Sensitive Detection Of Dopamine Research Articles

A simple one-pot synthesis of graphene nanosheet/SnO2 nanoparticle hybrid nanocomposites and their application for selective and sensitive electrochemical detection of dopamine.

A novel one-pot synthesis of graphene nanosheet/SnO2 nanoparticle hybrid nanocomposites (GN/SnO2) was realized by using graphene oxide nanosheets (GONs) functionalized with sodium dodecyl sulfonate and SnCl2 as the starting materials. The morphology and structure of the synthesized SDS-GN/SnO2 nanocomposites were characterized by Raman spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction analysis. It was found that SnO2 nanoparticles were homogeneously distributed on the graphene nanosheets. The electrochemical behavior of dopamine (DA) at the SDS-GN/SnO2 nanoparticle modified electrode was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that the modified electrode exhibited excellent electrocatalytic activity towards the electrochemical oxidation of DA. The separation of the oxidation peak potentials for ascorbic acid (AA)-DA, uric acid (UA)-DA and UA-AA obtained by DPV is about 132 mV, 128 mV and 260 mV, respectively, which allows selective and sensitive detection of DA in the presence of AA and UA. The anodic peak currents were linear with the concentration of DA in the range from 1.0 × 10-7 to 1.0 × 10-5 M with a coefficient of 0.9980. The detection limit was 80 nM (S/N = 3). The proposed method could be applied for the determination of DA in real human urine samples.

Nafion/Quercetin/Graphene Composite-Modified Glassy Electrode for Selective and Sensitive Detection of Dopamine

Glassy carbon electrode (GCE) was modified using graphene (G), quercetin (Qu) and Nafion in this sequence to fabricate Nafion-Qu-G composite-modified GCE (Nafion/Qu/G/GCE). The as-prepared modified electrode combining the advantages of Nafion, Qu and G was employed for the selective and sensitive detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). Compared with GCE, Qu/GCE, G/GCE and Qu/G/GCE, the Nafion/Qu/G/GCE was more electroactive and selective for DA. Differential pulse voltammetry (DPV) was used for electrochemical detection, the separations of the oxidation peak potentials for AA-DA and DA-UA were about 304 mV and 136 mV, which allowed selectively determining DA. In phosphate buffer solution (PBS) of pH 6.8, the Nafion/Qu/G/GCE provided a detection limit of 2.31×10-8 mol/L (S/N=3) for DA. Linearity (R=0.9963) of the peak currents against the concentration of DA was found over the range of 1.0×10-7 to 1.0×10-3 mol/L. Furthermore, the modified electrode exhibited good reproducibility and stability.

Selective Determination of Dopamine at Poly Sulfosalicylic Acid/Graphene Modified Electrode with Composite Properties of Biochemical Materials

A new type of poly (sulfosalicylic acid)/graphene modified electrode (PSA/GH/GCE) was fabricated by dispensing graphene (GH) on glassy carbon electrode (GCE) and then electro-polymerized sulfosalicylic acid onto GH/GCE with cyclic voltammtry method. It can be used with composite properties of biochemical materials for highly selective and sensitive detection of dopamine (DA) even in the presence of mass ascorbic acid (AA). The linear response range for DA was 70 nM to 700 μM, and the detection limit was 20 nM (S/N = 3).

New Approach for the Surface Enhanced Resonance Raman Scattering (SERRS) Detection of Dopamine at Picomolar (pM) Levels in the Presence of Ascorbic Acid

The development of a novel surface-enhanced resonance Raman scattering (SERRS) platform that allows fast and sensitive detection of dopamine (DA) has been reported. The iron-nitrilotriacetic acid attached silver nanoparticle (Ag-Fe(NTA)) substrate provides remarkable sensitivity and reliable repeatability. The advantages of both the surface functionalization for specific analytes and the SERRS are integrated into a single functional unit. While the silver core gives the necessary enhancing properties, the Fe-NTA receptors can trap DA adjacent the silver core and the NTA-Fe-DA complex formed provides resonance enhancement with a 632.8 nm laser. DA could be detected in pM level without any pretreatment with a reliable discrimination against AA, by utilizing low laser power (10 mW) and short data acquisition time (10 s). The high sensitivity along with the improved selectivity of this sensing approach is a significant step toward molecular diagnosis of Parkinson's disease.

