Determination Of Dopamine Research Articles

Conductive PEDOT:PSS copolymer electrode coatings for selective detection of dopamine in ex vivo mouse brain slices

A novel voltammetric sensor was developed to selectively determine dopamine (DA) concentration in the presence of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC). This sensor utilizes a modified pencil graphite electrode (PGE) coated with a newly synthesized poly (3,4-ethylene dioxythiophene) (PEDOT):poly (styrene sulfonate-co-2-(3-(6-Methyl-4-oxo-1,4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate) (P(SS-co-UPyMA)) composite. The PEDOT:P(SS-co-UPyMA) (PPU) composite was characterized using nuclear magnetic resonance, X-ray photoelectron, and Raman spectroscopies. The PPU-coated PGE was characterized using electrochemical techniques, including cyclic and differential pulse voltammetry. Compared to uncoated, PPU-coated PGE demonstrated improved sensitivity and selectivity for DA. The sensor exhibited a dynamic linear range of 0.1–300 μM for DA, with a detection limit of 44.4 nM (S/N = 3). Additionally, the PPU-coated PGE showed high reproducibility and storage stability for four weeks. To demonstrate its practical applicability, the PPU-coated PGE sensor was used for ex vivo brain slice samples from control and Parkinson's disease model mice.

Electrochemical sensing based on biomass-derived, hierarchical, porous carbon for simultaneous detection of dopamine and uric acid

This study reported a facile, one-step activation strategy for fabricating hierarchical, nitrogen- and sulfur-doped, porous, activated carbon (NSPAC) utilizing a NaOH/thiourea aqueous system. The morphology, amorphous nature, surface area, pore volume, and elemental composition of the NSPAC was characterized using SEM, HRTEM, EDS, XRD, Raman, BET, and XPS. The as-prepared, porous carbon exhibited a large specific surface area of 1800 m2·g−1, a well-developed pore structure, and good nitrogen- and sulfur-doping of 3.29% and 0.32% respectively. The NSPAC was employed as sensitive material for constructing electrochemical sensors to determine dopamine (DA) and uric acid (UA). The glassy carbon electrode (GCE) modified with the NSPAC (NSPAC/GCE) shows excellent electrocatalytic activity and separation performance, with 135 mV of peak-to-peak separation for DA and UA. The linear response concentration of DA and UA ranges from 0.2 to 100.0 μM and from 0.2 to 50.0 μM respectively, and both have a detection limit of 0.1 μM. The analytical parameters of the sensor are excellent, and the activated carbon prepared using the alkali urea system shows considerable promise as an effective platform for monitoring trace dopamine and uric acid in biological samples.

Electrochemical Sensor Based on Reduced Graphene Oxide Incorporated with Magnetite and Silver Nanoparticles Composite Electrode for Determination of Dopamine

Dopamine determination has become crucial as the abnormal levels of dopamine can potentially cause psychological disorders as well as Parkinson’s disease. Herein, a novel electrochemical sensing platform based on magnetite (Fe3O4), silver nanoparticles (AgNPs) and reduced graphene oxide (rGO) composite, denoted as rGO-Fe3O4/AgNPs was facilely synthesized using a modified Hummer’s two-step synthesis and co-precipitation approach without the use of any other oxidants or stabilizers. This composite was designed as an electrochemical sensor for exceptionally sensitive DA detection in human urine samples. The microscopic study of the composite revealed that the Fe3O4 and AgNPs were extensively decorated onto the rGO surface. The optimized scan rate of 100 mV s−1 and neutral pH of the supporting electrolyte for the composite-modified electrode was further used to determine dopamine (DA) in human urine samples. DA displayed an anodic peak at 0.20 V vs Ag/AgCl (3.0 mol l−1 KCl) utilizing differential pulse voltammetry technique. With detection limits of 3.98 nM, the analytical curves obtain a wide range of linear from 0.015 μM to 100 μM. The designed sensor had several advantages, including ease of preparation, low cost of nanomaterials utilized, and rapid response.

