Trace Dopamine Research Articles

Metal organic framework modified with carbon nanotube as an electrochemical sensor: Fabrication, excellent stability and sensitive detection of dopamine

Dopamine (DA) is a very important drug, however, excessive use can lead to DA becoming a micropollutant in water environments, which is an unfortunate consequence. The accurate determination of dopamine content is of great significance and has also attracted high attention from people. In this work, an electrochemical sensor (MOFCN) based on carbon nanotubes (CNTs) modified copper-based metal–organic framework (Cu-MOF) was developed using the hydrothermal method for sensitive detection of dopamine. The Cu-MOF, which are surrounded by CNTs, provide a favorable surface for the full utilization of the excellent conductivity property of carbon nanotube. The surface area of MOFCN is bigger than that of original Cu-MOF. The electrochemical sensing functions of the prepared MOFCN were evaluated by cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) techniques. Under optimal conditions, there was a good linear relationship between peak current and DA concentration in the range of 0.5 to 100 µM with a detection limit (LOD) as low as 0.13 µM. The current modified MOFCN sensor was employed to quantify trace DA concentrations in actual water sample, reaching satisfactory recovery rates ranging from 97.5 % to 105 %. The interference effect on the determination of DA showed the excellent selectivity of MOFCN using the DPV technique. A comprehensive investigation was undertaken into the kinetics and underlying mechanisms of the electrochemical reaction. The transfer of electrons and hydrogen ions facilitates the transformation of DA into dopaminoquinones (DQ), a process that is accelerated by the augmented availability of active sites in the designed sensor. The present study proposes a method for the precise and efficient analysis, which proves that the proposed sensor is highly effective for detecting DA in Environmental water samples.

Engineering FeOOH/Fe2O3@Carbon Interfaces With Biomass-Derived Carbon Nanodot/Iron Colloids for Efficient Redox-Modulated Dopamine Voltammetric Detection.

The Fe2+/Fe3+ redox couple is effective for voltammetric detection of trace dopamine (DA). However, achieving adequate concentrations with high electroactive surface area (ECSA), DA affinity, and fast interfacial charge transfer is challenging. Consequently, most reported Fe-based sensors have a high nanomolar range detection limit (LOD). Herein, we address these limitations by manipulating the phase and morphology of FeOOH/Fe2O3 heterojunctions anchored on sp2-carbon. FeOOH/Fe2O3 is synthesized by variable temperature aging of unique Fe5H9O15/Fe2O3@sp2-carbon colloidal nanoparticles, which form via chelation between biomass-derived carbon nanodots (CNDs) and Fe2+ ions. At 27 °C and 120 °C, Fe5H9O15/Fe2O3@sp2-carbon transforms into β-FeOOH/Fe2O3 nanoparticles and α-FeOOH/Fe2O3 nanosheet, respectively. The β-FeOOH/Fe2O3 interface exhibits higher eg orbital electron occupancy than α-FeOOH/Fe2O3, thereby facilitating oxygen adsorption and the generation of Fe2+/Fe3+ sites near the polarization potential of DA. This facilitates interfacial electron transfer between Fe3+ and DA. Moreover, its nanoparticle morphology enhances ECSA and DA adsorption compared to α-FeOOH/Fe2O3 nanosheets. With a LOD of ~3.11 nM, β-FeOOH/Fe2O3 surpasses the lower threshold in humans (~10 nM) and matches noble-metal sensors. Furthermore, it exhibits selective detection of DA over 10 biochemicals in urine. Therefore, the β-FeOOH/Fe2O3@sp2-C platform holds promise as a low-cost, easy-to-synthesize, and practical voltammetric DA monitor.

