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1.
J Neural Eng ; 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32000145

RESUMO

OBJECTIVES: With the rapid development of EEG-based wearable healthcare devices and brain-computer interfaces (BCIs), reliable and user-friendly EEG sensors for EEG recording especially at the forehead sites are highly desirable and challenging. However, the existing EEG sensors cannot meet the requirements, since wet electrodes require tedious setup and conductive pastes or gels, and most dry electrodes show unacceptable high contact impedance. In addition, the existing electrodes cannot absorb sweat effectively, which would cause cross-interferences even short circuits between adjacent electrodes, especially in the moving scenarios, or hot and humid environment. To resolve these problems, a novel printable flexible Ag/AgCl dry electrode array was developed for EEG acquisition at forehead sites, mainly consisting of screen-printing Ag/AgCl coating, conductive sweat-absorbable sponges and flexible tines. APPROACH: A systematic method was also established to evaluate the flexible dry electrode array. MAIN RESULTS: The experimental results show the flexible dry electrode array have reproducible electrode potential, relative low electrode-skin impedance, and good stability. Moreover, the EEG signals can be effectively captured with high quality that is comparable with that of wet electrodes. SIGNIFICANCE: All the results confirmed that the feasibility for forehead EEG recording in real-world scenarios using the proposed flexible dry electrode array, with a rapid and facile operation as well as advantages of self-application, user-friendliness and wearing comfort.

2.
Biomolecules ; 10(1)2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31936417

RESUMO

A novel tantalum pentoxide nanoparticle-electrochemically reduced graphene oxide nanocomposite-modified glassy carbon electrode (Ta2O5-ErGO/GCE) was developed for the detection of oxytetracycline in milk. The composition, structure and morphology of GO, Ta2O5, and Ta2O5-ErGO were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Oxytetracycline electrochemical behavior on the bare GCE, GO/GCE, ErGO/GCE, and Ta2O5-ErGO/GCE was studied by cyclic voltammetry. The voltammetric conditions (including scan rate, pH, deposition potential, and deposition time) were systematically optimized. With the spacious electrochemical active area, the Ta2O5-ErGO/GCE showed a great magnification of the oxidation signal of oxytetracycline, while that of the other electrodes (GCE, GO/GCE, ErGO/GCE) could not reach the same level. Under the optimum conditions, the currents were proportional to the oxytetracycline concentration in the range from 0.2 to 10 µM, and a low detection limit of 0.095 µM (S/N = 3) was detectable. Moreover, the proposed Ta2O5-ErGO/GCE performed practically with satisfactory results. The preparation of Ta2O5-ErGO/GCE in the current work provides a minor outlook of detecting trace oxytetracycline in milk.

3.
Bioelectrochemistry ; 131: 107393, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31698180

RESUMO

A tryptophan (Trp) molecularly imprinted electrochemical sensor was fabricated by drop-coating an imprinted chitosan film on the surface of a glassy carbon electrode modified with multi-walled carbon nanotubes (MIP-MWCNTs/GCE). The surface morphology and electrochemical properties of the MIP-MWCNTs/GCE were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. The electrochemical performance of the MIP-MWCNTs/GCE with Trp showed that the signal of the oxidation current of Trp obtained with MIP-MWCNTs/GCE was significantly enhanced relative to that of the uncovered GCE, indicating that the modified electrode can accelerate electron transfer and has strong selectivity for Trp. The experimental conditions were optimized in parallel, and under the optimal conditions, the MIP-MWCNTs/GCE showed a good linear relationship between the Trp oxidation peak current and Trp concentrations in the ranges of 2.0 nM-0.2 µM, 0.2 µM-10 µM and 10 µM-100 µM The limit of detection (LOD) was 1.0 nM (S/N = 3), and the modified electrode had good reproducibility and stability. Finally, the MIP-MWCNTs/GCE was successfully applied to the determination of Trp in the human serum samples.


