Amperometric Glucose Biosensor Based on the Deposition of Copper and Glucose Oxidase onto Glassy Carbon Transducer

ABSTRACT

The performance of a first generation glucose amperometric biosensor based on the entrapment of glucose oxidase (GOx) within a net of copper electrodeposited onto activated glassy carbon electrode, is described. The copper electrodeposited offers an efficient electrocatalytic activity towards the reduction of enzymatically-liberated hydrogen peroxide, allowing for a fast and sensitive glucose quantification. The influence of the electrodeposition conditions (pH, potential, time, copper salt and enzyme concentrations) on the response of the bioelectrode was evaluated from the amperometric signals of hydrogen peroxide and glucose. The combination of copper electrodeposition with a nation membrane allows an excellent selectivity towards easily oxidizable compounds such as uric and ascorbic acids at an operating potential of -0.050 V. The response is linear up to 2.0 × 10^?2 M glucose, the detection limit being 1.2 × 10^?3 M.     

Amperometric Glucose Biosensors Based on Glassy Carbon and SWCNT‐Modified Glassy Carbon Electrodes

Different carbonaceous materials, such as single‐walled carbon nanotubes (SWCNTs) and glassy carbon submitted to an electrochemical activation at +1.80 V (vs. SCE) for 900 s, have been used with the aim of comparing their performances in the development of enzyme electrodes. Commercial SWCNTs have been pretreated with 2.2 M HNO₃ for 20 h prior to use. The utility of activated GC as promising material for amperometric oxidase‐based biosensors has been confirmed. With glucose oxidase (GOx) as a model enzyme, glucose was efficiently detected up to 1 mM without the use of a mediator. Both electrodes operated in stirred solutions of 0.1 M phosphate buffer (pH 5.5), containing dissolved oxygen, at a potential of ?0.40 V vs. SCE. Although the performances of the two carbonaceous materials were comparable, the biosensors based on activated GC were characterized by a practically unchanged response 40 days after the fabrication, a better signal to noise ratio, and a little worse sensitivity. In addition, the preparation procedure of such biosensors was more simple, rapid and reproducible.     

芦丁修饰电极研究多巴胺的电化学响应

通过循环伏安法(CV)制备了芦丁修饰电极,研究多巴胺(DA)在修饰电极上的电化学行为.结果表明,芦丁修饰膜对DA的氧化有明显的催化作用,并且可以消除抗坏血酸(AA)对DA测定的干扰.DA的浓度在1.0×10-7～9.5×10-6 mol/L范围内与其氧化峰电流呈线性关系,相关系数为0.9996,检出限为1.0×10-8 mol/L.将该修饰电极用于注射液样品中DA的测定,结果表明该修饰电极可用于实际样品分析.     

Glassy Carbon Electrodes Modified with Multiwall Carbon Nanotubes Dispersed in Polylysine

We report the analytical performance of glassy carbon electrodes (GCE) modified with a dispersion of multiwall carbon nanotubes (MWCNT) in polylysine (Plys) (GCE/MWCNT‐Plys). The resulting electrodes show an excellent electrocatalytic activity towards different bioanalytes like ascorbic acid, uric acid and hydrogen peroxide, with important decrease in their oxidation overvoltages. The dispersion of 1.0 mg/mL MWCNT in 1.0 mg/mL polylysine is highly stable, since after 2 weeks the sensitivity for hydrogen peroxide at GCE modified with this dispersion remained in a 90% of the original value. The MWCNT‐Plys layer immobilized on glassy carbon electrodes has been also used as a platform to build supramolecular architectures by self‐assembling of polyelectrolytes based on the polycationic nature of the polylysine used to disperse the nanotubes. The self‐assembling of glucose oxidase has allowed us to obtain a supramolecular multistructure for glucose biosensing. The influence of glucose oxidase concentration and adsorption time as well as the effect of using polylysine or MWCNT‐Plys as polycationic layers for further adsorption of GOx is also evaluated.     

