Sensitive Detection Of Dopamine Research Articles

Construction of aptamer-based liquid crystal-aqueous sensing interface for the sensitive detection of dopamine

ABSTRACT Dopamine (DA) is an important neurotransmitter, playing significant roles in various psychological and physiological process of human body. However, the development of a simple, highly sensitive and cost-effective method for DA detection is still challenging. In this study, we report a simple, sensitive and label-free liquid crystal (LC)-based aptasensor for DA detection using a LC-aqueous interface with hexadecyltrimethylammonium bromide (CTAB) as a mediator. In the presence of DA, the specific DA-aptamer binding would weaken the electrostatic interaction between the aptamer and CTAB. This, in turn, promotes the assembly of CTAB at LC-aqueous interface and consequently induces a planar-to-homeotropic anchoring transition of LCs at the interface, which allows the detection of DA under polarized optical microscope (POM) with high sensitivity and specificity. By analysing the variation in dark pixel ratio in POM images of LC films, quantitative detection of DA can be achieved. The results show a linear detection range for DA from 10 pM to 1 μM with a detection limit as low as 2.51 pM (S/N = 3). Moreover, the feasibility of the LC-based aptasensor for DA detection in urine samples has been also validated.

The layer-by-layer assembled ERGO+/ERGO− multilayer modified electrode for sensitive detection of dopamine

Graphene materials represented by graphene oxide (GO) have been widely regarded as functional coatings or films to modify surface of the electrode for detecting dopamine molecules. However, interfacial material properties for detection sensitivity, film stability, and applicability to electrodes are still highly desired. Herein, we first present a screen-printing carbon electrode (SPCE) coated with an electrochemically reduced layer-by-layer (LbL) assembled multilayer driven by an electrostatic interaction between positively charged polyethyleneimine-modified GO with amine groups (ERGO+) and negatively charged carboxyl-functionalized GO (ERGO−), which is briefly described as (ERGO+/ERGO−)n/SPCE. Firstly, without using conventional glassy carbon and gold electrodes, SPCE was tried to make coatings adapt to more flexible and unstable electrodes, simultaneously guaranteeing higher detection performance. Secondly, although a variety of electrochemical sensors such as GO−/SPCE and ERGO−/SPCE were obtained through the drop-casting technique, as-prepared (ERGO+/ERGO−)n/SPCE showed much higher electrocatalytic activities with enhanced peak current signals and reduced charge transfer resistance. Finally, excellent electrochemical properties and sensing performances of the (ERGO+/ERGO−)n/SPCE sensor for detection of dopamine were demonstrated, especially having a linear range of 1 μM to 1000 μM. Meanwhile, the detection limit is as low as 0.39 μM and S/N is equal to 3. The present work offers a potential direction to develop GO modified electrodes for sensitive biomolecular detection.

Covalent organic frameworks surface-anchored with silver nanoparticles for colorimetric detection of dopamine based on its oxidase-mimicking activity

Sensitive detection of dopamine (DA) is essential for the diagnosis of nervous system diseases. Herein, a nanozyme-based colorimetric platform for DA determination was proposed. Using an imine-type covalent organic framework (COF-TD) as a host matrix, a nanozyme (AgNPs@COF-TD) was fabricated by anchoring silver nanoparticles (AgNPs) on the surface of COF-TD via in situ reduction of silver ions. Various characterization results confirmed the successful synthesis of flower-like AgNPs@COF-TD with surface-anchored AgNPs, which could expose more active sites. The as-prepared AgNPs@COF-TD exhibited satisfactory oxidase-mimicking activity with a low Km, which could catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB) with significant absorbance at 657 nm. The introduction of DA not only reduced blue oxTMB to colorless TMB but also competed with TMB for the active sites of AgNPs@COF-TD, making a significant decrease in absorbance. Therefore, a label-free sensing strategy based on the oxidase-mimicking activity of AgNPs@COF-TD was successfully established for the colorimetric detection of DA, with a detection limit down to 0.2 μM. The practical applicability of this assay was further validated by analyzing DA-spiked human urine samples. This work provided a facile approach to prepare COF-based nanozymes, and demonstrated their great potential in colorimetric detection and bioanalysis.

