Simultaneous Determination Of Dopamine Research Articles

Self-assembled ordered AuNRs-modified electrodes for simultaneous determination of dopamine and topotecan with improved data reproducibility.

Gold nanomaterials have been widely explored in electrochemical sensors due to their high catalytic property and good stability in multi-medium. In this paper, the reproducibility of the signal among batches of gold nanorods (AuNRs)-modified electrodes was investigated to improve the data stabilization and repeatability. Ordered and random self-assembled AuNRs-modified electrodes were used as electrochemical sensors for the simultaneous determination of dopamine (DA) and topotecan (TPC), with the aim of obtaining an improved signal stability in batches of electrodes and realizing the simultaneous determination of both substances. The morphology and structure of the assemblies were analyzed and characterized by UV-Vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). Electrochemical studies showed that the ordered AuNRs/ITO electrodes have excellent signal reproducibility among several individuals due to the homogeneous mass transfer in the ordered arrangement of the AuNRs. Under the optimized conditions, the simultaneous detection results of DA and TPC showed good linearity in the ranges 1.75-45 μM and 1.5-40 μM, and the detection limits of DA and TPC were 0.06 μM and 0.17 μM, respectively. The results showed that the prepared ordered AuNR/ITO electrode had high sensitivity, long-term stability, and reproducibility for the simultaneous determination of DA and TPC, and it was expected to be applicable for real sample testing.

Glassy carbon electrode modified with a film of tetraruthenated nickel(ii) porphyrin located in natural smectite clay's interlayer for the simultaneous sensing of dopamine, acetaminophen and tryptophan.

A supramolecular complex μ-meso-tetra(4-pyridyl) porphyrinate nickel(ii)tetrakis[bis(bipyridine)(chloro)ruthenium(ii)] ([NiTPyP{Ru(bipy)2Cl}4]4+) was intercalated into the interlayer space of natural smectite clay (shortened as Ba) collected in a Cameroonian deposit at Bagba hill. Physicochemical characterization of the resulting material using ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) confirmed the intercalation of the porphyrin within the interlayer space of the clay. The intercalated clay was then used to form a stable thin film onto a glassy carbon electrode (GCE) by drop casting a suspension of the hybrid material. The GCE modified with the intercalated organoclay endowed the electrode with a larger electrochemically active surface area, good stability, high selectivity, and sensitivity toward dopamine (DA), acetaminophen (AC) and tryptophan (Trp). In addition, it was observed that the modified electrodes exhibited good and pH-dependent electrocatalytic properties toward these analytes. The simultaneous determination of DA, AC and Trp at [NiTPyP{Ru(bipy)2Cl}4]4+-Ba/GCE was thus possible without the interference of one analyte on the others, and the resulting calibration curve exhibits two segments for the three analytes. For DA, AC and Trp, the detection limits were found to be 0.8 μM, 0.3 μM and 0.3 μM, respectively. The [NiTPyP{Ru(bipy)2Cl}4]4+-Ba/GCE modified electrodes were successfully applied for the determination of AC in Paracetamol, a commercial product, and Trp in real pharmaceutical formulation samples.

An efficient sensor based on anodic activation of graphene oxide for sensitive and selective determination of dopamine in blood serum

A native graphene oxide (NGO) prepared by Hummers modified method was used as the template materials for the fabrication of electrochemically oxidative graphene oxide (OGO) onto a glassy carbon electrode (GCE). The fabrication of OGO-GCE persuaded via anodic reversible potentiodynamic of NGO base surface materials that increases the concentration of oxygen functionalities. The development of a new aldehyde/alcoholic functional group on OGO-GCE characterized by XPS analysis is a marked signal for oxygen richness surface which provoked on the cost of sp2 hybridized function. The EIS data underline that OGO-GCE promote the electron transfer kinetics much more than NGO-GCE by 9 times as estimated by the rate constant calculation. The XPS and EIS data highlight the influence of anodic treatment on increasing the interlayer spacing distance between the resultant OGO. Differential pulse voltammetry (DPV) results were evident for a promising efficiency of OGO-GCE on the simultaneous determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA). In addition, the selectivity of the proposed sensor for DA quantification in the presence of high concentrations of AA and UA was achieved successfully with a detection limit (DL3s) approach to 12 nM. The analytical performance of OGO-GCE on serum blood revealed its potential application for trace DA quantification.