Influence of Dopamine Concentration and Surface Coverage of Au Shell on the Optical Properties of Au, Ag, and AgcoreAushell Nanoparticles

Gold (Au), silver (Ag), and Ag(core)Au(shell) nanoparticles (NPs) were explored as optical sensing agents for the sensitive detection of dopamine (DA) neurotransmitters in surface-enhanced Raman scattering (SERS) measurements. In these colloidal systems, dopamine (DA) molecules played as a cross-linker between M NPs (Au or Ag NPs), allowing them to reside in the confined junctions (i.e., hot spots) between aggregated NPs. The progressive addition of DA molecules (from 1 × 10(-6) to 1 × 10(-3) M) consequently decreased a primary absorption peak attributed to the characteristic M NPs and generated a secondary absorption peak at longer wavelengths attributed to heavily aggregated M NPs formed by molecular bridging effects of DA molecules at high concentrations. The aggregation degree of M NPs was also dependent on the surface states of Au and Ag NPs, i.e., DA molecules with positive amine groups induced more aggregations of Au NPs in comparison to Ag NPs with less negative charges. As the final outcome, Au NPs demonstrated higher sensitivity in SERS detection of DA at low concentrations (1 × 10(-7) to 1 × 10(-5) M), whereas Ag NPs exhibited the stronger Raman signals of DA molecules at high concentrations (1 × 10(-4) to 1 × 10(-3) M). Besides, Ag(core)Au(shell) NPs with the lowest surface coverage of Au shell exhibited more sensitive and stronger SERS activity for DA molecules than that of singular Au NPs, probably due to the combined contribution by Ag core with strong SERS intensity and Au shell with high SERS sensitivity.

Tellurium-nanowire-coated glassy carbon electrodes for selective and sensitive detection of dopamine

Tellurium-nanowire-coated glassy carbon electrodes (TNGCEs) have been fabricated and employed for selective and sensitive detection of dopamine (DA). TNGCEs were prepared by direct deposition of tellurium nanowires, 600±150nm in length and 16±3nm in diameter, onto glassy carbon electrodes, which were further coated with Nafion to improve their selectivity and stability. Compared to the GCE, the TNGCE is more electroactive (by approximately 1.9-fold) for DA, and its selectivity toward DA over ascorbic acid (AA) and uric acid (UA) is also greater. By applying differential pulse voltammetry, at a signal-to-noise ratio of 3, the TNGCE provides a limit of detection of 1nM for DA in the presence of 0.5mM AA and UA. Linearity (R2=0.9955) of the oxidation current at 0.19V against the concentration of DA is found over the range 5nM–1μM. TNGCEs have been applied to determine the concentration of dopamine to be 0.59±0.07μM in PC12 cells.

Electrochemical detection of dopamine using porphyrin-functionalized graphene

A new type of porphyrin-functionalized graphene was synthesized and used for highly selective and sensitive detection of dopamine (DA). The aromatic π–π stacking and electrostatic attraction between positively-charged dopamine and negatively-charged porphyrin-modified graphene can accelerate the electron transfer whereas weakening ascorbic acid (AA) and uric acid (UA) oxidation on the porphyrin-functionalized graphene-modified electrode. Differential pulse voltammetry was used for electrochemical detection, the separation of the oxidation peak potentials for AA-DA, DA-UA and UA-AA is about 188mV, 144mV and 332mV, which allows selectively determining DA. The detection limit of DA can be as low as 0.01μM. More importantly, the sensor we presented can detect DA in the presence of large excess of ascorbic acid and uric acid. With good sensitivity and selectivity, the present method was applied to the determination of DA in real hydrochloride injection sample, human urine and serum samples, respectively, and the results was satisfactory.

A novel quantum dot–laccase hybrid nanobiosensor for low level determination of dopamine

This work reports a novel nanobiosensor based on a thioglycolic acid (TGA)-capped CdTe quantum dot-laccase (Lac) enzyme system for sensitive detection of dopamine (DA). The enzyme used catalyzes the oxidation of DA to dopamine-o-quinone (DOQ), which can selectively quench the strong luminescence of CdTe nanocrystals at neutral pH. The relationship between luminescence intensity of CdTe nanocrystals and DA concentration is nicely described by the Stern-Volmer equation. At an optimum pH of 7.4, the proposed sensor gives a linear calibration over a DA concentration range of 0.3 to 100 μM, with a limit of detection of 0.16 μM and a response time of 2 min. The relative standard deviation for seven replicate determinations of 6.0 μM of DA was found to be 3.7%. The sensor was successfully applied to the determination of DA in a blood plasma sample and in a DA injection formulation.

