)在该修饰电极上的电化学行为.扫描电子显微镜图显示,MWCNTs在IL - CS中能良好分散,并形...     

碳纳米管的酞菁钴修饰及其对香兰素的电催化性能

通过酰胺化反应制备了四-2,9,16,23-氨基酞菁钴(TAPcCo)与多壁碳纳米管(MWCNTs)的复合材料,红外光谱、扫描电镜和紫外可见吸收光谱分析表明复合材料中酞菁分子与碳管之间是通过酰胺键结合的,紫外吸收光谱还表明两者之间存在着强烈的电子相互作用。同时还研究了复合材料修饰的玻碳电极对香兰素(VNL)的电催化作用。循环伏安法表明,修饰电极对VNL有着良好的电催化活性,相对于裸玻碳电极VNL在修饰电极上峰电位负移了20mV,峰电流增大了12倍,且VNL在电极表面的反应受吸附控制。方波伏安法证实了这一反应过程中有质子参与。同时,方波伏安法研究还发现:峰电流与香兰素浓度在4.2μmol·L-1～5mmol·L-1范围内呈良好的线性关系,检出限(3.3S/N)为0.44μmol·L-1。     

功能化碳纳米管表面高分散的钯纳米粒子在碱性溶液中的甲醇氧化行为

本工作中在水溶液体系中以芳烃重氮盐修饰的多壁碳纳米管(MWNT)为载体构筑了钯(Pd)纳米粒子碳纳米管复合结构。以MWNT的侧壁上C-C共价键接的氨基苯甲酸为沉积活化中心,制备了高分散高催化活性的钯(Pd)纳米粒子。结构成分和形貌分别用XRD和TEM表征。循环伏安(CV) 和交流阻抗的研究表明上述复合结构在碱性溶液中对甲醇的电催化氧化有很高的活性及稳定性。芳烃重氮盐修饰的MWNT是一种非常好的催化剂载体,而Pd-MWNT复合材料在燃料电池有着广泛的应用前景。     

聚多巴胺/多壁碳纳米管/玻璃碳电极上多巴胺的电分析

基于多巴胺（DA）在多壁碳纳米管（MWCNTs）修饰玻璃碳（GC）电极上的电聚合,制得聚多巴胺(PDA)/MWCNTs/GC电极,并对该修饰电极进行了电化学阻抗谱 (EIS)和循环伏安法(CV)表征。 在该修饰电极上,DA呈现良好的电化学行为。在pH=7.4磷酸缓冲溶液中其氧化电流显著高于在裸电极上的响应,且能有效地抑制2.0 mmol/L抗坏血酸(AA)或K4Fe(CN)6的直接电化学响应,表明MWCNTs可增敏信号,且阳离子选择透过性PDA膜可抑制阴离子的电化学干扰。 采用CV实验检测DA,DA氧化的半微分伏安峰高(ipa-sd)与多巴胺浓度在0.08～1.76 μmol/L范围内呈线性关系,在无抗坏血酸和有0.5 mmol/L抗坏血酸共存时的线性回归方程分别为ipa-sd(μA/s1/2)=0.107+0.405c(μmol/L)（r2=0.986）和ipa-sd(μA/s1/2)=0.628+0.649c(μmol/L)(r2=0.992),检测限均为8.0×10-8 mol/L(S/N=3)。 该法用于盐酸多巴胺注射液中多巴胺的快速测定,结果满意。     

Comparison of the Electrochemical Reactivity of Electrodes Modified with Carbon Nanotubes from Different Sources

The electrochemical activity of five different commercial carbon nanotubes (CNT), prepared by the ARC discharge and chemical vapor deposition (CVD) methods, has been assessed and compared. The various multi‐walled CNT were immobilized onto a glassy carbon electrode using three different dispersing agents (Nafion, concentrated nitric acid and dimethylformamide (DMF)) and their voltammetric response to ferricyanide, NADH and hydrogen peroxide examined. SEM was used to characterize the surface morphology. The corresponding cyclic voltammetry and amperometric data showed that the electrocatalytic activity, the background current and the electroanalytical performance are strongly depended on the preparation of the CNT and on the dispersing agent used. The most favorable amperometric detection of NADH and hydrogen peroxide is observed at the NanoLab CVD‐produced CNT in connection to a DMF‐surface dispersion. ARC‐produced CNT display a smaller capacitance, particularly in connection to the DMF dispersion. Such differences in the electrochemical reactivity are attributed to the different surface chemistries (primarily defect densities) of the corresponding CNT layers, associated with the different production and dispersion protocols.     