Assuntos
Carbono/química , Eletrodos , Impressão Molecular , Nanotubos de Carbono/química , Triptofano/análise , Técnicas Eletroquímicas/métodos , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Nanomaterials (Basel) ; 9(10)2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31640135

RESUMO

For the enhancement of the anticorrosion and antibacterial performance of the biomedical alloy Ti6Al4V, a novel Cu incorporated multilayer Ta2O5ceramic composite coating Cu-Ta2O5/Ta2O5/Ta2O5-TiO2/TiO2/Ti (coating codeCu-MTa2O5) was developed by radio frequency (RF) and direct current (DC) reactive magnetron sputtering. Meanwhile, to better display the multilayer Ta2O5 coating mentioned above, a monolayer Ta2O5 ceramic coating was deposited onto the surface of Ti6Al4V alloy as a reference. The surface morphology, microstructure, phase constituents, and elemental states of the coating were evaluated by atomic force microscopy, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. The adhesion strength, wettability, anticorrosion and antibacterial properties of the coating were examined by a scratch tester, contact angle measurement, electrochemical workstations, and plate counting method, respectively. The results showed that the deposited coatings were amorphous and hydrophobic. Cu doped into the Ta2O5 coating existed as CuO and Cu2O. A Ta2O5-TiO2/TiO2/Ti multi-interlayer massively enhanced the adhesion strength of the coating, which was 2.9 times stronger than that of the monolayer Ta2O5coating. The multilayer Cu-MTa2O5 coating revealed a higher corrosion potential and smaller corrosion current density as compared to the uncoated Ti6Al4V, indicating the better anticorrosion performance of Ti6Al4V. Moreover, a 99.8% antibacterial effect of Cu-MTa2O5 coated against Staphylococcus aureuswas obtained.

5.
Nanomaterials (Basel) ; 9(7)2019 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-31262035

RESUMO

In this paper, the preparation, characterization, and electrochemical application of Cu2O nanoparticles and an electrochemical reduced graphene oxide nanohybrid modified glassy carbon electrode (denoted as Cu2O NPs‒ERGO/GCE) are described. This modified electrode was used as an electrochemical sensor for the catalytic oxidation of rhodamine B (RhB), and it exhibited an excellent electrochemical performance for RhB. The oxidation potential of RhB was decreased greatly, and the sensitivity to detect RhB was improved significantly. Under optimum conditions, a linear dynamic range of 0.01-20.0 µM and a low detection limit of 0.006 µM were obtained with the Cu2O NPs‒ERGO/GCE by using second‒order derivative linear sweep voltammetry. In addition, the selectivity of the prepared modified electrode was analyzed for the determination of RhB. The practical application of this sensor was investigated for the determination of RhB in food samples, and satisfactory results were obtained.

6.
Biomolecules ; 9(7)2019 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-31336671

RESUMO

In this paper, a tryptophan (Trp) molecularly imprinted chitosan film was prepared on the surface of an acetylene black paste electrode using chitosan as the functional polymer, Trp as the template molecule and sulfuric acid as the crosslinking agent. The surface morphologies of non-imprinted and imprinted electrodes were characterized by scanning electron microscopy (SEM). The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. Some factors affecting the performance of the imprinted electrode such as the concentration of chitosan, the mass ratio of chitosan to Trp, the dropping amount of the chitosan-Trp mixture, the solution pH, and the accumulation potential and time were discussed. The experimental results show that the imprinted electrode exhibit good affinity and selectivity for Trp. The dynamic linear ranges of 0.01-4 M, 4-20 M and 20-100 M were obtained by second derivative linear sweep voltammetry, and the detection limit was calculated to be 8.0 nM. The use of the imprinted electrode provides an effective method for eliminating the interference of potentially interfering substances. In addition, the sensor has high sensitivity, reproducibility and stability, and can be used for the determination of Trp in pharmaceutical preparations and human serum samples.

