Electrocatalytic Behavior of Levodopa at MultiWall Carbon Nanotubes and 4-((E)-(2-Methyl-4-Nitrophenylimino) Methyl) Benzene-1,2-Diol Modified Glassy Carbon Electrode

This work describes a glassy carbon electrode (GCE) modified by 4-((E)-(2-methyl-4-nitrophenylimino) methyl) benzene-1,2-diol (abbreviated as MBD) and multiwall carbon nanotubes (MWNT) as an electrochemical sensor for monitoring of levodopa (LD) concentration. Different electrochemical parameters of MBD were obtained at MWCNT-GCE by cyclic voltammetry. Also the electrocatalytic behavior of LD was investigated at the MBD-MWNT-GCE by cyclic voltammetry, chronoamperometry and differential pulse voltammetry. Using the electrocatalysis of LD V in phosphate buffer solution pH 7.0 on this modified electrode it is possible to obtain a linear calibration curve from 5.0 10 – 7 to 9.0 10 – 4 M and a detection limit of 0.37 μM for LD by differential pulse voltammetry. The electrode was successfully applied for determination of LD in real sample. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3493

[Bis(2-hydroxyl imino)1-phenyl, 2-(2-qunolile)1-ethanona]Aluminium(III) Complex as Carrier for a Salicylate-Sensitive Electrode

A salicylate-selective electrode based on the complex [bis(2-hydroxyl imino)1-phenyl,2-(2- qunolile)1-ethanona]Aluminium(III) as the membrane carrier was developed. The electrode exhibited a good Nernstian slope of –59.1 ± 0.4 mV / decade (mean value ± standard deviation, n = 5) and a linear range of 1.0 × 10–6– 1.0 × 10–1 mol L–1 for salicylate. The limit of detection was 5.0 × 10–7 mol L–1. The electrode had a fast response time of 15 s and could be used for more than three months. The selectivity coefficients were determined by the fixed interference method (FIM) and could be used in the pH range of 2.0–7.8. It was employed as an indicator electrode for direct the determination of salicylate in pharmaceutical samples

Multiwall Carbon Nanotubes Modified Carbon Paste Electrode for Determination of Copper(II) by Potentiometric and Impedimetric Methods

Abstract A chemically modified carbon paste electrode with multiwall carbon nanotube (MWCNT) was prepared and used as a sensor for Cu 2+ ion. The unique chemical and physical properties of CNT have paved the way to new and improved sensing devices. A central composite chemometrics design was applied for multivariate optimization of the effects of three significant parameters (Graphite powder (X 1 ), MWCNT (X 2 ) and Ionophre (X 3 )) influencing the response of the electrode. In the optimized conditions, the electrode exhibits a Nernstian slope of 30.1 mV/decade in a linear range between 1.0×10 -6 to1.0×10 -1 M over a wide pH range (2.0-6.5). Importantly, the effect of the MWCNT on the performance of electrode was investigated by impedance technique, that showed the MWCNT helps the transduction of the signal in carbon paste electrode and the charged transfer resistance (R ct ) was reduced. The impedimetric results indicated that the linear concentrations range was 1.0×10 −7 to 1.0×10 −1 M and in comparison with potentiometry, the pH range increased to 2.0−7.5. JNS All rights reserve

Nanostructured Modified Electrode for Electrocatalytic Determination of Epinephrine in the Presence of Acetaminophen

Abstract In this paper, a nanostructured modified electrode was fabricated by incorporating of 2,2′-[1,9-nonanediylbis(nitriloethylidyne)]-bishydroquinone (NNH) as a newly synthesized modifier and TiO 2 nanoparticles to the carbon paste (MTCPE) and then was used for the electroanalysis of epinephrine (EP). The electrochemical studies were carried out by using cyclic voltammetry, chronoamperometry and differential pulse voltammetry (DPV) techniques. It has been found that the oxidation of EP at the surface of this electrode occurs at a potential about 235 mV less positive than that of an unmodified carbon paste electrode. A dynamic range of 1.0-2000.0 µM, with a detection limit of 0.37 µM for EP, was obtained using DPV. Also, this modified electrode exhibits well separated oxidation peaks for EP and acetaminophen (AC) using DPV. JNS All rights reserve

