Simultaneous Determination Of Dopamine Research Articles

Polymeric nanoparticle of copper(II)-4,4′-dicyanamidobiphenyl ligand: Synthetic, spectral and structural aspect; application to electrochemical sensing of dopamine and ascorbic acid

In this research, new polymer of 4,4′-dicyanamidobiphenyl (bpH2)-Cu(II) complex, [Cu(bp)(H2O)2]n, has been synthesized and characterized by FT-IR, UV–vis spectroscopy and elemental analysis. The spherical morphology of Cu nanoparticles was confirmed by scanning electron microscopy (SEM) image and the transmission electron microscopy (TEM) image showed that the particle size dimensions of Cu nanoparticles were about 80nm. Thermal gravimetric analysis (TGA) results indicated that this polymer was thermally stable. Hence, the prepared polymer was used as a modifier for the electrochemical determination of dopamine (DA) and ascorbic acid (AA). Compared to the bare carbon paste electrode (CPE) and multiwall carbon paste electrode (CNTPE), bpCu modified CPE (bpCu-CPE) exhibits much higher electrocatalytic activities toward the oxidation of dopamine and ascorbic acid with an increase in peak currents and a decrease in oxidation overpotentials. The effects of scan rate, concentration and pH were also studied. Differential pulse voltammetry results show that DA and AA could be detected selectively and sensitively at bpCu-CPE with peak-to-peak separation of 200mV. Relative standard deviations for AA and DA determinations were less than 2.5%, and the linear response ranges of the electrode were 0.05–30.0μmolL−1 for AA and DA, respectively. The calculated detection limits were 0.02 and 0.04μmolL−1 (S/N=3) for AA and DA, respectively. In addition, the presented method was successfully applied for the simultaneous determination of DA and AA in urine and blood samples with reliable recovery.

Poly(ionic liquids) functionalized polypyrrole/graphene oxide nanosheets for electrochemical sensor to detect dopamine in the presence of ascorbic acid.

Novel poly(ionic liquids) functionalized polypyrrole/graphene oxide nanosheets (PILs/PPy/GO) were prepared by the polymerization of 1-vinyl-3-ethylimidazole bromide (VEIB) on the surface of N-vinyl imidazolium modified PPy/GO nanosheets. Due to the synergistic effects of GO with well-defined lamellar structures, conductive PPy and biocompatible PILs, PILs/PPy/GO modified glassy carbon electrode (GCE) presented the excellent electrochemical catalytic activity towards dopamine (DA) with good stability, high sensitivity and wide linear range in the present of ascorbic acid (AA) with high concentration. PILs played an essential role for the simultaneous determination of DA and AA in a mixture, whose existence effectively improved the transmission mode of electrons and resulted in the different electrocatalytic performance towards the oxidation of DA and AA. It is indicated that PILs/PPy/GO nanosheets can act as a good steady and sensitive electrode material for the development of improved DA sensors.

Simultaneous analysis of dopamine and 5-hydroxyindoleacetic acid at nanogold modified screen printed carbon electrodes

A convenient, low cost, and sensitive electrochemical method, based on a disposable gold nanoparticles modified screen printed carbon sensor (AuNPs/SPCs), is described for the simultaneous determination of dopamine (DA) and 5-hydroxyindole acetic acid (5-HIAA). The presence of the excess of ascorbic acid and uric acid did not interfere in the determination. Field emission scanning electron microscopy (FE-SEM) and electrochemical impedance spectroscopy (EIS) were used to characterize the surface morphology of the AuNPs modified SPCs. The modified electrode exhibited good electrocatalytic properties toward the oxidation of DA and 5-HIAA. A peak potential difference of 230mV between DA and HIAA was large enough to determine DA and 5-HIAA individually and simultaneously. The anodic peak currents of DA and 5-HIAA were found to be linear in the concentration range of 0.2–100μM and 0.5–200μM with the detection limit of 8nM and 22nM, respectively. The analytical utility of method was checked by determining the DA in various pharmacological dosage forms. The utility of AuNPs/SPCs was also demonstrated successfully for the simultaneous determination of DA and 5-HIAA in human plasma and urine samples.