MOF-derived Co3O4/FeCo2O4 incorporated porous biomass carbon: Simultaneous electrochemical determination of dopamine, acetaminophen and xanthine

A novel sensing system was constructed by biomass carbon/MOF-derived Co3O4/FeCo2O4 (BC/Co3O4/FeCo2O4) composite decorated with glassy carbon electrode (GCE) for exploiting to determine dopamine (DA), acetaminophen (AC), and xanthine (XA) simultaneously. The BC/Co3O4/FeCo2O4 composite was synthesized via a facile in-situ growth process and calcination treatment, coupled with hydrothermal reaction. This composite could appreciably enlarge the electrochemically active surface area of as-prepared sensor to promote electron transfer resulting in enhanced response signals. Applying BC/Co3O4/FeCo2O4/GCE sensor under the optimum conditions, the differential pulse voltammetry (DPV) current responses vs. concentration are linear in the wider ranges of 0.1–250 μM, 0.1–220 μM, and 0.5–280 μM, along with low detection limits (LOD, S/N = 3) of 0.04587 μM, 0.02886 μM, and 0.1209 μM for DA, AC and XA correspondingly. Moreover, the proposed sensor exhibited a satisfying selectivity, stability and reproducibility as well. Finally, this sensor had been utilized to detect DA, AC and XA successfully in real samples with satisfactorily apparent recoveries, providing a promising application for further sensing analysis.

Selective Voltammetric Detection of Dopamine in the Presence of Ascorbic Acid at Poly(p-methoxyphenol)-Modified Electrode

A gold electrode was modified with electropolymerized films of p-methoxyphenol by its oxidative polymerization from an alkaline solution by cyclic voltammetry. The modified electrode was then used to determine dopamine (DA) in the presence of a high concentration of ascorbic acid (AA) by differential pulse voltammetry. The peak positions as well as relative sensitivity DA/AA were affected by the potential window used for the polymerization. For polymerization between 0 and 1.0 V, the peak potentials recorded in a phosphate buffer solution (pH = 7.2) were 516 and 312 mV versus Ag/AgCl for DA and AA, respectively. In addition to the effects of pH and the type of electrolyte on the linearity range and detection limit are investigated. The detection limit for 3s-test is 0.1 nM. The high selectivity and sensitivity for DA was found to be due to charge discrimination/analyte accumulation.

Design of novel, simple, and inexpensive 3D printing-based miniaturized electrochemical platform containing embedded disposable detector for analytical applications.

This paper describes the development of a novel, simple, and inexpensive electrochemical device containing an integrated and disposable three-electrode system for detection. The base of this platform consists on a PDMS structure containing microchannels which were prototyped using 3D-printed molds. Pencil graphite leads were inserted into these microchannels and utilized as working, counter and reference electrodes in a novel design. Morphological analysis and electrochemical experiments with benchmark redox probes were carried out in order to evaluate the performance and characterize the miniaturized device proposed. Even using inexpensive materials and a simple fabrication protocol, the electrochemical platform developed provided good repeatability and reproducibility over a low cost (ca. $2 per device), acceptable lifetime (ca. 250 voltammetric runs) and extremely reduced consumption of samples and reagents (order of µL). As proof of concept, the analytical feasibility of the platform was investigated through the simultaneous determination of dopamine (DOPA) and acetaminophen (AC). The two analytes showed linear dependence on the concentration range from 1 to 15µM and the LODs achieved were 0.21µM for DOPA and 0.29µM for AC. Moreover, the platform was successfully applied on the determination of DOPA and AC in spiked blood serum and urine samples. The results obtained with the device described here were better than some reports in literature that use more costly electrodic materials and complex modification steps for the detection of the same analytes.