BSA nanoclusters-based sensor for detection of dopamine in schizophrenia from biofluids

Objective To develop nontoxic and stable fluorescent emission B-Cu nanoclusters (NCs) for the specific detection of dopamine at low concentrations in cerebrospinal fluid (CSF). Significance Fluorescent gold and copper NCs conjugated with proteins, such as bovine serum albumin (BSA), offer photostability and healthcare potential. This study focused on fabricating B-Cu NCs that exhibited superior characteristics for sensitive dopamine detection. Methods The study employed various instrumental techniques including attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), spectrofluorometry, and transmission electron microscopy (TEM) to characterize the formulated B-Cu NCs. The NCs were synthesized, resulting in particle size ∼300 nm. The highest observed fluorescence was recorded at 24542.81 relative fluorescence units (RFU). Results The introduction of dopamine at concentrations of 0.1, 0.2, 0.3, and 0.4 ng/mL led to decreased fluorescence in both B-Au and B-Cu NCs due to an electron transport system. This reduction in fluorescence allowed dopamine concentration analysis in phosphate buffer and biological fluids such as blood plasma and CSF. B-Cu NCs showed potential as a biosensing system for point-of-care (POC) applications, specifically for diagnosing schizophrenia. Conclusion The study successfully synthesized stable and nontoxic B-Cu NCs with enhanced fluorescent emission properties. These NCs exhibited the capacity to detect dopamine at low concentrations in CSF. The study’s findings hold promise for future applications, particularly in the development of a B-Cu NCs-based biosensing system for convenient POC detection of schizophrenia by both patients and clinicians. The potential impact of this technology on healthcare and biomedical fields is substantial.

Quantification of Plasma Dopamine in Depressed Patients Using Silver-Enriched Silicon Nanowires as SERS-Active Substrates.

A decrease in the levels of dopamine (DA)─a key catecholamine biomarker for major depressive disorder─highlights the need for quantitative analysis of biological fluids to aid in the early diagnosis of diverse neuropsychiatric disorders. This study developed silicon nanowires enriched with silver nanoparticles to serve as a surface-enhanced Raman scattering (SERS) substrate to enable precise and sensitive quantification of blood plasma DA levels in humans. The silver-enriched silicon nanowires (SiNWs@Ag) yielded flower-like assemblies with densely populated SERS "hot spots," allowing sensitive DA detection. By correlating DA concentration with Raman intensity at 1156 cm-1, the plasma DA levels in treatment-naïve patients with major depression (n = 18) were 2 orders of magnitude lower than those in healthy controls (n = 18) (6.56 × 10-10 M vs 1.43 × 10-8 M). The plasma DA concentrations differed significantly between the two groups (two-tailed p = 5.77×10-7), highlighting a distinct demarcation between depression patients and healthy controls. Furthermore, the SiNWs@Ag substrate effectively differentiated between DA and norepinephrine (NE) in mixtures at nanomolar levels, demonstrating its selective detection capability. This study represents the first report on the quantitative detection of DA levels in human blood samples from individuals with major depression using an SERS technique, emphasizing its potential clinical utility in the evaluation and diagnosis of neuropsychiatric disorders.

Hydrogen Peroxide and Dopamine Sensors Based on Electrodeposition of Reduced Graphene Oxide/Silver Nanoparticles.

In this work, silver nanoparticles (AgNPs)/reduced graphene oxide (rGO) nanocomposites were electrodeposited on glassy carbon electrodes (GCE) to construct electrochemical sensors for the detection of hydrogen peroxide (H2O2) and dopamine (DA). The AgNPs were synthesized on graphene oxide (GO) by the hydrothermal method, followed by the reduction of the GO during the electrodeposition process, resulting in the formation of the nanocomposites on the surface of the electrodes. The generation of AgNPs on the graphene sheets was verified by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The AgNPs/rGO/GCE showed a linear response to H2O2 in the range of 5 μM to 620 μM, with a sensitivity of 49 μA mM-1cm-2 and a limit of detection (LOD) of 3.19 μA. The linear response of the AgNPs/rGO/GCE to DA ranged from 1 μM to 276 μM, the sensitivity was 7.86 μA mM-1cm-2, and the LOD was 0.18 μM. Furthermore, DA and H2O2 were detected simultaneously in the same solution without interferences, and the sensors displayed good stability over time. The preparation method for the sensors is relatively eco-friendly, convenient, and efficient, exhibiting great potential for sensitive detection of DA and H2O2.

Simultaneous and sensitive detection of dopamine and acetaminophen at a glassy carbon electrode modified with a carbonized-ZIF-67/Super P nanocomposite

Fabrication of C-ZIF-67/SP/GCE for the simultaneous detection of DA and AC.