Simultaneous determination of dopamine, ascorbic acid and uric acid using a multi-walled carbon nanotube and reduced graphene oxide hybrid functionalized by PAMAM and Au nanoparticles

A nanohybrid (RGO–PAMAM–MWCNT–AuNPs) for simultaneous electrochemical determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) was reported in this paper.

Modification of electrode surface with covalently functionalized graphene oxide by l-tyrosine for determination of dopamine

An l-tyrosine (l-Tyr) covalently functionalized graphene oxide (GO) composite (Tyr–GO) has been prepared through amide bonds, which is further used to modify glassy carbon electrode (GCE) by simple dipping-drying method. The differential pulse voltammetry (DPV) peaks of dopamine (DA) and ascorbic acid (AA) can be completely separated with a peak potential difference of 414mV by using the fabricated Tyr–GO/GCE, holding promise for simultaneous determination of DA and AA. The peak currents are linearly with the concentration of DA in the range from 1.0×10−6 to 5.0×10−4mol/L with a detection limit of 2.8×10−7mol/L. In addition, the modified electrode exhibits excellent reproducibility and stability.

Dispersible mesoporous carbon nanospheres as active electrode materials for biomolecular sensing

Mesoporous carbon electrode materials have attracted attention in analytical chemistry and materials science, particularly in the electrochemical determination of biomolecules, because of their open-pore structure, large surface area, and high electrochemical activity. In this study, novel mesoporous carbon nanospheres (MCNSs) with open-pore structure, which is beneficial in preparing dispersible phases of powders for sensor fabrication, were designed and synthesized using a facile soft template approach. The accessibility of the MCNS-based active electrode material was demonstrated by simultaneous determination of dopamine, ascorbic acid, and uric acid at physiological pH. The dispersibility of MCNS was manifested by the improved stability and reproducibility of the fabricated electrochemical sensor. Meanwhile, another two similar nanospheres, namely, carbon nanospheres without open-pore structure and electrochemically inert mesoporous silica nanospheres, were also fabricated to determine the origin of the catalytic activity of the MCNSs. The high activity of the MCNS-based electrode materials can be attributed to their nanoporous structure and conductive carbon skeleton that contains high degree of defects. In addition, highly open nanopores allowed easy access of the targets to the defective sites on the nanopore walls, thereby enhancing catalytic activity and reducing response time.

Simultaneous determination of neurotransmitters and a neuroprotector in human blood serum and urine samples using a diazonium grafted gold nanoparticle film electrode

An electrode modified with a film of aminophenyl grafted gold nanoparticles (AP-AuNPs) was used for the simultaneous determination of the neurotransmitters dopamine (DA) and adenosine (AD) in the presence of the neuroprotector guanosine (GN) at physiological pH. A bare glassy carbon electrode was unable to resolve the voltammetric signals of DA, GN and AD as a result of surface fouling caused by the oxidation products. However, the electrode modified with an AP-AuNP film separated the voltammetric signals of DA, GN and AD with potential differences of 800 mV between DA and GN and 340 mV between GN and AD; their oxidation peak currents were also enhanced. The simultaneous determination of DA, GN and AD was successfully achieved at the electrode modified with an AP-AuNP film using differential pulse voltammetry. The amperometric current response increased linearly with increasing concentrations of DA, GN and AD in the ranges 4.0 × 10−8 to 1 × 10−4 M, 7.0 × 10−8 to 5 × 10−5 M and 2.0 × 10−7 to 1 × 10−4 M, respectively, and the detection limits were 8.0 × 10−11 M for DA, 2.6 × 10−8 M for GN and 5.1 × 10−8 M for AD (S/N = 3). The practical application of the electrode modified with an AP-AuNP film was demonstrated by simultaneously determining the concentrations of DA, GN and AD in human blood serum and urine samples.