Graphene Oxide Based Photoinduced Charge Transfer Label-Free Near-Infrared Fluorescent Biosensor for Dopamine

While the super fluorescence quenching capacity of graphene and graphene oxide (GO) has been extensively employed to develop fluorescent sensors, their own unique fluorescence and its potential for chemo-/biosensing have seldom been explored. Here we report a GO-based photoinduced charge transfer (PCT) label-free near-infrared (near-IR) fluorescent biosensor for dopamine (DA). The multiple noncovalent interactions between GO and DA and the ultrafast decay at the picosecond range of the near-IR fluorescence of GO resulted in effective self-assembly of DA molecules on the surface of GO, and significant fluorescence quenching, allowing development of a PCT-based biosensor with direct readout of the near-IR fluorescence of GO for selective and sensitive detection of DA. The developed method gave a detection limit of 94 nM and a relative standard deviation of 2.0% for 11 replicate detections of 2.0 μM DA and was successfully applied to the determination of DA in biological fluids with quantitative recovery (98-115%).

A Selective Voltammetric Method for Detecting Dopamine at Quercetin Modified Electrode Incorporating Graphene

AbstractThe development of a quercetin‐graphene composite‐modified glassy carbon electrode (Qu/GH/GCE) for the selective and sensitive detection of dopamine (DA) is described in this paper. To fabricate the Qu/GH/GCE, graphene (GH) was first coated onto the surface of a glassy carbon electrode (GCE) and then quercetin (Qu) was electrodeposited on the GH matrix. Transmission electron microscopy (TEM) was used to characterize the morphology of the obtained GH and Qu/GH, and the electrochemical properties of the modified electrode were studied using electrochemical techniques. The as‐prepared Qu/GH/GCE occupied a synthetic property between GH and Qu. The common overlapped electrochemical oxidation peaks of DA and AA were completely separated and a remarkable increasing electron‐oxidation current of DA occurred on the Qu/GH/GCE, which enabled the sensitive and selective electrochemical detection of DA in the presence of ascorbic acid (AA) with peak difference of ca. 452 mV between DA and AA. The peak current obtained at 0.174 V (vs. saturated calomel electrode, SCE) from differential pulse voltammetry (DPV) is linearly dependent on the DA concentration in the range from 3.0×10−8 to 4.0×10−4 mol/L with a detection limit of 1.0×10−8 mol/L. Furthermore, the Qu/GH/GCE exhibits good reproducibility and stability, and has been used for the determination of DA in samples of rat’s striatum tissue with satisfactory results.

Graphite oxide bulk modified carbon paste electrode for the selective detection of dopamine: A voltammetric study

A novel electrochemical sensor for the selective and sensitive detection of dopamine (DA) in presence of large excess of ascorbic acid (AA) and uric acid (UA) at physiological pH was developed by the bulk modification of carbon paste electrode (CPE) with biocompatible graphite oxide (GO). Very small quantity of GO in carbon paste matrix imparted selectivity through electrostatic interactions. The modifier was characterized using infrared spectroscopy and powder X-ray diffraction. Large peak separation, good sensitivity and stability allow this modified electrode to analyze DA individually and simultaneously along with AA and UA. Applying differential pulse technique, DA could be detected even in the presence of 1000 fold excess of AA and UA. A linear dynamic range of 0.07–70 μM with detection limit of 1.5 × 10 −8 M was obtained for DA. None of the bulk modified electrodes reported in the literature have shown such a low detection limit at the physiological pH. The practical application of the modified electrode was demonstrated by spiking the human blood serum and cerebral fluid with dopamine and the results obtained were satisfactory.

Selective and sensitive detection of dopamine in the presence of ascorbic acid by molecular sieve/ionic liquids composite electrode

A simple, sensitive, and reliable method based on a molecular sieve/ionic liquids composite electrode has been successfully developed for selective determination of dopamine (DA). The electrochemical behavior of dopamine (DA) at the modified electrode was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). The influence of experimental parameters including pH of solution, amount of modifier, accumulation potential and time on the response of DA was investigated. At the optimum conditions, the peak current of DA was linear with the concentration of DA in the wide range of 5.0 × 10 −8 mol L −1 to 8 × 10 −4 mol L −1, with the correlation coefficient of 0.9982. The detection limit was 1.0 × 10 −8 mol L −1 ( S/ N = 3) in the presence of 0.2 mM ascorbic acid (AA). The interference studies showed that the modified electrode had excellent selectivity. What's more, the modified electrode also exhibited good reproducibility and stability for determination of DA, and could be applied to determine human serum samples.