纳米金修饰玻碳电极在抗坏血酸共存下选择性测定多巴胺

利用电沉积的方式制备了纳米金 ( Nano- gold,NG)修饰玻碳电极 ( GCE)。该电极对多巴胺 ( DA)和抗坏血酸 ( AA)均有催化作用 ,且多巴胺在纳米金修饰玻碳电极上有较强的吸附作用。同时研究了磷酸缓冲溶液的 p H值和离子强度对 DA的电化学行为的影响。纳米金修饰玻碳电极在 DA和 AA的混合溶液中的循环伏安图上可观察到两个明显分开的氧化峰 ,峰电位差达到 1 5 0 m V。据此 ,提出了两种利用该电极在抗坏血酸共存下选择性测定多巴胺的方法 ,线性范围分别为 3.0× 1 0 - 6 ～1 .0× 1 0 - 4mol/ L和 1 .2 5× 1 0 - 6 ～ 1 .0× 1 0 - 4mol/ L。     

Glucose Biosensor Based on Multi‐Walled Carbon Nanotube Modified Glassy Carbon Electrode

An amperometric glucose biosensor based on multi‐walled carbon nanotube (MWCNT) modified glassy carbon electrode has been developed. MWCNT‐modified glassy carbon electrode was obtained by casting the electrode surface with multi‐walled carbon nanotube materials. Glucose oxidase was co‐immobilized on the MWCNT‐modified glassy carbon surface by electrochemical deposition of poly(o‐phenylenediamine) film. Enhanced catalytic electroreduction behavior of oxygen at MWCNT‐modified electrode surface was observed at a potential of ?0.40 V (vs. Ag|AgCl) in neutral medium. The steady‐state amperometric response to glucose was determined at a selected potential of ?0.30 V by means of the reduction of dissolved oxygen consumed by the enzymatic reaction. Common interferents such as ascorbic acid, 4‐acetamidophenol, and uric acid did not interfere in the glucose determination. The linear range for glucose determination extended to 2.0 mM and the detection limit was estimated to be about 0.03 mM.     

Electrocatalytic Behavior of Glassy Carbon Electrodes Modified with Multiwalled Carbon Nanotubes and Cobalt Phthalocyanine for Selective Analysis of Dopamine in Presence of Ascorbic Acid

This work describes the development, electrochemical characterization and utilization of a cobalt phthalocyanine modified carbon nanotube electrode for the quantitative determination of dopamine in 0.2 mol L^?1 phosphate buffer contaminated with high concentration of ascorbic acid. The electrode surface was analyzed by cyclic voltammetry and electrochemical impedance spectroscopy which showed a modified surface presenting a charge transfer resistance of 500 Ω, against the 16.46 kΩ value found for the bare glassy carbon surface. A pseudo rate constant value of 5.4×10^?4 cm s^?1 for dopamine oxidation was calculated. Voltammetric experiments showed a shift of the peak potential of DA oxidation to less positive value at 390 mV as compared with that of a bare GC electrode at 570 mV. The electrochemical determination of dopamine, in presence of ascorbic acid in concentrations up to 0.1 mol L^?1 by differential pulse voltammetry, yielded a detection limit as low as 2.56×10^?7 mol L^?1.     

Direct Determination of Trace Dopamine in an Ascorbic Acid Solution at a Bare Glassy Carbon Electrode Using Differential Pulse Voltammetry

It is difficult to monitor dopamine (DA) accurately with a bare glassy carbon electrode because of the interference of ascorbic acid (AA). In this paper, a method for the determination of DA in an AA solution using differential pulse voltammetry was established. Because AA loses its electrochemical activity after being oxidized, hydrogen peroxide was used to oxidize AA, and the interference of AA was completely eliminated. As a result, trace DA could be directly determined in the AA solution with a bare glassy carbon electrode. When trace DA was determined in a 1.0 mmol L^?1 AA solution, there was a wide linear range from 3.0×10^?8 mol L^?1 to 1.0×10^?5 mol L^?1. The application of this method was demonstrated by the selective measurement of DA in an injection without pretreatment.     