Eco-friendly synthesized silver-magnetic nanocomposite supported on nanocellulose modified glassy carbon electrode as an electrochemical sensor for simultaneous determination of dopamine and acetaminophen

Herein, a novel and eco-friendly synthesis of electrochemical sensor for simultaneous determination of dopamine (DA) and acetaminophen (AC) based on silver-magnetic nanocomposite supported on nanocellulose modified glassy carbon electrode (Ag-Fe3O4/NC/GCE). The synthesized nanomaterials have been characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDX). Important parameters such as scan rate and pH effects were studied to achieve the ideal conditions. The linearity ranges and the detection limits of DA and AC were 0.01–10.0 μM, 0.05–15.0 μM, 6.0 and 8.0 nM, respectively. The developed sensor was applied to real samples for the simultaneous determination of DA and AC.

Simultaneous determination of dopamine and uric acid based on electrocatalytic oxidation of Cu2O-Au and polyaniline nanocomposites

Effective detection of dopamine (DA) and uric acid (UA) has significant diagnostic values, while the analytical methods with high convenience, distinguishability and sensitivity still need to be developed. A highly sensitive and selective electrochemical sensor based on a polyaniline (PANI) nanocomposite embedding Au and Cu2O hybrid (PANI/Cu2O-Aux) with adjustable proportions of Cu2O and Au was developed for simultaneous detection of dopamine (DA) and uric acid (UA) in the presence of high concentrations of ascorbic acid (AA) and other interferents. The Cu2O-Aux architecture improved the electrocatalytic activity by inducing a modifiable synergistic effect between Au and Cu2O. Differential pulse voltammetry (DPV) responses of DA and UA on modified electrodes of PANI/Cu2O-Aux showed remarkable enhancement compared to the single-component Au or Cu2O-decorated PANI. The optimal ratio of Cu2O: Au was 1:1, which gave the highest redox signals for DA and UA. The DPV response ranges of simultaneous detection were 0.01–200 μM for DA and 0.1–1000 μM for UA, with detection limits (S/N = 3) of 0.0076 μM and 0.035 μM, respectively. The sensor also exhibited excellent anti-interference and stability, and was successfully applied to measure DA and UA in human urine samples with high accuracy. This research demonstrates the tunability of catalytic properties in PANI/Cu2O-Aux nanocomposites by the integration of binary nanocatalysts, providing insights into both structural and practical aspects.

CeO2 nanocubes-based electrochemical sensor for the selective and simultaneous determination of dopamine in the presence of uric acid and ascorbic acid

CeO2 nanocubes-based electrochemical sensor for the selective and simultaneous determination of dopamine in the presence of uric acid and ascorbic acid

Ultra-sensitive electrochemical sensors for simultaneous determination of dopamine and serotonin based on titanium oxide-gold nanoparticles-poly Nile blue (in deep eutectic solvent)

Determining blood serum levels of dopamine (DA) and serotonin (SE), which are important neurotransmitters, is of great importance in diagnosing and treating many diseases. In this work, a new disposable sensor was developed for the simultaneous determination of DA and SE. First, titanium oxide nanoparticles (TiO2NP) were modified on the screen-printed carbon electrodes (SPCE) by physical adsorption. Then, AuNP was coated on SPCE/TiO2NP by cyclic voltammetry (CV). Finally, a deep eutectic solvent (DES) appropriate for green chemistry, ethylene glycol/choline chloride, was used to electro-polymerize Nile blue (NB) on SPCE/TiO2NP/AuNP. The materials of TiO2NP, AuNP, and PNBDES were characterized by FE-SEM-EDX, XRD, and FTIR. The effects of TiO2NP, AuNP, and PNBDES modification order on the electrode surface on the separation of differential pulse voltammetry (DPV) peaks of DA and SE were investigated. DPV analysis conditions (deposition time and potential) and pH effect were examined. Analytical parameters of the prepared sensor were determined for both individual and simultaneous determination of DA and SE. The detection limits (3 σ/m) for simultaneous detection are 1.39 nM and 2.47 nM for DA and SE, respectively. The sensor's repeatability, reproducibility, and reusability were examined for the simultaneous determination of DA and SE. Application stability of the developed sensor was determined as 20 days and storage stability as 4 weeks. The selectivity of the DA and SE sensor in the presence of ascorbic acid, uric acid, glucose, and citric acid was investigated, and it was observed that the selectivity of the sensor was satisfactory. The disposable sensor simultaneously determined DA and SE in blood serum samples, and high recoveries were acquired. A new disposable sensor with great repeatability and reproducibility was created for the quick, practical, selective, and simultaneous analysis of DA and SE at low concentrations.