Electrocatalytic detection of dopamine at single-walled carbon nanotubes–iron (III) oxide nanoparticles platform

Electrochemical sensors using edge-plane pyrolytic graphite electrode (EPPGEs) modified with single-wall carbon nanotubes–iron (III) oxide (SWCNT/Fe2O3) nanoparticles for the sensitive detection of dopamine (DA) are described for the first time. The surface of the EPPGE-SWCNT–Fe2O3 was characterized using field emission scanning electron microscopy, atomic force microscopy and energy dispersive X-ray spectroscopy while the electrochemical properties were investigated using the cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy techniques. When compared with the bare electrode or electrodes without the Fe2O3 nanoparticles, the EPPGE-SWCNT–Fe2O3 gave best response (7 times more than bare EPPGE and 2-fold more than the other two modified electrodes) towards the detection of DA. Also, the EPPGE-SWCNT–Fe2O3 showed the best analytical performance for DA with an electron transfer rate constant of ∼0.26cms−1, a sensitivity of 3.44μAμM−1, a limit of detection of 0.36μM, a catalytic rate constant of 8.7×105cm3mol−1s−1, and a diffusion coefficient of 3.5×10−5cm2s−1. This electrode can be reliably used to assay DA in its real drug composition.

Highly sensitive response to dopamine at a modified electrode involving a composite film with Au nanoparticles dispersed in a fluorocarbon polymer

A new approach for the highly sensitive detection of dopamine by a novel composite film involving gold nanoparticles trapped in a negatively-charged fluorocarbon polymer (Nafion) on a glassy carbon (GC) electrode fabricated by a simple method is described. Gold nanoparticles with an average diameter of 2.3 nm ± 0.2 nm are dispersed throughout the whole Nafion film. The introduction of gold nanoparticles into the Nafion film not only gives a highly active electrode surface area but also increases the conductivity of the Nafion film and the resulting Au/Nafion/GC electrode combines the advantages of the properties of gold nanoparticles and the selective pre-concentration ability of Nafion. For positively charged dopamine, the results show a decrease in the redox peak separation and a high sensitivity. The oxidation peak current of dopamine was shown to vary linearly with dopamine concentration over a wide range from 0.4 to 50.0 μmol/L with a detection limit of 0.3 μmol/L. Negatively charged ascorbic acid shows no redox waves at concentrations up to 1.0×10−4 mol/L.

Simple and sensitive detection of dopamine in the presence of high concentration of ascorbic acid using gold nanoparticles as colorimetric probes

A highly sensitive and selective method is presented for colorimetric determination of dopamine using gold nanoparticles (AuNPs). Dopamine induces the aggregation of AuNPs, this resulting in a color change from red to blue or purple. Aggregation is accelerated by the presence of Cu(II), especially at low concentrations of dopamine. The concentration of dopamine can be quantified visually or using a UV-vis spectrometer. The detection limit is as low as 30 nM. The assay is simple, inexpensive, and highly sensitive. Ascorbic acid in even 100-fold molar excess does not interfere. The mechanism of the aggregation of the AuNPs is discussed.

Highly Selective and Sensitive Detection of Dopamine in the Presence of Excessive Ascorbic Acid Using Electrodes Modified with C60‐Functionalized Multiwalled Carbon Nanotube Films

AbstractElectrochemical detection of dopamine (DA) in the presence of a large excess of ascorbic acid (AA) was investigated with a novel all‐carbon nanocomposite film of C60‐MWCNTs (C60‐functionalized multi‐walled carbon nanotubes) using a bare MWCNTs film as control. Although both films can selectively detect DA from AA by separating their oxidation potentials, the C60‐MWCNTs film shows special selectivity and good sensitivity for detecting DA. On one hand, the C60‐MWCNTs composite film shows a higher activity for DA oxidation with enhanced peak current. On the other hand, the C60‐MWCNTs composite film effectively suppresses the oxidation of AA. Remarkably, it is found that the oxidation current of DA is over 2 times higher than that of AA even when the concentration of AA is about 3 to 4 orders of magnitude higher than that of DA. This offers a tremendous advantage for the simple and clean detection of DA free of the interfering AA signal in a real assay. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectrometry are used to characterize the C60‐MWCNTs composite film. These novel properties are interpreted to arise from the facile electron transfer between C60 and MWCNTs in the C60‐MWCNTs nanocomposite film.