Simultaneous in vivo voltammetric determination of dopamine and 5-Hydroxytryptamine in the mouse brain

We developed a voltammetric method to determine dopamine (DA) and 5-Hydroxytryptamine (5-HT) selectively and simultaneously in the mouse brain based on the graphene-iron-tetrasulfophthalocyanine (GR-FeTSPc)-coated carbon fiber microelectrode (GR-FeTSPc/CFME). The GR-FeTSPc composites possess an improved solubility in aqueous solution and the GR-FeTSPc/CFME exhibits an enhanced electro-catalytic activity towards the oxidation of DA and 5-HT. The reversible redox peaks are observed for DA with the redox peak potentials of 0.15 V and 0.10 V respectively, and only an oxidation peak at 0.36 V for 5-HT can be seen at the GR-FeTSPc/CFME. Differential Pulse Voltammetry (DPV) was used to determinate DA and 5-HT simultaneously, and the detection limits (S/N = 3) were 50 nM for DA and 20 nM for 5-HT respectively. Additionally, the microsensor exhibits good selectivity against AA and homovanillic acid. The experiment results indicate that this microsensor can determine the release of DA and 5-HT simultaneously in the mouse brain on line in vivo and at the same time it can monitor the two biomolecules concentrations changes with time. The research may offer a new method to monitor the release of DA and 5-HT in vivo.

Evaluation of the usefulness of a novel electrochemical sensor in detecting uric acid and dopamine in the presence of ascorbic acid using a screen-printed carbon electrode modified with single walled carbon nanotubes and ionic liquids

A novel sensor was developed in order to determine dopamine (DP) and uric acid (UA) by adsorptive voltammetry, using optimal amounts of single walled carbon nanotubes (SWCNT) dispersed in chitosan solution (cs) and deposited on a screen-printed carbon electrode (SPCE). The electrode surface (cs-SWCNT/SPCE) was treated with the ionic liquid (IL) 1 butyl-3-metilimidazolium tetrafluorborate (BMIMBP4). The electro-catalytic properties of the cs-SWCNT-IL/SPCE were studied with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrode surface was studied using scanning electron microscopy (SEM). Anodic peak currents for DP and UA with BMIMBP4 in the presence of ascorbic acid (AA) increased by 17.0 and 70.0% respectively. Optimal parameters were (pH 2.4; adsorption time; tADS 100s and adsorption potential; EADS -0.10 V). Anodic peak currents were proportional to the concentration between 0.5 and 5.0 μmol L−1 using standard solutions of PD and UA respectively, and 0.50–30.0 μmol L−1 for DP and 0.50–1000 μmol L−1 for UA with real samples. Detection limits were 0.16 μmol L−1 for DP and 0.17 μmol L−1 for UA. The sensor was used in the determination of AU and DP in human urine samples spiked with quantities of DP with recovery between 85 and 102% for DA and UA respectively.

Development of a disposable and low-cost electrochemical sensor for dopamine detection based on poly(pyrrole-3-carboxylic acid)-modified electrochemically over-oxidized pencil graphite electrode

In this study, preparation of a single-use electrochemical sensor for the selective and sensitive determination of dopamine (DOP) was investigated by electrochemical polymerization of pyrrole-3-carboxylic acid on electrochemically over-oxidized pencil graphite electrode (p(P3CA)/EOPGE). Cyclic voltammetry measurements of Fe(CN)64−/3− indicated that the electrochemically over-oxidized PGE (EOPGE) showed superior electron transfer characteristics according to bare PGE. The ionized carboxyl groups found in the structure of poly(pyrrole-3-carboxylic acid) (p(P3CA)) showed high affinity towards positively charged DOP. The combination of the advantages of EOPGE and p(P3CA) in p(P3CA)/EOPGE led to a synergistic effect on the electrochemical oxidation of DOP. The effects of experimental variables on the voltammetric performance of the p(P3CA)/EOPGE were examined by preparing the electrodes at different conditions. The p(P3CA)/EOPGE showed high selectivity towards DOP by discriminating its oxidation potential from the common interfering substances such as ascorbic and uric acids. The p(P3CA)/EOPGE showed linear responses in the electrochemical oxidation of DOP between the concentration values of 0.025µM and 7.5µM. Detection limit was determined as 0.0025µM according to signal to noise ratio (S/N: 3). Analytical application of p(P3CA)/EOPGE was successfully tested in the determination of DOP in blood serum and pharmaceutical samples.

