Quantitative Determination Of Dopamine Research Articles

Interfacial galvanic replacement strategy for Pd-doped NiFe MOF nanosheets with highly efficient dopamine detection.

Aninterfacial galvanic replacement strategy to controllable synthesize palladium nanoparticles (Pd NPs)-modified NiFe MOF nanocomposite on nickel foam, which served as an efficient sensing platform for quantitative determination of dopamine (DA). Pd NPs grown in situ on the nanosheets of NiFe MOF via self-driven galvanic replacement reaction (GRR) and well uniform distribution was achieved. This method effectively reduced the aggregation of metallic nanoparticles and significantly promoted the electron transfer rate during the electrochemical process, leading to improved electrocatalytic activity for DA oxidation. Remarkably, the precisely constructed biosensor achieved a low detection limit (LOD) of 0.068µM and recovery of 94.1% (RSD 6.7%, N = 3) for simulated real sample detection and also exhibited superior selectivity and stability. The results confirmed that the as-fabricated Pd-NiFe/NF composite electrode could realize the quantitative determination of DA and showed promising prospects in real sample biosensing.

Quantitative determination of dopamine in the presence of interfering substances supported by machine learning tools

In the field of neuroscience as well as in the clinical setting, the neurotransmitter dopamine (DA) is an analyte which is important for research as well as medical purposes. There are plenty of methods available to measure dopamine quantitatively, with voltammetric ones such as differential pulse voltammetry (DPV) being among the most convenient and simple ones. However, dopamine often occurs, either naturally or because of the requirements of involved enzymatic systems, alongside substances that can influence the signal it produces upon electrochemical conversion. An example for such substances is the magnesium ion, which itself is not electrochemically active in the potential range needed for DA oxidation, but influences the dopamine signal. We have characterized the properties of DPV signals subject to the interaction between DA and Mg2+ and show that, although these properties are changing in a nonlinear fashion when both concentrations are varying, relatively simple linear mathematical models can be used to determine dopamine concentrations quantitatively in the presence of magnesium ions. The focus of this study is thus, the mathematical treatment of experimental data in order to overcome an analytical problem and not the investigation of the chemical background of DA-Mg2+ interaction.

DNA-modulated single-atom nanozymes with enhanced enzyme-like activity for ultrasensitive detection of dopamine.

Despite the current progress in optimizing and tailoring the performance of nanozymes through structural and synthetic adaptation, there is still a lack of dynamic modulation approaches to alter their catalytic activity. Here, we demonstrate that DNA can act as an auxiliary regulator via a straightforward incubation method with Fe-N-C single-atom nanozymes (SAzymes), causing a leap in the enzyme-like activity of Fe-N-C from moderate to a higher level. The DNA-assisted enhancement is attributed to the increased substrate affinity of Fe-N-C nanozymes through electrostatic attraction between the substrate and DNA. Based on the prepared DNA/Fe-N-C system, colorimetric sensors for dopamine (DA) detection were constructed. Surprisingly, the incorporation of DNA not only enabled the detection of DA in a low concentration range, but also greatly improved the sensitivity with a 436-fold decrease in detection limit. The quantitative determination of DA was achieved in two-segment linear ranges of 0.01-4 μM and 5-100 μM with an ultralow detection limit of 9.56 nM. The DNA/Fe-N-C system shows superior performance compared to the original Fe-N-C system, making it an ideal choice for nanozyme-based biosensors. This simple design approach has paved the way for enhancing nanozyme activity and is expected to serve as a general strategy for optimizing biosensor performance.

