金电极表面聚赖氨酸固定微过氧化物酶-11的电化学研究

通过聚赖氨酸修饰将微过氧化物酶-11(MP-11)固定在金电极表面,制备成MP-11修饰电极.修饰在电极表面上的MP-11的血红素活性中心与电极之间可进行直接的电子传递反应,其氧化还原式电位为-0.39V.该修饰电极对氧的还原具有电催化活性.当MP-11与咪唑发生轴向配位反应时,其氧化还原式电位发生负移,此时对氧的还原不再具有电催化活性.     

蒽醌/聚吡咯复合膜修饰电极的电化学行为和电催化活性

在水溶液中制备了掺杂蒽醌磺酸盐(AQS)的聚吡咯(PPy)/玻碳复合膜修饰电极,采用循环伏安法和旋转圆盘电极技术研究了该修饰电极在不同pH值溶液中的电化学行为以及在pH=5.5的磷酸盐缓冲溶液中对氧还原反应的电催化性能和动力学.结果表明,与裸玻碳电极相比,PPy膜的存在不仅降低了AQS的反应电位和峰电位差,而且增大了其氧化还原反应的峰电流,H2AQ/HAQ-氧化还原对的电离常数为9.5.AQS/PPy膜修饰电极上氧的还原主要是两电子还原为H2O2的不可逆过程,H2AQ对氧还原反应起主要催化作用,还原过程符合异相氧化还原催化机理.该修饰电极具有良好的电化学重现性.     

磁性纳米微球-血红蛋白修饰电极的电化学行为及对H2O2电催化还原的研究

将天然高分子壳聚糖(CS)包裹碳包铁的磁性纳米微球(CFN/CS)修饰于玻碳电极表面,并利用戊二醛将血红蛋白(Hb)交联在CFN/CS上,制备了Hb-CFN/CS-GC电极。循环伏安法和电化学交流阻抗法实验结果表明,Hb在CFN/CS-GC电极表面仍保持较好的生物活性,能稳定有效地进行直接电子转移反应。电化学研究表明该修饰电极对H2O2有良好的电催化还原作用,在pH 7.0的磷酸盐(PBS)介质中,H2O2在5.2×10-5~2.3×10-3mol/L浓度范围内,其浓度与还原峰电流呈良好线性关系,检出限为8.7×10-6mol/L。该修饰电极有着良好的重现性和稳定性。     

乳过氧化物酶与伴刀豆球蛋白A共修饰电极的电化学活性研究

用乳过氧化物酶(LPO)和伴刀豆球蛋白A(Con A)共修饰金电极,首次得到了乳过氧化物酶的直接电化学响应,在此基础上研究了乳过氧化物酶对过氧化氢(H2O2)的电催化活性,并研究了一氧化氮(NO)对LPO电催化活性的影响.在Con A的作用下,乳过氧化物酶在循环伏安图中显示1对准可逆的氧化还原峰,表现出薄层电化学行为.在pH 7.4的磷酸缓冲溶液中的表观氧化还原电位为 -190 mV.该共修饰电极对H2O2表现出电催化还原活性,由此构建的传感器对H2O2的检测范围是2.0×10-5 ～4.0×10-3 mol/L.实验发现,微摩尔量级的NO会抑制乳过氧化物酶对H2O2的催化活性.     

碳纳米管负载纳米铂修饰电极及电催化氧化H2O2的研究

采用化学气相沉积法在碳纳米管(CNT)上负载Pt纳米颗粒,并制备了CNT-Pt修饰玻碳电极(CNT-Pt/GCE).研究了该修饰电极在磷酸缓冲液中对H2O2的电催化氧化作用以及实验条件的影响.计算了H2O2在CNT-Pt/GCE上的电极反应速率常数.结果表明,CNT-Pt/GCE对H2O2的电化学氧化具有良好的催化作用,电极反应速率常数比铂电极高约2.65倍.初步探讨了电催化氧化机理,为酶电化学传感器的研制提供了一条新的途径.     