Development of Novel Cobalt Tungstate Anchored on MCM-41 for Sensitive Detection of Dopamine in Human Urine Samples

In this study, MCM-41/CoWO4 nanocomposite has been used for electrochemical detection of dopamine neurotransmitters. The cobalt tungstate nanoparticles (CoWO4) were synthesized through facile hydrothermal method and MCM-41/CoWO4 nanocomposite was prepared by ultrasonication method. The as-synthesized MCM-41/CoWO4 nanocomposite was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman techniques. The electrochemical performance of the nanocomposite was examined using electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry studies. The GCE/MCM-41/CoWO4 electrode exhibited a linear range, better sensitivity, and limit of detection (LOD) of 10–170 μM, 0.3361 μA μM−1 cm−2 and 7.2 nm, respectively. Moreover, the GCE/MCM-41/CoWO4 electrode demonstrated good repeatability, reproducibility, and stability. In addition to that, the real sample analysis was conducted using human urine with excellent recovery and RSD percentage.

One-Pot Hydrothermal Synthesis of mSiO2-N-CDs with High Solid-State Photoluminescence as a Fluorescent Probe for Detecting Dopamine

An effective fluorescent probe (mSiO2-N-CDs) was prepared by embedding N-CDs into mesoporous silica via a simple one-pot hydrothermal reaction and applied to the detection of dopamine (DA). Mesoporous silica not only provided a skeleton to prevent the aggregation of N-CDs but also a medium for the centrifugal collection of N-CDs, avoiding the need for dialysis and freeze-drying. The formation process, phase composition, morphology, and luminescence properties of the composite were studied in detail. The synthesized mSiO2-N-CDs possessed spherical morphology, a smooth surface, and a diameter of approximately 150 nm. The fluorescence results indicated that mSiO2-N-CDs emitted intense blue color fluorescence at 465 nm under the optimal excitation of 370 nm. Because the mesoporous silica effectively inhibited the self-quenching caused by the aggregation of N-CDs, the quantum yield of solid mSiO2-N-CDs powder reached 32.5%. Furthermore, the emission intensity of the solid mSiO2-N-CDs remained constant for 28 days. The good sensitivity and selectivity of mSiO2-N-CDs for DA enabled the establishment of a rapid, simple, and sensitive DA detection method. The linear range was 0–50 µM and the limit of detection was calculated to be 107 nM. This method was used for the determination of DA in urine, with recovery rates ranging between 98% and 100.8%. In addition, the sensing mechanism was characterized by fluorescence lifetime decay and UV–VIS spectral analysis.

A colorimetric/electrochemical sensor based on coral-like CuCo2O4@AuNPs composites for sensitive dopamine detection.

As a central neurotransmitter, DA (dopamine) plays a vital part in human metabolism, and its accurate detection is of great significance in disease diagnosis. In this work, we used Cu/Co bimetallic metal-organic frameworks (MOFs) as templates and gold nanoparticles (AuNPs) to construct novel nanocomposite coral-like CuCo2O4@AuNPs with strong peroxidase activity and electrochemical response. The coral-like CuCo2O4@AuNPs showed excellent peroxidase activity, and the Km value was as low as 0.358mM. In the presence of H2O2, the colorless substrate 3,3',5,5', -tetramethylbenzidine (TMB) can be catalytically oxidized into a blue product. Simultaneously, coral-like CuCo2O4@AuNPs, as an electroactive substance, possess strong electrocatalytic activity, which enhances the electron-transfer rate and promotes excellent current response. In the presence of DA, coral-like CuCo2O4@AuNPs can catalyze the oxidation of DA to dopaquinone, which further enhances the electrochemical signal. In addition, DA captures hydroxyl radicals and inhibits the oxidation of TMB, resulting in an obvious color change (blue turns colorless) and realizing colorimetric detection with the naked eye. On this basis, we successfully established a dual-mode colorimetric/electrochemical sensor using coral-like CuCo2O4@AuNP nanocomposites as a dual-signal probe. Combining colorimetric and electrochemical detection, the sensor achieved a wide linear range (0-1mM) and a low detection limit (0.07μM) for DA concentration. It was also successfully used for the detection of DA in human serum and urine with good results. In summary, this work provides an intuitive, economical, sensitive, and promising platform for DA detection.