Novel hybrid material based on Ru complex and its RuO2 oxide for dopamine and dopamine-uric acid simultaneous determination

New binuclear ruthenium (III) complex was synthesized and characterized by elemental analysis, electrospray ionization mass spectrometry (ESI/MS), molar conductance, Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectrophotometry and cyclic voltammetry (CV). These techniques suggested that the Ru (III) complex presented a distorted octahedral coordination geometry. Then, hybrid materials (rGO/RuO2 and rGO/Ru complex/RuO2) were prepared after calcination of the Ru (III) complex with reduced graphene (rGO) under oxygen atmosphere at 700 and 400 °C, respectively. These composites were characterized by attenuated total reflection (ATR), scanning electron microscopy (SEM) and map analyses, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopic (XPS), zeta potential analysis, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). XRD analysis showed that the obtained oxides are crystalline solids, corresponding to RuO2 phases. In the second part of this study, the modified screen-printed carbon electrodes (SPCE) based on these hybrid materials were prepared and used as novel sensors for the detection of dopamine (DA) and uric acid (UA) using differential pulse voltammetry (DPV). The results showed that SPCE/rGO/Ru complex/RuO2 and SPCE/rGO/RuO2 electrodes exhibited a low dopamine detection limit (LOD) of 0.135 μmolL−1 and 1.22 μmol L−1, respectively. The simultaneous determination of DA and UA on SPCE/rGO/Ru complex/RuO2 showed LOD values of 57.4 and 93.48 nM. The reproducibility, repeatability and stability of this sensor were confirmed by RSD% values of 3.8, 2.2 and 4.5%, respectively.

Electrochemical Sensing of Dopamine and Epinephrine Using Self‐assembled Fe3O4 Magnetic Nanoparticles on a Pyridine‐grafted Glassy Carbon Electrode

AbstractA magnetic nanomaterial based electrochemical sensor was developed by immobilizing Fe3O4 nanoparticles (ca. 12 nm d.) on a pyridine molecule grafted glassy carbon electrode (Py‐GCE) for the selective and sensitive determination of two important neurotransmitters, dopamine (DA) and epinephrine (EP) at neutral pH. The synthesised Fe3O4 magnetic nanoparticleswere characterized by FTIR, UV‐Vis, TEM, XRD and XPS methods, whereas thefabricated electrodeswere characterized by using SEM, ATR‐FTIR, CV and EIS techniques. Differential pulse voltammetry was used for the determination of DA and EP in the linear range of 0.2 to 1.2 μM with the detection limits (S/N=3) of 0.34 nM and 0.61 nM, respectively. The sensor electrode exhibited high stability, reproducibility, good selectivity in the presence of potential interfering agents viz. ascorbic acid, uric acid, citric acid, glucose, etc. Theproposed method was successfully applied for the simultaneous determination of DA and EP in human blood sample and the recovery result was excellent.

A facile approach to synthesis methylene blue/reduced graphene oxide nanocomposite and simultaneous determination of dopamine and uric acid

A facile approach to synthesis methylene blue/reduced graphene oxide nanocomposite and simultaneous determination of dopamine and uric acid

A low-cost high-entropy porous CrO/CrN/C biosensor for highly sensitive simultaneous detection of dopamine and uric acid

A low-cost high-entropy porous CrO/CrN/C biosensor was fast fabricated by mechanical milling strategy for simultaneous detection of dopamine (DA) and uric acid (UA). Biosensor carrier derived from the natural waste jasmine flowers (JF) could be coated by DA and then coordinated with Cr3+ with the aid of high-energy mechanochemistry, which fabricate porous Cr-JFC/DAC electrode with highly dispersed CrO/CrN sites. The formed large amount of high active sites significantly enhanced the biosensor’s response signal and resolution for the detection of DA and UA. Moreover, the high surface (950.1 m2/g), enriched interface and conductive carbon carrier efficiently improved the electrical signal transfer of biosensor. The Cr-JFC/DAC2 modified electrode was used for the simultaneous determination of DA and UA in the range of 0.05 ∼ 4 μM with a limit of detection (LOD) 10.65 and 17.54 nM (S/N = 3) respectively. The LOD were 1 ∼ 2 orders of magnitude less than reported state-of-the-art non-precious metal sensors, and even lower than those of most precious metal sensors. The analytical performance of the Cr-JFC/DAC2-modified electrodes has been evaluated using human serum samples with recoveries of 97.00%∼104.00%, good anti-interference and stability. Therefore, the Cr-JFC/DAC2/Nafion/GCE exhibited a great potential in the real application to simultaneously detect DA and UA.

