Voltammetric Studies Research Articles

MoS2 blended MWCNT hybrid nanocomposites and its enhanced super capacitive features

The present work addresses a simple and sensitive approach to synthesize a 2D bare MoS2 and graphene analog MoS2/MWCNT nanocomposites as an effective electrode material for high-performance supercapacitors. The MoS2/MWCNT nanocomposites were prepared via simple hydrothermal treatment. The structural, functional, and morphological analysis were accessed through XRD, HRTEM, FESEM, FTIR, and RAMAN Spectroscopy augmenting the successful formation of MoS2/MWCNT nanocomposites. The structural analysis confirms the formation of the hexagonal phase. The morphological analysis possesses the nano-sphere-like structure which is made up of crumpled nanosheets. The chemical bonding and the location of Mo–S and CC bands were confirmed at 428 and 1651 C m-1 respectively. Detailed electrochemical analysis through cyclic voltammetric study, Galvanostatic Charge/discharge and electrochemical impedance techniques shows that as prepared m-M10 sample exhibits excellent super capacitive performances when compared to other samples. This electrode obtained a maximum specific capacitance of 848 F g-1 with a current density 1 A g-1. This material retains 82% of its initial capacitance after 5000 repeated charge-discharge cycles. It exhibits very less charge transfer resistance 0.2Ω and lesser than other electrodes.

Overcoming the Potential Window-Limited Functional Group Compatibility by Alternating Current Electrolysis.

The functional group compatibility of an electrosynthetic method is typically limited by its potential reaction window. Here, we report that alternating current (AC) electrolysis can overcome such potential window-limited functional group compatibility. Using alkene heterodifunctionalization as a model system, we design and demonstrate a series of AC-driven reactions that add two functional groups sequentially and separately under the cathodic and anodic pulses, including chloro- and bromotrilfuoromethylation as well as chlorosulfonylation. We discovered that the oscillating redox environment during AC electrolysis allows the regeneration of the redox-active functional groups after their oxidation or reduction in the preceding step. As a result, even though redox labile functional groups such as pyrrole, quinone, and aryl thioether fall in the reaction potential window, they are tolerated under AC electrolysis conditions, leading to synthetically useful yields. The cyclic voltammetric study has confirmed that the product yield is limited by the extent of starting material regeneration during the redox cycling. Our findings open a new avenue for improving functional group compatibility in electrosynthesis and show the possibility of predicting the product yield under AC electrolysis from voltammogram features.

Ferrocenyl-Substituted Triazatruxenes: Synthesis, Electronic Properties, and the Impact of Ferrocenyl Residues on Directional On-Surface Switching on Ag(111).

We report on seven new ferrocenyl-(1, 3)- and ferrocenylethynyl-modified N,N',N″-triethyltriazatruxenes (EtTATs) 4-7 as well as the dodecyl counterpart 2 of compound 1 and their use as molecular switching units when deposited on a Ag(111) surface. Such functional units may constitute a new approach to molecule-based high-density information storage and processing. Besides the five compounds 1-3, 6, and 7, where the 3-fold rotational symmetry of the triazatruxene (TAT) template is preserved, we also included 2-ethynylferrocenyl-TAT 4 and 2,2'-di(ethynylferrocenyl)-TAT 5, whose mono- and disubstitution patterns break the 3-fold symmetry of the TAT core. Voltammetric studies indicate that the ferrocenyl residues of compounds 1-7 oxidize prior to the oxidation of the TAT core. We have noted strong electrostatic effects on TAT oxidation in the 2,2',2″-triferrocenyl-TAT derivatives 1 and 2 and the 3,3',3″-isomer 3. The oxidized complexes feature multiple electronic excitations in the near-infrared and the visible spectra, which are assigned to dδ/δ* transitions of the ferrocenium (Fc+) moieties, as well as TAT → Fc+ charge-transfer transitions. The latter are augmented by intervalence charge-transfer contributions Fc → Fc+ in mixed-valent states, where only a part of the available ferrocenyl residues is oxidized. EtTAT was previously identified as a directional three-level switching unit when deposited on Ag(111) and constitutes a trinary-digit unit for on-surface information storage. The symmetrically trisubstituted compound 6 retains this property, albeit at somewhat reduced switching rates due to the additional interaction between the ferrocenyl residues and the Ag surface. In particular, the high directionality at low bias and the inversion of the preferred sense of the on-surface rocking motion with either a clockwise or counterclockwise switching sense, depending on the identity of the surface enantiomer, are preserved. Unsymmetrical substitution in mono- and diferrocenylated 4 and 5 alters the underlying ratchet potential in a manner such that a two-state switching between the two degenerate surface conformations of 4 or a pronounced suppression of switching (5) is observed.