Graphene oxide-Ag/poly-l-lysine modified glassy carbon electrode as an electrochemical sensor for the determination of dopamine in the presence of ascorbic acid

Abstract The graphene oxide (GO) and Ag hybrid matrix GO-Ag were coated onto the glassy carbon electrode (GCE) surface, then, poly- l -lysine films (PLL) were prepared by electropolymerization with cyclic voltammetry (CV) method to prepare GO-Ag/PLL modified glassy electrode (GO-Ag/PLL/GCE). The electrochemical sensor based on GO-Ag/PLL/GCE was used to sensitively determine dopamine (DA) in the presence of ascorbic acid (AA). Electrochemical behaviors of DA and AA mixture were investigated on GO-Ag/PLL/GCE by CV, which gave a baseline separation of the oxidation peak potential by 232 mV. So the modified electrode was suitable for determine of DA in the presence of AA. The GO-Ag/PLL/GCE electrode improved the DA electrochemical catalytic oxidation, which demonstrates that GO-Ag/PLL/GCE has a remarkable electrocatalytic activity towards the oxidation of DA. Moreover, PLL modified electrodes have good stability, excellent permselectivity, more active sites and strong adherence to electrode surface, which enhanced electrocatalytic activity. Under the optimized conditions, there were linear relationships between the peak currents and the concentrations in the range of 0.1–10 μM for DA, with the limit of detection (LOD) (based on S/N = 3) of 0.03 μM for DA. The GO-Ag/PLL/GCE sensor was successfully applied to the determination of DA in bovine serum samples and showed high selectivity, sensitivity, and reproducibility.

Selective recognition of 5-hydroxytryptamine and dopamine on a multi-walled carbon nanotube-chitosan hybrid film-modified microelectrode array.

It is difficult to determine dopamine (DA) and 5-hydroxytryptamine (5-HT) accurately because of the interference of ascorbic acid (AA) in vitro, which has a high concentration and can be oxidized at a potential close to DA and 5-HT at a conventional electrode, combined with the overlapping voltammetric signal of DA and 5-HT at a bare electrode. Herein, chitosan (CS) was used as a stabilizing matrix by electrochemical reaction, and multi-walled carbon nanotubes (MWCNTs) were modified onto the microelectrode array (MEA). The CS-MWCNT hybrid film-modified MEA was quite effective at simultaneously recognizing these species in a mixture and resolved the overlapping anodic peaks of AA, DA and 5-HT into three well-defined oxidation peaks in differential pulse voltammetry (DPV) at −80 mV, 105 mV and 300 mV (versus Ag|AgCl), respectively. The linear responses were obtained in the range of 5 × 10−6 M to 2 × 10−4 M for DA (r = 0.996) and in the range of 1 × 10−5 M to 3 × 10−4 M for 5-HT (r = 0.999) using the DPV under the presence of a single substance. While DA coexisted with 5-HT in the interference of 3 × 10−4 M AA, the linear responses were obtained in the range of 1 × 10−5 M to 3 × 10−4 M for selective molecular recognition of DA (r = 0.997) and 5-HT (r = 0.997) using the DPV. Therefore, this proposed MEA was successfully used for selective molecular recognition and determination of DA and 5-HT using the DPV, which has a potential application for real-time determination in vitro experiments.

One-pot synthesis of graphene–chitosan nanocomposite modified carbon paste electrode for selective determination of dopamine

article i nfo Background:A simple, rapid, low-cost and environmentally friendly method was developed to determine dopamine (DA) in the presence of ascorbic (AA) and uric acid (UA) based on a novel technique to prepare a graphene-chitosan (GR-CS) nanocomposite and modify it on the surface of carbon paste electrode (CPE). For our design, CS acts as a media to disperse and stabilize GR, and then GR plays a key role to selective and sensitive determination of DA. Results: Under physiological conditions, the linear range for dopamine was determined from 1 × 10 -4 to 2 × 10 -7 mol/L with a good correlation coefficient of 0.9961 in the presence of 1000-fold interference of AA and UA.

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.