Comparison of the Electrochemical Reactivity of Carbon Nanotubes Paste Electrodes with Different Types of Multiwalled Carbon Nanotubes

Carbon nanotubes (CNTs) are widely used in electrochemical studies. It is reported that CNTs with different source and dispersed in different agents [1] yield significant difference of electrochemical reactivity. Here we report on the electrochemical performance of CNTs paste electrodes (CNTPEs) prepared by multiwalled carbon nanotubes (MWNTs) with different diameters, lengths and functional groups. The resulting electrodes exhibit remarkable different electrochemical reactivity towards redox molecules such as NADH and K₃[Fe(CN)₆]. It is found that CNTPEs prepared by MWNTs with 20–30 nm diameter show highest catalysis to NADH oxidation, while CNTPEs prepared by MWNTs with carboxylate groups have best electron‐transfer rate (The peak‐peak separation (ΔE_p) is +0.108 V for MWNTs with carboxylate groups, +0.155 V for normal MWNTs, and +0.174 V for short MWNTs) but weak catalysis towards oxidation of NADH owing to the hydrophilicity of carboxylate groups. The electrochemical reactivity depends on the lengths of CNTs to some extent. The ‘long’ CNTs perform better in our study (The oxidation signals of NADH appear below +0.39 V for ‘long’ CNTs and above +0.46 V for the ‘short’ one totally). Readers may get some directions from this article while choose CNTs for electrochemical study.     

Electrochemical Behavior and Determination of Uric Acid at Single-Walled Carbon Nanotube Modified Gold Electrodes

The voltammetric behavior of uric acid was studied at a single-walled carbon nanotube (SWNT) modified gold electrode. Uric acid can effectively accumulate at this electrode and produce an anodic peak at about 0.45 V (vs. SCE) in pH 5.0 sodium acetate buffer solutions (HAc-NaAc). The experimental parameters, such as solution pH, accumulation time, and amount of SWNT, were optimized for determination. Under the optimum conditions, the anodic peak current is linear to the uric acid concentration over the range of 1.0×10⁻⁷ M to 2.5×10⁻⁵ M with a correlation coefficient of 0.998. The detection limit was 5.0×10⁻⁸ M for 60 s accumulation. The electrode could be easily regenerated and exhibited good stability. A 5.0×10⁻⁶ M uric acid solution was measured ten times using the same electrode, and the relative standard deviation of the peak current was 1.3%. This method was successfully applied to the determination of uric acid in human urine samples, and the recovery was 97–99%. The feasibility for simultaneous determination of xanthine, ascorbic acid and uric acid was discussed. These species did not interfere with each other in a certain concentration range. The influence of some surfactants on the anodic peak was also examined.     

氮掺杂碳纳米管修饰电极的电化学行为

制备了氮掺杂改性的碳纳米管, 并用循环伏安法(CV)测定了多巴胺(DA)和抗坏血酸(AA)在不同氮含量的碳纳米管修饰电极上的电化学行为. 结果表明, 氮掺杂碳纳米管修饰电极对AA和DA有不同的电催化行为, 其中高氮含量修饰电极对AA的催化作用强, 而低氮含量修饰电极对DA的催化作用强. 微分脉冲伏安法(DPV)的结果显示, DA的氧化峰电流与其浓度在5.0×10^－6～2.0×10^－4 mol/L范围内呈良好的线性关系, 检出限达1.64×10^－6 mol/L (S/N＝3); AA氧化峰电流与其浓度在3.0×10^－5～1.0×10^－2 mol/L范围内呈良好的线性关系, 检出限达3.26×10^－6 mol/L (S/N＝3). 该修饰电极在AA大量存在(AA浓度为DA浓度两万倍)时可选择性地实现多巴胺的测定而不造成干扰.     

Effect of the Dispersing Agent on the Electrochemical Response of Glassy Carbon Electrodes Modified with Dispersions of Carbon Nanotubes

The electrochemical response of a glassy carbon electrode modified with carbon nanotubes (CNT) dispersed in two solvents, water and DMF, and two polymers, chitosan and Nafion is reported. The films were homogeneous when the dispersing agent was water or DMF. In the case of polymers, the surfaces present areas with different density of CNTs. A more sensitive electrochemical response was obtained when CNTs are dispersed in the solvents. In the case of CNT dispersed with polymers, the nature of the polymer demonstrated to be a critical parameter not only for dispersing the nanotubes but also for the electrochemical activity of the resulting electrodes.     

