间苯二酚在金纳米粒子/碳纳米管修饰电极上的电化学行为

制备了金纳米粒子/碳纳米管复合修饰玻碳电极,并用于研究间苯二酚的电化学反应过程,结果发现金纳米粒子与碳纳米管均对间苯二酚的电化学反应具有催化作用,复合修饰电极很好地利用了两种纳米粒子的电催化活性,对间苯二酚具有更强的电化学催化效果,为应用电化学技术进行间苯二酚的检测提供了可能。同时研究了碳纳米管的用量、复合膜的层数、pH值、介质和扫速等条件对间苯二酚的电化学信号的影响情况。     

三维金纳米团簇/多壁碳纳米管-Nafion膜修饰电极的电化学制备及血红蛋白的直接电化学

用改进的全电化学三步法制备三维金纳米团簇/多壁碳纳米管(3D Au/MWCNTs)纳米复合材料,并用Nafion(Nafion)膜进行涂布固定,制得3D Au/MWCNTs-Nafion修饰电极.利用透射电子显微镜(TEM)和能量色散光谱(EDS)对所得纳米复合材料的形貌进行表征.3D Au/MWCNTs具有金纳米核团簇而成的特殊圆丘状三维结构,电化学活性表面积(ECSA)比均匀分散的Au/MWCNTs提高了一个数量级,可有效提高血红蛋白(Hb)在电极表面的负载量.运用循环伏安法和计时电流法对3D Au/MWCNTs-Nafion修饰电极的生物电催化性质进行研究,其在Hb溶液中显示了良好的电催化活性和稳定性:还原氧化峰电流高,反应可逆性好,提供了有利于Hb直接电子转移的电化学环境.固载于Au/MWCNTs-Nafion上的Hb能够保持其生物活性,对双氧水(H2O2)表现出良好的催化性能,这是3D Au纳米团簇和MWCNTs共同作用的结果.实验表明,3D Au/MWCNTs-Nafion修饰电极结构特殊、性能优越,对Hb的直接电化学研究具有积极的促进作用,为准确高效的检测Hb及相关生物活性物质提供了新的电极选择.     

血红蛋白在纳米金修饰电极上的电化学研究

氧化还原蛋白在电极上的直接电化学研究不但能获得有关蛋白质和酶的热力学和动力学性质等重要信息,为开发新型生物传感器和生物反应器提供理论指导,而且对了解它们在生命体内的电子转移机理和生理作用机制具有重要意义。血红蛋白(Hb)是以血红素为辅基的蛋白质,在生物体中的主要     

血红蛋白/带正电的纳米金层层自组装膜修饰电极的制备及其电催化性能

利用自组装技术和静电吸附作用, 将带正电荷的纳米金(nano-Au^Å)和带负电荷的血红蛋白(Hb)层层自组装于L-半胱胺酸(L-cys)修饰的金电极表面, 从而制得用于检测过氧化氢(H2O2)的无电子媒介体的第三代电流型生物传感器({Hb/nano-Au^Å}5/L-cys/gold). 通过电子显微镜技术和微量电泳技术考察了不同粒径正电荷的纳米金的相关特征; 通过交流阻抗技术、原子力显微镜技术、循环伏安法和计时电流法考察了电极表面的电化学特性, 并对该传感器的作用机理及性能进行了详细的研究. 用计时电流法测得H2O2的线性范围为2.1×10^-8 ~ 1.2×10^-3 mol/L (r = 0.994), 检出限为1.1×10^-8 mol/L, 米氏常数(K_m^app)为0.10 mmol/L. 实验结果表明, 该方法与单层带正电的纳米金固载血红蛋白及带负电的纳米金层层自组装固载血红蛋白相比, 显著提高了血红蛋白的固定量, 并能保持血红蛋白的生物活性, 从而增强了传感器的灵敏度和稳定性, 拓宽了线性响应范围及降低了检测下限.     

金纳米粒子/碳纳米管修饰电极对4 壬基酚的电催化氧化及检测研究

制备了金纳米粒子/碳纳米管修饰玻碳电极(AuNPs-CNTs/GCE),采用循环伏安法和线性扫描伏安法研究了4-壬基酚在修饰电极上的电化学行为,并建立了一种灵敏简便地检测4-壬基酚的电化学方法。优化了pH值、扫描速率、富集时间等测定参数,并计算出pH值与氧化峰电压、扫描速率与氧化峰电流之间的数量关系。在pH 10.0的BR缓冲溶液中,4-壬基酚在AuNPs-CNTs/GCE上出现灵敏的氧化峰,氧化电位为0.51 V。与裸玻碳电极(GCE)和单一碳纳米管修饰电极(CNTs/GCE)相比,AuNPs-CNTs/GCE明显提高了4-壬基酚的氧化电流。在优化实验条件下,4-壬基酚的浓度分别在0.05～4μmol/L和6～14μmol/L范围内与氧化峰电流呈良好的线性关系,检出限为0.023μmol/L,对于实际样品测定的回收率为95%～104%。该修饰电极具有良好的重现性和稳定性,可用于环境样品中4-壬基酚的直接检测。     