7.
Nanomaterials (Basel) ; 9(6)2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31159377

RESUMO

Various morphologies of iron oxide nanoparticles (Fe2O3 NPs), including cubic, thorhombic and discal shapes were synthesized by a facile meta-ion mediated hydrothermal route. To further improve the electrochemical sensing properties, discal Fe2O3 NPs with the highest electrocatalytic activity were coupled with graphene oxide (GO) nanosheets. The surface morphology, microstructures and electrochemical properties of the obtained Fe2O3 NPs and Fe2O3/GO nanohybrids were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. As expected, the electrochemical performances were found to be highly related to morphology. The discal Fe2O3 NPs coupled with GO showed remarkable electrocatalytic activity toward the oxidation of dopamine (DA) and uric acid (UA), due to their excellent synergistic effect. The electrochemical responses of both DA and UA were linear to their concentrations in the ranges of 0.02-10 µM and 10-100 µM, with very low limits of detection (LOD) of 3.2 nM and 2.5 nM for DA and UA, respectively. Moreover, the d-Fe2O3/GO nanohybrids showed good selectivity and reproducibility. The proposed d-Fe2O3/GO/GCE realized the simultaneous detection of DA and UA in human serum and urine samples with satisfactory recoveries.

8.
Nanomaterials (Basel) ; 9(6)2019 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-31159490

RESUMO

This study reports facile synthesis of MnO2 nanoflowers/N-doped reduced graphene oxide (MnO2NFs/NrGO) composite and its application on the simultaneous determination of dopamine (DA) and uric acid (UA). The microstructures, morphologies, and electrochemical performances of MnO2NFs/NrGO were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), respectively. The electrochemical experiments showed that the MnO2NFs/NrGO composites have the largest effective electroactive area and lowest charge transfer resistance. MnO2NFs/NrGO nanocomposites displayed superior catalytic capacity toward the electro-oxidation of DA and UA due to the synergistic effect from MnO2NFs and NrGO. The anodic peak currents of DA and UA increase linearly with their concentrations varying from 0.2 µM to 6.0 µM. However, the anodic peak currents of DA and UA are highly correlated to the Napierian logarithm of their concentrations ranging from 6.0 µM to 100 µM. The detection limits are 0.036 µM and 0.029 µM for DA and UA, respectively. Furthermore, the DA and UA levels of human serum samples were accurately detected by the proposed sensor. Combining with prominent advantages such as facile preparation, good sensitivity, and high selectivity, the proposed MnO2NFs/NrGO nanocomposites have become the most promising candidates for the simultaneous determination of DA and UA from various actual samples.

9.
Biomolecules ; 9(6)2019 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-31234553

RESUMO

In this study, we reported facile synthesis of Fe3O4/C composite and its application for the cost-effective and sensitive determination of tryptophan (Trp) in human serum samples. Fe3O4/C composites were prepared by a simple one-pot hydrothermal method followed by a mild calcination procedure, using FeCl3∙6H2O as Fe3O4 precursor, and glucose as reducing agent and carbon source simultaneously. The Fe3O4/C composite modified glassy carbon electrode (Fe3O4/C/GCE) was prepared by drop-casting method. The microstructure and morphology of Fe3O4/C composite was characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Due to large specific surface area and synergistic effect from Fe3O4 nanoparticles and carbon coating, Fe3O4/C composite showed excellent electrocatalytic activity toward the oxidation of Trp. As a result, the proposed Fe3O4/C/GCE displayed superior analytical performances toward Trp determination, with two wide detection ranges (1.0-80 µM and 80-800 µM) and a low detection limit (0.26 µM, S/N = 3). Moreover, successful detection of Trp in human serum samples further validate the practicability of the proposed sensor.