基于中性红功能化多壁碳纳米管修饰电极对H2O2的电催化

制备了中性红功能化的多壁碳纳米管复合材料,中性红通过1-乙基-3(3-二甲基氨基丙基)碳化二亚胺(EDC)和乙二胺四乙酸(EDTA)共价组装到壳聚糖修饰的多壁碳纳米管表面。扫描电子显微镜(SEM),红外光谱、电化学方法用于表征复合材料。研究了复合材料修饰电极的电化学行为及对H2O2的电催化作用。结果表明:该电极对H2O2有明显的电催化作用。计时电流响应与H2O2的浓度在0.5~80μmol/L范围内成良好的线性关系,检出限为0.14μmol/L(S/N=3)。修饰电极具有良好的稳定性和重现性,已用于样品分析。     

基于离子液体、壳聚糖、纳米银和血红蛋白修饰电极的过氧化氢传感器的制备与研究

以离子液体1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)、壳聚糖(CS)、纳米银(Nano-Ag)为修饰剂,制备了Nano-Ag/CS/BMIMPF6/Au/CME修饰电极,将血红蛋白(Hb)固载在修饰电极表面,离子液体优良的导电性和Nano-Ag高的表面活性和强的吸附性,为Hb的吸附和在修饰电极表面的直接电子转移构建了一个良好的微环境,同时也提高了Hb的电催化活性,并以此制备了具有良好催化活性的H2O2生物传感器。研究了修饰电极的特性,优化了修饰电极的实验条件,详细的讨论了Hb在电极上的电子转移机理以及H2O2的电化学行为,并对实际样品中的H2O2进行了检测,获得较好结果。     

壳聚糖-磷酸二氢胆碱凝胶固定肌红蛋白的直接电化学和电催化

使用壳聚糖和亲水性离子液体磷酸二氢胆碱形成的复合水凝胶固定肌红蛋白(Mb)制备修饰电极。在修饰电极表面,实现了Mb的直接电化学和对O2、H2O2的电催化。同时,该修饰电极表现出了较高的热稳定性。研究表明该新型复合水凝胶具备较好的生物相容性,使膜内的Mb保持了其天然构象和活性,并且很大程度地提高了修饰电极的导电性,促进了Mb和电极之间的电子传递,在直接电化学、生物催化和第三代生物传感器的制备等领域有良好的应用前景。     

基于Ag_2S-MWNTs的肌红蛋白直接电化学研究

制备了硫化银-多壁碳纳米管(Ag2S-MWNTs)纳米复合材料,构置了Mb-Ag2S-MWNTs-CHIT/GCE,并研究了肌红蛋白(Mb)在该修饰电极上的直接电化学和电催化行为。采用扫描电镜和透射电镜表征了Ag2SMWNTs的形貌,利用循环伏安法对Mb的电化学行为进行研究。Ag2S能够均一、稳定的在MWNTs表面生长,所构置的修饰电极在PBS中出现一对峰形良好的、准可逆的氧化还原峰,并对过氧化氢(H2O2)表现出良好的电催化作用,测定H2O2的线性范围为1.0×10-6~2.5×10-4mol·L-1,检出限为3×10-7mol·L-1(S/N=3)。Ag2S-MWNTs纳米复合材料能显著提高氧化还原蛋白质(酶)的直接电子传递速率,所构置的修饰电极可为制备基于蛋白质(酶)的第三代电化学生物传感器提供一良好的研究平台。     

三维有序结构的金掺杂纳米TiO_2修饰电极用于H_2O_2的测定

在ITO玻璃表面构建了三维有序多孔结构的金掺杂纳米Ti O2薄膜(3DOM GTD/ITO),同时制备了一种细胞色素c(Cyt c)酶生物传感器(Cyt c/3DOM GTD/ITO)。通过透射电镜(TEM)、扫描电镜(SEM)对修饰电极进行表征。紫外-可见光谱实验表明吸附在GTD上的Cyt c能够保持其生物活性,二级结构未被破坏。同时研究了Cyt c在3DOM GTD/ITO修饰电极表面的直接电化学及对H2O2的电催化行为。结果显示,Cyt c在3DOM GTD/ITO修饰电极上有显著的直接电化学响应,峰电流与扫描速度呈线性关系,说明该电极过程是表面电化学控制过程。Cyt c/3DOM GTD/ITO修饰电极对H2O2具有良好的催化性能,线性范围为3.0×10-7~1.70×10-5mol/L,检出限为3.6×10-8mol/L(S/N=3),响应时间为5 s,且该修饰电极具有较好的重现性和稳定性。     