Reliable ratiometric colorimetric monitoring of dopamine in practice based on the catalytic signal amplification of nano CeO2/CuO modified carboxylated chitosan

To reliably monitor dopamine (DA), a common neurotransmitter, a kind of nano CeO2/CuO modified carboxylated chitosan nanozyme (CeO2/CuO@CC) was constructed under microwave-assisted conditions. The proposed CeO2/CuO@CC exhibited superior synergistic- enhancement oxidase-like activity, with high specific surface area and superior stability. It could accelerate the oxidization of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxTMB in the air. What’s more, the presence of trace DA could exclusively change the enzyme-like activity of CeO2/CuO@CC, accompanied with visual color changes from blue to colorless. Under the optimized conditions, there expressed double ratiometric linear relationships between lg(A652/A285)/lg(A370/A285) and cDA, with a large linear range between 6.0 × 10−9 and 1.0 × 10−5 M of DA. When applied for visual detection of DA in real samples, the detection limit was low to 2.0 × 10−9 M with RSD % less than 4.14 %. The mechanisms for enhanced oxidase-mimic activity of CeO2/CuO@CC and its selective detection of DA were proposed. This work will offer an insight to design efficient nanozyme for visual detection of bio-analytes in practice.

Rheological behavior of hydrophobic association polyacrylamides with high salt resistance and corrosion inhibition: Cross-linking modification based on trace dopamine hydrochloride derivatives

Hydrophobic association polyacrylamides (HAPAMs) have great potential for use in polymer flooding because of their unique aggregative, hygroscopic, and other compatible properties; however, their poor solubility in high-salt reservoir environments is one of the drawbacks of current polymers for enhanced oil recovery (EOR) applications. Herein, an amphipathic hydrophobic monomer (hexadecyldimethylallyl ammonium chloride, DMAAC16) and a dopamine hydrochloride-derived monomer (DAAM) were successfully introduced into HAPAM to synthesize novel dopamine hydrochloride-modified hydrophobic association polymers (HAPAMC16D). As a result, HAPAMC16D exhibited not only good comprehensive properties based on its porous network structure but also excellent viscosity due to the presence of the DAAM monomer. When the concentration of the polymer solution was greater than the critical association concentration (CAC), the apparent viscosity reached 614 mPa s at 5 g/L C16D5. Importantly, the salt resistance increased significantly in the representative sodium and calcium ion tests, which was attributed to the degree of chemical cross-linking and the intermolecular hydrophobic bonding force. The temperature and salt resistance tests simulating different environments for EOR showed that C16D4 had an apparent viscosity of 158 mPa s, a retention rate of 28.52 % at 90 °C and a total dissolved solids (TDS) greater than 30,000. Additionally, the weight loss method and electrochemical experiments indicated that the highly salt-resistant hydrophobic association polymers had favorable corrosion inhibition effects, with an inhibition efficiency of up to 99.02 % in the 1 M hydrochloric acid-Q235 carbon steel system. This hydrophobic association strategy provides a new approach for designing highly salt-resistant materials for polymer flooding in harsh reservoir environments.

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.

Synchronous Fe3+-Enhanced Colorimetric and Liquid SERS-Based Detection of Dopamine Using Core–Shell Plasmonic Nanoparticles

Reliable and direct detection of dopamine (DA), which is a crucial neurotransmitter, is required to diagnose dopamine-related diseases. However, the plasmonic colloidal sensing systems without prefunctionalization (e.g., aptamer, receptor, antibody, etc.) have not been well-established for trace DA detection yet. Herein, we develop a synchronous colorimetric and liquid-surface-enhanced Raman scattering (SERS) sensing system for the sensitive and selective detection of DA neurotransmitters using Au–Ag core–shell nanoparticles (Au@Ag CSNPs). The DA-mediated aggregation of Au@Ag CSNPs changed their plasmon resonance, leading to a distinct color change of the CSNP dispersion and generation of strong electromagnetic “hot spots” in the clustered CSNPs. Notably, the addition of Fe3+ ions to the CSNP dispersion intensified the DA-mediated aggregation of CSNPs, which significantly improved the colorimetric response and liquid-SERS detection of DA in the nanomolar range. Notably, the dual-mode sensing system without prefunctionalization demonstrated highly selective detection of the DA analyte against similar catecholamines (such as norepinephrine and epinephrine), which can be potentially applied to the selective discrimination of trace DA in real samples.