芯片毛细管电泳集成电化学检测装置和4种碳纤维电极的比较研究

自行设计组装了微流控芯片安培检测系统,以自制的碳纤维微米电极、碳纤维纳米电极、单壁碳纳米管修饰的碳纤维微米电极以及碳纤维微盘电极等4种电极为检测器,采用柱末检测的模式,考察了其对儿茶酚胺类物质多巴胺与异丙肾上腺素的分离检测效果以及电极的灵敏度。结果表明,在检测电位为0.6V、0.02mol/LTris-HCl(pH8.0)为缓冲溶液的优化条件下,检测多巴胺与异丙肾上腺素的分离度分别为0.64、1.06、0.61和1.22;灵敏度(S/N=3)分别为1.7×10-7、5.9×10-8、2.3×10-8和5.3×10-7,碳纤维纳米电极同时具备了较高的分离度与灵敏度。将碳纤维纳米电极应用于测定鼠嗜铬神经细胞瘤细胞(PC12)中神经递质多巴胺,以异丙肾上腺素为内标,测得单个PC12细胞中多巴胺含量为(0.57±0.07)fmol(n=5),与文献报道值相符。     

纳米碳管电极的制备与电化学检测性能研究

纳米碳管由于其独特的物理和化学性能及广阔的应用前景而备受关注,其相关研究涉及到众多领域[1￣3]。在电化学分析领域,与其它碳电极材料相比,纳米碳管电极具有较大的电极表面积和较高的电子传递速率,其使用能增大响应电流、降低检出限,是目前电化学分析电极中一个十分引人注目     

Electrochemical Sensing of Uric Acid Using Glassy Carbon Modified with Multiwall Carbon Nanotubes Dispersed in Polyethylenimine

This work reports the advantages of using glassy carbon electrodes modified with multiwall carbon nanotubes (MWCNT) dispersed in polyethylenimine (PEI). The presence of MWCNTs wrapped by PEI largely facilitated the strong adsorption of uric acid (UA) and allowed its highly sensitive and selective quantification even in the presence of high excess of ascorbic acid. The selected conditions for the electrochemical sensing were 5 s accumulation at ?0.300 V under stirring and quantification in a 0.050 M phosphate buffer solution pH 7.40 by differential pulse voltammetry adsorptive‐stripping after medium exchange. The platform allowed the successful application in the quantification of UA in urine.     

Electrochemical Studies of Cytochrome c on Electrodes Modified by Single-Wall Carbon Nanotubes

Single wallcarbonnanotubes (SWNTs)modifiedgoldelectrodeswerepreparedbyusingtwodifferentmethods .Theelectrochemicalbehaviorofcytochromeconthemodifiedgoldelectrodeswasinves tigated .ThefirstkindofSWNT modifiedelectrode (notedasSWNT/Auelectrode)waspreparedbytheadsorptionofcarboxyl terminatedSWNTsfromDMFdispersiononthegoldelectrode .TheoxidativelyprocessedSWNTtipswerecovalentlymodifiedbycouplingwithamines (AET)toformamidelinkage .ViaAu—Schemicalbonding ,theself assembledmonolayerofthi…     

Electrochemical Determination of Tannins Using Multiwall Carbon Nanotubes Modified Glassy Carbon Electrode

A novel chemically modified electrode is prepared on the basis of the attachment of multiwall carbon nanotubes (MWNTs) to the surface of a glassy carbon electrode (GCE) in the presence of a hydrophobic surfactant. The electrochemical behavior of tannins at the MWNTs-modified GCE is investigated. Tannins yield a well-defined oxidation at about 0.30 V (SCE) at the MWNTs-modified GCE. MWNT-film shows remarkable enhancement effect on the oxidation peak current of tannins. The experimental parameters are optimized, and a direct electrochemical method to detect tannins is proposed. The oxidation peak current is proportional to the concentration of tannins over the range from 4 × 10^–7 to 2 × 10^–4 M, and the detection limit is 1 × 10^–7 mol/l after 5 min of accumulation. The relative standard deviation of 6% for determination of 2 × 10^–6 mol/l tannins indicates excellent reproducibility. The analysis method is demonstrated by using tea and Chinese gall samples.