10.
Nanomaterials (Basel) ; 9(5)2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-31052573

RESUMO

Ti6Al4V titanium alloy has been widely used as medical implant material in orthopedic surgery, and one of the obstacles preventing it from wide use is toxic metal ions release and bacterial implant infection. In this paper, in order to improve corrosion resistance and antibacterial performance of Ti6Al4V titanium alloy, ZnO doped tantalum oxide (TaxOy) multilayer composite coating ZnO-TaxOy/TaxOy/TaxOy-TiO2/TiO2/Ti (ZnO-TaxOy) was deposited by magnetron sputtering at room temperature. As a comparison, monolayer TaxOy coating was prepared on the surface of Ti6Al4V alloy. The morphology and phase composition of the coatings were investigated by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD), the elemental chemical states of coating surfaces were investigated by X-ray photoelectron spectroscope (XPS). The adhesion strength and corrosion resistance of the coatings were examined by micro-scratch tester and electrochemical workstations, respectively. The results show that the adhesion strength of multilayer ZnO-TaxOy coating is 16.37 times higher than that of single-layer TaxOy coating. The ZnO-TaxOy composite coating has higher corrosion potential and lower corrosion current density than that of TaxOy coating, showing better corrosion inhibition. Furthermore, antibacterial test revealed that multilayer ZnO-TaxOy coating has a much better antibacterial performance by contrast.

11.
Biomolecules ; 9(5)2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-31072043

RESUMO

In this paper, a nanocomposite of cuprous oxide and electrochemically reduced graphene oxide (Cu2O‒ERGO) was prepared by a simple and low-cost method; hereby, a new method for the electrochemical determination of tryptophan (Trp) by this composite modified glassy carbon electrode (GCE) is proposed. The prepared materials and modified electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV). The results showed that Cu2O‒ERGO/GCE had good electrocatalytic activity for Trp. The effects of supporting electrolyte, scanning rate, accumulation potential, and accumulation time on the determination of Trp were studied. Under the optimum experimental conditions, Trp was quantitatively analyzed by square-wave voltammetry (SWV). The oxidation peak current of Trp had a good linear relationship with its concentration in the range of 0.02‒20 µM, and the detection limit was 0.01 µM (S/N = 3). In addition, the modified electrode has high sensitivity, good repeatability, and long-term stability. Finally, the proposed method has been successfully applied in the determination of Trp concentration in practical samples.


Assuntos
Cobre/química , Eletroquímica/métodos , Grafite/química , Nanocompostos/química , Nanopartículas/química , Triptofano/análise , Calibragem , Eletrodos , Humanos , Limite de Detecção , Nanopartículas/ultraestrutura , Oxirredução , Reprodutibilidade dos Testes , Ácidos Sulfúricos/química , Triptofano/sangue , Difração de Raios X
12.
Nanomaterials (Basel) ; 9(6)2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31142057

RESUMO

l-tryptophan is one of the eight kinds of essential amino acids for sustainable human life activity. It is common to detect the concentration of tryptophan in human serum for diagnosing and preventing brain related diseases. Herein, in this study, GCE (glassy carbon electrode) modified by Ta2O5-reduced graphene oxide (-rGO) composite (Ta2O5-rGO-GCE) is synthesized by the hydrothermal synthesis-calcination methods, which is used for detecting the concentration of tryptophan in human serum under the as-obtained optimal detection conditions. As a result, the obtained Ta2O5-rGO-GCE shows larger electrochemical activity area than other bare GCE and rGO-GCE due to the synergistic effect of Ta2O5 NPs and rGO. Meanwhile, Ta2O5-rGO-GCE shows an excellent response to tryptophan during the oxidation process in 0.1 M phosphate buffer solution (pH = 6). Moreover, three wide linear detection range (1.0-8.0 µM, 8.0-80 µM and 80-800 µM) and a low limit of detection (LOD) of 0.84 µM (S/N = 3) in the detection of tryptophan are also presented, showing the larger linear ranges and lower detection limit by employing Ta2O5-rGO-GCE. Finally, the as-proposed Ta2O5-rGO-GCE with satisfactory recoveries (101~106%) is successfully realized for the detection of tryptophan in human serum. The synthesis of Ta2O5-rGO-GCE in this article could provide a slight view for the synthesis of other electrochemical catalytic systems in detection of trace substance in human serum.