Ferrocene‐Functionalized Multiwalled Carbon Nanotubes for the Simultaneous Determination of Dopamine, Uric Acid, and Xanthine

AbstractIn this proof‐of‐concept study, ferrocene‐modified multiwalled carbon nanotubes (Fc‐MWCNT) were synthesized by amide coupling and the resulting product was characterized by transmission electron microscopy and Fourier‐transform infrared spectroscopy. The Fc‐MWCNT were used in a graphite paste electrode (GPE) for the highly sensitive simultaneous determination of dopamine (DA), uric acid (UA), xanthine (XA) by differential pulse voltammetry. The sensor displayed a linear range up to 4.5, 14, and 82.0 μM with a limit of detection of 2.0, 10.0 and 5 nM for DA, UA, and XA, respectively. In addition, the modified GPE/Fc‐MWCNT displayed a high stability, reproducibility, and repeatability. The GPE/Fc‐MWCNT was used for simultaneous determination of DA, UA, and XA in two different real samples with a recovery rate of 95–104 %.

Mo-W-O nanowire intercalated graphene aerogel nanocomposite for the simultaneous determination of dopamine and tyrosine in human urine and blood serum sample

• A novel electrochemical sensor was fabricated based on Mo-W-O nanowire intercalated graphene aerogel nanocomposite for the first time. • The proposed Mo-W-O/GA nanocomposite was prepared by two steps, facile hydrothermal and freeze-drying method. • Owing to the huge surface area, high porosity, and excellent conductivity of the GA facilitates the electron transfer process during the electrochemical reaction. • The proposed sensor was used to detect the dopamine and tyrosine in human urine and blood serum with satisfactory results. In recent years, most people affected by neurotransmitters and amino acid-related diseases, which cause more disorders in the human brain and body. And hence monitoring the trace level of neurotransmitters and amino acids is necessary. Nowadays transition bimetallic oxides (TBMO’s) play a vital role in sensing application due to their unique physical, electrical, and chemical properties. As the carbon-based materials, importantly graphene aerogel (GA) have a high surface area to enhance the conductivity of the electrode material. Here, we reported a molybdenum tungsten oxide nanowire intercalated graphene aerogel (Mo-W-O/GA) nanocomposite-based sensor for the simultaneous detection of dopamine (DA) and tyrosine (Tyr). The proposed Mo-W-O/GA nanocomposite was prepared by two steps, facile hydrothermal and freeze-drying method. The formation of the nanocomposite was verified by various spectroscopic techniques. The resulting Mo-W-O/GA/GCE could be used for the quick and sensitive simultaneous determination of DA and Tyr in the presence of other bio interfering compounds. The Mo-W-O/GA sensor exhibited maximum performance toward DA and Tyr under optimum conditions. The sensor parameter such as linear range and lower detection limit (LOD) of Mo-W-O/GA/GCE for the determination of DA was 0.001–448.0 μM and 0.8 nM respectively, and for the determination Try a linear range of 0.001–478.0 µM and LOD of 1.4 nM was obtained. The newly proposed sensor was used for precise sensing of DA and Tyr in human urine and blood serum samples with good satisfactory recoveries.

A covalent organic polymer-TiO2/Ti3C2 heterostructure as nonenzymatic biosensor for voltammetric detection of dopamine and uric acid.

Heterostructures have potential to blend the advantages of each material, even exhibiting the evolutionary performance due to synergistic effects. Herein, covalent organic polymers (NUF) are integrated with a TiO2/Ti3C2Tx nanocomposite (TiO2/TiCT) to form TiO2/TiCT-NUF heterojunctions as an enlarged nonenzymatic biosensor for dopamine (DA) and uric acid (UA). Detection is performed by differential pulse voltammetry (DPV). TheTiO2/TiCT/NUF exhibits high sensing activity with low detection limits of 0.2 and 0.18nM (S/N = 3) inthe concentration ranges from 0.002 to 100μM and 0.001 to 60μM for simultaneous determination of DA and UA, respectively. In addition, the TiO2/TiCT/NUF provides good selectivityand reproducibility for DA and UA detection in urine and serum samples with recoveries of 98.4 to 100.9%. The proposed heterojunctions manifest an intriguing potential as a candidate of an electrochemical sensor for sole and simultaneous detection of DA and UA.

