A Bioanode Using Thermostable Alcohol Dehydrogenase for an Ethanol Biofuel Cell Operating at High Temperatures

To extend the range of biofuel cell applications, we wish to increase their maximum operational temperatures. Using a thermostable alcohol dehydrogenase as a biocatalyst, we prepared an enzyme‐immobilized bioanode that can operate at high temperatures. The catalytic current for ethanol oxidation was increased using this electrode at temperatures up to 80 °C.     

Employing Methylene Green Coated Carbon Nanotube Electrodes to Enhance NADH Electrocatalysis for Use in an Ethanol Biofuel Cell

We prepared and characterized electrocatalysts based on multiwalled carbon nanotubes (MWCNTs) coated with methylene green (MG). These electrocatalysts can regenerate nicotinamide adenine dinucleotide (NAD⁺), so they are potentially applicable in the field of bioelectronics. NADH oxidation occurs between 0.14±0.002 and 0.16±0.002 V vs. Ag/AgCl. The most efficient bioanode furnishes 88±7 µW cm^?2 and 500 µA cm^?2 and an open circuit voltage of 590±22 mV. In conclusion, we obtained a reliable and easy‐to‐prepare electrocatalyst that can regenerate NAD⁺ and may be applicable in biosensors and bioelectronic devices that use a wide range of NAD⁺‐dependent enzymes.     

A Novel Polycatechol/Ordered Mesoporous Carbon Composite Film Modified Electrode and Its Electrocatalytic Application

Polycatechol (PCC) was prepared by electropolymerizing catechol (CC) on the surface of an ordered mesoporous carbon (OMC) modified electrode for the first time. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) were used to characterize the structure and electrochemical behaviors of PCC/OMC nanocomposite film. Compared with the bare GC and OMC/GC electrodes, the PCC/OMC/GC electrode exhibits a good electrocatalysis toward the oxidation of NADH at 0.0 V with a high sensitivity (8.7 mA/mM). These make PCC/OMC/GC electrode a promising candidate for stable and efficient electrochemical sensors for the detection of NADH.     

阿魏酸聚合修饰玻碳电极的制备及其对NADH的催化氧化

研究了阿魏酸修饰电极的制备、性质及对NADH的电催化作用.该电极在0.1mol/L磷酸缓冲溶液(pH=6.60)中,于-0.1～+0.50V(vs.Ag/AgCl)电位范围内呈现一对氧化还原峰,其式量电位E₀为+0.188V(vs.Ag/AgCl),且E₀随pH增加而负向移动.电子转移系数为0.496,表观电极反应速率常数(ks)为6.6s^-1.电极反应的电子数为1且有1个质子参与.该修饰电极对NADH氧化具有很好的催化作用.在NADH存在下,电极过程由扩散控制,扩散系数为1.76×10^-6cm²/s.NADH浓度在0.01～5.0mmol/L范围内与峰电流呈现良好的线性关系.通过计时安培法测得催化速率常数为6.82×10³mol^-1·L·s^-1.     

Amperometric Determination of Ascorbic Acid at an Electrodeposited Redox Polymer Film Modified Gold Electrode

A sensitive and selective electrochemical method for the determination of ascorbic acid was developed. It was shown that a hydrated osmium complex‐containing redox polymer film can be electrodeposited at the gold electrode and it exhibits excellent electrocatalytic activity towards the oxidation of ascorbic acid. In contrast to a bare gold electrode, the oxidation current of ascorbic acid increased greatly and the oxidation peak potential shifted negatively to about 0.01 V (vs. SCE) at the modified electrode. Amperometric measurements were performed at an applied potential of 0.01 V and a linear response was obtained in the range of 2–400 μM with a limit of detection (LOD) of 0.6 μM (S/N=3). The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of uric acid and dopamine. The proposed procedure was successfully applied to the determination of ascorbic acid in human urine samples.     

新型电聚合交联聚苯胺电化学传感器的研制及其在抗坏血酸测定中的应用

以苯胺、对苯二胺、1,3,5-三苯胺基苯为单体,采用循环伏安法在金电极上电化学聚合制备了一种新型的交联聚苯胺(CPAN)电化学传感器。采用交流阻抗谱和电化学方法对该传感器进行了表征。结果表明:交联剂1,3,5-三苯胺基苯结构单元被成功地引入到聚苯胺链中,所得的CPAN与线性聚苯胺(LPAN)相比,导电性增强,电子传输速率加快。CPAN/Au电极对抗坏血酸具有良好的电催化氧化作用,在优化的条件下,测得抗坏血酸浓度在1.0×10-4～1.0×10-2 mol.L-1范围内与传感器峰电流呈线性关系,检出限(3S/N)为3.3×10-5 mol.L-1。该传感器的响应时间为5s,测定结果的相对标准偏差(n=6)为2.0%～2.5%,回收率在98.0%～102%之间。     