Persistent luminescence nanoparticles/hierarchical porous ZIF-8 nanohybrids for autoluminescence-free detection of dopamine

Accurate quantitative detection of biomarkers in complex samples is of remarkable significance for clinical diagnosis and follow-up therapy, which remains challenging due to the severe interference from sample matrix. Herein, a background-free sensing platform toward ultrasensitive dopamine (DA) detection is developed based on a multifunctional nanohybrid by integrating ultrasmall Cr3+-doped zinc gallate (ZnGa2O4:Cr3+, ZGC) persistent luminescence nanoparticles (PLNPs) with hierarchical porous zeolite imidazole framework-8 (HZIF-8). The ZGC PLNPs decorated on the surface of HZIF-8 have long-lasting near-infrared emission and act as signal element, whereas the hierarchically porous HZIF-8 scaffold can serve as an analyte concentrator to enrich DA around ZGC PLNPs. Furthermore, the oxidative polymerization of enriched DA is favored in the alkaline microenvironment provided by 2-methylimidazole in HZIF-8, producing polydopamine (PDA) which finally quenches the luminescence of ZGC/HZIF-8 via photoinduced electron transfer (PET) mechanism. Under the optimized conditions, the proposed nanoplatform exhibits excellent sensitivity and selectivity for the determination of DA in the range of 0.0025–75 μM with a limit of detection down to 0.0010 μM. Benefiting from the superior excitation-free persistent luminescence, this platform also shows satisfactory feasibility in quantitative determination of DA in human serum samples. This new strategy can contribute to the development of PLNPs-based biosensors for practical application in clinical analysis.

A digital SERS sensing platform using 3D nanolaminate plasmonic crystals coupled with Au nanoparticles for accurate quantitative detection of dopamine.

We report a digital surface-enhanced Raman spectroscopy (SERS) sensing platform using the arrays of 3D nanolaminate plasmonic crystals (NLPC) coupled with Au nanoparticles and digital (on/off) SERS signal analysis for the accurate quantitative detection of dopamine (DA) at ultralow concentrations. 3D NLPC SERS substrates were fabricated to support the optically dense arrays of vertically-stacked multi-nanogap hotspots and combined with Raman tag-conjugated Au nanoparticles for NLPC-based dual-recognition structures. We demonstrate that the 3D NLPC-based dual-recognition structures including Au nanoparticle-induced additional hotspots can enable more effective SERS enhancement through the molecular recognition of DA. For the accurate quantification of DA at ultralow concentrations, we conducted digital SERS analysis to reduce stochastic signal variation due to various microscopic effects, including molecular orientation/position variation and the spatial distribution of nanoparticle-coupled hotspots. The digital SERS analysis allowed the SERS mapping results from the DA-specific dual-recognition structures to be converted into binary "On/Off" states; the number of "On" events was directly correlated with low-abundance DA molecules down to 1 pM. Therefore, the digital SERS platform using the 3D NLPC-based dual-recognition structures coupled with Au nanoparticles and digital SERS signal analysis can be used not only for the ultrasensitive, accurate, and quantitative determination of DA, but also for the practical and rapid analysis of various molecules on nanostructured surfaces.

Gold nanoparticle-based detection of dopamine based on fluorescence resonance energy transfer between a 4-(4-dialkylaminostyryl)pyridinium derived fluorophore and citrate-capped gold nanoparticles.

A colorimetric/fluorometric dual-signal assay is described for the determination of dopamine (DA). A nanoprobe was obtained by linking a 4-(4-dialkylaminostyryl)pyridinium derived fluorophore to citrate-capped gold nanoparticles (AuNPs). The fluorescence of the fluorophore is quenched by the AuNPs via fluorescence resonance energy transfe. In the presence of DA, the catechol group of DA can absorb on the surface of AuNPs to induce aggregation, which is accompanied by a color change from red to blue. The yellow fluorescence of the fluorophore with excitation/emission maximum at 365/570nm is recovered. The dual-signal detection allows the quantitative analysis of DA within 300μM by the colorimetric method and 80μM by the fluorometric method. The detection limits for the colorimetric/fluorometric methods are 1.85μM and 0.29μM, respectively. Quantitative determination of DA in spiked urine samples was successfully demonstrated, with recoveries ranging from 98.2 to 106.0%. Graphical abstract A colorimetric/fluorometric dual-signal assay is described for the determination of dopamine by linking a fluorophore to gold nanoparticles. The dopamine causes aggregation of the nanoparticles to induce color change, which is followed by the recovery of the fluorescence.