Simultaneous electrochemical determination of benzenediol compounds in environmental samples using nano architectures of hydrogen ammonium zinc molybdate layered double hydroxides integrated with carbon black modified electrode

Phenolic compounds, such as benzenediol (BD), are toxic and exhibit poor biodegradability, posing a threat to human health and the environment, even at low concentrations. Therefore, the simultaneous detection of BD at low detection limits and a wide detection range is of significant interest for monitoring water quality and environmental remediation efforts. In this study, we developed a novel electrochemical sensor for BD based on a nanocomposite (NC) of hydrogen ammonium zinc molybdate layered double hydroxide (AZnMo-LDHs) and carbon black (CB) as a modification for the electrode. Various characterization methods were employed to verify the morphological, structural, and physical-chemical properties of AZnMo-LDHs/CB NC. The NC-modified electrode exhibited low electrical resistance, high electrocatalytic activity, and fast electron transport, thanks to the synergistic effects between AZnMo-LDHs and CB. Additionally, the NC-modified electrode demonstrated excellent electrochemical performance in selectively and simultaneously detecting hydroquinone (HQ), catechol (CC), and resorcinol (RC). Differential pulse voltammetric studies confirmed that AZnMo-LDHs/CB NC enabled the detection of HQ, CC, and RC within linear response ranges of 0.05–971 μM, 0.1–1036 μM, and 0.5–1408.5 μM, respectively, with detection limits of 0.0054 μM, 0.0018 μM, and 0.075 μM. To validate the sensor's practical application, we tested it with multiple environmental samples, including water and soil, and obtained excellent recovery rates for HQ, CC, and RC.

Phosphate-driven H2O2 decomposition on DNA-bound bio-inspired activated carbon-based sensing platform for biological and food samples.

Hydrogen peroxide (H2O2) is one of the most important reactive oxygen species (ROS). Increased endogenous H2O2 levels indicate oxidative stress and could be a potential marker of many diseases, including Alzheimer's, cardiovascular diseases, and diabetes. However, consuming H2O2-incorporated food has adverse effects on humans and is a serious health concern. We used salmon testes DNA with bio-inspired activated carbon (AC) as an electrocatalyst for developing a novel H2O2 sensor. The phosphate backbone of DNA contains negatively charged oxygen groups that specifically attract protons from H2O2 reduction. We observed a linearity range of 0.01-250.0μM in the H2O2 reduction peak current with a detection limit of 2.5 and 45.7nM for chronoamperometric and differential pulse voltammetric studies. High biocompatibility of the sensor was achieved by the DNA, facilitating endogenous H2O2 detection. Moreover, this non-enzymatic sensor could also help in the rapid screening of H2O2-contaminated foods.

Effect of Substituents on Solubility, Medicinal, Absorption, Emission and Cationic/Anionic Detection Properties of Anthraquinone Derivatives.

