Analytical & Bioanalytical Electrochemistry
Volume:12 Issue: 3, Mar 2020

Fast and sensitive response electrochemical sensor based on CoFe2O4 nanoparticle and 1-buthyl-3-methyl imidazolium bromide room temperature ionic liquids carbon paste electrode (CoFe2O4/NP/ILs/CPE) is fabricated for the determination of Xanthine (Xt) in the presences of Caffeine in fish and fruit samples. In the first step, CoFe2O4/NP was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and results showed synthesized nanoparticle with diameter between 26.92-29.22 nm. The electro-oxidation of Xt and Caffeine occurred at a potential about 0.7 V and 1.1 V, which was much better in comparison with bare carbon paste electrode in phosphate buffer (pH=6.0) at the surface of the (CoFe2O4/NP/ILs/CPE). Other electrochemical techniques were also investigated including cyclic voltammetry, differential pulse voltammetry (DPV) and chronoamperometry at CoFe2O4/NP/ILs/CPE. At optimized conditions for Xt and Caffeine analysis, DPV peak currents showed a wide linear dynamic ranging from 8.0 nM to 500 μM and detection limit for Xt was 3.0 nM and of course we obtained good dynamic range between 0.1 to 300 μM and good limit of detection 0.05 μM for caffeine. As a result, the proposed electrode could determine Xt in the presences of Caffeine in real samples with good selectivity and high sensitivity.

Mg alloys have a vast usage where weight reduction is really significant since they do the features really well for materials of ultra-light weight. However, Mg is inherently a reactive metal and its alloys generally possess quite weak corrosion resistance that widely restricts their technological usages, especially in some rough service conditions. Despite, many investigations on the passive and electrochemical properties of Mg alloys and their relation with the microstructure of these alloys, few reports have been devoted to investigate the semiconducting behavior of the formed oxide layers on these alloys. Mott–Schottky measurement is a major in-situ technique to analyze semiconductor behavior of passive layers. In this review, the semiconducting properties of formed passive layers on Mg alloys (AZ91D, AZ31B, AZ80, Mg-Y-Rare Earth-Zr alloys) by Mott–Schottky measurement has been assessed. Mott–Schottky measurements revealed the formed passive films on Mg alloys show mainly n-type behavior regardless the microstructure, pH, immersion time, and temperature of electrolyte.

Macrocycles and p-benzoquinones (p-BQ) have been generally connected as potential co-synergist redox models in aerobic oxidation. To get insight for the synergist oxidation of hydroquinones (H2Q), thus, we synthesized and characterized dibenzotetraaza [14]annulene type macrocycles of FeIII and CoII metal ions and described by utilizing different examinations including molar conductance, IR, UV-Vis, mass and cyclic voltammetric measurements. The spectroscopic and computational studies proposed that the macrocycles have saddle shape distorted octahedral structure. These macrocycles demonstrated the reversible and quasi-reversible redox process pursued by Randles-Sevcik equation, demonstrating the adjustment of unusual oxidation conditions of metal ions. Further, the experimental consequences presented herein enlighten the catalytic activity of these macrocycles towards the oxidation of H2Q. The results indicated that in the absence of macrocycles, the molecular oxygen is inactive with H2Q but in presence of synthesized macrocycles H2Q initiates prompt oxidation with the production of H2O2. Moreover, CoII macrocycle was found to be an efficient catalyst for the oxidation of H2Q into corresponding benzoquinones.

The objective of this work was to demonstrate the effect of fluoride and propolis extract on the corrosion behavior of commercially pur titanium (cp-Ti grade 2) in artificial saliva. The inhibition studies were approved out on cp-Ti as dental implant in Fusayama-Meyer with the propolis extract using potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). Parameters, such as concentration of the inhibitor, time of immersion were varied and optimized. The results showed that either the NaF or the presence of propolis extract in medium saliva had a significant influence on the corrosion rate (Icorr) and polarization resistance (Rp): the Icorr value increased and Rp decreased in medium containing fluoride, but the presence of propolis in media improved the corrosion resistance of this metal.

In this review, we focus on cyclic voltammetry as a reliable electrochemical technique to study mechanisms, kinetics and thermodynamics of various types of drug-drug interactions. While we present and discuss six theoretical models relevant to analyze drug-drug (or drug-DNA) interactions, we also give hints about recent experimental achievements in this field. In addition, we provide the readers several sets of simulated voltammograms and data in tabular form, which can be used to recognize particular mechanism of drug-drug interactions in cyclic voltammetry. Moreover, we give hints to the voltammetric procedures that allow access to kinetics and thermodynamics parameters, which are relevant to various types of drug-drug interactions. The results we present in this work can be of big help to the scientists working in the field of pharmacy, pharmacology, medicinal chemistry and bio-electrochemistry.