Preparation of an Electrode That Immobilizes NAD‐Dependent Alcohol Dehydrogenase by Using a Redox Polymer Containing 1,10‐Phenanthroline‐5,6‐dione

A redox polymer (PAHA‐Ru), modified electrode exhibited excellent catalytic activity for the electrochemical oxidation of β‐nicotinamide adenine dinucleotide (NADH). PAHA‐Ru was composed of carboxyl groups and ruthenium complexes containing 1,10‐phenanthroline‐5,6‐dione (phen‐dione). The stability of the PAHA‐Ru film was increased by incorporating poly(diallyldimethylammonium chloride) (PDDA) owing to the formation of a polyelectrolyte complex between the PAHA‐Ru and PDDA. The catalytic efficiency of the oxidation of NADH using the PAHA‐Ru/PDDA‐modified electrode was also greater than that using a PAHA‐Ru‐modified electrode. NAD‐dependent alcohol dehydrogenase (ADH) was entrapped in the PAHA‐Ru/PDDA film on the surface of the glassy carbon electrode. Electrochemical oxidation of ethanol using the ADH‐entrapped electrode was also observed.     

聚N,N-双水杨醛乙二胺合钴修饰超微电极的制备及其在一氧化氮测定中应用的研究

通过电化学聚合法制备了聚Ｎ，Ｎ－双水杨醛乙二胺合钴［ｐｏｌｙＣｏ（Ｓａｌｅｎ）］修饰超微电极，研究了该修饰电极的电催化性质及其在一氧化氮（ＮＯ）测定中的应用．实验结果表明，ｐｏｌｙＣｏ（Ｓａｌｅｎ）修饰超微电极对ＮＯ的测定有高的灵敏度，ＮＯ的浓度在２．０×１０－８～２．８×１０－６ｍｏｌ／Ｌ范围内，电流与浓度呈良好的线性关系，线性相关系数为０．９９９８，检出限为１．０×１０－８ｍｏｌ／Ｌ；该电极进一步修饰Ｎａｆｉｏｎ后，生物体中常见的物质如抗坏血酸、儿茶酚胺类神经递质的代谢物、ＮＯ的氧化产物ＮＯ－２等不干扰测定．本传感器可以满足ＮＯ在体分析的需要．     

Preparation of Carbon Nanotubes/Neutral Red Composite Film Modified Electrode and Its Catalysis on Rutin

Neutral red was directly electropolymerized onto the carbon nanotubes modified electrode. A polymerized neutral red/carbon nanotubes composite film was characterized by scanning electron micrograph (SEM) and cyclic voltammetry (CV). Well‐defined voltammetric responses are observed for [Fe(CN)₆]^4?/3? on the composite film modified glassy carbon electrode. And it's found that this modified electrode has good catalysis on the redox of rutin. Differential pulse voltammetry method was used to determinate the concentration of rutin and obtain a linear equation between the current and concentration in a certain range. The modified electrode is satisfied with us for its good sensibility and stability.     

Electrochemical Preparation of Poly(acriflavine) Film‐Modified Electrode and Its Electrolcatalytic Properties Towards NADH,Nitrite and Sulfur Oxoanions

Electrochemical polymerization of acriflavine (AF) was carried out onto glassy carbon electrodes (GCE) from the aqueous buffer solution containing 1.5×10^?3 M AF monomer (pH 3.5) which produced a thin electrochemically active film. This is noted as poly(AF) film modified electrodes (PAF/GCE). This modified electrode was shown a stable reversible redox couple centered at +0.22 V in pH 3.5 buffer solutions. PAF/GCE was found to be more stable in acidic solutions and its formal potential was found to be pH dependent with a slope close to ?60 mV/pH. The electrochemical deposition kinetics of poly(AF) onto gold coated quartz crystal was studied by using electrochemical quartz crystal microbalance (EQCM) combined with cyclic voltammetry (CV). PAF/GCE was found be good mediator for electrochemical oxidation of reduced nicotinamide adenine dinucleotide (NADH) in pH 5 buffer solutions. The electrocatalytic oxidation of SO and electrocatalytic reduction of NO , SO and S₂O were carried out at PAF/GCE electrode in acidic aqueous solutions. The electrocatalytic oxidation of NADH was also investigated by using amperometric method.     

Direct Modification of a Glassy Carbon Electrode with Toluidine Blue Diazonium Salt: Application to NADH Determination and Biosensing of Ethanol

We describe here the covalent modification of a glassy carbon electrode with toluidine blue (TB) diazonium salt, which is generated in situ from the reaction between the aromatic amino phenyl group of TB and sodium nitrite. TB is attached directly to the electrode surface without any cross‐linking agent or complex matrices. The resulting TB films exhibit excellent electrocatalytic behavior toward NADH oxidation. Low potential detection of NADH is performed at 0.15 V vs. Ag/AgCl. Furthermore, an ethanol biosensor is developed using the TB modified electrode and alcohol dehydrogenase. The great stability and reusability, excellent electrochemical reversibility, technically simple preparation and short preparation time make this method suitable for low‐cost bioelectronical devices.     