Anthraquinones constitute an important class of compounds with wide applications. The solubility of derivatives at 298.15K was discussed in ethanol-water solution and at atmospheric pressure, the solubility of 1-amino-4-hydroxy-9,10-anthraquinone (AHAQ) in binary solvents (ethanol-water combinations) was determined. Colour strength and fastening properties depend upon the kind and position of a hydrophobic group connected to the phenoxy ring of Anthraquinone moiety. There is a continuing interest in the creation of novel anthraquinone derivatives with biological activities since they have demonstrated potential for treating multiple sclerosis. For this purpose, by utilizing voltammetric and absorption studies, interactions of various derivatives with calf thymus DNA (ct-DNA) and the cationic surfactant cetyltrimethylammoniumbromide (CTAB) were examined. Here prominent Hydrophobic interaction and electron transfer resulting in binding to CTAB micelles were observed. The polarity index of the media was assessed and associated with the electrochemical parameters. The medicinal behaviour of Anthraquinone derivatives was a result of electron transfer reactions with DNA. UV-Visible and fluorescence properties were due to the transitions between n* and π* orbitals. Large absorption band with low dichroic ratio was characteristic of various derivatives of Anthraquinone. Presence of -NH group proves various derivatives remarkable calorimetric and anionic sensors.

Tailored solution combustion method for enhancing high voltage electrochemical performance Li1.2Ni0.1Mn0.6Co0.1O2 as cathode material for lithium-ion batteries

The Lithium and Manganese-rich layered oxides with the formula Li1.2Ni0.1Mn0.6Co0.1O2 (LMR-NMC) are considered the most promising cathode materials for next-generation lithium-ion batteries due to their high energy densities, low cost, high thermal stability, and environmental safety. This paper reports the synthesis of LMR-NMC oxides in the presence of glycine-urea or citric acid-urea as surface modifiers for LMR-NMC-A and LMR-NMC-B, respectively using the solution combustion technique. The crystal structures of LMR-NMC-A and LMR-NMC-B samples were confirmed to have Hexagonal α-NaFeO2 structures in the R-3m space group. The HRSEM images reveal two different morphologies of the samples; Nano platelet (LMR-NMC-A) and Cubic-like (LMR-NMC-B). The cyclic voltammetric studies (CV) performed at a low scan rate value of 0.1 mV s−1 and a potential window of 2.0–5.0 V confirm the formation of the irreversible Li2MnO3 phase above 4.8 V in the first cycle and the presence of three redox peaks corresponding to Ni2+/Ni4+, Co2+/Co3+, and Mn3+/Mn in the subsequent cycles. The electrochemical properties of LMR-NMC-A and LMR-NMC-B electrodes demonstrated an initial discharge-specific capacity of 325.21 mAh g−1 and 300 mAh g−1, respectively, in a potential range between 2.0 and 5.0 V at a 0.1C rate. A comparison of the electrochemical properties of both morphologies of LMR-NMC revealed that the Nanoplatelet-like (LMR-NMC-A) sample performs better than the cubic-like (LMR-NMC-B) sample. The Nanoplatelet-like layered oxide demonstrated a high specific capacity of 180 mAh g−1 at a 1C rate and a high Coulombic efficiency of 86% after 200 cycles. BET indicates that LMR-NMC-A has a significantly higher surface area and substantial pore volume than LMR-NMC-B, addressing high voltage working capability, low voltage fading, and high specific capacitance values to a greater extent. These findings confirm the suitability of LMR-NMC-A as a cathode material for lithium-ion batteries used in high-load appliances and heavy vehicles.

Voltammetric determination of organic UV filters by carbon paste electrodes modified with pyridinium-based ionic liquids