Fabrication of Au Nanoparticle-Decorated MoS2 Nanoslices as Efficient Electrocatalysts for Electrochemical Detection of Dopamine

Herein, MoS2 nanoslices were simply prepared by using ultrasonic treatment, and were further decorated with Au nanoparticles (AuNPs) through an electrodeposition process to obtain the MoS2/Au nanocomposites. The obtained nanocomposites display synergetic electrocatalytic effect for the oxidation of dopamine due to the large surface area and two-dimensional structure of the MoS2 nanoslices, combining with the high catalytic activity and good conductivity of AuNPs. An electrochemical sensor was constructed based on MoS2/Au-modified carbon paste electrode, for sensitive and quantitative determination of dopamine. The prepared electrochemical sensor proves excellent analytical performances: very high sensitivity, wide linear ranges (0.5–300 μM), and low detection limit (76 nM). Moreover, the dopamine sensor also displays high selectivity, good reproducibility and stability, and can be used in real sample analysis. The method of fabricating high-efficiency electrocatalysts and electrochemical sensors proposed in this study provides a good reference for developing more functionalized nanocomposites and for extending practical applications.

MOF-derived N-doped nanoporous carbon framework embedded with Pt NPs for sensitive monitoring of endogenous dopamine release

A Pt NPs encapsulated hollow N-doped carbon framework was constructed by calcinating sandwich-like zinc imidazole framework (ZIF)-67 in N2 atmosphere, and employed for electrochemical detection of dopamine. The morphology and element distribution of this framework was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The MOF-derived N-doped nanoporous carbon framework can take advantage of the nanoporous features from carbon structures, while Pt NPs maintained good dispersity during calcination. Furthermore, the relevant electrochemical performances were evaluated by amperometry and differential pulse voltammetry (DPV), and the results confirmed that such a structure will robustly promote the electron conduction and mass transfer of dopamine (DA), allowing the quantitative determination of DA with a wide linear range, a low limit of detection (LOD), a high sensitivity and a good selectivity. Based on these observations, the Pt NPs encapsulated hollow N-doped carbon framework modified glassy carbon electrode (CN@Co/Pt/Co-GCE) was further utilized to monitor the endogenous DA released from C6 cells by extracellular K+ stimulation.

Electrochemical Determination of Dopamine Using a Novel Perylenediimide-Derivative Modified Carbon Paste Electrode

ABSTRACTA novel perylenediimide derivative, N,N′-bis(4-{2-[2-(2-methoxyethoxy ethoxy]ethoxy}phenyl)-3,4:9,10-perylene tetracarboxydiimide, was utilized for the modification of a carbon paste electrode to develop a practical and sensitive electrochemical sensor for dopamine detection. The effects of experimental parameters (modifier amount, pH, and scan rate) on the dopamine peak current were examined. The performance of the modified carbon paste electrode was evaluated under optimum conditions and 4.6-fold increase in the peak current was obtained compared to an unmodified carbon paste electrode. The linear range was between 1 and 100 µM dopamine and the limits of detection and quantification were 0.011 and 0.036 µM, respectively. The developed sensor was also applied for the quantitative determination of dopamine in injections and promising results were obtained.