MXene‐Coated Liposome‐Quercetin‐Functionalized Gold Nanoparticles for Electrochemical Detection of Dopamine

This study reports a novel electrochemical approach for selective dopamine (DA) sensing. DA is a potential neurological biomarker for human aging and other neurodegenerative disorders, particularly Alzheimer's disease. The sensor is constructed using titanium‐based MXene and quercetin (Qu)‐loaded liposome functionalized with gold nanoparticles (AuNPs) (MXene/Lip‐Qu@AuNPs). MXene/Lip‐Qu@AuNPs is coated on a glassy carbon electrode (GCE) for DA sensing. The MXene provides high conductivity for electrochemical measurements of DA. The modified GCE is employed for DA sensing against various interferants, including ascorbic acid, aspartic acid, arginine, and cysteine. The proposed MXene/Lip‐Qu@AuNP‐based GCE exhibits sufficient detection limits of 0.35 and 0.72 μM for DA sensing using cyclic voltammetry and differential pulse voltammetry methods within a linear concentration range of 1–10 μM, respectively. The proposed sensor is used to detect DA in human serum samples. Hence, the proposed novel sensor is highly convenient and provides highly selective and sensitive DA detection.

Nanozyme catalyzed-SERRS sensor for the recognition of dopamine based on AgNPs@PVP with oxidase-like activity

Dopamine (DA), as one of the most significant neurotransmitters, is closely related to several diseases. Achieving rapid and sensitive detection of DA remains a challenge. Herein, we proposed a simple, fast, and sensitive method for DA recognition based on surface-enhanced resonance Raman scattering (SERRS) technique. The synthesized silver nanoparticles coated with polyvinylpyrrolidone (AgNPs@PVP) with oxidase activity could not only oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) directly to produce a blue oxidation state TMB (oxTMB) but also could be used as the SERS substrate to generate a strong SERRS signal. When DA was added to the above system, the blue color faded along with the decrease in the SERRS signal. The change value of SERRS intensity was in proportion to the concentration of DA in the range of 0.1–10 μM with a limit of detection of 40 nM. This method presented great potential for the recognition of DA-related diseases.

LuMA-Functionalized Thermosensitive Hydrogel: A Versatile and Robust Dopamine-Triggered Platform for Diverse Biomolecules Sensing.

It is of great significance for the analysis of multiple biomarkers because a single biomarker is difficult to accurately achieve early diagnosis, disease course monitoring, and prognosis evaluation. Herein, a luminescence thermosensitive hydrogel was synthesized by radical polymerization using a methacrylic acid derivative monomer of luminol (LuMA) as luminescent, N-isopropylacrylamide (NIPAM) as thermosensitive monomer, and acrydite-oligonucleotides [dopamine (DA) aptamer, DNA C1, and DNA C2] as recognition elements. The combined DA based on the affinity interaction between the DA and the aptamer on the hydrogel polymer chain was electrochemically oxidized to dopamine quinone during the electrochemiluminescence (ECL) scanning, which effectively quenched the ECL signal of LuMA due to the resonance energy transfer (RET). In addition, the thermosensitive hydrogel showed swelling-collapse characteristics when the temperature was below and above the volume phase transition temperature. Undergoing the collapse process initiated by the temperature, the RET efficiency was further enhanced due to the shortened distance between the energy donor and acceptor, showing a 1.4 times signal amplification and achieving sensitive detection of DA with a limit of detection (LOD) of 1.7 × 10-10 M. For a proof of concept application, coupled with the target-induced release of DA from the DNA-magnetic beads bioconjugations based on duplex-specific nuclease (DSN)-assisted target recycling amplification strategy and DNAzyme cleavage reaction, this ECL-RET approach was successfully used to evaluate multiple targets including miRNA-141 and MUC1 with the LOD of 2.5 aM and 1.6 fg/mL, respectively. The excellent performances of the versatile and robust ECL-RET hydrogel in multiple target sensing showed potential applications in clinical diagnosis and disease therapeutic assay.

Facile fabrication of Fe-Fe3C nanoparticles decorated with carbon nanotubes for sensitive dopamine detection

In this study, we present an electrochemical sensor with superior sensitivity and selectivity for dopamine (DA) detection. The sensor was created using a nanocomposite of iron-iron carbide nanoparticles decorated with carbon nanotubes (Fe-Fe3C@CNTs) to modify a glassy carbon electrode (GCE). The Fe-Fe3C@CNTs nanocomposite can be synthesized by a facile microwave-assisted synthesis method with just adopting ferrocene and carbon fiber as raw material and heat source, respectively. The electron microscopy (EM) results indicate that the Fe-Fe3C nanoparticles encapsulated with graphitic layer were decorated with CNTs. An investigation of the electrochemical responses of the Fe-Fe3C@CNTs/GCE sensor to DA was performed using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Notably, in ideal experimental settings, the sensor demonstrated a minimal limit of detection (LOD) of 0.01 μM within a range of linearity from 0.05 to 40 μM, even under a high concentration of uric acid (UA) interference. Moreover, the utility of the produced Fe-Fe3C@CNTs/GCE sensor was further validated through successful DA testing in urine samples of human.