High loading of uniformly dispersed Pt nanoparticles on polydopamine coated carbon nanotubes and its application in simultaneous determination of dopamine and uric acid

Multiwalled carbon nanotubes (MWCNT) were homogeneously covered with a bio-functional polydopamine (PDOP) by a simple dip-coating approach in mild basic solution. Then, uniformly dispersed and highly loaded platinum nanoparticles (PtNPs) were deposited on MWCNT@PDOP by a mild reductant, and were characterized by transmission electron microscopy and x-ray photoelectron spectroscopy. Afterwards, this nanocomposite was modified on the glass carbon electrode and applied to simultaneously determine dopamine (DA) and uric acid (UA) by differential pulse voltammetry (DPV). Results showed that a linear electro-oxidation response was found for DA and UA in the range of 0.25–20 μM and 0.3–13 μM with the detection limit (S/N = 3) of 0.08 μM and 0.12 μM, respectively. In addition, the detection sensitivities for DA and UA by DPV were 1.03 μA μM−1 and 2.09 μA μM−1, respectively, which were much higher than those from a cyclic voltammogram. Finally, the reproducibility and stability of the nanocomposite were also evaluated, demonstrating that such MWCNT@PDOP@PtNPs can be a promising candidate for advanced electrode material in electrochemical sensing and other electrocatalytic applications.

Simultaneous electrochemical determination of dopamine and ascorbic acid using AuNPs@polyaniline core–shell nanocomposites modified electrode

A simple and effective strategy was proposed for synthesis of AuNPs@polyaniline (AuNPs@PANI) core–shell nanocomposites. AuNPs@PANI nanocomposites were prepared by one-step chemical oxidative polymerization of aniline using chloroaurate acid as the oxidant and AuNPs as the seeds. The synthesized AuNPs@PANI nanocomposites were characterized with transmission electron microscope and UV–vis absorption spectra. Cyclic voltammetric experiments indicated that AuNPs@PANI nanocomposites showed excellent electroactivity in neutral and even alkaline solution. The obtained AuNPs@PANI nanocomposites-modified electrode was fabricated to simultaneously determine dopamine (DA) and ascorbic acid (AA) by differential pulse voltammetry. The separation between the two peak potentials of DA and AA oxidation is 236mV. The catalytic peak currents were linearly with the concentrations of DA and AA in the range of 10–1700 and 20–1600μM with correlation coefficients of 0.9997 and 0.9998, respectively. The detection limits for DA and AA were 5 and 8μM, respectively.

Simultaneous electrochemical determination of dopamine, ascorbic acid and uric acid using poly(acid chrome blue K) modified glassy carbon electrode

A novel polymerized film of acid chrome blue K (ACBK) was prepared on the surface of a glassy carbon electrode (GCE) by electropolymerization, and then the modified electrode was successfully used to simultaneously determine dopamine (DA), ascorbic acid (AA) and uric acid (UA). The characterization of electrochemically synthesized poly-ACBK film was investigated by atomic force microscopy (AFM), attenuated total reflection (ATR)–FTIR, electrochemical impedance spectroscopy (EIS) and voltammetric methods. The poly-ACBK modified GCE exhibited excellent electrocatalytic activity towards the oxidations of DA, AA and UA in 0.05 mM phosphate buffer solution (pH 4.0). The separations of anodic peak potentials of AA/DA, DA/UA and AA/UA on this modified electrode are 193, 166 and 359 mV in DPV, respectively. Under the optimum conditions, the calibration curves for DA, AA and UA were obtained in the range of 1.0–200.0, 50.0–1000.0 and 1.0–120.0 μM, respectively. The detection limits (S/N = 3) were 0.5, 10.0 and 0.5 μM for DA, AA and UA, respectively. With good selectively and sensitivity, the present method was applied to the determination of DA in dopamine hydrochloride injections, AA in vitamin C tablets and UA in urine samples.