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.

Ag nanozyme strengthened by folic acid: Superior peroxidase-mimicking activity and application for visual monitoring of dopamine.

Dopamine (DA) is an important neurotransmitter; however, any excess or deficiency of DA will cause several diseases in humans. To monitor DA efficiently and conveniently, a Ag nanozyme strengthened by bioactive folic acid (FA@AgNPs) was developed by homogeneous redox assembly. After the microstructure and performance were characterized in detail, it was noted that the proposed FA@AgNPs possessed superior peroxidase-like activity due to the ultra-small Ag nanoparticles and multiple amino, hydroxyl, and aromatic rings in FA. FA@AgNPs accelerated the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with a low Michaelis constant (Km) and high maximal reaction rate (Vmax). Importantly, the characteristic absorbance intensity of FA@AgNPs-TMB-H2O2 at 652 nm (A652) was exclusively deteriorated in the presence of trace DA, accompanied by a visual color change from blue to colorless. Under the optimized conditions (pH 4.0, 300 μL 1.5 mM TMB, 300 μL 1.0 M H2O2 and incubated for 30 min at room temperature), there expressed an excellent linear relationship between lgA0/A652 and cDA from 1.0 ×10-8 to 6.67×10-6 mol/L with a low limit detection of 7.1×10-10 mol/L (S/N=3). When applied for monitoring of DA in real fruit juice and pharmaceutical samples, the recovery was between 96.6% and 104.9%, with RSD less than 2.2%. The enhanced peroxidase-like activity of the FA@AgNP system and its selective recognition mechanism for DA are also proposed.

Manganese‐Induced Highly Fluorescent Oligodopamine for Sensitive Detection of Dopamine Neurotransmitter by Catalytic Action of H2O2/MnO2 Nanosheets

Dopamine (DA) is a catecholamine, which plays an important role as neurotransmitter in the central nervous system. Optical sensing technology is commonly used for the rapid detection of DA through the formation of fluorescent polydopamine (PDA). However, it is difficult to quantify low levels of DA (≤10−8 m) because the resulting PDA has a low fluorescence (FL) efficiency. In this study, DA analyte is polymerized into highly fluorescent oligodopamine (F‐ODA) by the catalytic action of H2O2/MnO2 nanosheets, so‐called Mn2+@F‐ODA (i.e., manganese (2+) coordinated oligodopamine derivatives). Compared to the F‐ODA prepared by NaOH oxidation, Mn2+@F‐ODA exhibits a stronger FL intensity with a maximal peak at 465 nm. Mn2+@F‐ODA produces a distinct FL emission that allows for the detection of trace DA (10−8–10−12 m) with a detection limit of 10−13 m. The FL intensity of Mn2+@F‐ODA shows a suitable logarithmic linearity over four orders of the magnitude from 10−8–10−11 m. The developed chemical strategy suggests potential applications of Mn2+@F‐ODA for the sensitive detection of DA neurotransmitters.

Highly catalysis MOFCe supported Ag nanoclusters coupled with specific aptamer for SERS quantitative assay of trace dopamine

A cerium metal organic framework-loaded silver nanocluster (MOFCeAgNC) is synthesized by a facile stirring procedure with trimesic acid, cerium nitrate, silver nitrate and NaBH4, which exhibites strong catalytic activity in the indicated reaction of HAuCl4-sodium lactate (SL). MOFCeAgNC can sensitively detect dopamine (DA) by surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) techniques with a detection concentration range of 0.01–0.25 nmol/L and a detection limit of 0.008 nmol/L. Based on the specific binding of aptamer (Apt)-DA and the catalytic amplification strategy of MOFCeAgNC on HAuCl4-SL, a sensitive and convenient DA platform for dual-mode detection of SERS and RRS is constructed. In addition, the platform is successfully applied to detect DA in human serum with satisfactory recoveries (95.7–102%).