Effect of Tris on catalytic activity of MP-11

The effect of tris(hydroxymethyl)aminomethane (Tris) on the catalytic activity and microstructure of heme undecapeptide, microperoxidase-11 (MP-11) in the aqueous solution was investigated using cyclic voltammetry, circular dichroism (CD) spectroscopy, UV-vis absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found for the first time that Tris would inhibit the catalytic activity and electrochemical reaction of MP-11 at the glassy carbon (GC) electrode. This is mainly due to the fact that Tris would induce more alpha-helix and beta-turn conformations from the random coil conformation of MP-11, cause the asymmetric split-up in the Soret band region of MP-11, increase the non-planarity of the heme of MP-11, and change the electron densities of N, O and S atoms of MP-11. Meanwhile, It was found that the electrochemical reaction of MP-11 with Tris at GC electrode is diffusion-controlled, and the diffusion coefficient of MP-11 and the rate constant for the heterogeneous electron transfer of MP-11 in the presence of Tris are decreased by 19% and 16%, respectively. Further experiments showed that the electrocatalytic current of MP-11 on the reduction of H2O2 is decreased by about 25% after the addition of Tris to the MP-11 solution.     

微过氧化物酶-11修饰电极对O2和H2O2的电催化还原

运用电化学循环伏安法和旋转圆盘电极技术研究了Ｏ２和Ｈ２Ｏ２在Ｎａｆｉｏｎ膜固定的微过氧化物酶－１１修饰的玻磷（ＭＰ－１１＋Ｍａｆｉｏｎ／Ｇｃ）电极上的电化学还原,结果表明,饰电极 对Ｏ２和Ｈ２Ｏ２的还原均具电催化作用。测定和比较了Ｏ２和Ｈ２Ｏ２在ＭＰ－１１＋Ｎａｆｉｏｎ／ＧＣ的电极上电催化还原反应的一些动力学参数。发现Ｏ２在修饰电极上经历了四电子还原,且还原过程与溶液的ＰＨ值有关。     

血红蛋白在壳聚糖修饰碳纳米管上的电化学特性及对过氧化氢的电催化分析

用壳聚糖对多壁碳纳米管进行修饰,构建了一种用于固定血红蛋白的新型复合材料,并研究了血红蛋白在该碳纳米管上的电化学性质及其对过氧化氢的电催化活性.扫描电镜结果表明,壳聚糖修饰的多壁碳纳米管呈单一的纳米管状,并能均匀分散在玻碳电极表面.紫外光谱分析表明血红蛋白在该复合膜内能很好地保持其原有的二级结构.将该材料固定在玻碳电极上后,血红蛋白能成功地实现其直接电化学.根据峰电位差随着扫描的变化,计算得到血红蛋白在壳聚糖修饰的碳纳米管膜上的电荷转移系数为0.57,表观电子转移速率常数为7.02 s-1.同时,该电极对过氧化氢显示出良好的催化性能,电流响应信号与H2O2浓度在1.0×10-6 ～1.5×10-3 mol/L间呈线性关系,检出限为5.0×10-7 mol/L.修饰电极显示了良好的稳定性.     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11NiO6-39 and SiW11MnO6-39 on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11O39Ni(H2O)6-(SiNiW11) and SiW11O39Mn(H2O)6-(SiMnW11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-3 and NO-2 were comparatively studied.     