Electrochemical Sensor for the Quantification of Dopamine Using Glassy Carbon Electrodes Modified with Single‐Wall Carbon Nanotubes Covalently Functionalized with Polylysine

We report a dopamine electrochemical sensor based on the modification of glassy carbon electrodes (GCE) with polylysine‐functionalized single‐wall carbon nanotubes (SWCNT‐PLys). The resulting electrodes (GCE/SWCNT‐PLys) showed a significant improvement in the electrooxidation of dopamine with drastic decrease in the peak potentials separation and important enhancement in the associated currents. Dopamine was detected by differential pulse voltammetry‐adsorptive stripping with medium exchange at nanomolar levels even in the presence of high excess of ascorbic and uric acids. The sensor was successfully used for the quantification of dopamine in urine samples enriched with the neurotransmitter.     

Studies on the Electrochemistry of Dopamine at a Pyrocatechol Sulfonephthalein Modified Glassy Carbon electrode

IntroductionThere has been a considerable interest in developing the methods to measure the secretionneurotransmitters. Electrochemical teChniques have proven to be significantly advantageous tothe biosciencesLlj. The application of ultramicroelectrodes to neuroscien.ce, which has been pioneered by Adams[2], to monitor the concentration of neurotransmitters in the central nervesystem has had a special impact. Several neurotransmitters, e. g., dopamine(DA) are electroactlve and therefore can …     

Adsorption and Electrooxidation of DNA at Glassy Carbon Electrodes Modified with Multiwall Carbon Nanotubes Dispersed in Glucose Oxidase

We are proposing for the first time the successful immobilization of DNA at glassy carbon electrodes (GCE) modified with carbon nanotubes (CNT) dispersed in glucose oxidase (GOx) (GCE/CNT‐GOx) either by direct adsorption or by layer‐by‐layer self‐assembling using polydiallyldimethylamine (PDDA). The presence of GOx allows an efficient dispersion of CNT and gives a most favorable environment that promotes the adsorption and makes possible a more sensitive electrooxidation of DNA. The PDDA incorporated in the self‐assembled architecture largely facilitates the adsorption and electrooxidation of dsDNA and the adsorbed layer can be successfully used for evaluating the interaction of DNA with methylene blue.     

2,2‐Bis(3‐Amino‐4‐hydroxyphenyl)hexafluoropropane Modified Glassy Carbon Electrodes as Selective and Sensitive Voltammetric Sensors. Selective Detection of Dopamine and Uric Acid

2,2‐bis(3‐Amino‐4‐hydroxyphenyl)hexafluoropropane (BAHHFP) was electro‐polymerized oxidatively on glassy carbon by cyclic voltammetry. The activity of the modified electrode towards ascorbic acid (AA), uric acid (UA) and dopamine (DA) was characterized with cyclic voltammetry and differential puls voltammetry (DPV). The findings showed that the electrode modification drastically suppresses the response of AA and shifts it towards more negative potentials. Simultaneously an enhancement of reaction reversibility is seen for DA and UA. Unusual, selective preconcentration features are observed for DA when the polymer‐modified electrode is polarized at negative potential. In a ternary mixture containing the three analytes studied, three baseline resolved peaks are observed in DPV mode. At physiological pH 7.4, after 5 min preconcentration at ?300 mV, peaks positions were ?0.073, 0.131 and 0.280 V (vs. Ag/AgCl) for AA, DA and UA, respectively. Relative selectivities DA/AA and UA/AA were over 4000 : 1 and 700 : 1, respectively. DA response was linear in the range 0.05–3 μM with sensitivity of 138 μA μM^?1 cm^?2 and detection limit (3σ) of 5 nM. Sensitive quantification of UA was possible in acidic solution (pH 1.8). Under such conditions a very sharp peak appeared at 630 mV (DPV). The response was linear in the range 0.5–100 μM with sensitivity of 4.67 μA μM^?1 cm^?2 and detection limit (3σ) of 0.1 μM. Practical utility was illustrated by selective determination of UA in human urine.     

多巴胺和抗坏血酸在CPB现场修饰碳糊电极上的电化学及电化学动力学性质

用现场修饰方法制备了溴化十六烷基吡啶(CPB)修饰碳糊电极(CPB/CPE)。运用循环伏安法(cyclic voltammetry,CV)、电位阶跃计时电流法(chronoamperometry,CA)及电位阶跃计时库仑法(chronocoulometry,CC)法研究了多巴胺(DA)和抗坏血酸(AA)在裸碳糊(CPE)和CPB/CPE上的电化学行为,测得了动力学参数如电荷转移系数α,扩散系数D,反应级数和电极反应速率常数kf。研究结果表明CPB/CPE可用于AA和DA共存体系中DA的电化学选择性测定。     

聚溴酚蓝修饰玻碳电极的制备及电化学性质

在含溴酚蓝的磷酸缓冲溶液中,应用循环伏安法于经预处理的玻碳电极上形成聚合物薄膜.结果表明,在-1. 0V~+1. 8V(vs.Ag/AgCl)扫描电位之间形成的薄膜具有较高的电活性和稳定性.该电极对抗坏血酸电化学氧化有催化作用,既使抗坏血酸的氧化电位负移了 270mV,又增大了其氧化峰电流.催化峰电流与抗坏血酸浓度在 2. 5~250μg/mL范围内呈良好的线性关系.     

基于铂微粒和Nafion膜修饰玻碳电极的甲醛传感器

通过在Nafion膜修饰玻碳电极表面电沉积铂微粒制备了甲醛电化学传感器(Pt/Nafion/GCE)。利用循环伏安法研究了甲醛在该传感器上的电化学行为,优化了实验参数,在此基础上建立了用伏安法直接测定甲醛的新方法。在酸性溶液中,甲醛的氧化峰电流与其浓度在1.0×10-6~1.0×10-3mol/L的范围内呈良好的线性关系(r=0.9995),检出限为5.0×10-7mol/L。本文所提出的测定甲醛的方法具有较高的灵敏度和较好的重现性。     

Unadulterated Glucose Biosensor Based on Direct Electron Transfer of Glucose Oxidase Encapsulated Chitosan Modified Glassy Carbon Electrode

Glucose oxidase (GOD) was encapsulated in chitosan matrix and immobilized on a glassy carbon electrode, achieving direct electron transfer (DET) reaction between GOD and electrode without any nano‐material. On basis of such DET, a novel glucose biosensor was fabricated for direct bioelectrochemical sensing without any electron‐mediator. GOD incorporated in chitosan films gave a pair of stable, well‐defined, and quasireversible cyclic voltammetric peaks at about ?0.284 (E_pa) and ?0.338 V (E_pc) vs. Ag/AgCl electrode in phosphate buffers. And the peak is located at the potentials characteristic of FAD redox couples of the proteins. The electrochemical parameters, such as midpoint potential (E_1/2) and apparent heterogeneous electron‐transfer rate constants (k_s) were estimated to ?0.311 V and 1.79 s^?1 by voltammetry, respectively. Experimental results indicate that the encapsulated GOD retains its catalytic activity for the oxidation of glucose. Such a GOD encapsulated chitosan based biosensor revealed a relatively rapid response time of less than 2 min, and a sufficient linear detection range for glucose concentration, from 0.60 to 2.80 mmol L^?1 with a detection limit of 0.10 mmol L^?1 and electrode sensitivity of 0.233 μA mmol^?1. The relative standard deviation (RSD) is under 3.2% (n=7) for the determination of practical serum samples. The biologic compounds probably existed in the sample, such as ascorbic acid, uric acid, dopamine, and epinephrine, do not affect the determination of glucose. The proposed method is satisfactory to the determination of human serum samples compared with the routine hexokinase method. Both the unique electrical property and biocompatibility of chitosan enable the construction of a good bio‐sensing platform for achieved DET of GOD and developed the third‐generation glucose biosensors.     

在抗坏血酸存在下用L-赖氨酸修饰玻碳电极测定多巴胺

采用电化学氧化法制备了L-广赖氮酸单分子层修饰玻碳电极,研究了多巴胺（DA）和抗坏血酸（AA）在该电极上的电化学行为。结果表明,L-广赖氨酸单分子层修饰玻碳电极不仅能改善多巴胺和抗坏血酸的电化学行为,而且能将多巴胺和抗坏血酸二者在裸电极上的完全重叠的单氧化峰分开成为两个完全独立的氧化峰,循环伏安（CV）图上峰间距为507mV,差分脉冲伏安（DPV）图上峰间距为460mV,由此可实现在AA的共存下对样品中的DA进行选择性测定。     

基于羧基化多壁碳纳米管修饰玻碳电极快速检测氨基脲的研究

基于羧基化多壁碳纳米管修饰的玻碳电极(CMWCNTs/GCE),构建了一种灵敏检测氨基脲(SEM)的电化学传感器.采用傅里叶变换红外光谱、透射电子显微镜、电化学阻抗谱对修饰材料进行表征.结果表明,羧基化的多壁碳纳米管出现羧基碳氧双键的红外特征峰,管径明显减小,长度变短,电化学阻抗值显著减小.在1 mol/L HAc-NaAc缓冲液中,利用循环伏安法和时间-电流曲线研究了SEM在CMWCNTs修饰电极上的电化学行为.SEM在修饰电极上呈现不可逆的氧化峰.与裸电极相比,氧化峰电流明显增大.在最佳实验条件(pH 7.0,扫描速度为0.1 V/s)下,测得SEM在5.00×10-6~1.09×10-3mol/L浓度范围内与氧化峰电流呈线性关系,线性方程为IP(μA)=-0.472+0.0599C(μmol/L),相关系数r=0.997,检出限为1.88×10-7 mol/L(S/N=3).在实际猪肝样品检测中加标回收率为92.8%~98.0%.     

Amperometric Glucose Sensor Fabricated by Combining Glucose Oxidase Micelle Membrane and Aminated Glassy Carbon Electrode

Abstract

An amperometric glucose biosensor based on the detection of the reduction of oxygen has been developed by combining an aminated glassy carbon electrode with a polystyrene (PS) membrane containing glucose oxidase (GOD) micelles. The structure of GOD micelles contained in PS membrane was observed by scanning electron microscope. The micelle has a roughly spherical shape, and the enzyme colony is contained inside the micelle. This glucose sensor exhibited good sensitivity with short response time (within 2 min). A good linear relationship was observed in the concentration range of 0.2 mM to 2.6 mM when the applied potential was ? 0.45 V vs. Ag/AgCl.     

Study of Factors Affecting the Performance of Voltammetric Copper Sensors Based on Gly‐Gly‐His Modified Glassy Carbon and Gold Electrodes

This paper reports a study of the factors affecting the analytical performance of gold and glassy carbon electrodes modified with the tripeptide Gly‐Gly‐His for the detection of copper ions. Gly‐Gly‐His is attached to a glassy carbon (GC) surface modified with 4‐carboxyphenyl moieties or a gold surface modified with 3‐mercaptopropionic acid by the reaction of the N‐terminal amine group of the peptide with the carboxylic acid groups of the monolayer via carbodiimide activation. X‐ray photoelectron spectroscopy was used to characterize the steps in the biosensor fabrication. It was found that the analytical performance of a sensor prepared with Gly‐Gly‐His on a GC electrode was similar to that on a gold electrode under the same conditions. The performance was greatly enhanced at higher temperature, no added salt during copper accumulation and longer accumulation time within a pH range of 7–9. Interference studies and investigations of stability of the Gly‐Gly‐His sensor are reported. Analysis of natural water samples show that the sensors measure only copper ions that can complex at the sensor surface. Strongly complexed copper in natural water is not measured. Despite greater stability of diazonium salt derived monolayers on carbon surfaces compared with alkanethiols self‐assembled monolayers on gold, the stability of the sensors was essentially the same regardless of the modification procedure.