One step electrosynthesis of polyacrylamide crosslinked by reduced graphene oxide and its application in the simultaneous determination of dopamine and uric acid

Polyacrylamide (PAM)/reduced graphene oxide (rGO) nanocomposite (PAM/rGO) with rGO nanosheets as cross-linkers were synthesized via electropolymerizing acrylamide in an aqueous suspension of GO containing sodium nitrate and potassium persulfate. The PAM/rGO was characterized with X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). XRD patterns of the PAM/rGO indicated that rGO was fully exfoliated into individual sheets in the polymer matrix. SEM study exhibits the highly uniform coverage of PAM/rGO membrane on the GCE and its fibrous nanostructure. The electrochemical characteristics of the PAM/rGO modified glassy carbon electrode (GCE) were investigated with cyclic voltammetry (CV), suggesting the extraordinary electrocatalytic effect of PAM/rGO/GCE towards the electro-oxidation of UA and DA. The PAM/rGO/GCE behaved linearly to DA and UA in the concentration range of 3×10−7 to 5×10−5M and 1×10−6 to 5×10−5M with a detection limit of 1×10−7M and 5×10−7M, respectively. The proposed method was successfully utilized for simultaneous determination of UA and DA in real samples.

The influence of organization of LbL films containing a silsesquioxane polymer on the electrochemical response of dopamine

This paper describes the construction, evaluation, and application of an electrochemical sensor for the determination of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). Satisfactory results were achieved for the simultaneous determination of DA and UA, it was verified that it is possible to detect AA in the presence of DA, but high concentrations of AA interfere in detection of DA. The sensor was constructed using the layer-by-layer (LbL) technique with the modification of the surface of indium tin oxide coated glass (ITO) substrate with nanostructured films comprising a 3-n-propylpyridinium silsesquioxane polymer (SiPy+Cl−) and nickel(II) tetrasulfophthalocyanine (NiTsPc). Using the square wave voltammetry technique (SWV), the LbL modified electrodes produced at different pHs (pH 2 and 8) were used to determine DA in the presence UA, and the electrochemical responses of the electrodes were compared. It was observed that the electrodes with the highest concentration of monomeric species showed the highest current intensity and the lowest peak potential for the DA and UA analytes in analysis of DA and UA, individually and simultaneously, with peak potential separation of 460 mV versus Ag/AgCl. Applying SWV, a linear dynamic range of 10–99 μmol L−1 and 100–900 μmol L−1 with detection limit of 16.8 μmol L−1 and 58.3 μmol L−1 was obtained for DA and UA, respectively. The method has good selectivity and sensitivity, and it was successfully applied to the simultaneous determination of DA and UA in spiked human urine sample.

Simultaneous and sensitive detection of dopamine and uric acid using a poly(L-methionine)/gold nanoparticle-modified glassy carbon electrode

A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine) (PMT)-modified glassy carbon electrode (GCE) to form a nano-Au/PMT composite-modified GCE (nano-Au/PMT/GCE). Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode. The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH = 7.00). Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0 × 10 −8 to 10 −6 mol/L for DA and 7.0 × 10 −8 to 10 −6 mol/L for UA. The detection limits were 3.7 × 10 −8 mol/L for DA and 4.5 × 10 −8 mol/L for UA at a signal-to-noise ratio of 3. According to our experimental results, nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA. A glassy carbon electrode modified with gold nanoparticles and poly(L-methionine) exhibited high electrocatalytic activity towards the oxidation of dopamine and uric acid. This electrode allowed sensitive and selective determination of dopamine and uric acid at nanomolar levels.

Simultaneous voltammetric determination of dopamine and epinephrine in human body fluid samples using a glassy carbon electrode modified with nickel oxide nanoparticles and carbon nanotubes within a dihexadecylphosphate film.

A simple and highly selective electrochemical method was developed for the single or simultaneous determination of dopamine (DA) and epinephrine (EP) in human body fluids using a glassy carbon electrode modified with nickel oxide nanoparticles and carbon nanotubes within a dihexadecylphosphate film using square-wave voltammetry (SWV) or differential-pulse voltammetry (DPV). Using DPV with the proposed electrode, a separation of ca. 360 mV between the peak reduction potentials of DA and EP present in binary mixtures was obtained. The analytical curves for the simultaneous determination of dopamine and epinephrine showed an excellent linear response, ranging from 7.0 × 10(-8) to 4.8 × 10(-6) and 3.0 × 10(-7) to 9.5 × 10(-6) mol L(-1) for DA and EP, respectively. The detection limits for the simultaneous determination of DA and EP were 5.0 × 10(-8) mol L(-1) and 8.2 × 10(-8) mol L(-1), respectively. The proposed method was successfully applied in the simultaneous determination of these analytes in human body fluid samples of cerebrospinal fluid, human serum and lung fluid.