Biopolymer and carbon nanotubes interface prepared by self-assembly for studying the electrochemistry of microperoxidase-11

Stable films of biopolymer chitosan and carbon nanotubes were prepared by a layer-by-layer self-assembly technique. Atomic force microscopy, scanning electron microscopy, cyclic voltammetry, and UV-vis spectroscopy were used to characterize the film assembly. Atomic force microscopy and scanning electron microscopy showed that an even, stable film was formed. The UV-vis spectroscopy and cyclic voltammetry study indicated the uniform growth of the film. The property of the self-assembled multilayer film in promoting protein electron transfer was demonstrated by incorporating microperoxidase-11 in the film. Microperoxidase-11 in the multilayer film could transfer electrons with the electrode indicating that carbon nanotubes could wire the protein to the electrode. The electrocatalytic activity of the microperoxidase-11 containing multilayer film-modified electrode toward H(2)O(2) and O(2) was investigated. The results showed that along with the increase in the assembled layers the electrocatalytic reduction potentials of H(2)O(2) and O(2) shifted positively. The prepared multilayer film of chitosan and carbon nanotubes containing protein was a sensitive interface for electrocatalytic study.     

锰取代Keggin型杂多酸[ZnW11O39Mn(H2O)]8-在化学修饰玻碳电极上的多层组装及电催化性能研究

在4-氨基苯甲酸修饰的玻碳电极上制备了过渡金属取代杂多酸[ZnW₁₁O₃₉Mn(H₂O)]^8-(ZnW₁₁Mn)多层膜.各层的循环伏安行为证明膜的增长均匀,峰电流随层数的增加而增加.与其在溶液中的氧化还原行为相比,多层膜中的ZnW₁₁Mn显示出一些特殊的性质.还讨论了pH对其氧化还原行为的影响.该多层膜对BrO₃^-和H₂O₂的还原及抗坏血酸的氧化具有较好的电催化性能.     

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW11 NiO39^6- and SiW11 MnO39^6- on 4-Aminothiophenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW11 O39 Ni(H2O)^6- (SiNiW11) and SiW11 O39Mn( H2O)^6-( SiMnW11 ) were first immobilized on a 4-aminothiophenol (4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these muhilayer film electrodes for the reduction of BrO3^- and NO2^- were comparatively studied.     

A New Material Based on Nanostructured Prussian Blue Analogue Film Doped with Ce(III) for Development of Hydrogen Peroxide Sensor

Prussian blue analogue nanoparticles doped with Ce(III) (CeHCF) have been synthesized using chitosan (CS) and poly(diallyldimethylammonium chloride) (PDDA) as protective matrix and were cast onto a glassy carbon electrode surface directly. Transmission electron microscopy, UV‐Vis absorption spectroscopy and resonance Rayleigh scattering technique were employed to characterize the PB analogue nanoparticles protected with CS and PDDA. Compared with the bare glassy carbon electrode, the modified electrode exhibited excellent performances for determining H₂O_2. This work demonstrates the feasibility of the CS‐PDDA‐CeHCF nanoparticles modified glassy carbon electrode for practical sensing applications.     

Electrocatalytic reduction of dioxygen on a glassy carbon electrode modified with adsorbed cobaloxime complex.

The preparation and electrochemical properties of a glassy carbon (GC) electrode modified with cobaloxime complex were investigated. The complex of the type [CoIII(DO)(DOH)pn)Cl2] where (DO)(DOH)pn = N2,N2'-propanediylbis-2,3-butanedione-2-imine-3-oxime) was adsorbed irreversibly and strongly on the surface of preanodized glassy carbon electrode. Electrochemical behavior and stability of modified GC electrode were investigated by cyclic voltammetry. The electrocatalytic reduction of dioxygen has been studied using this modified glassy carbon electrode by cyclic voltammetry, chronoamperometry and rotating disk electrode voltammetry as diagnostic techniques. The modified electrode showed excellent eletrocatalytic ability for the reduction of dioxygen to hydrogen peroxide in acetate buffer (pH 4.0) with overpotential 1.0 V lower than the plain glassy carbon electrode. The formal potential for this modified electrode is not shifted to more negative potentials by repeated reduction-oxidation cycles in oxygen-saturated supporting electrolyte solution. The apparent electron transfer rate constant (kS), the transfer coefficent (alpha) and the catalytic rate constant of O2 reduction at a GC modified electrode were determined by cyclic voltammetry and rotating disk electrode voltammetry and were found to be around 2.6 s(-1), 0.33 and 2.25 x 10(4) M(-1) s(-1). Based on the results, a catalytic mechanism is proposed and discussed.