Green synthesis of reduced graphene oxide-Ag nanoparticles as a dual-responsive colorimetric platform for detection of dopamine and Cu2+

A one pot rapid and green synthesis approach using pine (Pinus densiflora) leaf extracts was developed to prepare AgNPs decorated with graphene nanocomposites (rGO@AgNPs). The rGO@AgNPs was used for an innovative, facile and reliable dual functional assay of dopamine (DA) and copper ions (Cu2+). Synergistic interactions of DA with rGO@AgNPs through π-π interactions and hydrogen bindings could induce aggregation of the rGO@AgNPs and color changing of the solution from yellow to brown. The UV–vis absorption ratio (A515/A405), corresponded to the color changes, was monitored for quantitative determination of DA. The sensor was also utilized to detect Cu2+ through an anti-aggregation mechanism. Cu2+ ions could prevent aggregation of rGO@AgNPs through formation of a complex with DA, and DA acted as a selective chelating agent for Cu2+. In the presence of a certain amount of DA, the aggregation of rGO@AgNPs decreased by increasing the concentration of Cu2+ ions in the solution. It accompanies with a color change from brown to yellow and increasing the absorption ratio of A405/A515. The limit of detection (LOD) for DA and Cu2+ were estimated as 16 and 9.8 nM, respectively. The green synthesized rGO@AgNPs were used for selective detection of DA and Cu2+ in human urine and tomato samples.

Selective Detection of Dopamine in the Presence of Ascorbic and Uric Acids through its Covalent Immobilization on Gold Mercaptopropionic Acid Self‐assembled Monolayer

AbstractA simple, stable and recoverable sensor is developed based on selective and covalent immobilization of dopamine (DA) on the gold (Au) electrode modified by mercaptopropionic acid (MPA) self‐assembled monolayers and then, activated with 1‐ethyl‐3(3‐(dimethylamino)propyl)‐carbodiimide hydrochloride (EDC)/n‐hydroxysuccinimide (NHS) activators. Fabrication steps and analytical application of this modified electrode toward quantitative determination of DA in the presence of ascorbic and uric acids are verified by cyclic and differential pulse voltammetry (CV and DPV) methods in the absence of any redox probe. The oxidation peak current of adsorbed DA changed linearly with the concentration of DA in the range of 0.5 to 600.0 μM with a detection limit of 0.064 μM, and the RSDs varied from 1.4 to 3.5 % for n=3 at each point. Finally, the fabricated sensor is used successfully for electroanalytical determination of DA in human blood plasma and pharmaceutical injection real samples.

Sensitive detection of dopamine using micelle-enhanced and terbium-sensitized fluorescence

A new terbium sensitized spectrofluorimetric method was developed for the determination of trace amounts of dopamine (DA) using ethylenediaminetetraacetic acid as co-ligand and cetyltrimethylammonium chloride as sensitizer. UV absorption and fluorescent spectra were used to investigate the photophysical properties of the ternary complex. Under the optimum conditions, the enhanced fluorescence intensities of the Tb(III) complexes increased linearly with the concentration of DA over the ranges 8 × 10–8–5 × 10–5 M and the limit of detection for DA was found to be 2.4 × 10–8 M. The proposed method has been applied for the quantitative determination of DA in a pharmaceutical preparation and urine samples. The possible energy transfer mechanisms in the lanthanide complexes were discussed.

Quantitative determination of dopamine in human plasma by a highly sensitive LC–MS/MS assay: Application in preterm neonates

The determination of dopamine facilitates better understanding of the complex brain disorders in the central nervous system and the regulation of endocrine system, cardiovascular functions and renal functions in the periphery. The purpose of this study was to develop a highly sensitive and reliable assay for the quantification of dopamine in human neonate plasma. Dopamine was extracted from human plasma by strong cation exchange (SCX) solid phase extraction (SPE), and subsequently derivatized with propionic anhydride. The derivatized analyte was separated by a Waters Acquity UPLC BEH C18 column using gradient elution at 0.4ml/min with mobile phases A (0.2% formic acid in water [v/v]) and B (MeOH–ACN [v/v, 30:70]). Analysis was performed under positive electrospray ionization tandem mass spectrometer (ESI–MS/MS) in the multiple reaction monitoring (MRM) mode. The stable and relatively non-polar nature of the derivatized analyte enables reliable quantification of dopamine in the range of 10–1000pg/ml using 200μl of plasma sample. The method was validated with intra-day and inter-day precision less than 7%, and the intra-day and inter-day accuracy of 91.9–101.9% and 92.3–102.6%, respectively. The validated assay was applied to quantify dopamine levels in two preterm neonate plasma samples. In conclusion, a sensitive and selective LC–MS/MS method has been developed and validated, and successfully used for the determination of plasma dopamine levels in preterm neonates.