Simultaneous determination of dopamine, uric acid and ascorbic acid using a glassy carbon electrode modified with reduced graphene oxide

A facile and cost-effective approach has been developed towards electrochemical fabrication of a reduced graphene oxide (RGO) modified glassy carbon electrode (RGO/GCE). Scanning electron microscopy (SEM) images show that RGO is covered completely on the surface of glassy carbon electrodes. The RGO/GCE is used to detect dopamine (DA), uric acid (UA) and ascorbic acid (AA) simultaneously via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Compared with bare GCE, RGO/GCE exhibits much high electrocatalytic activities toward the oxidation of DA, UA and AA, and three well-defined fully resolved anodic peaks were found in the CV curve at RGO/GCE. The GCEs modified with different amounts of RGO have an obvious influence on the determination of DA, UA and AA. By changing the concentrations of DA, UA and AA in the three substances coexisting system, the linear response ranges for the determination of DA, UA and AA were 0.1–400 μM, 2–600 μM, and 0.7–100 μM with the limit of detection (LOD) (S/N = 3) were estimated to be 0.1 μM, 1 μM and 0.7 μM, respectively. Moreover, it is found that RGO/GCE displays high reproducibility and selectivity for the determination of DA, UA and AA.

Simultaneous determination of dopamine, ascorbic acid and uric acid at electrochemically reduced graphene oxide modified electrode

A facile electrochemical method was applied to prepare electrochemically reduced graphene oxide (ERGO). The morphology and structure of ERGO were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and X-ray diffraction (XRD). Compared with the bare glassy carbon electrode (GCE), ERGO modified GCE (ERGO/GCE) exhibits much higher electrocatalytic activities toward the oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA) with increasing of peak currents and decreasing of oxidation overpotentials. Differential pulse voltammetry results show that DA, AA and UA could be detected selectively and sensitively at ERGO/GCE with peak-to-peak separation of 240mV and 130mV for AA–DA and DA–UA, respectively. The linear ranges for AA, UA and DA are 500–2000μM, 0.5–60μM and 0.5–60μM, respectively. Meanwhile, due to the negligible response to physiological level of AA (0.1mM), ERGO/GCE could be used for the determination of DA in biological sample with high sensitivity and good selectivity. In addition, the presented method was successfully applied for the simultaneous determination of DA, AA and UA in urine sample with reliable recovery. This work provides a simple and green route to construct graphene-based electrochemical sensor, which is promising for the simultaneous determination of DA, AA and UA.

A novel electrocatalytic platform for separation of the overlapping voltammetric responses of AA, DA and UA

A novel electrocatalytic platform based on 5,15-bis (p-amino)-tetraphenylporphyrin (BATPP)/α-Al2O3 composites (sensitive materials) coated on glassy carbon electrodes, which was constructed by a simple electrochemical method, is reported. The directly simultaneous electrocatalytic oxidation and selective voltammetric peak separation of a mixture including ascorbic acid (AA), dopamine (DA) and uric acid (UA) in a phosphate buffer solution was investigated. The results showed that the platform resolved the overlapping voltammetric responses of AA, DA and UA with potential differences of 136 mV (AA to DA), 143 mV (DA to UA) and 279 mV (AA and UA) for cyclic voltammetry (CV). These results will open new opportunities for the development of an electrochemical sensor for the simultaneous determination of DA, UA and AA in real sample analyses in future.

Simultaneous determination of dopamine and uric acid in the presence of ascorbic acid using Pt nanoparticles supported on reduced graphene oxide

In this paper, a Pt/reduced graphene oxide (Pt/RGO) modified glassy carbon electrode was prepared for the detection of dopamine (DA) and uric acid (UA) in the presence of high concentration of ascorbic acid (AA). The electrochemical behavior of the Pt/RGO modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry, which showed good performance toward individual detection of DA and UA and even their simultaneous detection in the presence of 1.0mM AA. Evidently, the electro-oxidation peak currents displayed linear relationship with the associated DA and UA concentrations in the range of 10.0-170.0 μM and 10.0-130.0 μM, respectively, with the detection limits of 0.25 μM for DA and 0.45 μM for UA at three folds of the signal-to-noise ratio. The good performance of the Pt/RGO modified electrode provided a promising alternative in routine sensing applications.