13.
Molecules ; 24(6)2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30934654

RESUMO

The nanohybrid of electrochemically-reduced graphene oxide (ERGO) nanosheets decorated with MnO2 nanorods (MnO2 NRs) was modified on the surface of a glassy carbon electrode (GCE). Controlled potential reduction was applied for the reduction of graphene oxide (GO). The characterization was performed by scanning electron microscopy, X-ray diffraction and cyclic voltammetry. Compared with the poor electrochemical response at bare GCE, a well-defined oxidation peak of sunset yellow (SY) was observed at the MnO2 NRs-ERGO/GCE, which was attributed to the high accumulation efficiency as well as considerable electrocatalytic activity of ERGO and MnO2 NRs on the electrode surface. The experimental parameters for SY detection were optimized in detail. Under the optimized experiment conditions, the MnO2 NRs-ERGO/GCE showed good linear response to SY in concentration range of 0.01⁻2.0 µM, 2.0⁻10.0 µM and 10.0⁻100.0 µM with a detection limit of 2.0 nM. This developed method was applied for SY detection in soft drinks with satisfied detected results.


Assuntos
Técnicas Eletroquímicas , Eletrodos , Corantes de Alimentos/análise , Grafite/química , Compostos de Manganês/química , Nanotubos/química , Óxidos/química , Concentração de Íons de Hidrogênio , Nanotubos/ultraestrutura , Reprodutibilidade dos Testes , Análise Espectral
14.
Nanomaterials (Basel) ; 9(3)2019 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-30871263

RESUMO

4-nitrophenol (4-NP) is a hazardous waste and a priority toxic pollutant identified by US Environmental Protection Agency (EPA). Hence, in this paper, a voltammetric sensor was proposed for the direct and sensitive detection of 4-nitrophenol (4-NP) at nanomolar level in complex matrices by using graphene and acetylene black paste hybridized electrode (GR/ABPE). Under optimal conditions, the calibration curve demonstrates a linear relationship for 4-NP in the range from 20 nM to 8.0 µM and 8.0 µM to 0.1 mM separately with the detection limit of 8.0 nM. In addition to it, the performance of the GR/ABPE in practical applications was evaluated by detecting 4-NP in various water samples, and satisfactory recoveries were realized. Therefore, GR/ABPE may have a great potential application for facile and sensitive detection of 4-NP in complex matrices at nanomolar level.

15.
Nanomaterials (Basel) ; 9(1)2019 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-30669370

RESUMO

A new electrochemical sensor for nanomolar rutin detection based on amine-functionalized Fe3O4 nanoparticles and electrochemically reduced graphene oxide nanocomposite modified glassy carbon electrode (NH2-Fe3O4 NPs-ErGO/GCE) was fabricated through a simple method, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and electrochemical technique were used to characterize the modified electrode. The electrochemical behavior of rutin on the Fe3O4 NPs-ErGO/GCE was studied in detail. The electrochemical response of rutin at this modified electrode was remarkably higher than that of the bare GCE or other modified GCE (GO/GCE, Fe3O4 NPs-GO/GCE, and ErGO/GCE). Under the optimum determination conditions, Fe3O4 NPs-ErGO/GCE provided rutin with a broader detection range of 6.0 nM⁻0.1 µM; 0.1⁻8.0 µM and 8.0⁻80 µM, a minimum detectable concentration of 4.0 nM was obtained after 210 s accumulation. This novel method was applied in determination of rutin in pharmaceutical tablets and urine samples with satisfactory results.