Quantitative determination of dopamine in single rat pheochromocytoma cells by microchip electrophoresis with only one high-voltage power supply.

We developed a method for the direct identification of dopamine in single cultured rat pheochromocytoma cells by capillary electrophoresis using an end-channel carbon fiber nanoelectrode amperometric detector. The operation mode was designed to achieve single-cell injection and lysis in microfluidic chip electrophoresis with only one high-voltage power supply. The separation and detection conditions were optimized. Four catecholamines were baseline-separated and determined with this system, and the cell density and liquid height of the reservoirs were accommodated for single cell loading, docking and analysis. The microchip capillary electrophoresis system was successfully applied to determine dopamine in single cultured rat pheochromocytoma cells.

Construction of Supramolecular Systems for the Selective and Quantitative Determination of Dopamine in the Presence of Ascorbic Acid

This work presents the construction of supramolecular systems formed by the modification of carbon paste electrodes, CPE, with multiwalled-carbon nanotubes, MWCNT, and b-cyclodextrin, CPE/MWCNT/β-CD, a novel conducting polymer produced by electrochemical polymerization of β-CD, CPE/poly-β-CD and another formed with MWCNT, β-CD and poly-β-CD, CPE/MWCNT/β-CD/poly-β-CD. With these modified electrodes, analyses were performed to understand the effect of such surface modifications on the electrochemical response of the analyte dopamine, which was surface-immobilized through formation of the said inclusion complex, as evidenced by the adsorption process that controlled the overall reaction rate of the oxidation process. Moreover, it is shown that the heterogeneous rate constant, k0, of Dopamine oxidation is highly increased in the presence of poly-β-CD.

Salsolinol and isosalsolinol: Condensation products of acetaldehyde and dopamine. Separation of their enantiomers in the presence of a large excess of dopamine

Dopamine (DA) condenses, at least in vitro, with acetaldehyde, the primary metabolite of ethanol, to form the regioisomers salsolinol (SAL) and isosalsolinol (isoSAL). An alternative in vivo route to SAL, requiring a decarboxylation step, has been suggested via condensation of DA with pyruvic acid. SAL has been proposed as a mediator of the rewarding effects of ethanol in the brain. We have now shown by HPLC, nuclear magnetic resonance (NMR) and mass spectrometry (MS) that the commercially available SAL contains about 10% of isoSAL, whose biological activity is unknown. If SAL is indeed the biologically active metabolite, rather than isoSAL, it is also unknown whether the rewarding molecule is (S)- or (R)-SAL. We have developed methodologies for the quantitative determination of DA, SAL and isoSAL using ion-pair reversed-phase HPLC, and for the separation of DA from (S)- and (R)-SAL and an isoSAL enantiomer on a β-cyclodextrin-modified column, in both cases with electrochemical detection. A significant advance over earlier methods was achieved for the analysis of (S)- and (R)-SAL in the presence of a large excess of DA (100:1 DA-SAL ratio), as expected to occur in vivo, by suppressing the DA peak by selective derivatization with 2,3-naphthalenedicarboxaldehyde into a molecule that is electrochemically silent at the electrode potential used. The methodologies developed will allow the separation and determination of the pharmacological activity of these two products of condensation of acetaldehyde with DA. Further, the techniques for (S)- and (R)-SAL separation at a high DA:SA ratio will allow the existence of a putative (R)-SAL synthase to be determined and, if it exists, its role in alcoholism.