Simultaneous Determination of Dopamine, Serotonin and Ascorbic Acid at a Glassy Carbon Electrode Modified with Carbon-Spheres

A novel glassy carbon electrode (GCE) modified with carbon-spheres has been fabricated through a simple casting procedure. The modified GCE displays high selectivity and excellent electrochemical catalytic activities towards dopamine (DA), serotonin (5-HT), and ascorbic acid (AA). In the co-existence system, the peak separations between AA and DA, DA and 5-HT, and AA and 5-HT are large up to 230, 180, and 410 mV, respectively. Differential pulse voltammetry (DPV) has been employed to simultaneously detect DA, 5-HT, and AA, and the linear calibration curves for DA, 5-HT, and AA are obtained in the range of 20.0–150.0 μM, 40.0–750.0 μM and 300.0–2,000.0 μM with detection limits (S/N = 3) of 2.0 μM, 0.7 μM and 0.6 μM, respectively. The proposed electrode has been applied to detect DA, 5-HT, and AA in real samples using standard addition method with satisfactory results.

Simultaneous determination of dopamine and uric acid using layer-by-layer graphene and chitosan assembled multilayer films

Multilayer films containing graphene (Gr) and chitosan (CS) were prepared on glassy carbon electrodes with layer-by-layer (LBL) assembly technique. After being characterized with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM), the electrochemical sensor based on the resulted films was developed to simultaneously determine dopamine (DA) and uric acid (UA). The LBL assembled electrode showed excellent electrocatalytic activity towards the oxidation of DA and UA. In addition, the self-assembly electrode possessed an excellent sensing performance for detection of DA and UA with a linear range from 0.1 μM to 140 µM and from 1.0 µM to 125 µM with the detection limit as low as 0.05 µM and 0.1 µM based on S/N=3, respectively.

Chemometric Strategies to Develop a Nanocomposite Electrode for Simultaneous Determination of Ascorbic Acid, Dopamine, and Uric Acid

AbstractA simple and sensitive method for simultaneously measuring dopamine (DA), ascorbic acid (AA), and uric acid (UA) using a poly(1‐aminoanthracene) and carbon nanotubes nanocomposite electrode is presented. The experimental parameters for composite film synthesis as well as the variables related to simultaneous determination of DA, AA, and UA were optimized at the same time using fractional factorial and Doehlert designs. The use of carbon nanotubes and poly(1‐aminoanthracene) in association with a cathodic pretreatment led to three well‐defined oxidation peaks at potentials around −0.039, 0.180 and 0.351 V (vs. Ag/AgCl) for AA, DA, and UA, respectively. Using differential pulse voltammetry, calibration curves for AA, DA, and UA were obtained over the range of 0.16–3.12×10−3 mol L−1, 3.54–136×10−6 mol L−1, and 0.76–2.92×10−3 mol L−1, with detection limits of 3.95×10−5 mol L−1, 2.90×10−7 mol L−1, and 4.22×10−5 mol L−1, respectively. The proposed method was successfully applied to determine DA, AA, and UA in biological samples with good results.

Development of Amperometric Biosensors Based on Nanostructured Tyrosinase-Conducting Polymer Composite Electrodes

Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 μM, with a detection limit of 4.18 μM.

Highly selective and sensitive dopamine and uric acid electrochemical sensor fabricated with poly (orotic acid)

A novel dopamine (DA) and uric acid (UA) electrochemical sensor (poly-OA/CPE) was fabricated by electrochemical polymerization of orotic acid (OA) on a carbon paste electrode (CPE). The sensor was characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) and the electrochemical behaviors of DA and UA were investigated. The experimental results illustrated that the sensor has an excellent electrocatalytic activity towards the oxidation of DA and UA. By using differential pulse voltammetry (DPV) method, low detection limits (S/N=3) of 0.08μM and 0.28μM for DA and UA were obtained, with the linear calibration curves over the concentration range of 0.31–15.21μM and 17.71–141.01μM for DA and 0.82–11.32μM and 13.62–200.62μM for UA, respectively. Moreover, the sensor exhibits good selectivity and sensitivity toward simultaneous determination of DA and UA. The practical analytical utility is illustrated by the determination of DA in pharmaceutical samples without any preliminary treatment.