Catalytic SrMoO4 nanoparticles and conducting polymer composite sensor for monitoring of K+-induced dopamine release from neuronal cells.

Octahedral SrMoO4 nanoparticles (NPs) with a high degree of crystallinity and controlled size (250-350 nm) were synthesized for the first time by employing a facile hydrothermal method. The prepared NPs were composited with a carboxyl group bearing conducting polymer (2,2:5,2-terthiophene-3-(p-benzoic acid, TBA)) to attain a stable sensor probe (pTBA/SrMoO4) which was analyzed using various surface analysis methods. The catalytic performance of the composite electrode was explored as an oxidation catalyst for biological molecules through anchoring on the conducting polymer layer, which functioned as a matrix to enhance the stability and selectivity of the sensor probe. The pTBA/SrMoO4 coated on glassy carbon displayed excellent electrocatalytic performance for the oxidation of some biologically important molecules, including dopamine (DA) in neuronal cells. The sensor immobilized with the catalyst showed an excellent response for DA with a dynamic range between 0.2 and 500 μM and a detection limit of 5 nM. The proposed sensor demonstrates the detection of trace DA released from PC12 cells under K+ stimulation, followed by inhibition of the release of exogenic DA by a Ca2+ channel blocker (nifedipine). The developed method provides an interesting way to monitor the effect of extracellular substances on living cells and the drug potency test.

Morphology-dependent MnO2/nitrogen-doped graphene nanocomposites for simultaneous detection of trace dopamine and uric acid.

Four nanostructured MnO2 with various controllable morphologies, including nanowires, nanorods, nanotubes and nanoflowers were synthesized, and then further composited with nitrogen-doped graphene (NG) with the assistance of ultrasonication. The surface morphologies, phase structures, and electrochemical performances of the proposed MnO2/NG nanohybrids were investigated by various techniques, and their catalytic activities on the electrooxidation of dopamine (DA) and uric acid (UA) were compared systematically. The sensing performances were found to be highly correlated with their morphologies. Among these morphologies, the nanoflower-like MnO2, composited with NG, displayed the most sensitive response signals for DA and UA. The boosted electrocatalytic activity was ascribed to the unique porous structure, large electroactive area, and low charge transfer resistance (Rct), which facilitated the electron transfer between electrode and analytes. Two linear response ranges (0.1μM-10μM and 10μM-100μM) were accompanied with very low detection limits of 34nM and 39nM for DA and UA, respectively. Moreover, the successful application of the MnO2NFs/NG composites for the simultaneous detection of DA and UA in human serum was realized using second-derivative linear sweep voltammetry (SDLSV). These findings give valuable insights for understanding the morphology-dependent sensing properties of MnO2 based nanomaterials, which is conducive to the rapid development of ubiquitous MnO2-based electrochemical sensors.

Highly sensitive and selective label-free detection of dopamine in human serum based on nitrogen-doped graphene quantum dots decorated on Au nanoparticles: Mechanistic insights through microscopic and spectroscopic studies