Simultaneous determination of dopamine and serotonin on gold nanocluster/overoxidized-polypyrrole composite modified glassy carbon electrode

A promising electrochemical biosensor was developed by electrodeposition of gold nanoclusters on insulating overoxidized-polypyrrole (PPyox) film modified glassy carbon electrode (GCE). The nano-Au/PPyox composite-coated GCE was used to determine dopamine (DA) and serotonin (5-HT), exhibiting stable and sensitive current responses toward DA and 5-HT oxidation. The sensor was also quite effective to simultaneously determine these species in a mixture and resolved the overlapping anodic peaks of 5-HT, DA and ascorbic acid (AA, 1000-fold) into three well-defined voltammetric peaks in differential pulse voltammetry (DPV) at 0.37, 0.20 and 0.01 V (versus SCE), respectively. The linear response was obtained in the range of 7.0 × 10 −9 to 2.2 × 10 −6 M with a detection limit of 1.0 × 10 −9 M for 5-HT, and in the range of 7.5 × 10 −8 to 2.0 × 10 −5 M with a detection limit of 1.5 × 10 −8 M for DA (s/n = 3), respectively. The oxidation of 5-HT and DA were controlled by the adsorption surface process, as well as the competitive adsorption between 5-HT and DA were investigated at the nano-Au/PPyox/GCE. The designed sensor had been successfully applied for the determination of 5-HT and DA in human blood serum and obtained satisfactory results.

Determination of dopamine in rat striatum by microdialysis and high-performance liquid chromatography with electrochemical detection on a functionalized multi-wall carbon nanotube electrode

High performance liquid chromatography coupled with microdialysis sampling and electrochemical detection (HPLC-ECD) has been used to determine dopamine (DA). In the HPLC-ECD a multi-wall carbon nanotube electrode chemically modified with carboxyl groups (MWNT-COOH CME) was used as the working electrode for determination of DA. The results indicated that the MWNT-COOH CME enabled efficient electrocatalytic oxidation of DA with relatively high sensitivity and stability and long life. Peak currents for dopamine were linearly dependent on concentration in the range 5.0 x 10(-9) to 5.0 x 10(-5) mol L(-1) and the calculated detection limit (S/N=3) was 2.5 x 10(-9) mol L(-1). The method had been successfully used to measure dopamine in rat striatal microdialysate. To study the physiological effect of nitric oxide (NO) on striatal release of DA, 0.5 mmol L(-1) sodium nitroprusside (SNP) was a continuously perfused into rat striatum. This resulted in a 46% increase in DA basal level.

Selective determination of dopamine in the presence of ascorbic acid at the carbon atom wire modified electrode

To determine dopamine (DA) in the presence of high concentration of ascorbic acid (AA), a glassy carbon electrode modified by carbon atom wires (CAWs), a kind of new homemade material, was investigated by cyclic voltammetry. It was found that the electrochemical responses of DA were affected by the presence of AA, the pH value of the electrolytic solution and an acid treated process on CAWs. The HNO 3 treated CAW modified electrode exhibited excellent ability to discriminate DA from AA by means of cyclic voltammetry and the separation of their anodic peak potentials was apart as wide as 0.298 V in pH 6.00 phosphate buffer solution containing 0.50 mM DA and 5.00 mM AA at the scan rate of 50 mV/s at the modified electrode.

A chitosan-multiwall carbon nanotube modified electrode for simultaneous detection of dopamine and ascorbic acid.

A chemically modified electrode based on a chitosan-multiwall carbon nanotube (MWNT) coated glassy carbon electrode (GCE) is described, which exhibits an attractive ability to determine dopamine (DA) and ascorbic acid (AA) simultaneously. The modified electrode exhibited a high differential pulse voltammetry (DPV) current response to DA at 0.144 V and AA at -0.029 V (vs. SCE) in a 0.1 mol l(-1) phosphate buffer solution (pH = 7.2). The properties and behaviors of the chitosan-multiwall carbon nanotube modified electrode (MC/GCE) were characterized using cyclic voltammetry (CV) and DPV methods. The mechanism for the discrimination of dopamine from ascorbic acid at MC/GCE is discussed. The linear calibration range for DA and AA were 5 x 10(-7) mol l(-1) to 1 x 10(-4) mol l(-1) (r = 0.997), and 5 x 10(-6) mol l(-1) to 1 x 10(-3) mol l(-1) (r = 0.996), respectively. The MC/GCE showed good sensitivity, selectivity and stability.