Vancomycin-Stabilized Platinum Nanoparticles with Oxidase-like Activity for Sensitive Dopamine Detection.

The development of efficient, reliable, and sensitive dopamine detection methods has attracted much attention. In this paper, vancomycin-stabilized platinum nanoparticles (Van-Ptn NPs, n = 0.5, 1, 2) were prepared by the biological template method, where n represented the molar ratio of vancomycin to Pt. The results show that Van-Pt2 NPs had oxidase-like activity and peroxidase-like activity, and the mechanism was due to the generation of reactive oxygen 1O2 and OH. Van-Pt2 NPs exhibited good temperature stability, storage stability, and salt solution stability. Furthermore, Van-Pt2 NPs had almost no cytotoxicity to A549 cells. More importantly, the colorimetric detection of DA in human serum samples was performed based on the oxidase-like activity of Van-Pt2 NPs. The linear range of DA detection was 10-700 μM, and the detection limit was 0.854 μM. This study establishes a rapid and reliable method for the detection of dopamine and extends the application of biosynthetic nanoparticles in the field of biosensing.

Electrochemical sensor based on three-dimensional Skeleton/Skin ink for the ultrasensitive detection of dopamine released from neural cells

The development of a miniaturized and low-cost platform for the simultaneous and high-sensitive detection of the nervous system metabolites has gained great interest for early diagnosis and prognostic monitoring of some diseases. Herein, a three-dimensional (3D) interpenetrating hydrogel ink synthesized through a simple hydrothermal assembly way was utilized for the sensitive detection of dopamine released from neural cells in vivo. Carbon nanotubes (CNTs) were utilized as the structural framework, while reduced graphene nanosheets were employed as the outer covering, resulting in the formation of a “skeleton/skin” structure. The attachment of hydrophilic IL molecules onto the graphene nanosheets confers distinctive hydrophilic traits on the resulting nanocomposite material. Consequently, this facilitates its effortless conversion into freestanding paper-like material via printing. The modified electrode was proved to be efficient in electrochemical detection of dopamine by means of DPV, despite the existence of interfering substances like ascorbic and uric acid. With a sensitivity of 41.86 μA μM−1 cm−2 and a low detection limit of 2 nM (S/N = 3), the paper electrode exhibited a linear response ranging from 0.01 to 50 μM. Furthermore, the rGO-CNT-IL was used to determine dopamine levels in the neural cells. The modified paper electrode can also be potentially applied for further drug detection, health monitoring and other biological applications.

Sulfur-vacancy-enriched MoS2-CNTs with highly dispersed Au particles for sensitive dopamine detection

Introducing targeted surface defects sites to regulate the electronic structure is a key method to enhance the electrocatalytic activity of materials. This study reports an electrochemical dopamine sensor using sulfur vacancy (Sv) rich MoS2-CNTs with coaxial hierarchical structure and highly dispersed active gold particles (Au-Sv-MoS2-CNTs). MoS2 with sulfur vacancies expands the layered structure beyond the MWCNT's cylinder rather than being restricted to its surface and has active Au deposition sites along the edges. With optimal conditions, the proposed coaxial, hierarchical-structured Au-Sv-MoS2-CNTs show remarkable detection performance for the rapid detection of DA at concentrations as low as 2 nM in phosphate buffered saline (PBS). In addition, the sensor selectivity and anti-interference qualities are evaluated using chronoamperometry. Furthermore, it successfully detected the analyte from injection of dopamine hydrochloride and bovine serum samples with recovery rates ranging from 99.3% to 102.6% and relative standard deviations (RSD) less than 5%. Density functional theory (DFT) simulations demonstrate that the modifications of Sv and Au NPs could tune the electronic structure of the sensor and facilitate the adsorption and electrocatalytic reaction of DA on Au-Sv-MoS2-CNTs. This study reveals that vacancy engineering and morphology control are emerging strategies for the fabrication of biosensors.