Effect of Enzyme and Cofactor Immobilization on the Response of Ethanol Oxidation in Zirconium Phosphate Modified Biosensors

Two different self‐contained ethanol amperometric biosensors incorporating layered [Ru(phend)₂bpy]²⁺‐intercalated zirconium phosphate (ZrP) as the mediator as well as yeast‐alcohol dehydrogenase (y‐ADH) and its cofactor nicotinamide adenine dinucleotide (NAD⁺) were constructed to improve upon a design previously reported where only this mediator was immobilized in the surface of a modified electrode. In the first biosensor, a [Ru(phend)₂bpy]²⁺‐intercalated ZrP modified carbon paste electrode (CPE) was improved by immobilizing in its surface both y‐ADH and NAD⁺ using quaternized Nafion membrane. In the second biosensor, a glassy carbon electrode was modified with [Ru(phend)₂bpy]²⁺‐intercalated ZrP, y‐ADH, and NAD⁺ using Nafion as the holding matrix. Calibration plots for ethanol sensing were constructed in the presence and absence of ZrP. In the absence of ZrP in the surface of the modified glassy carbon electrode, leaching of ADH was observed as detected by UV‐vis spectrophotometry. Ethanol sensing was also tested in the presence and absence of ascorbate to measure the selectivity of the sensor for ethanol. These two ethanol biosensors were compared to a previously reported one where the y‐ADH and the NAD⁺ were in solution, not immobilized.     

Preparation and Electrochemical Behaviour of Silver Pentacyanonitrosylferrate Film Modified Glassy Carbon Electrode and Its Electrocatalytic Oxidation to L‐cysteine

A glassy carbon (GC) electrode modified with silver pentacyanonitrosylferrate (AgPCNF) film as a redox mediator was fabricated. Cyclic voltammetry was used to study the redox property of AgPCNF modified electrode. The modified electrode showed a well‐defined redox couple due to [Ag^IFe^III/II(CN)₅NO]^1‐/2‐system. The effects of scan rates, supporting electrolytes and solution pHs were studied on the electrochemical behavior of the modified electrode. The feasibility of using the AgPCNF modified electrode to measure L ‐cysteine was investigated. It showed an excellent electrocatalytic activity towards the oxidation of L ‐cysteine and the anodic currents were proportional to the L ‐cysteine concentration in the range of 0.1 μM to 20 μM, the linear regression equation is I_pa(μA) = ‐68.58 ‐ 5.78C_{L ‐cysteine} (μM), with a correlation coefficient 0.998 for N = 23. The detection limit was down to 3.5 × 10^‐8 M (three times the ratio of signal to noise).     

一种新的修饰电极的制备及其应用于对苯二酚的高选择性测定

通过电聚合酸性络蓝K于多壁碳纳米管修饰玻碳电极上构建了一种新的修饰电极。研究了该电极的电化学性质,结果表明:该电极表现出优异的电催化和选择性能,可在异构体存在下伏安法选择测定对苯二酚。线性范围在1×10-6~1×10-4mol.L-1,检出限为1×10-7mol.L-1。所制作的电极对水样进行了测定所得结果与光谱法的结果一致。     

Nano TiO2 Modified Carbon‐ceramic Electrode and Its Application for Electrocatalytic Oxidation of NADH

The electrocatalytic oxidation of nicotinamide adenine dinucleotide (NADH) was studied on nanoTiO₂ modified sol‐gel electrode, using cyclic voltammetry, chronoamperometry and differential pulse voltammetry as diagnostic techniques. It is demonstrated that TiO₂ nanoparticles on sol‐gel network catalyze the oxidation of NADH in the absence of any electron transfer mediators. Effect of various parameters such as pH, scan rate, TiO₂ percentage on the response of modified electrode was studied. In addition, scanning electron microscopy (SEM) was used to characterize the surface morphology of the spots. A dynamic range between 0.5–50 μM with detection limit of 0.35 μM was obtained with DPV studies. This method was successfully used for determination of NADH in cucumber cotyledons samples. The electrode showed relatively good stability over more than 2 months.     

