Selective detection of dopamine based on the unique property of gold nanofilm

Employing Conductive Metal-Organic Frameworks for Voltammetric Detection of Neurochemicals

This paper describes the first implementation of an array of two-dimensional (2D) layered conductive metal-organic frameworks (MOFs) as drop-casted film electrodes that facilitate voltammetric detection of redox active neurochemicals in a multianalyte solution. The device configuration comprises a glassy carbon electrode modified with a film of conductive MOF (M₃HXTP₂; M = Ni, Cu; and X = NH, 2,3,6,7,10,11-hexaiminotriphenylene (HITP) or O, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP)). The utility of 2D MOFs in voltammetric sensing is measured by the detection of ascorbic acid (AA), dopamine (DA), uric acid (UA), and serotonin (5-HT) in 0.1 M PBS (pH = 7.4). In particular, Ni₃HHTP₂ MOFs demonstrated nanomolar detection limits of 63 ± 11 nM for DA and 40 ± 17 nM for 5-HT through a wide concentration range (40 nM-200 μM). The applicability in biologically relevant detection was further demonstrated in simulated urine using Ni₃HHTP₂ MOFs for the detection of 5-HT with a nanomolar detection limit of 63 ± 11 nM for 5-HT through a wide concentration range (63 nM-200 μM) in the presence of a constant background of DA. The implementation of conductive MOFs in voltammetric detection holds promise for further development of highly modular, sensitive, selective, and stable electroanalytical devices.

In-situ graft-crosslinked gold nanoparticles with high-density surface defects and coated with a polytaurine membrane for the voltammetric determination of dopamine

Well-dispersed and graft-crosslinked gold nanoparticles (AuNPs) were synthesized by the reduction of tetrachloroaurate with hydrazine at room temperature. The AuNPs possess a high density of surface defects which is due to grafting of n-octanoic acid to polyvinylpyrrolidone. The physical and chemical properties of the resulting AuNPs were characterized by UV-vis, XRD, TEM/HRTEM, SAED, and XPS, respectively. The modified AuNPs were placed on a glassy carbon electrode (GCE) in an electropolymerized taurine layer to obtain a sensitive, selective, stable and rapid electrochemical dopamine sensor. The peak current, typically measured at 0.17 V (vs. SCE), increases linearly in the 1.0 to 120 μM dopamine concentration range, and the limit of detection (at S/N = 3) is 0.16 μM with a sensitivity of 2.94 μA·μM^-1·cm^-2. The sensor was successfully applied to the determination of dopamine in injections and spiked serum samples. The recoveries from spiked serum samples range from 97.5 to 102.4%, with RSDs ranging between 2.8 and 3.4%. Graphical abstract Schematic representation of a glassy carbon electrode modified with in-situ graft-crosslinked gold nanoparticles combined with an electropolymerized polytaurine membrane. The sensor exhibits excellent features towards dopamine determination.

Highly selective enzymatic-free electrochemical sensor for dopamine detection based on the self-assemblied film of a sandwich mixed (phthalocyaninato) (porphyrinato) europium derivative

An efficient enzymatic-free electrochemical sensor is firstly developed based on the self-assemblied film of a sandwich mixed (phthalocyaninato) (porphyrinato) europium(III) double-decker complex, Eu(Pc)[T(OH)PP], [Pc = phthalocyaninate, T(OH)PP = 5,10,15,tris (4-tert-butylphenyl)-20-(4-hydroxyphenyl)porphyrinate] prepared by using a solution-processing QLS method. The Eu(Pc)[T(OH)PP]semiconducting active layer on an ITO working electrode leads to a good sensing property for the detection of dopamine with an excellent selectivity, due to the high Eu(Pc)[T(OH)PP] molecular ordering/packing in the QLS film and more favorable interaction between the Eu(Pc)[T(OH)PP] and DA molecules. The amperometric responses are linearly proportional to the concentration of dopamine in the range of 8–100 [Formula: see text]M, with a low detection limit of 4.8 [Formula: see text]M and good sensitivity, indicating the great potential of electroactive tetrapyrrole rare earth sandwich type complexes in the field of nonenzymatic electrochemical sensors.