碳纳米管/纳米金修饰金电极上柔红霉素电化学行为的研究

将碳纳米管与纳米金结合修饰在金电极上制成修饰电极,并用于柔红霉素(DNR)的电化学行为研究和检测.在4.4 mmol/L磷酸盐缓冲溶液(pH=5.81)中,DNR在碳纳米管-纳米金/Au电极上有一对灵敏的氧化还原峰.还原峰电流与DNR的浓度在3.2×10-8～1.0×10-6mol/L和1.0× 10-6～2.2× 1...     

金纳米粒子/碳纳米管修饰电极吸附伏安法测定微量间苯二胺

运用循环伏安法及线性扫描伏安法研究了间苯二胺在金纳米粒子/碳纳米管修饰玻碳电极上的电化学行为,优化并建立了一种直接测定间苯二胺的电化学分析方法。结果表明,与裸玻碳电极相比,金纳米粒子/碳纳米管修饰电极能显著提高间苯二胺的氧化峰电流。在优化条件下,氧化峰电流与间苯二胺浓度在3.0×10-8~1.0×10-6mol/L范围内呈现良好的线性关系,检出限为1.0×10-8mol/L,对1.0×10-7mol/L的间苯二胺溶液平行测定10次的RSD为4.2%。测定了实验室废水中的间苯二胺含量,3次测定结果的平均回收率为99.7%,RSD为2.1%。     

对硫磷在单壁碳纳米管/金-四氧化三铁纳米粒子复合材料修饰电极上的电化学响应及其测定

制备了单壁碳纳米管/金-四氧化三铁纳米粒子复合材料修饰玻碳电极,用循环伏安法研究了对硫磷在该电极上的电化学行为。该电极对对硫磷具有较好的富集和催化特性,在优化条件下,对硫磷的浓度与其峰电流在2.0×10-9～1.0×10-6 mol/L范围内呈线性关系,其检出限为1.0×10-9 mol/L。对1.0×10-7 mol/L的对硫磷溶液平行测定9次的RSD为3.9%(n=9)。用该电极对不同蔬菜样品中的对硫磷进行测定,平均回收率在96.0%～105.5%之间,相对标准偏差在3.3%～3.9%之间。     

金纳米粒子/碳纳米管复合修饰玻碳电极对对苯二酚氧化还原反应的电催化性能

以对苯二酚为目标化合物比较研究了金纳米粒子、碳纳米管、金纳米粒子/碳纳米管3种纳米粒子修饰电极的电催化性能,结果发现:3种纳米粒子修饰电极均对对苯二酚的电化学信号具有增强作用。电化学阻抗谱和修饰层数试验表明:金纳米粒子的增强效果来自于金纳米粒子的电催化作用,碳纳米管的增强作用来自于电催化作用与大的电极表面积,金纳米粒子/碳纳米管复合修饰电极综合利用了两种纳米粒子的特性,表现出了更为优良的电催化行为。对苯二酚在修饰电极上的电化学过程均为扩散控制过程。     

肌红蛋白在碳纳米管修饰电极上的直接电化学和电催化性能

将肌红蛋白(Mb)通过吸附的方法固定在碳纳米管(CNT)表面, 用AFM、XPS、UV-Vis和FTIR对其进行了表征, 研究了CNT对Mb直接电子转移反应的促进作用. 循环伏安结果表明, Mb在CNT表面能进行有效和稳定的直接电子转移反应, 其循环伏安曲线上表现出一对良好的、几乎对称的氧化还原峰; 在20−160 mV•s−1的扫速范围内, 式量电位E0′几乎不随扫速而变化, 其平均值为(−0.343±0.001) V (vs SCE, pH 7.0); Mb在CNT表面直接电子转移的表观速率常数为(3.11±0.98) s−1; 式量电位E0′与溶液pH的关系表明, Mb的直接电化学过程是一个有H+参与的电极过程. 进一步的实验结果显示, 固定在CNT表面的Mb能保持其对H2O2和O2还原的生物电催化活性.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin on Aligned Carbon Nanotubes Based Electrodes Modified with Au Nanoparticles and SiO2 Gel

Here we report on the preparation and characterization of new electrodes based on aligned carbon nanotubes (ACNTs) for hemoglobin (Hb) electrochemistry and electrocatalysis. The ACNTs are obtained by a thermal chemical vapor deposition method under normal pressure. Then the electrodes are elaborated by first sputtering a thin Au film (thickness of 200 nm) onto the top of the ACNTs, and then removing the Au layer/ACNTs from the quartz substrate with the aide of hydrofluoric acid (HF) treatment. Field emission scanning electron microscopy (FESEM) demonstrates that after nitric acid (HNO₃) treatment, the nanotubes of the removed Au layer are totally tip‐opened, purified and organized in a perfect vertically aligned architecture. The final ACNTs electrode is obtained by attaching the Au layer of ACNTs onto a glassy carbon electrode. Then the electrode was modified to act as a matrix for hemoglobin (Hb) immobilization and as an electrode for Hb electroanalysis by the assistance of Au nanoparticles (AuNPs) and SiO₂ gel. Due to the individual specific effects of AuNPs, SiO₂ gel and ACNTs, the resulting SiO₂/Hb‐AuNPs/ACNTs electrode showed good direct electrochemistry of Hb with an apparent Michaelis? Menten constant of 0.44 mM. The electrode showed an excellent electrocatalytic activity towards H₂O₂, possessing a linear range from 40 µM to 4 mM and the detection limit was 22 µM based on a signal to noise ratio of 3.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin at PAMAM Dendrimer-MWNTs-Au Nanoparticles Composite Film Modified Glassy Carbon Electrode

The direct electron transfer of hemoglobin at the PAMAM-MWNTs-AuNPs composite film modified glassy carbon electrode was studied. In a phosphate buffer solution(PBS, pH=7.0), the formal potential(E 0' ) of Hb was –0.105 V versus SCE, the electron transfer rate constant was 4.66 s –1 . E 0′ of Hb at the modified electrode was linearly varied in a pH range of 5.0—8.0 with a slope of –49.2 mV/pH. The Hb/PAMAM-MWNTs-AuNPs/GCE gave an ex-cellent electrocatalytic response to the reduction of hydrogen peroxide. The catalytic current increased linearly with H 2 O 2 concentration in a range of 1.0×10 ?6 to 2.2×10 ?3 mol/L. The detection limit was 2.0×10 ?7 mol/L at a signal to noise ratio of 3. The Michaelis-Menten constant(K ma pp ) was 2.95 mmol/L.     

Electrodeposited Graphene and Silver Nanoparticles Modified Electrode for Direct Electrochemistry and Electrocatalysis of Hemoglobin

By using a 1‐butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the working electrode, graphene (GR) nanosheets and silver nanoparticles (Ag NPs) were step by step electrodeposited on the surface of the CILE with potentiostatic method. The fabricated Ag/GR/CILE was used as a new platform for protein electrochemistry and hemoglobin (Hb) was immobilized on its surface with chitosan (CTS) as film forming material. In 0.1 mol/L phosphate buffer solution, a pair of well‐defined and quasi‐reversible redox peaks appeared on the CTS/Hb/Ag/GR/CILE with a formal peak potential of ?0.202 V (vs. SCE) and a peak‐to‐peak separation (ΔE_p) of 68 mV, which indicated that direct electrochemistry of Hb was realized on the modified electrode. The results could be attributed to the synergistic effects of Ag NPs and GR nanosheets on the electrode surface, which provided a specific three‐dimensional structure with high conductivity and good biocompatibility. The Hb modified electrode showed excellent electrocatalysis to the reduction of trichloroacetic acid in the concentration range from 0.8 to 22.0 mmol/L with a detection limit of 0.42 mmol/L (3σ). Moreover, the modified electrode exhibited favorable reproducibility, long term stability and accuracy, with potential applications in the third‐generation electrochemical biosensor.     

Hemoglobin Modified Carbon Paste Electrode: Direct Electrochemistry and Electrocatalysis

Abstract

A new hemoglobin (Hb) modified carbon paste (CP) electrode was fabricated by simply mixing the hemoglobin with carbon powder and paraffin homogeneously. To prevent the leakage of Hb from the electrode surface, a Nafion film was further applied on the surface of Hb-carbon composite paste electrode. Direct electrochemistry of hemoglobin in the paste electrode was easily achieved, and a pair of well-defined quasi-reversible redox peak of heme Fe(III)/Fe(II) couple appeared with the formal potential (E^0′) as ?0.335 V (vs. Saturated calomel electrode; CE) in pH 7.0 phosphate buffer solution (PBS). The fabricated Hb modified electrode showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA) and H₂O₂.     