The rapid and sensitive voltammetric determination of organic UV filters benzophenone-3 (BP-3) and avobenzone (AVO) was performed by an ionic liquid carbon paste electrode (IL-CPE). Namely, the synthesized pyridinium-based ILs, 1-butyl-3-methylpyridinium chloride ([N–C4–3C1Py]Cl) and 1-ethoxyethyl-3-methylpyridinium chloride ([N–C2OC2–3C1Py]Cl) were compared as bulk CPE modifiers for BP-3 determination. [N–C4–3C1Py]Cl-CPE showed more favorable interactions with the target analyte, and it was tested for AVO determination, too. Cyclic voltammetric (CV) studies suggested that the irreversible electrode reaction is adsorption controlled in the case of both UV filters. Also, the square-wave adsorptive stripping voltammetric (SW-AdSV) method was optimized for quantifying selected UV filters. In the model solutions, the linear calibration curve was obtained by the SW-AdSV method in the concentration range from 0.05 to 0.89 μg mL−1 at pH 3.0 for BP-3 (Eacc = −0.7 V, tacc = 100 s), and from 0.05 to 1.77 μg mL−1 at pH 11.98 for AVO (Eacc = 0.2 V, tacc = 100 s). The evaluated limit of detection (LOD) was 0.015 μg mL−1 in both cases, while the relative standard deviation (RSD) was lower than 1.5%. The affordable IL-based voltammetric sensor fulfills the main requirements for application in real samples due to an adequate selectivity towards selected analytes in the presence of interferents usually found in swimming pool water. Therefore, the BP-3 and AVO were quantified in a swimming pool water matrix with good repeatability and recovery. The obtained results demonstrate an excellent potential of the IL-CPEs, especially of the [N–C4–3C1Py]Cl-CPE, for determining selected UV filters in various real samples.

Voltammetric studies on the interaction of ds-DNA with anti-cancer agents imatinib and erlotinib – Comparison of Au and Pt nanoparticle effects to drug-DNA complex formation

The interactions of imatinib (IMA) and erlotinib (ERL) with calf-thymus double-stranded deoxyribonucleic acid (ds-DNA) were studied by using monometallic (Au and Pt) and bimetallic (Au + Pt) nanoparticles modified DNA biosensors. The prepared electrochemical biosensors were designed to show the interaction between IMA (or ERL) and ds-DNA. The characterization of the prepared sensors was carried out by energy-dispersive X-ray spectroscopy (EDX). The influence of Au, Pt, and Au + Pt nanoparticles in the modified biosensor was investigated to elucidate the interaction between the anti-cancer drugs and ds-DNA. The interaction was realized based on the electrochemical oxidation signal (at about +0.80 V) of the guanine (dGu) base of ds-DNA by differential pulse voltammetry (DPV) in pH 4.8 acetate buffer. The effect of the nanoparticle’s concentration and interaction time of IMA (and ERL) with ds-DNA on the electrochemical response of dGu were optimized. The results showed that Au + Pt nanoparticles, especially for IMA, significantly affected the binding constant value of the drugs to ds-DNA. Interaction studies have also shown that the binding mode for IMA and ERL could be intercalation and groove binding and the binding constant values were found to be 68.3 × 106 M−1 and 27.3 × 107 M−1, respectively.

Colorimetric, fluorometric, and electrochemical sensing of cyanide ion in aqueous media using merocyanine-ferrocene conjugate

Rapid detection of hazardous ions has received a considerable deal of attention in recent decades due to its usefulness in preserving a greener environment for humans. The severe toxicity of cyanide (CN–) ions is a major environmental problem. Therefore, a substituted merocyanine salt having a ferrocene segment was designed and synthesized with the expectation to yield a probe with colorimetric, and electrochemical properties. The merocyanine derivative was characterized by NMR, IR, and high-resolution mass spectrometric analysis. The merocyanine salt was screened for the colorimetric detection of toxic ions in aqueous media. Utilizing UV–vis, fluorescence spectroscopy, cyclic voltammetry, and digital image analysis, an acceptable limit of detection value was witnessed. A hypochromic and hypsochromic shift in the absorption spectra was observed in the presence of cyanide ions. The 1H NMR spectroscopy shows the interaction of CN– with the probe at the spiro-carbon of the merocyanine salt and metal center of the ferrocene segment. The electrochemical input during cyclic voltammetric studies resulted in the formation of C–C bonds on complexation with cyanide ions due to an increase in electron density on the nitrogen atom of the indoline segment. The limit of detection calculated using UV–visible spectroscopy was 2.28 µM, fluorescence spectroscopy provided 1.48 µM , and 0.61 µM was witnessed using cyclic voltammetry.

Enhanced Electroreduction of Acetophenone Using Lipase Stabilization: Improved Conversion to 1‐Phenylethanol

AbstractFew works present effective or viable alternatives to the problem of the electroreduction of acetophenone which usually leads to the pinacol dimer as a primary product in addition to 1‐phenylethanol. Here, various lipases were applied in acetophenone electroreduction. The optimized reaction conditions are tin/lead (63 : 37) combined working electrode coated with Nafion film modified with lipase from Thermomyces lanuginosus, a platinum counter electrode, applied potential of −2.0 V vs. Ag/AgCl (KCl 3.0 mol L−1), acetate buffer (0.1 mol L−1) pH 5.0 in 4 hours, and led to the formation of 87.8 % of 1‐phenylethanol. The same working electrode was used five times over five days, and the conversion remained constant. A voltammetric study indicates an alteration of the electroreduction mechanism in the presence of the cited lipase. Adding lipase from Thermomyces lanuginosus directly in the medium immobilized in a clay mineral or in silica gel (Lipolase 100T) resulted in even higher conversions (93.2–93.9 %). The modified electrode improved the methodology regarding enzyme stability, process reproducibility, and material reusability.

Quasi-Solid State Polymer Electrolytes Based on PVdF-HFP Host Polymer for Sodium-Ion Secondary Batteries

Prices of lithium raw materials keep on increasing exponentially due to their heavy consumption for lithium batteries used in portable electronic devices as well as automobiles. Also, the global lithium deposits are very limited. Hence, sodium-ion batteries (SIBs) have been heavily investigated as cheaper alternatives to expensive lithium-ion batteries, mainly due to the abundance of sodium raw materials. However, one of the major bottlenecks faced by the material research community to commercialize SIBs is the poor ionic conductivity of sodium-ion conducting electrolytes at ambient temperature, especially in the solid-state. Very recently, quasi-solid state polymer electrolytes (QSSPEs) have been proposed to overcome this challenge. In this work, a set of QSSPEs have been synthesized by using poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) host polymer and NaBF4 ionic salt dissolved in EC/PC plasticizer/solvent mixture. The highest conducting composition; 6 PVdF-HFP: 14 NaBF4: 40 EC: 40 PC (wt.%); showed an ambient temperature ionic conductivity of 4.1x10-3 S cm-1. The activation energy is almost same for all the sample compositions studied in this work suggesting that the activation process is mainly controlled by EC/PC. DC polarization test on highest conducting electrolyte composition with a configuration of SS/QSSPE/SS revealed that the electrolyte is predominantly ionic conductor with negligible electronic conductivity; a much desired property for a good electrolyte. Linear sweep voltammetric studies confirmed that the electrochemical stability window of the highest conducting electrolyte is about 3.6 V. This highest conducting electrolyte composition is found to be highly suitable for practical applications in sodium batteries.

Electrocatalytic reduction of Cr(VI) on gold-based electrodes in acidic medium: A systematic approach to chromium detection

In the present research, gold immobilized on different substrates (Au, GC, Pt) was examined to fabricate a Cr(VI) sensor in an acidic medium via reduction reactions. Comparative analysis revealed that Au-Pt electrode exhibited better electrocatalytic activity towards the reduction of Cr(VI) compared to Au, Au-Au or Au-GC electrode, which is emphatically discussed in this article. Specifically, the inner α-Au2O3 species of Au matrix on the catalytic surface played a key role in catalyzing Cr(VI) in the acidic medium. Voltammetric investigations revealed that the concerned electrode process is proton-dependent. From hydrodynamic voltammetric studies, it was found that the reduction reaction follows a multistep reaction mechanism with a single electron transfer rate-determining step over the Au-Pt surface. The Cr(VI) reduction reaction follows 1st order kinetics at the Au-Pt electrode surface, where the standard rate constant (k) was found to be 1.4×10−2 cm−1. The excellent improvement of reduction current over the Au-Pt surface was exploited in the fabrication of the Cr(VI) sensor. The developed sensor detects Cr(VI) ions with a linear dynamic range of 10 to 130 μM, whereas the sensitivity and limit of detection values are 3.21 μAμM−1cm−2 and 2.97 μM, respectively. Overall, the findings highlight the promising performance of the Au-Pt electrode in detecting Cr(VI) ions and provide valuable insights into the underlying catalytic diagnosis.