Distinguishing catecholamines: Dopamine determination in the presence of epinephrine in water/acetonitrile mixtures

Several neural circuits within the hypothalamus, cerebellum and frontal cortex are simultaneously regulated by multiple catecholamines (CA). Yet, analytical methods that allow determination of CA either have low time resolution (microdialysis) or have poor selectivity (electrochemistry). In this study we used the structural difference between dopamine (DA) and epinephrine (EP) (primary amine group vs. methylated amine) as a distinguishable feature for the electrochemical detection of DA in DA/EP mixtures. Primary amino group of DA was activated in acetonitrile-water mixtures which provided an additional oxidation peak absent in the methylated amino group from EP. First, a systematic study of the effect of the water content in water/acetonitrile mixtures on the electrochemical response of DA is presented. It was found that the electrochemical reversibility of the main redox processes of DA is affected by the water content in acidified (1.0 mM HClO4) water/ACN mixtures. Decreasing the water content from 100% to 5% results in a progressive decrease of the DA reversibility and more importantly, promotes the appearance of a new redox signal, presumably associated to the oxidation of the amine center. That oxidation signal was used to achieve a simultaneous determination of DA and EP in water/acetonitrile mixtures (5% H2O) using square wave voltammetry. Results show an accurate determination of DA while offering an estimate of the concentration of EP. Our study opens up a new strategy for simultaneous electrochemical detection of either DA-EP or NE-EP, which in the future could be applied to surface modified microelectrodes for in vivo applications using the time resolution provided by fast-scan cyclic voltammetry, FSCV.

Electrochemical sensor based on dual-template molecularly imprinted polymer and nanoporous gold leaf modified electrode for simultaneous determination of dopamine and uric acid.

A novel electrochemical sensor based on dual-template molecularly imprinted polymer (MIP) with nanoporous gold leaf (NPGL) was established for the simultaneous determination of dopamine (DA) and uric acid (UA). NPGL acts as an enlarged loading platform to enhance sensing capacity, and the MIP layer was synthesized in situ in the presence of monomer and dual templates (DA and UA) to provide specific recognition. Under the optimal conditions, the sensor shows a good linear range of 2.0~180μM for DA at a working potential of 0.15V (vs. Ag/AgCl) and 5.0~160μM for UA at 0.35V (vs. Ag/AgCl), with the respective detection limit of 0.3μM and 0.4μM (S/N = 3). Good selectivity of the sensor to its dual templates was confirmed as the sensing signals are significantly different between templates and interfering species. The responses maintained higher than 96% of the initial values after 30-day storage, and the day-to-day relative standard deviation is less than 3.0%. Real sample simultaneous determination of DA and UA was conducted with bovine serum, and the results were in good agreement with those from high-performance liquid chromatography. It can be concluded that this work offers a reliable, facile, fast, and cost-effective method of simultaneous quantification of two or more chem-/bio-molecules. Graphical abstract.

Ruthenium Nanoparticles Uniformly‐designed Chemically Treated Graphene Oxide Nanosheets for Simultaneous Voltammetric Determination of Dopamine and Acetaminophen

AbstractA new nanocomposite based on ruthenium nanoparticles (RuNPs) uniformly designed at chemically treated graphene oxide nanosheets (CTGONS) was prepared as active electrode for simultaneously sensing of dopamine (DA) and acetaminophen (AC) in the presence of high concentration of ascorbic acid (AA). The RuNPs actively decorates the CTGONS with uniform dispersion like pump sputtering of paints. The CTGONS of hexagonal nanosheets, 2D orientation, chemically treated to the reduced forms and active decoration by RuNPs lead to formation of high catalytic active sites and high loading of targets at the electrode surface. The suitable accommodation of RuNPs/CTGONS to fast response of targets ascertains a high catalytic activity, and fast charge transport. The RuNPs/CTGONS nanocomposite shows an obvious catalytic oxidation signal for DA and AC. The highly sensitive and selective electrode was designed based on RuNPs/CTGONS due to the large peak potentials separation of DA to AC of 0.22 V with sufficient electron mediating behavior. Moreover, the nanocomposite electrode shows individual and simultaneous determination of DA and AC with linear calibration plots from 5–120 μM and 10–120 μM, where their detection limits were calculated to be 0.018±0.002 and 0.023±0.003 μM, respectively. Finally, the analytical application of the RuNPs/CTGONS electrode was applied for the determination of DA and AC in the serum of human blood.