A rapid, facile and label-free sensing strategy is developed for the detection of dopamine (DA) in the real samples by exploiting nitrogen-doped graphene quantum dots (N-GQDs) decorated on Au nanoparticles ([email protected]). The as-grown [email protected] exhibits strong blue fluorescence at room temperature and the fluorescence intensity is drastically quenched in presence of DA in neutral medium. The mechanistic insight into the DA sensing by [email protected] is explored here by careful monitoring of the evolution of the interaction of Au NPs and N-GQDs with DA under different conditions through electron microscopic and spectroscopic studies. The highly sensitive and selective detection of DA over a wide range is attributed to the unique core-shell structure formation with [email protected] hybrids. The quenching mechanism involves the ground state complex formation as well as electron transfer from N-GQDs. The presence of Au NPs in [email protected] hybrids accelerates the quenching process (~14 fold higher than bare N-GQDs) by the formation of stable dopamine-o-quinone (DQ) in the present detection scheme. The fluorescence quenching follows the linear Stern-Volmer plot in the range 0–100 μM, establishing its efficacy as a fluorescence-based DA sensor with a limit of detection (LOD) 430 nM. Further, based on the systematic change in the intensity of absorption peak of [email protected] with DA concentration, the well-known Hill equation is introduced for the sensing of DA in the range 0–10 μM with detection limit 40 nM. The proposed sensing method has a high selectivity towards DA over a wide range of common biological molecules as well as metal ions. The quenching in [email protected] fluorescence intensity makes it possible to determine the spiked DA in human serum in the linear range from 0.0 to 80.0 μM with the limit of detection (LOD) 590 nM, which is ~27 fold lower than the lowest abnormal concentration of DA in serum (16 μM). This sensing scheme is also successively applied to trace DA in Brahmaputra river water sample with LOD 480 nM including its satisfactory recovery (95–112%). Our studies reveal a novel sensing pathway for DA through the core-shell structure formation and it is highly promising for the design of efficient biological and environmental sensor.

Schiff-base reaction induced selective sensing of trace dopamine based on a Pt41Rh59 alloy/ZIF-90 nanocomposite

Zeolitic imidazole frameworks (ZIFs) are a new class of functional porous materials with attractive characters, such as gas storage, selective separation, catalysis, and drug delivery. We report herein using nanoscale ZIF-90 crystals with free aldehyde group of imidazole-2-carboxaldehyde (ICA) ligand for the selective electrochemical detection of dopamine. The averaged adsorption enthalpy ΔH (i.e., isosteric heat) of ZIF-90 to dopamine is estimated as 72 kJ mol−1 according to grand canonical Monte Carlo (GCMC) simulation. With further modification of a Pt41Rh59 alloy nanocatalyst, the electrochemical sensing performances towards dopamine are improved. The synergetic effect generated by a Pt41Rh59/ZIF-90 nanocomposite endows it a low detection limit of 1 nM and good specificity. The different anti-interference mechanisms to coexisting redox active species and amino analogues are also included in this work. The strategy demonstrated here may be extended to tune metal nodes as well as ligands of ZIFs crystals and further regulating their functionalities for different target molecules identification.

Nafion coated Au nanoparticle-graphene quantum dot nanocomposite modified working electrode for voltammetric determination of dopamine

In this work, glassy carbon electrode was modified by Nafion coated gold nanoparticle-graphene quantum dots (Au-GQDs-Nafion) nanocomposite and used for voltammetric determination of trace dopamine. The properties of the as-prepared material were characterized by UV–vis spectrometry, fluorescence spectrometry and TEM. The Au-GQDs-Nafion composite showed the excellent synergistic effect for the electrochemical detection of dopamine (DA). Under optimum conditions, the differential voltammetric (DPV) peak current and the concentration of DA displayed a linear range of 2 μM to 50 μM with the detection limit of 0.84 μM. Furthermore, the as-prepared electrode also showed selectivity toward DA detection in the existence of uric acid (UA) and ascorbic acid (AA). The interference experiment showed, that most of the ions did not show obvious influence on the detection of DA. The modified electrode presented reasonable stability and reproducibility in the voltammetric determination of DA, and also the nanocomposite was applied for the real sample analysis in human urine.