Microfluidic flow injection analysis system for the electrochemical detection of dopamine using diazonium-grafted copper nanoparticles on multi-walled carbon nanotube-modified surfaces

In this proof-of-concept study, a microfluidic flow injection analysis (FIA) system was developed using multi-walled carbon nanotube-modified screen-printed carbon electrodes (CNTSPEs) that were modified with copper nanoparticles (CuNPs) following the electrodeposition of the diazonium salt of 4-aminothiophenol to form 4-thiophenol-conjugated CuNPs (CuNPs-CNTSPE). Transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) were used to characterize the size of CuNPs, morphology and elemental analysis of CuNPs-CNTSPE, respectively. Using electrochemical impedance spectroscopy (EIS), the charge-transfer resistance (Rct) of CuNPs-CNTSPE was found to be 20-fold lower than that of CNTSPE. The CuNPs-CNTSPE displayed an oxidation peak for dopamine at −0.08 V which is ∼80 mV lower than the one detected using CNTSPE. The modified electrode was used in microfluidic flow injection analysis and offline systems for sensitive detection of dopamine (DA). The pH, flow rate, loop volume, concentration, and type of surfactant were all optimized for on-chip detection. Under the optimal conditions, using phosphate electrolyte solution (pH 6) containing 0.05% (w/v) Tween 20® as the carrier at a flow rate of 0.6 mL min−1 and a loop volume of 50 μL, the calibration curve was linear from 1.5 to 500 nM with a limit of detection of 0.33 nM. This technique was used for the successful detection of DA in real samples with recovery ranging from 96.5% to 103.8%. The microfluidic FIA system described here has the potential to be used as an electrochemical point-of-care device for rapid DA detection with high sensitivity and reproducibility.

Rich‐defect carbon nanotubes for highly sensitive detection of Dopamine

AbstractDopamine (DA) plays an essential role in the central nervous, renal, hormonal and cardiovascular systems. Various modified carbon nanotubes (CNT)‐based dopamine sensors have been reported, but inexpensive, highly sensitive plain CNT‐based ones are seldom studied. In this work, a facile and inexpensive CNT‐based DA sensor is made by rich‐defect multi‐walled carbon nanotubes (RD‐CNT) via an ultrasound method. The defect and elemental states of the RD‐CNT are systematically studied by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HR‐TEM), Raman spectroscopy, X‐ray powder diffraction (XRD) and X‐ray‐photoelectron spectroscopy (XPS). Results show that massive holes and cracks exist in RD‐CNT. The level of defects increases from the additional exposed edges. The electrochemical characterizations indicate that the electrochemical sensor has the highest sensitivity of 438.4 μA/(μM ⋅ cm2) among all carbon materials‐based DA sensors while well meeting the clinically required detection range and selectivity. The DA sensor was further used to detect live healthy human serum and live PC12 cells with satisfactory results, thus holding great promise for an inexpensive but sensitive DA sensor in practical applications of clinical diagnosis and biological research.

A novel electrochemical sensor based on DUT-67/ZnCo2O4-MWCNTs modified glassy carbon electrode for the simultaneous sensitive detection of dopamine and uric acid

Uric acid and dopamine are closely related to the health of the organism, so it is important to determine them simultaneously and efficiently. In this paper, the metal-organic framework DUT-67 was in situ grown on the surface of bimetallic oxide ZnCo2O4 nanoflowers, and then ultrasonically compounded with multi-walled carbon nanotubes (MWCNTs) to prepare DUT-67/ZnCo2O4-MWCNTs composite. The prepared composite was characterized by XRD, SEM, XPS, FTIR, BET and other techniques. Finally, an electrochemical sensor based on DUT-67/ZnCo2O4-MWCNTs composite modified glassy carbon electrode for simultaneous detection of dopamine (DA) and uric acid (UA) was fabricated. The introduction of ZnCo2O4 into the composite efficiently overcame the disadvantage of the easy aggregation of DUT-67 and produced a synergistic effect with MWCNTs. The electron transfer rate between the electrode and the electrolyte solution was accelerated, and the detection signals of the target molecules were amplified. After characterizing the electrochemical properties of the composite electrode, it was found that the constructed electrochemical sensor showed low detection limits for DA and UA, which were 12 nM and 8.7 nM, respectively, and the wide linear range of 1.0–180.0 μM. Besides, the sensor had excellent reproducibility, repeatability, anti-interference and stability. The proposed sensor was also successfully used to determine the contents of DA and UA in dopamine injection and urine samples with relatively satisfactory recovery rates. This work not only provides a new strategy for the preparation of MOF modified electrodes, but also has a potential application prospect in bioassays.