16.
Nanoscale Res Lett ; 14(1): 35, 2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30684022

RESUMO

For an economical use of solar energy, photocatalysts that are sufficiently efficient, stable, and capable of harvesting light are required. Composite heterostructures composed of noble metals and semiconductors exhibited the excellent in catalytic application. Here, 1D Ag/Au/AgCl hollow heterostructures are synthesized by galvanic replacement reaction (GRR) from Ag nanowires (NWs). The catalytic properties of these as-obtained Ag/Au/AgCl hollow heterostructures with different ratios are investigated by reducing 4-nitrophenol (Nip) into 4-aminophenol (Amp) in the presence of NaBH4, and the influence of AgCl semiconductor to the catalytic performances of Ag/Au bimetals is also investigated. These hollow heterostructures show the higher catalytic properties than pure Ag NWs, and the AgCl not only act as supporting materials, but the excess AgCl is also the obstacle for contact of Ag/Au bimetals with reactive species. Moreover, the photocatalytic performances of these hollow heterostructures are carried out by degradation of acid orange 7 (AO7) under UV and visible light. These Ag/Au/AgCl hollow heterostructures present the higher photocatalytic activities than pure Ag NWs and commercial TiO2 (P25), and the Ag/Au bimetals enhance the photocatalytic activity of AgCl semiconductor via the localized surface plasmon resonance (LSPR) and plasmon resonance energy transfer (PRET) mechanisms. The as-synthesized 1D Ag/Au/AgCl hollow heterostructures with multifunction could apply in practical environmental remedy by catalytic manners.

17.
Biomolecules ; 10(1)2019 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-31906220

RESUMO

Bacterial infection and toxic metal ions releasing are the challenges in the clinical application of Ti6Al4V alloy implant materials. Copper is a kind of long-acting, broad-spectrum and safe antibacterial element, and Ta2O5 has good corrosion resistance, wear-resistance and biocompatibility, they are considered and chosen as a potential coating candidate for implant surface modification. In this paper, magnetron sputtering technology was used to prepare copper doped Ta2O5 multilayer composite coating Cu-Ta2O5/Ta2O5/Ta2O5-TiO2/TiO2/Ti (Cu-MTa2O5 for short) on Ti6Al4V alloy surface, for studying the effect of copper incorporation on the microstructure, wettability, anticorrosion and antibacterial activities of the composite coating. The results showed that Cu-MTa2O5 coating obviously improves the hydrophobicity, corrosion resistance and antibacterial property of Ti6Al4V alloy. In the coating, both copper and Ta2O5 exhibit an amorphous structure and copper mainly presents as an oxidation state (Cu2O and CuO). With the increase of the doping amount of copper, the grain size, roughness, and hydrophobicity of the modified surface of Ti6Al4V alloy are increased. Electrochemical experiment results demonstrated that the corrosion resistance of Cu-MTa2O5 coated Ti6Al4V alloy slightly decreased with the increase of copper concentration, but this coating still acts strong anticorrosion protection for Ti6Al4V alloy. Moreover, the Cu-MTa2O5 coating can kill more than 97% of Staphylococcus aureus in 24 h, and the antibacterial rate increases with the increase of copper content. Therefore, Cu-MTa2O5 composite coating is a good candidate for improving anticorrosion and antibacterial properties of Ti6Al4V alloy implant medical devices.

18.
Colloids Surf B Biointerfaces ; 172: 565-572, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30218982

RESUMO

A novel manganese dioxide nanorods-electrochemically graphene oxide nanocomposites modified glassy carbon electrode (MnO2NRs-ErGO/GCE) was developed for the rapid and sensitive detection of Amaranth in foodstuffs. The morphology, structure and composition of MnO2NRs, ErGO, and MnO2/ErGO were characterized by SEM and XRD. The electrochemical behavior of Amaranth on the bare GCE, ErGO/GCE, and MnO2NRs-ErGO/GCE were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The voltammetric conditions (including pH, scan rate, accumulation potential as well as time) were optimized systematically. Due to large electrochemical active area and low charge transfer resistance, the MnO2NRs-ErGO/GCE exhibited a great enhancement effect on the oxidation of Amaranth, and significant increased the oxidation peak current ipa (approximately 38-fold increase compared to that of bare GCE). Under the optimum voltammetric conditions, the ipa varied linearly with Amaranth concentration in the range of 0.02 µM-10 µM, and 10 µM-400 µM with a low detection limit of 1.0 nM (S/N = 3). Moreover, satisfactory results were obtained in the analysis of real samples. Together with the merits of rapidness, cost-effectivity, high sensitivity and selectivity, the result suggests the proposed MnO2NRs-ErGO/GCE have broad application prospects on the sensitive detection of Amaranth in various real samples.