An ultra-sensitive electrochemical sensor based on 2D g-C3N4/CuO nanocomposites for dopamine detection

A facile sensor based on two-dimensional (2D) g-C3N4/CuO nanocomposites was proposed for electrochemical detection of dopamine (DA). The 2D g-C3N4/CuO nanocomposites were fabricated by a pyrolysis technique using melamine and cupric acetate monohydrate as precursors. The 2D g-C3N4/CuO nanocomposites prepared have a larger conductivity and a narrower band-gap than that of pure g-C3N4, resulting in higher electrochemical activity for sensing of DA. The response of this sensor is linear over the range of 2.00 × 10−9 to 7.11 × 10−5 mol L−1 with a detection limit of 1.00 × 10−10 mol L−1. The ultra-high sensitivity can be attributed to an electron transfer process on the surface of the sensor, where the 2D g-C3N4/CuO is a powerful electron donor and the oxidized DA quinone functions as an efficient electron acceptor, as confirmed by density functional theory (DFT) calculations. The sensor showed a high selectivity to DA over common interfering biological small molecules (including glucose, uric acid and ascorbic acid), as the DA quinone possesses the most positive electrostatic potential and the smallest electron-injection-barrier between the 2D g-C3N4/CuO and DA quinone, which was also supported by DFT calculations. The proposed novel sensor provides a facile yet ultra-sensitive electrochemical sensing method for detecting trace DA in real biological samples.

Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine

Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10−9 M to 4.0 × 10−5 M with the detection limit of 3.6 × 10−10 M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis.

Supportless electrochemical sensor based on molecularly imprinted polymer modified nanoporous microrod for determination of dopamine at trace level

In this work, we developed a novel freestanding metallic microrod as working electrode for highly sensitive and selective electrochemical detection of trace dopamine (DA). The electrode was facilely fabricated via first dealloying smooth Au–Ag alloy microrod (AMR) into nanoporous Au–Ag alloy microrod (NPAMR) and further modifying with electro-polymerized molecularly imprinted polymer (MIP). Influencing factors during electro-polymerization process including pH value and molar ratio of monomer to template molecule were optimized. Under the optimal conditions, a linear range from 2×10−13 to 2×10−8M for measuring DA was obtained with an ultralow detection limit of 7.63×10−14M (S/N=3). In addition, the MIP-modified electrode (MIP/NPAMR) was successfully employed to test DA in serum and brain samples.

Direct Determination of Trace Dopamine in an Ascorbic Acid Solution at a Bare Glassy Carbon Electrode Using Differential Pulse Voltammetry

It is difficult to monitor dopamine (DA) accurately with a bare glassy carbon electrode because of the interference of ascorbic acid (AA). In this paper, a method for the determination of DA in an AA solution using differential pulse voltammetry was established. Because AA loses its electrochemical activity after being oxidized, hydrogen peroxide was used to oxidize AA, and the interference of AA was completely eliminated. As a result, trace DA could be directly determined in the AA solution with a bare glassy carbon electrode. When trace DA was determined in a 1.0 mmol L−1 AA solution, there was a wide linear range from 3.0×10−8 mol L−1 to 1.0×10−5 mol L−1. The application of this method was demonstrated by the selective measurement of DA in an injection without pretreatment.

Amperometric detection of dopamine in human serumby electrochemical sensor based on gold nanoparticles doped molecularly imprinted polymers

In this work, a highly sensitive and selective biomimetic electrochemical sensor for the amperometric detection of trace dopamine (DA) in human serums was achieved by gold nanoparticles (AuNPs) doped molecularly imprinted polymers (MIPs). Functionalized AuNPs (F-AuNPs), a novel functional monomer bearing aniline moieties on the surface of the AuNPs, were prepared via a direct synthesis method and then used to fabricate the conductive MIPs film on the modified electrode by electropolymerization method in the presence of DA and p-aminobenzenethiol (p-ATP). The obtained electrochemical sensor based on the conductive film of AuNPs doped MIPs (AuNPs@MIPs) could effectively minimize the interferences caused by ascorbic acid (AA) and uric acid (UA). The linear range for amperometric detection of DA was from 0.02μmolL−1 to 0.54μmolL−1 with the detection limit of 7.8nmolL−1 (S/N=3). Furthermore, the AuNPs@MIPs modified electrode (AuNPs@MIES) was successfully employed to detect trace DA in different human serums.