NanomolarFluorescentDetectionofGuanine Using Tin Porphyrin.

5,10,15,20-tetramethoxyphenylporphyrinatotin (IV) (SnTMPP) was synthesised. SnTMPP exhibited Soret band at 432nm and emission peaks at 629 and 682nm. The fluorescence intensity of SnTMPP was quenched in the presence of guanine linearly in the range 4 × 10-9M to 7.2 × 10-8M and the quenching response was found to be stable even in the presence of other nucleosides such as adenine, cytosine, uracil, thymine, alanine, aspartic acid and ascorbic acid. The detection limit was found to be 0.17nM and the mechanism behind the decrease in the fluorescence intensity of SnTMPP in the presence of guanine is due to dynamic quenching, which was confirmed by cyclic voltammetric studies and life time studies. The CV studies illustrates the possibilty for an electron transfer between the guanine and the electron deficient metal core of SnTMPP.

Formic acid oxidation on different coverages of Bismuth-modified Pt(1 0 0): A detailed voltammetric and FTIR study

The formic acid oxidation reaction (FAOR) on bismuth-modified Pt(100) is studied using electrochemical techniques and FITR spectroscopy at different bismuth coverages and formic acid concentrations. The results clearly show that: (1) The measured currents for the Bi-modified Pt(100) surface contain contributions from both the Pt-Bi ensembles and the Pt sites far from the Bi adatoms. (2) The catalytic effect of bismuth is not linked to the adsorption of formate on Pt sites. (3) The bismuth not only improves the activity of the FAOR through the active intermediate but also inhibits the CO poison by a third-body effect. (4) The experimental results indicate that the catalytic activity is linked to the Pt-Bi ensembles. The active species, formate, adsorbs on the Bi site and the neighboring Pt sites facilitate the cleavage of the C–H bond. (5) From the concentration dependence, the reaction order for formate on bismuth-modified Pt(100) is 1 at low potentials. In contrast, a reaction order of 0.5 is obtained at higher potentials. These results are in agreement with the proposed mechanism.

Voltammetric studies and spectroscopic investigations of the interaction of an anticancer drug bevacizumab-DNA and analytical applications of disposable pencil graphite sensor

A sensitive, simple, fast electrochemical biosensor for the DNA interaction of bevacizumab (BEVA), which is used as a targeted drug in cancer treatment, was developed using the differential pulse voltammetry (DPV) technique with pencil graphite electrode (PGE). In the work, PGE was electrochemically activated in a supporting electrolyte medium of +1.4 V/60 s (PBS pH 3.0). Surface characterization of PGE was carried out by SEM, EDX, EIS, and CV techniques. Determination and electrochemical properties of BEVA were examined with CV and DPV techniques. BEVA gave a distinct analytical signal on the PGE surface at a potential of +0.90 V (vs. Ag/AgCl). In the procedure proposed in this study, BEVA gave a linear response on PGE in PBS (pH 3.0 containing 0.02 M NaCl) (0.1 mg mL−1 – 0.7 mg mL−1) with LOD and LOQ values of 0.026 mg mL−1 and 0.086 μg mL−1, respectively. BEVA was reacted with 20 μg mL−1 DNA in PBS for 150 s and analytical peak signals for adenine and guanine bases were evaluated. The interaction between BEVA-DNA was supported by UV–Vis. Absorption spectrometry and the binding constant was determined as 7.3 × 104.