Electrochemical oxidation of leaves extract of lemon verbena and the flowers extract of echium amoenum have been studied in the absence and presence of barbituric acid and 1,3 dimethyl barbituric acidin aqueous solutions and biological pH, using cyclic voltammetry method. The results showed that the electrochemically generated compounds in leaves extract of lemon verbena and the flowers extract of echium amoenum, participate in the chemical reaction with barbituric acid and 1,3 dimethyl barbituric acid. Based on our results, leaves extractof lemon verbena and the flowers extract of echium amoenum have a high antioxidant activity in comparison with galic acid, salicylic acid and quercetin as standard antioxidants and simultaneous can be useful for the treatment of barbiturate poisoning before starting clinical treatments. The antioxidant activity of luteoline and verbascoside (as the main and natural compounds in lemon verbena) against some of the reactive oxygen species (ROS) generation enzymes, Cytochrome P450 3A4 (4D75), Myeloperoxidase (1DNW) and Thyosine (3nm8) has been performed through molecular docking studies. The results indicated that these natural compounds bound exclusively to the binding site of ROS generation enzymes and has a remarkable role in suppressing the destructive effects of oxidative stress in the biological system of the human body.

The strontium ion, in water-soluble forms, is one of the major pollutant in drinking water. Therefore, a simple, rapid, selective, and sensitive potentiometric carbon paste electrode was developed to measure strontium ion in real samples with complex matrices. To prepare the potentiometric sensor, a synthetic ligand ((E)-4-(((2-amino-4-chlorophenyl)imino)methyl)-5-(hydroxymethyl)-2-methyl pyridine-3-ol) as an efficient ionophore and an ionic liquid (1-Butyl-3-methylimidazolium hexafluorophosphate) as a suitable binder were dispersed in a mixture of graphite powder and graphene oxide. The composition of the sensor was optimized using a central composite design (full factorial) to reduce the number of experimental runs and investigate interactions between effective factors. The proposed sensor showed a Nernstian behavior in the linear concentration range of 1×10-8 to 1.0×10-1 M with a low detection limit (1.59×10−9 M) and suitable relative standard division (1.01 %). The proposed sensor can be well applied in the pH range of 3.00-9.50 for the analyte determination. Moreover, the proposed electrode as an indicator electrode was successfully used to measure the Sr(II) concentration in the depilatory powder, toothpaste, and raticide samples.

Disposable, selective and low-cost carbon nanotube modified electrodes were fabricated for the electrochemical detection of neonicotinoid insecticide, Clothianidin (CLT). Almost 2 folds’ increase at Clothianidin reduction signal was obtained by using single-walled carbon nanotube modified electrodes (SWCNT-PGE) compared to unmodified electrodes. These nanomaterials modified electrodes developed in this study will enable simple, rapid and inexpensive identification of the neonicotinoid insecticides, Clothianidin and it is hoped that this technique developed by using these nanosensors will be an alternative to the expensive and time consuming chromatographic techniques with its advantages of adapting to the sensor chip technology for the routine analysis of agricultural products.

In this study, a new molecularly imprinted polymer with nanoporous material of zirconium metal-organic frameworks (Zr-MOF/MIP) for diclofenac (DFC) measurement is presented. The Zr-MOF/MIP was prepared by electropolymerization method, the Zr-MOFs were used to increase electrode surface and the DFC and para- aminobenzoic acid (pABA) were used as template and functional monomer, respectively. Zr--MOFs was characterized by using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The electrochemical performance was investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Sensor response was evaluated by comparing the electrochemical response of Zr-MOF/MIP, with that of non- Imprinted polymer (NIP), in a 2.0 mM potassium ferrocyanide solution containing 0.2 mM sodium sulfate as probe solution. Measurements were carried out in the potential range of -0.6 to +1.0 V with scan rate of 50 mV/s. The calibration curve of diclofenac was linear in the concentration range of 6.5 μM to 1.5×10+3 μM. Detection limit was obtained 0.1 μM and relative standard deviation of several (n=7) replicate measurements for 1.0 mM DFC concentration has obtained 1.8%. Furthermore, favorable sensitivity, selectivity, good reproducibility and long-term stability, was obtained in the experiment and the proposed electrode was applied for the determination of DFC in pharmaceutical commercial sample with satisfactory results.

Isatins, derivatives of indole, represent important class of compounds belonging to nitrogen heterocycles. These compounds comprise synthetically vital substrates that are used as precursors for drug synthesis and raw materials for heterocycles etc. Research in this group of compounds has engrossed interest among scientific community in recent and past as Isatins are known to possess immense biological activities. Present work delineates synthesis, characterization, electrochemical and antimicrobial studies of four substituted derivatives of isatin derivatives. The cyclic voltammetric studies of all the analytes showed that four derivatives have better electro catalytic activity towards the analytes at glassy carbon electrode. These synthesized isatin derivatives were screened for their antimicrobial activity against Gram-negative bacteria (Escherichia coli and Staphylococcus aureus) and fungi such as Candida albicans and Penicillin chrysogenum, and found to possess considerable antimicrobial activity suggesting their effectiveness in developing antibiotics and novel drugs.