新型石墨烯-壳聚糖/二茂铁衍生物/细胞色素c修饰电极的制备及其用于亚硝酸钠的检测研究

具有共轭结构的分子导线是构筑分子电子器件的重要组成单元,而含有二茂铁单元的该类化合物具有良好的电化学性质,被广泛研究。基于此,本实验通过Sonogashira交叉偶联等反应合成了一种新型二茂铁乙炔衍生物( Fc-NH2),并经红外( IR)、核磁共振(1 H NMR和13 C NMR)、质谱( MS)和循环伏安( CV)等方法表征。利用Fc-NH2与石墨烯-壳聚糖( GH-CS)之间的相互作用制备了GH-CS/Fc-NH2复合物,并成功用于细胞色素c(Cytc)的固定,得到GH-CS/Fc-NH2/Cytc修饰电极。研究表明,GH-CS/Fc-NH2/Cytc/GCE在-0.2 V附近出现一对峰,对应于Cytc的可逆氧化还原峰。此电极对NaNO2有良好的电催化作用,在1×10-7~1.5×10-4 mol/L范围内,NaNO2浓度与氧化峰电流呈良好的线性关系,检测限低至4×10-8mol/L。此修饰电极不但可以实现细胞色素c的直接电化学,也可以用于定量检测NaNO2。     

Preparation of Sb2O3‐loaded Activated Carbon Particle Electrode and Its Electrocatalytic Degradation of Methyl Orange in a Three‐dimensional Electrode Cell

Electrocatalysis on the degradation of methyl orange is investigated using Sb₂O₃‐loaded activated carbon (Sb₂O₃/AC), a new particle electrode. The electrode was prepared by an impregnation method. An orthogonal array with four factors and three levels was selected to carry out the experiment. Electrocatalysis on the degradation of methyl orange through Sb₂O₃/AC was characterized by a series of parameters, including the amount of the particle electrode, the concentration of Na₂SO₄, the cell voltage, and the electrolysis time, and the results were compared with those of a conventional AC particle electrode. The results indicate that calcination temperature has the greatest impact on the catalytic activity of the particle electrode. The optimal conditions for preparing the Sb₂O₃/AC electrode include an 8 mL SbCl₃ solution, 90 min hydrolysis time, 400 °C calcination temperature, and 180 min calcination time. As well, the degradation efficiency of the Sb₂O₃/AC electrode is consistently higher than that of the AC electrode under the same electrolysis conditions. The electrochemical oxidation of methyl orange of both electrodes conformed to pseudo first‐order kinetics, but the rate constant of the Sb₂O₃/AC electrode was 2.29 times that of the AC electrode; this is likely due to the high electrocatalytic activity of the experimental electrode. The electrocatalysis results exhibited the synergetic effects of AC and Sb₂O₃ in the new particle electrode.     

铂微粒修饰碳纳米管-纳米TiO2/聚苯胺复合膜电极的制备及其电化学性能

采用循环伏安法,在200 mmol.L-1苯胺与500 mmol.L-1H2SO4的混合溶液中,在-0.1 V~0.9 V扫描(50 mV.s-1),实现了苯胺在碳纳米管-纳米TiO2膜电极上的电化学聚合,得到翠绿色的聚苯胺膜(PANI),并用交流阻抗谱对PANI的电化学性质进行了表征。在PANI电极上修饰铂,制得铂微粒修饰PANI电极(PANI-Pt)。研究发现PANI-Pt对抗坏血酸的氧化有很高的催化活性。     

Guanine/Ionic Liquid Derived Ordered Mesoporous Carbon Decorated with AuNPs as Efficient NADH Biosensor and Suitable Platform for Enzymes Immobilization and Biofuel Cell Design

Guanine‐ionic liquid derived ordered mesoporous carbon (GIOMC) decorated with gold nanoparticles was used as electrocatalyste for NADH oxidation and electrochemical platform for immobilization of glucose dehydrogenase (GDH) enzyme. The resulting GIOMC/AuNPs on the glassy carbon electrode can be used as novel redox‐mediator free for NADH sensing and this integrated system (GIOMC/AuNPs/GDH) shows excellent electrocatalytic activity toward glucose oxidation. Furthermore, the ionic liquid derived ordered mesoporous carbon derivate with Ph‐SO₃H (IOMC‐PhSO₃H) decorated with AuNPs has been developed to bilirubin oxidase enzyme (BOD) immobilization and the GC/IOMC‐PhSO₃H/BOD integrated system shows excellent bioelectrocatalytic activity toward oxygen reduction reaction. The proposed mesostructured platforms decorated by AuNPs have been developed to enhance mass transfer and charge transfer from biocatalyst to electrode, leading these bioanode and biocathode used for biofuel cell assembly. Integration designed bioanode and biocathode yielding a membrane‐less glucose/O₂ biofuel cell with power density of 33 (mW.cm⁻²) at 257 mV. The open circuit voltage of this biofuel cell and maximum produced current density were 508 mV and 0.252 (mA.cm⁻²) respectively.     

Electrochemical Preparation of Poly(Malachite Green) Film Modified Nafion‐Coated Glassy Carbon Electrode and Its Electrocatalytic Behavior Towards NADH,Dopamine and Ascorbic Acid

Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis.