Disposable Multiwalled Carbon Nanotube Printed Film Electrochemical Determination of Acetaminophen,Dopamine, and Uric Acid

A novel printed film consisting of multiwalled carbon nanotubes was fabricated on a polyethylene terephthalate substrate by means of a mass flexographic printing process. Potential applications of this film for electrochemical biosensing were examined through the oxidation of acetaminophen, dopamine, and uric acid in phosphate buffer (pH 7.0). The results demonstrate that the printed carbon nanotube film exhibits an enhanced electrochemical response toward these molecules. Dopamine and uric acid did not interfere with each other and, thus, their simultaneous determination may be performed. The results suggest the mass flexographic printing technique has potential application for the construction of low-cost, precise, and disposable multiwalled carbon nanotube films.     

Hollow Reticular Shaped Highly Ordered Rice Husk Carbon for the Simultaneous Determination of Dopamine and Uric Acid

We have prepared activated porous carbon material through simple pyrolysis method from rice husks (rhAC) for sensitive detection of dopamine (DA) and uric acid (UA). The prepared rhAC material was thoroughly characterized using various spectroscopic, microscopic, and electroanalytical techniques. Analysis of the voltammetric data showed that the analytes followed a first order reaction kinetics while following a 2e^?/2H⁺ transfer process. We have discussed the possible oxidation mechanism for the analytes based on the results from our experimental analysis. The rhAC_GCE sensor was tested for interference, reproducibility, and stability. The sensor was also tested to evaluate its applicability in real life.     

Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid at Pt Nanoparticles Decorated Multiwall Carbon Nanotubes Modified GCE

A modified electrode was fabricated by electrochemically deposition of Pt nanoparticles on the multiwall carbon nanotube covered glassy carbon electrode (Pt nanoparticles decorated MWCNT/GCE). A higher catalytic activity was obtained to electrocatalytic oxidation of ascorbic acid, dopamine, and uric acid due to the enhanced peak current and well‐defined peak separations compared with both, bare and MWCNT/GCE. The electrode surfaces were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). Individual and simultaneous determination of AA, DA, and UA were studied by differential pulse voltammetry. The detection limits were individually calculated for ascorbic acid, dopamine, and uric acid as being 1.9×10^?5 M, 2.78×10^?8 M, and 3.2×10^?8 M, respectively. In simultaneous determination, LODs were calculated for AA, DA, and UA, as of 2×10^?5 M, 4.83×10^?8 M, and 3.5×10^?7 M, respectively.     

聚钙羧酸修饰玻碳电极差分脉冲伏安法同时测定多巴胺和尿酸

采用电化学方法将钙羧酸(CCA)聚合修饰在玻碳电极(GCE)表面制备了聚钙羧酸指示剂修饰玻碳电极(PCCA/GCE),并用循环伏安法和交流阻抗法研究了电极的电化学性能。结果表明:在pH 6.0的磷酸盐缓冲溶液中,多巴胺(DA)和尿酸(UA)在聚钙羧酸修饰电极上的氧化峰得以分开,峰电位差为0.14V,据此提出了聚钙羧酸修饰电极差分脉冲伏安法同时测定多巴胺和尿酸的方法。DA和UA的浓度分别在5.0～43.8μmol.L-1和5.0～50.0μmol.L-1范围内与其氧化峰电流呈线性关系,检出限(3S/N)分别为0.2μmol.L-1和0.5μmol.L-1。方法可用于多巴胺注射液样品中DA和UA的测定,测定值的相对标准偏差(n=5)依次为2.43%和2.35%。     

Electropolymerization of Thin Film Conducting Polymer and Its Application for Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid

In this paper electropolymerization of a thin film of para‐phenylenediamine (PPD) is studied at glassy carbon electrode (GCE) in sulfuric acid media by cyclic voltammetry. The results showed that this polymer was conducting and had a reproducible redox couple in the potential region from 0.0 to 0.4 V in phosphate buffer solution. This modified GCE (p‐PPD‐GCE) was applied for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) using differential pulse voltammetry (DPV). The p‐PPD‐GCE in 0.1 M phosphate buffer solution (pH 5.0) separated the DPV signals of AA, DA and UA with sufficient potential differences between AA–DA and DA–UA and also enhanced their oxidation peak currents. The oxidation currents were increased from 2.0 to 2000.0 µM for AA, 10.0 to 1250.0 µM for DA and 50.0 to 1600.0 µM for UA. The detection limits were evaluated as 0.4, 1.0 and 2.5 µM for AA, DA and UA, respectively (S/N=3).     

Electrochemical Determination of Tyrosine in the Presence of Dopamine and Uric Acid at the Surface of Gold Nanoparticles Modified Carbon Paste Electrode

A gold nanoparticles modified carbon paste electrode (GN‐CPE) was used as a highly sensitive electrochemical sensor for determination of tyrosine (Tyr), dopamine (DA) and uric acid (UA) in phosphate buffer solution (PBS). The study and measurements were carried out by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry methods. In DPV, the GN‐CPE could separate the oxidation peak potentials of DA and UA present in the same solution, though at the unmodified CPE the peak potentials were indistinguishable. The prepared electrode showed voltammetric responses with high sensitivity and selectivity for Tyr, DA and UA in optimal conditions, which makes it very suitable for simultaneous determination of these compounds. The calibration curves for Try, DA and UA were linear for the concentrations of each species. The proposed voltammetric approach was also applied to the determination of Tyr concentration in human serum as a real sample.     

TiO2-石墨烯-Nafion复合膜修饰玻碳电极同时测定多巴胺和尿酸

利用在玻碳电极上修饰了TiO2-石墨烯-Nafion复合膜制得的修饰电极进行多巴胺(DA)和尿酸(UA)的同时测定。用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了该修饰电极的电化学行为。在pH为7.0的磷酸盐缓冲液(PBS)中,修饰电极对于DA和UA的电化学氧化具有良好的电催化性能。DA和UA的氧化峰电流分别在2～120和60～300μmol/L浓度范围内呈良好的线性关系,检出限分别为0.066和0.102μmol/L。实验结果表明,TiO2-石墨烯-Nafion复合膜修饰电极显著提高了检测的灵敏度,并表现出良好的选择性和重现性。     

单分子层γ-氨基丁酸共价修饰玻碳电极同时测定多巴胺、尿酸和抗坏血酸

采用电氧化法制备了一种新型γ-氨基丁酸(ABA)修饰的玻碳电极.X射线光电子能谱(XPS)和循环伏安法研究表明,ABA以单分子层状态以C—N键牢固地共价键合在电极表面.该修饰电极对多巴胺(DA)、尿酸(UA)和抗坏血酸(AA)都具有良好的电化学催化特性.在pH=7.0磷酸缓冲溶液中,DA,UA和AA分别于0.45,0.25和0.07V(vs.Ag/AgCl)有一个良好的、独立的阳极方波伏安峰,表明此修饰电极可用于这3种物质的同时测定.与DA,UA和AA的方波伏安峰电流呈线性关系的浓度范围分别为4.0～400,2.0～500和1.0～600μmol/L,检测限(3δ)分别为1.6,1.2和0.8μmol/L.该修饰电极具有良好的灵敏度、选择性和稳定性,并具有抗污染能力.     

金纳米粒子-石墨烯修饰玻碳电极的制备及对多巴胺、抗坏血酸和尿酸的同时检测

采用三步法制备了金纳米粒子-石墨烯层层组装的复合材料,并将其修饰在玻碳电极上,制备成一种新型的同时检测抗坏血酸(AA)、多巴胺(DA)和尿酸(UA)的电化学传感器。采用扫描电子显微镜(SEM)对复合材料进行了表征,并研究了传感器对AA、DA、UA电催化性能。结果表明:该传感器对AA、DA和UA的氧化具有很好的催化和分离效果,可实现AA、DA和UA的同时测定。在三者共存体系中,AA-DA、DA-UA、AA-UA的氧化峰电位差分别为152mV、161mV和313mV。线性范围分别为1.996×10-5~5.580×10-3、1.996×10-6~5.478×10-3和1.000×10-6~1.000×10-3 mol/L,检出限分别为1.200×10-5、1.030×10-7和4.100×10-7 mol/L。该修饰电极选择性好、稳定性高,有望用于实际样品中AA、DA和UA的同时检测。     

Synergistic Effect of Graphene and Multiwalled Carbon Nanotubes on a Glassy Carbon Electrode for Simultaneous Determination of Uric Acid and Dopamine in the Presence of Ascorbic Acid

A poly(diallyldimethylammonium chloride)-graphene-multiwalled carbon nanotube modified glassy carbon electrode was fabricated and evaluated by cyclic voltammetry and differential pulse voltammetry. The modified electrode offered high sensitivity, selectivity, excellent long-term stability, and electrocatalytic activity for uric acid and dopamine. This sensor showed wide linear dynamic ranges of 5.0 to 350.0 µmol L^?1 for uric acid and 10.0 to 400.0 µmol L^?1 for dopamine in the presence of 500 µmol L^?1 ascorbic acid. The limits of detection were 0.13 for uric acid and 0.55 µmol L^?1 for dopamine. This functionalized electrode has potential application in bioanalysis and biomedicine.     

A Novel Strategy for Simultaneous Determination of Dopamine and Uric Acid Using a Carbon Paste Electrode Modified with CdTe Quantum Dots

A novel CdTe quantum dots‐modified carbon paste electrode (QDMCPE) was fabricated and used to study the electrooxidation of dopamine and uric acid and their mixtures by electrochemical methods. Using square wave voltammetry (SWV), a highly sensitive and simultaneous determination of dopamine and uric acid was explored at the modified electrode. SWV peak currents of dopamine and uric acid increased linearly with their concentrations in the ranges of 7.5×10^?8–6.0×10^?4 M, and 7.5×10^?6–1.4×10^?3 M, respectively. Finally this new sensor was used for determination of dopamine and uric acid in some real samples.     

基于乙硫基取代的三层酞菁铕二聚体修饰ITO电极构筑电化学多巴胺和尿酸传感器

通过在水平和垂直两个方向上来扩展酞菁配合物的共轭结构, 合成了三明治三层酞菁铕二聚体配合物[Pc(SC₂H₅)₈]₂Eu₂[BiPc(SC₂H₅)₁₂]Eu₂[Pc(SC₂H₅)₈]₂, 使用Quasi-Langmuir-Sh?fer(QLS)方法将配合物薄膜修饰在氧化铟锡导电玻璃(ITO)电极表面, 利用多种谱学手段对配合物分子在薄膜内的排列进行表征, 发现分子采取J聚集模式Edge-on排列在ITO电极表面, 该薄膜具有良好的半导体性质, 导电率高达8.86×10^-5 S/cm. 将配合物薄膜修饰的ITO电极成功应用于多巴胺(DA)和尿酸(UA)的电化学灵敏检测, 最低检测限分别达到1.35和1.64 μmol/L, 灵敏度分别达到110和186.5 mA·μL·mol^-1 ·cm^-2.     

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.     

Monodispersed Gold Nanoparticles Decorated Carbon Nanotubes as an Enhanced Sensing Platform for Nanomolar Detection of Tramadol

A promising composite‐modified glassy carbon electrode is fabricated by electrodeposition of mono‐dispersed gold nanoparticles onto carbon nanotubes (AuNPs/CNTs/GCE). The electroanalysis of Tramadol (TRA) was achieved by different electrochemical techniques. The effect of different parameters including pH, concentration and potential scan on the oxidation current signal of TRA was investigated. Large excess of ascorbic acid (AA) and uric acid (UA) with a maximum molar ratio of 1/1000 and 1/100, respectively, did not interfere with the response of TRA. The detection limit with high sensitivity is 68 nM. TRA was successfully determined in pharmaceutical dosage forms, without any pretreatment of the samples.     

RNA Modified Electrodes for Simultaneous Determination of Dopamine and Uric Acid in the Presence of High Amounts of Ascorbic Acid

A promising electrochemical biosensor was fabricated by electrochemical grafting of ribonucleic acid (RNA) at 1.8 V (vs. SCE) on glassy carbon electrode (GCE) (denoted as RNA/GCE), for simultaneous detection of dopamine (DA) and uric acid (UA) with coexistence of excess amount of ascorbic acid (AA). The electrode was characterized by X‐ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The RNA modified layer on GCE exhibited superior catalytic ability and anionic exclusive ability in comparison with the DNA modified electrode. Three separated anodic DPV peaks were obtained at 0.312, 0.168 and ?0.016 V for UA, DA and AA, respectively, at the RNA/GCE in pH 7.0 PBS. In the presence of 2.0 mM AA, a linear range of 0.37 to 36 μM with a detection limit of 0.2 μM for DA, and in the range of 0.74 to 73 μM with a detection limit of 0.36 μM for UA were obtained. The co‐existence of 5000 fold AA did not interfere with the detection of DA or UA. The modified electrode shows excellent selectivity, good sensitivity and good stability.     

Facile Synthesis of Gold Nanoparticle-loaded Carbon Nanofiber Composites and Their Electrocatalytic Activity Towards Dopamine, Ascorbic Acid and Uric Acid

A facile approach for the synthesis of gold nanoparticle-loaded carbon nanofiber(Au/CNF) composites was developed. When applied to electrochemistry, these composites showed attractive performances such as high conductivity and facile electron transfer kinetics. Under physiological conditions, the Au/CNF composite modified electrode exhibits highly electrocatalytic activity for the oxidation of dopamine, ascorbic acid and uric acid. Owing to the good selectivity for the simultaneous detection of these three ...     

聚乙烯亚胺功能化石墨烯修饰电极同时测定抗坏血酸、 多巴胺、尿酸和色氨酸

制备了聚乙烯亚胺(PEI)功能化的石墨烯(G)修饰电极以实现抗坏血酸(AA)、 多巴胺(DA)、 尿酸(UA)和色氨酸(Trp)的分离及同时测定. 采用红外光谱(FTIR)、 紫外-可见吸收光谱(UV-Vis)、 X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对电极修饰材料进行了表征, 并优化了该修饰电极同时测定AA, DA, UA和Trp的实验条件. 在聚乙烯亚胺功能化石墨烯修饰的玻碳电极(PEI-G/GCE)上实现了AA, DA, UA 和Trp氧化峰的分离, AA-DA, DA-UA和UA-Trp的氧化峰电位差分别为298, 130和350 mV. 该修饰电极对AA, DA, UA和Trp的检测线性范围分别为50~5800, 30~2570, 0.05~400和6~1000 μmol/L; 检出限分别为16.67, 10, 0.017和2 μmol/L.     

Treated Screen Printed Electrodes Based on Electrochemically Reduced Graphene Nanoribbons for the Sensitive Voltammetric Determination of Dopamine in the Presence of Uric Acid

In this research, the graphene oxide nanoribbons (GONRs) were substantially synthesized by the oxidative longitudinal unzipping of the multi‐walled carbon nanotubes (MWCNTs). Then, a direct electrochemical technique was employed for reducing GONRs adsorbed on the screen printed carbon electrode (SPCE). Electrochemical reduction effectively eliminated the oxygen‐containing groups in the GONRs and produced the electrochemically reduced graphene nanoribbons (ERGNRs). Field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) were employed to characterize the materials. The modified SPCE with ERGNRs (ERGNRs/SPCE) displayed acceptable electrocatalytic characteristics towards the oxidation of dopamine (DA) and uric acid (UA) and applied to the simultaneous determination of these two analytes. ERGNRs/SPCE has a peak potential difference of 245 mV between DA and UA. The anodic peak currents of DA and UA were linear within the concentration ranges between 0.5 and 300.0 μM and 1.0 to 400.0 μM in phosphate buffer (pH=7.0) respectively. The detection limit of the technique for DA is 0.15 μM (S/N=3) and for UA is 0.3 μM (S/N=3). The proposed approach has been applied to the determination of DA and UA in real samples and generated acceptable outputs.     

Simultaneous Voltammetric Detection of Salsolinol and Uric Acid in the Presence of High Concentration of Ascorbic Acid with Gold Nanoparticles/Functionalized Multiwalled Carbon Nanotubes Composite Film Modified Electrode

This work demonstrates gold nanoparticles (AuNPs)/functionalized multiwalled carbon nanotubes (f‐MWCNT) composite film modified gold electrode via covalent‐bonding interaction self‐assembly technique for simultaneous determination of salsolinol (Sal) and uric Acid (UA) in the presence of high concentration of ascorbic acid (AA). In pH 7.0 PBS, the composite film modified electrode exhibits excellent voltammetric response for Sal and UA, while AA shows no voltammetric response. The oxidation peak current is linearly increased with concentrations of Sal from 0.24–11.76 μmol L^?1 and of UA from 3.36–96.36 μmol L^?1, respectively. The detection limits of Sal and UA is 3.2×10^?8 mol L^?1 and 1.7×10^?7 mol L^?1 , respectively.     

Simultaneous Determination of Ascorbic Acid,Dopamine and Uric Acid Based on Gold Nanoparticles‐PTCA‐Cys Composites Modified Electrodes

In this study, a nanocomposite of 3, 4, 9, 10‐perylenetetracarboxylic acid and L‐cysteine (PTCA‐Cys) with satisfactory water‐solubility and film‐forming ability was prepared and worked as substrate for modifying the glassy carbon electrode. Then, gold nanoparticles (AuNPs) were immobilized to achieve a PTCA‐Cys‐AuNPs modified electrode which provided more reaction positions on the sensor. Scanning electron microscopy, transmission electron microscopy, cyclic voltammetry and different pulse voltammetry were employed to characterize the assembly process of the sensor. The constructed sensor displayed desirable sensitivity, selectivity and stability towards the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Under the optimal experimental conditions, the oxidation peaks of AA, DA and UA appeared at 64, 240 and 376 mV, respectively. The corresponding linear response ranges were 3.2–435, 0.04–100 and 0.80–297 μM, and the detection limits were 1.1, 0.010 and 0.27 μM (S/N=3), respectively.