Determination of silver(I) by flame atomic absorption spectrometry after separation/preconcentration using modified magnetite nanoparticles

AbstractA new, simple, fast and reliable method has been developed for the separation/preconcentration of trace amounts of silver ions using 2-mercaptobenzothiazole/sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (MBT/SDS-ACMNPs) and their determination by flame atomic absorption spectrometry (FAAS). Optimal experimental conditions, including pH, sample volume, eluent concentration and volume, and co-existing ions, have been studied and established. Under optimal experimental conditions, the enrichment factor, detection limit, linear range and relative standard deviation (RSD) of Ag(I) ions were 250 (for 500 mL of sample solution), 0.56 ng mL−1, 2.0–100.0 ng mL−1 and 3.1% (for 5.0 μg mL−1, n=10), respectively. The presented procedure was successfully applied for determination of silver content in the different samples of water

Highly exposed {001} facets of titanium dioxide modified with reduced graphene oxide for dopamine sensing

Titanium dioxide (TiO2) with highly exposed {001} facets was synthesized through a facile solvo-thermal method and its surface was decorated by using reduced graphene oxide (rGO) sheets. The morphology and chemical composition of the prepared rGO/TiO2 {001} nanocomposite were examined by using suitable characterization techniques. The rGO/TiO2 {001} nanocomposite was used to modify glassy carbon electrode (GCE), which showed higher electrocatalytic activity towards the oxidation of dopamine (DA) and ascorbic acid (AA), when compared to unmodified GCE. The differential pulse voltammetric studies revealed good sensitivity and selectivity nature of the rGO/TiO2 {001} nanocomposite modified GCE for the detection of DA in the presence of AA. The modified GCE exhibited a low electrochemical detection limit of 6 μM over the linear range of 2–60 μM. Overall, this work provides a simple platform for the development of GCE modified with rGO/TiO2 {001} nanocomposite with highly exposed {001} facets for potential electrochemical sensing applications

Expression of Cystathionine β-synthase and Cystathionine γ-lyase in Human Pregnant Myometrium and Their Roles in the Control of Uterine Contractility

BACKGROUND: Human uterus undergoes distinct molecular and functional changes during pregnancy and parturition. Hydrogen sulfide (H(2)S) has recently been shown to play a key role in the control of smooth muscle tension. The role of endogenous H(2)S produced locally in the control of uterine contractility during labour is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Human myometrium biopsies were obtained from pregnant women undergoing cesarean section at term. Immunohistochemistry analysis showed that cystathionine-γ-lyase (CSE) and cystathionine-β-synthetase (CBS), the principle enzymes responsible for H(2)S generation, were mainly localized to smooth muscle cells of human pregnant myometrium. The mRNA and protein expression of CBS as well as H(2)S production rate were down-regulated in labouring tissues compared to nonlabouring tissues. Cumulative administration of L-cysteine (10(-7)-10(-2) mol/L), a precursor of H(2)S, caused a dose-dependent decrease in the amplitude of spontaneous contractions in nonlabouring and labouring myometrium strips. L-cysteine at high concentration (10(-3) mol/L) increased the frequency of spontaneous contractions and induced tonic contraction. These effects of L-cysteine were blocked by the inhibitors of CBS and CSE. Pre-treatment of myometrium strips with glibenclamide, an inhibitor of ATP-sensitive potassium (K(ATP)) channels, abolished the inhibitory effect of L-cysteine on spontaneous contraction amplitude. The effects of L-cysteine on the amplitude of spontaneous contractions and baseline muscle tone were less potent in labouring tissues than that in nonlabouring strips. CONCLUSION/SIGNIFICANCE: H(2)S generated by CSE and CBS locally exerts dual effects on the contractility of pregnant myometrium. Expression of H(2)S synthetic enzymes is down-regulated during labour, suggesting that H(2)S is one of the factors involved in the transition of pregnant uterus from quiescence to contractile state after onset of parturition