Selective response of dopamine in the presence of ascorbic acid and uric acid at gold nanoparticles and multi-walled carbon nanotubes grafted with ethylene diamine tetraacetic acid modified electrode

By grafting with ethylene diamine tetraacetic acid (EDTA), novel multi-walled carbon nanotube nano-composites (EDTA-MWCNTs) have been successfully prepared. The integration of gold nanoparticles (AuNPs) and novel functionalized matrix shows very promising applications in the fabrication of biosensors for sensitive detection of dopamine in the presence of ascorbic acid and uric acid with the combination of the chargerepelling property of carboxylic anion and the electrocatalytic effect of EDTA. The AuNPs and EDTA-MWCNTs modified film shows excellent sensitivity and selectivity for the dopamine analysis due to the synergic effect of AuNPs and EDTA-MWCNTs. As high as 2000 fold and 150 fold acceptable tolerance of ascorbic acid and uric acid for the determination of trace dopamine is reached, respectively. The linear concentration range for dopamine is from 1.0 × 10-8 to 6.0 × 10-6 mol.L-1, and the detection limit is 3.0 × 10-9 mol.L-1. The response of the sensor is very quick and response time is less than 1 s. The method can be applied to detect the dopamine in human urine samples.

Interference of Ascorbic Acid in the Sensitive Detection of Dopamine by a Nonoxidative Sensing Approach

The electrochemistry of a poly(anilineboronic acid)/carbon nanotube composite was studied in the presence of dopamine and ascorbic acid. To understand the binding affinity of dopamine and ascorbic acid to the boronic acid functional groups in the composite, the association constants between the diol groups in dopamine and ascorbic acid and the boronic acid were experimentally determined using a fluorescence-based binding assay. The results demonstrate that ascorbic acid could severely interfere with the detection of dopamine in nonoxidative boronic acid-binding approaches: Ascorbic acid was able to electrocatalytically reduce the fully oxidized polyaniline backbone during the electrochemical oxidation process; similarly to dopamine, ascorbic acid was also able to bind to the boronic acid groups through its planar diol group even though the binding affinity is much lower. The examination of the dopamine transduction mechanism and ascorbic acid interference mechanism in this nonoxidative approach will benefit the design of future boronic acid-based sensors.

Real-Time Detection of Dopamine Released from a Nerve Model Cell by an Enzyme-Catalyzed Luminescence Method and Its Application to Drug Assessment

A real-time observation of neurotransmitter release from a nerve cell is a useful method for not only neuroscience research, but also assessing of the influence of chemicals, including drugs, on the human nervous system. In this study, a more simple and sensitive method for real-time monitoring of dopamine release from a nerve model cell was developed. Highly sensitive detection of dopamine was performed by using tyramine oxidase for dopamine oxidation, which was followed by a luminol luminescence reaction. This enzyme-catalyzed luminescence method was applied to observe dopamine release from the PC12 cell as a nerve model cell upon stimulation with acetylcholine and an acetylcholine receptor agonist. The results demonstrated that the real-time monitoring of the activation of the PC12 cell was easily performed by this method. This method possessed many advantages, such as high sensitivity, rapid measurement and no pretreatment for cells. It might be applied to drug screening and the assessment of harmful influences of food additives and pesticides on the nerves.

Selective detection of dopamine in the presence of ascorbic acid by use of glassy-carbon electrodes modified with both polyaniline film and multi-walled carbon nanotubes with incorporated β-cyclodextrin

A simple, sensitive, and reliable method based on a combination of multi-walled carbon nanotubes with incorporated beta-cyclodextrin (beta-CD-MWNTs) and a polyaniline (PANI) film-modified glassy-carbon (GC) electrode has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The PANI film had good anti-interference properties and long-term stability, because of the permselective and protective properties of the conducting redox polymer film. The acid-treated MWNTs with carboxylic acid functional groups promoted the electron-transfer reaction of DA and inhibited the voltammetric response of AA. Sensitive detection of DA was further improved by the preconcentration effect of formation of a supramolecular complex between beta-CD and DA. The analytical response of the beta-CD-MWNTs/PANI film to the electrochemical behavior of DA was, therefore, better than that of a MWNTs/PANI film, a PANI film, or a bare glassy-carbon (GC) electrode. Under the conditions chosen a linear calibration plot was obtained in the range 1.0 x 10(-7)-1.0 x 10(-3) mol L(-1) and the detection limit was 1.2 x 10(-8) mol L(-1). Interference from AA was effectively eliminated and the sensitivity, selectivity, stability, and reproducibility of the electrodes was excellent for determination of DA.