Direct Electrochemistry of Hemoglobin and its Electrocatalysis Based on a Carbon Nanotube Paste Electrode

A new hemoglobin (Hb) and carbon nanotube (CNT) modified carbon paste electrode was fabricated by simply mixing the Hb, CNT with carbon powder and liquid paraffin homogeneously. To prevent the leakage of Hb from the electrode surface, a Nafion film was further applied on the surface of the Hb‐CNT composite paste electrode. The modified electrode was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Direct electrochemistry of hemoglobin in this paste electrode was easily achieved and a pair of well‐defined quasi‐reversible redox peaks of a heme Fe(III)/Fe(II) couple appeared with a formal potential (E^0′) of ?0.441 V (vs. SCE) in pH 7.0 phosphate buffer solution (PBS). The electrochemical behaviors of Hb in the composite electrode were carefully studied. The fabricated modified bioelectrode showed good electrocatalytic ability for reduction of H₂O₂ and trichloroacetic acid (TCA), which shows potential applications in third generation biosensors.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin–TiO2 Whisker Film Modified Glassy Carbon Electrode

In this study, Hb TiO₂ whisker nanocomposites are prepared by incorporating TiO₂ whisker with hemoglobin (Hb). Our studies illustrate that the self‐assembled Hb TiO₂ whisker films could efficiently facilitate the direct electron transfer of Hb on glassy carbon electrode (GCE). Moreover, our results demonstrate that the catalytic activity to the reduction of H₂O₂ could be observed on the Hb TiO₂ whisker modified GCE and the photovoltaic effect of TiO₂ whisker can greatly enhance the detection sensitivity of electrocatalytic reduction.     

血红蛋白在碳纳米管修饰碳糊电极上的直接电化学行为

利用吸附法将血红蛋白(Hb)固定在碳纳米管修饰碳糊电极表面,制成稳定的固载Hb碳纳米管修饰电极,研究了Hb在碳纳米管修饰电极上的直接电化学行为.固载Hb的碳纳米管修饰电极在pH=7.0的PBS（磷酸盐缓冲溶液）中有一对相当可逆的循环伏安氧化还原峰,为Hb血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰.式电位为－0.160 V(vs SCE),随扫描速度变化很小.电子转移数为1.021,近似为一个辅基发生电子转移.Hb在碳纳米管修饰电极表面的电子转移常数为0.0816 s－1,远大于亚甲蓝作媒介体时Hb的电子转移反应速率常数.应用于过氧化氢、三氯乙酸和硝基苯等的电催化还原,固定在碳纳米管修饰碳糊电极的血红蛋白表现出稳定且较高的催化活性.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin/ZnO‐Chitosan/nano‐Au Modified Glassy Carbon Electrode

The highly efficient H₂O₂ biosensor was fabricated on the basis of the complex films of hemoglobin (Hb), nano ZnO, chitosan (CHIT) dispersed solution and nano Au immobilized on glassy carbon electrode (GCE). Biocompatible ZnO‐CHIT composition provided a suitable microenvironment to keep Hb bioactivity (Michaelis‐Menten constant of 0.075 mmol L^?1). The presence of nano Au in matrix could effectively enhance electron transfer between Hb and electrode. The electrochemical behaviors and effects of solution pH values were carefully examined in this paper. The (ZnO‐CHIT)‐Au‐Hb/GCE demonstrated excellently electrocatalytical ability for H₂O₂. This biosensor had a fast response to H₂O₂ less than 4 s and excellent linear relationships were obtained in the concentration range from1.94×10^?7 to 1.73×10^?3 mol L^?1 with the detection limit of 9.7×10^?8 mol L^?1 (S/N=3) under the optimum conditions. Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results.     

Electrocatalysis of Hemoglobin in ZnO Nanoparticle/Ionic Liquid Composite Film Modified Glassy Carbon Electrode

A nanobiocompatible composite containing hemoglobin (Hb), ZnO nanoparticles (nano‐ZnO) and ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF₆) was fabricated and further modified on the glassy carbon electrode (GCE). The electrochemical behaviours of Hb in the composite film were carefully studied and a pair of quasi‐reversible redox peaks appeared in pH 7.0 phosphate buffer solution, which was attributed to the electrode reaction of Hb heme Fe(III)/Fe(II) redox couple. The presences of nano‐ZnO and BMIMPF₆ in the film can retain the bioactivity of Hb and greatly enhance the direct electron transfer of Hb. The immobilized Hb showed high stability and good electrocatalytic ability to the reduction of hydrogen peroxide and O₂.     

碳糊电极上无机膜固载血红蛋白的直接电化学

报道了用硅溶胶-凝胶(Sol-gel)膜将血红蛋白(Hb)固载于碳糊电极上的直接电化学行为.研究结果表明,Hb-Sol-gel修饰的碳糊电极在pH=7.0的缓冲溶液中于-0.275V(vs.Ag/AgCl)处有一对可逆的循环伏安氧化-还原峰,为Hb血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对的特征峰.HbFe(Ⅲ)/Fe(Ⅱ)电对的式量电位在pH5.0～11.0范围内与溶液pH值呈线性关系,表明Hb的电化学还原很可能是一个质子伴随着一个电子的电极过程.FTIR光谱证实,Sol-gel膜对Hb的固载没有破坏其天然结构.Hb-Sol-gel修饰的碳糊电极能够催化还原H₂O₂,可望将其用于制作第三代生物传感器.