Electrochemical Sensor for the Determination of Dopamine in Presence of High Concentration of Ascorbic Acid Using a Fullerene‐C60 Coated Gold Electrode

AbstractA fullerene‐C60‐modified gold electrode is employed for the determination of dopamine in the excess of ascorbic acid using square‐wave voltammetry. Based on its strong catalytic function towards the oxidation of dopamine and ascorbic acid, the overlapping voltammetric response of both the biomolecules at the bare electrode is resolved into two well‐defined voltammetric peaks with lowered oxidation potential and enhanced oxidation currents. Linear calibration curves for dopamine are obtained using square‐wave voltammetry over the concentration range 1 nM–5.0 μM in 0.1 M phosphate buffer solution at pH 7.2 with a correlation coefficient of 0.9931 and the detection limit (3σ) is estimated to be 0.26×10−9 M. The interference studies showed that the presence of physiologically common interferents (i.e. uric acid, citric acid, tartaric acid, glucose and sodium chloride) negligibly affects the response of dopamine. The practical analytical utility of the method is illustrated by quantitative determination of dopamine in commercially available pharmaceutical formulation and human body fluids, viz. urine and blood plasma, without any preliminary treatment.

A strategy for the determination of dopamine at a bare glassy carbon electrode: p-Phenylenediamine as a nucleophile

Electrochemical oxidation of dopamine (DA) in the presence of p-phenylenediamine (PPD) as a nucleophile in aqueous buffered solutions was studied. The results indicate that the o-dopaminoquinone ( o-DQ) electrochemically derived from DA participates in 1,4-Michael addition with PPD to form the corresponding new derivative (P2), which is present as the oxidized state (Q2) at the electrolysis applied potential. This reaction pathway inhibits the cyclization of o-DQ and thus, the formation of polymerized films on the electrode surface. The reduction current for Q2 to P2 can be used to determine DA concentration. A selective sensing and quantitative determination of DA by adding PPD and using a bare glassy carbon electrode in the presence of a high concentration of ascorbic acid was verified.

Simple Analysis Used in Diagnosis and Follow-up of Schizophrenic Patients

Dopamine acts as neurotransmitter in the central and peripheral sympathetic nervous system. Determination of dopamine (DO) was performed by spectrophotometric analysis depending on the formation of new colored compound. The proposed procedure was efficient in quantitative determination of DO as pure material in pharmaceutical preparations and in urine samples. DO concentration in urine sample of patient confirms the affection with schizophrenia and the proposed procedure was used to facilitate diagnosis and followup of schizophrenic patients. It is recommended to apply the proposed procedures as routine analysis in pharmaceutical companies for quality control and in analytical laboratories to diagnose and follow up schizophrenia.

Differential Pulse Techniques on Modified Conventional‐Size and Microelectrodes. Electroactivity of Poly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene] Coating Towards Dopamine and Ascorbic Acid Oxidation

AbstractPoly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene] modified conventional‐size and (ultra)microelectrodes are first investigated in acetonitrile and quasi‐neutral aqueous solution with respect to the repeatability of the responses obtained both in cyclic voltammetry and in differential pulse voltammetry. The reactivity towards ferrocene and hydroquinone, chosen as benchmark oxidizable substances in the two media, respectively, is considered. Comparison is made with the behavior of poly(3‐methylthiophene) as electrode coating, which is one of the most commonly used redox mediators in amperometric sensors based on coatings consisting of conducting polymers. The results confirm the appealing properties of poly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene], previously evidenced by us in different electrochemical studies: it exhibits particularly high stability and the characteristics of the current/potential curves obtained make it particularly suitable for analytical purposes. After performing these tests, the quantitative determination of dopamine by modified microelectrode is examined and the simultaneous voltammetric determination of ascorbic acid and dopamine is considered. The possibility of working profitably with a microelectrode at very low buffer‐supporting electrolyte concentration is ascertained.