One-Pot Green Synthesis of Graphene Nanosheets Encapsulated Gold Nanoparticles for Sensitive and Selective Detection of Dopamine

We report a simple new approach for green preparation of gallic acid supported reduced graphene oxide encapsulated gold nanoparticles (GA-RGO/AuNPs) via one-pot hydrothermal method. The as-prepared composites were successfully characterized by using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction techniques (XRD), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM) and elemental analysis. The GA-RGO/AuNPs modified electrode behaves as a hybrid electrode material for sensitive and selective detection of dopamine (DA) in presence of ascorbic acid (AA) and uric acid (UA). The GA-RGO/AuNPs modified electrode displays an excellent electrocatalytic activity towards the oxidation of DA and exhibits a wide linear response range over the DA concentrations from 0.01-100.3 μM with a detection limit (LOD) of 2.6 nM based on S/N = 3. In addition, the proposed sensor could be applied for the determination of DA in human serum and urine samples for practical analysis.

Synthesis of an ordered nanoporous Fe2O3/Au film for application in ascorbic acid detection

Ordered nanoporous Fe₂O₃/Au film was synthesized and used as an effective non-enzymatic sensor for detection of ascorbic acid.

Carbon dots and chitosan composite film based biosensor for the sensitive and selective determination of dopamine

A simple, sensitive and reliable dopamine (DA) biosensor was developed based on a carbon dots (CDs) and chitosan (CS) composite film modified glassy carbon electrode (CDs-CS/GCE). Under optimal conditions, the CDs-CS/GCE showed a better electrochemical response for the detection of DA than that of the glassy carbon electrode (GCE). The oxidation peak current (Ipa) of DA was linear with the concentration of DA in the range from 0.1 μM to 30.0 μM with the limit of detection as 11.2 nM (3S/N). The CDs-CS/GCE was applied to the detection of DA content in an injection solution of DA with satisfactory results.

Gold nanostructures on flexible substrates as electrochemical dopamine sensors

In this study, we fabricated Au nanowires (NWs), nanoslices (NSs), and nanocorals (NCs) on flexible polyethylene terephthalate (PET) substrates via direct current electrochemical depositions. Without any surface modification, the Au nanostructures were used as the electrodes for dopamine (DA) sensing. Among them, the Au NW electrode performed exceptionally well. The determined linear range for DA detection was 0.2-600 μM (N = 3) and the sensitivity was 178 nA/μM cm(2), while the detection limit was 26 nM (S/N = 3). After 10 repeated measurements, 95% of the original anodic current values were maintained for the nanostructured electrodes. Sequential additions of citric acid (CA, 1 mM), uric acid (UA, saturated), and ascorbic acid (AA, 1 μM) did not interfere the amperometric response from the addition of DA (0.1 μM).

Preparation and electrochemical characterization of a carbon ceramic electrode modified with ferrocenecarboxylic acid

The present paper describes the characterization of a carbon ceramic electrode modified with ferrocenecarboxylic acid (designated as CCE/Fc) by electrochemical techniques and its detection ability for dopamine. From cyclic voltammetric experiments, it was observed that the CCE/Fc presented a redox pair at E_pa = 405 mV and E_pc = 335 mV (ΔE = 70 mV), related to the ferrocene/ferrocenium process. Studies showed a considerably increase in the redox currents at the same oxidation potential of ferrocene (E_pa = 414 mV vs. Ag/AgCl) in the presence of dopamine (DA), differently from those observed when using only the unmodified CCE, in which the anodic peak increase was considerably lower. From SWV experiments, it was observed that the AA (ascorbic acid) oxidation at CCE/Fc occurred in a different potential than the DA oxidation (with a peak separation of approximately 200 mV). Moreover, CCE/Fc did not respond to different AA concentrations, indicating that it is possible to determine DA without the AA interference with this electrode.