Assuntos
Corante Amaranto/análise , Análise Custo-Benefício , Técnicas Eletroquímicas/economia , Técnicas Eletroquímicas/métodos , Grafite/química , Compostos de Manganês/química , Nanocompostos/química , Nanotubos/química , Óxidos/química , Calibragem , Eletrodos , Limite de Detecção , Oxirredução , Reprodutibilidade dos Testes , Difração de Raios X
19.
Sensors (Basel) ; 18(9)2018 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-30135387

RESUMO

A facile cuprous oxide nanoparticles functionalized electro-reduced graphene oxide modified glassy carbon electrode (denoted as Cu2O NPs-ERGO/GCE) was fabricated via a simple physical adsorption and electrochemical reduction approach. Cyclic voltammetry and second-order derivative linear scan voltammetry were used to investigate the electrocatalysis oxidation of vanillin on the Cu2O NPs-ERGO/GCE. The compound yielded a well-defined voltammetric response in 0.1 M H2SO4 at 0.916 V (vs. saturated calomel electrode (SCE)). A linear calibration graph was obtained in the concentration range of 0.1 µM to 10 µM and 10 µM to 100 µM, while the detection limit (S/N = 3) is 10 nM. In addition, the Cu2O NPs-ERGO/GCE presented well anti-interference ability, stability, and reproducibility. It was used to detect vanillin sensitively and rapidly in different commercial food products, and the results were in agreement with the values obtained by high performance liquid chromatography.

20.
Molecules ; 23(9)2018 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-30149513

RESUMO

Control and detection of sunset yellow is an utmost demanding issue, due to the presence of potential risks for human health if excessively consumed or added. Herein, cuprous oxide-electrochemically reduced graphene nanocomposite modified glassy carbon electrode (Cu2O-ErGO/GCE) was developed for the determination of sunset yellow. The Cu2O-ErGO/GCE was fabricated by drop-casting Cu2O-GO dispersion on the GCE surface following a potentiostatic reduction of graphene oxide (GO). Scanning electron microscope and X-ray powder diffractometer was used to characterize the morphology and microstructure of the modification materials, such as Cu2O nanoparticles and Cu2O-ErGO nanocomposites. The electrochemical behavior of sunset yellow on the bare GCE, ErGO/GCE, and Cu2O-ErGO/GCE were investigated by cyclic voltammetry and second-derivative linear sweep voltammetry, respectively. The analytical parameters (including pH value, sweep rate, and accumulation parameters) were explored systematically. The results show that the anodic peak currents of Cu2O-ErGO /GCE are 25-fold higher than that of the bare GCE, due to the synergistic enhancement effect between Cu2O nanoparticles and ErGO sheets. Under the optimum detection conditions, the anodic peak currents are well linear to the concentrations of sunset yellow, ranging from 2.0 × 10-8 mol/L to 2.0 × 10-5 mol/L and from 2.0 × 10-5 mol/L to 1.0 × 10-4 mol/L with a low limit of detection (S/N = 3, 6.0 × 10-9 mol/L). Moreover, Cu2O-ErGO/GCE was successfully used for the determination of sunset yellow in beverages and food with good recovery. This proposed Cu2O-ErGO/GCE has an attractive prospect applications on the determination of sunset yellow in diverse real samples.


Assuntos
Compostos Azo/análise , Cobre/química , Técnicas Eletroquímicas , Eletrodos , Grafite/química , Nanocompostos/química , Óxidos/química , Concentração de Íons de Hidrogênio , Nanocompostos/ultraestrutura , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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