Simultaneous and sensitive detection of dopamine and uric acid based on cobalt oxide-decorated graphene oxide composite

We demonstrate the simply prepared Co3O4 microsphere-decorated graphene oxide nanosheets (Co3O4/GO) modified electrode towards the single and simultaneous determination of dopamine (DA) and uric acid (UA). Various analytical techniques characterized the physicochemical properties of Co3O4/GO hybrid composite and EIS, CV, and DPV used to analyze the electrochemical characterization. This result indicates the simply prepared hybrid composite was confirmed the formation of Co3O4 has a spherical shape with an anchored surface of GO nanosheets. The proposed sensor has good electron transfer properties and excellent cycling stability. The detection potential difference between DA and UA is + 0.216 V. The electrooxidation response of modified electrode exhibits a wide linear range of DA and UA concentration from 0.2 → 1221 and 0.04 → 1217.2 µM with low detection limits of 0.0874 µM and 0.0131 µM, respectively. Besides, the fabricated sensor has high selectivity, excellent storage stability, reproducibility, and repeatability. Finally, the practical applicability of the contracted sensor was evaluated individual and simultaneous detection of DA and UA in human urine samples with satisfactory results.

Electrochemical Detection of Dopamine and Tyrosine using Metal oxide (MO, M=Cu and Ni) Modified Graphite Electrode: a Comparative Study

An electrochemical oxidation of dopamine (DA) and tyrosine (Tyr) by metal oxide (MO) modified electrode where M=Cu and Ni in phosphate buffer solution (PBS), pH 7.0 has been studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. CuO and NiO nanoparticles were prepared by sol-gel process and co-precipitation method respectively and their structure, composition and surface morphology were examined by SEM, XRD, FTIR, UV and Raman techniques. A simple drop cast method is employed for the surface modification of graphite electrode to prepare MO modified electrode and it exhibited good electrocatalytic activity towards detection of DA and Tyr. The present investigation on CV studies of DA at CuO modified electrode showed a reversible oxidation process with an anodic peak potential at +0.249V vs. SCE. However, no specific anodic oxidation peak identified with NiO modified electrode. Subsequent CV studies with Tyr at MO modified electrode (M=Cu, Ni) shows an irreversible oxidation process and both modified electrodes exhibited an anodic peak at a potential of +0.80V against very low or no anodic peak currents obtained at bare graphite electrode. Moreover, the CuO modified electrode (CMG) successfully separated the anodic signals of dopamine (DA), Ascorbic acid (AA) and Tyrosine in their ternary mixture whereas on bare graphite a single, overlapped oxidative peak was observed. In CV studies, the peak potential difference between AA-DA, DA-Tyr and AA-Tyr is 166 mV, 323 mV and 489 mV respectively and the corresponding peak potential separations are 209 mV, 400 mV and 609 mV respectively in differential pulse voltammetry (DPV). Owing to good stability, selectivity and simple low cost fabrication method, CuO modified electrode is found to be well suited for simultaneous determination of DA, AA and Tyr in their ternary mixture. Additionally, NiO modified electrode also shows good sensitivity towards the detection of tyrosine, so it acts as a good electrochemical sensor to assay tyrosine in the biological sample.

Simultaneous detection of dopamine, tyrosine and ascorbic acid using NiO/graphene modified graphite electrode

In this work, an electrochemical sensor is fabricated by decorating the surface of graphite electrode with NiO/graphene (NGMG) nanoparticles and employed for the detection of dopamine (DA), tyrosine (Tyr) and ascorbic acid (AA). The structure and morphology of prepared NiO nanoparticles are examined by XRD,SEM, FTIR and Raman techniques. The electrochemical properties have been investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperommety. The modified electrode is prepared by a simple drop casting method. The electrode shows good electro catalyticactivity towards oxidation of DA, Tyr and AA. It successfully separates the oxidation current signals of AA, DA and Tyr into clearly visible three distinct oxidation peaks compared to a single, overlapped oxidative peak on bare graphite electrode. The peak potential difference between AA-DA, DA-Tyr and AA-Tyr is 228 mV, 303 mV and 565 mV respectively in cyclic voltammetry (CV) studies and the corresponding peak potential separations are 243 mV, 318 mV and 561 mV respectively in differential pulse voltammetry (DPV). It is found that oxidation mechanism of DA, AA and Tyr on NGMG are different owing to a different type of interaction of the modified layer with the bio-analytes. The modified electrode, NGMG has high selectivity and sensitivity in addition to other factors like low cost, convenient and a hassle free electrochemical method for simultaneous determination of DA, AA and Tyr in their ternary mixture.