Electrocatalytic sensing of metronidazole by R-type hexagonal nanoferrites modified electrode

The current study was aimed to synthesize the R-type hexagonal nanoferrites (SrSn2Fe4O11) for electrochemical sensing of metronidazole (MN) in pharmaceutical and human specimen. The SrSn2Fe4O11 were prepared by sol-gel auto ignition method followed by structural and surface characterization by X-Ray diffraction (XRD) and atomic force microscopy (AFM) respectively. The resulting surface characterization data suggested that the synthesized SrSn2Fe4O11 have a single-phase crystalline structure with a crystalline size of 34.451 nm with surface topographical ranging from 0.506 to 3.37 nm. The SrSn2Fe4O11 modified glassy carbon electrode (SrSn2Fe4O11/GCE) was fabricated by a drop-casting method. The fabricated SrSn2Fe4O11/GCE was successfully applied for detecting MN in a phosphate buffer (PB) at pH-6, followed by a linear voltammetric response with the coefficient of determination (R2 = 0.998). The limit of detection and quantification (LOD/LOQ) for sensing MN was found to be 0.011 to 0.036 μM, respectively. A differential pulse voltammetric study of MN on SrSn2Fe4O11/GCE demonstrated a significant selectivity with RSD 2.0%. The proposed electrochemical method was successfully applied for the quantitative detection of MN in pharmaceutical preparations and biological specimen.

Facile fabrication of copper oxide modified sensor for determination of Mycophenolate mofetil in biological fluids: A cyclic voltammetric study

In the present work, the copper oxide nanoparticles (CuO Nps) was synthesized via chemical co-precipitation method for the detection of Mycophenolate mofetil (MMF). The synthesized Nps were characterised using traditional techniques namely X-ray diffraction (XRD), Scanning electron microscopy (SEM) and EDAX studies which showed better crystallinity with particle size of around 26 nm. The physiological pH of 7.4 was maintained throughout the studies. CuO Nps fabricated carbon paste electrode (CuO/FCPE) showed a considerable electroactive surface area with contrast to BCPE and showed better sensitivity and stable current responses. Further various other studies such as sweep rate, concentration, pH studies were carried out which showed lower LOQ and LOD i.e. 0.5 and 0.15 μM respectively. The developed electrode showed greater stability around 94% by retaining its activity. The fabricated electrode further studied for practical analysis of MMF in human urine trial which showed greater recovery of MMF in range of 96%–99%.

Electrochemical and theoretical study on interaction between erlotinib and DNA

A comprehensive investigation of tyrosine kinase inhibitor erlotinib (ERL) electrochemical behavior and interaction with DNA was performed with the aim to clarify its redox mechanism and to determine the mode of binding. Irreversible oxidation and reduction processes of ERL on glassy carbon electrode were investigated using three voltammetric techniques CV, DPV, SWV in pH range between 2.0 and 9.0. Oxidation was established as an adsorption-controlled process, while the reduction manifested diffusion-adsorption mixed controlled process in acidic medium and adsorption became predominant in the neutral solutions. According to the determined number of transferred electrons and protons, oxidation and reduction mechanism of ERL are proposed. To follow the interaction between ERL and DNA, the multilayer ct-DNA electrochemical biosensor was incubated in ERL solutions concentrations ranged from 2 × 10–7 M to 5 × 10–5 M (pH 4.6) for 30 min. SWV measurements have shown the decrease in deoxyadenosine peak current as a consequence of ERL increased concentration and binding to ct-DNA. The calculated value of binding constant was K = 8.25 × 104 M−1. Molecular docking showed that ERL forms hydrophobic interactions when docked into minor groove, as well as when intercalated, and molecular dynamics analysis predicted the stability of obtained complexes. These results together with voltammetric studies imply that the intercalation could be more dominant way ERL binding to DNA compared to minor groove binding.

Recycled and Nickel- or Cobalt-Doped Lead Materials from Lead Acid Battery: Voltammetric and Spectroscopic Studies.

The active mass of the plates of aspent car battery with higher wear after an efficient desulfatization can be used as sources of a new electrode. This paper proposes the recycling of spent electrodes from a lead acid battery and the incorporation of NiO or Co3O4 contents by the melt-quenching method in order to enrich the electrochemical properties. The analysis of X-ray diffractograms indicates the gradual decrease in the sulfated crystalline phases, respectively, 4PbO·PbSO4 and PbO·PbSO4 phases, until their disappearance for higher dopant concentrations. Infrared (IR) spectra show a decreasing trend in the intensity of the bands corresponding to the sulfate ions and a conversion of [PbO3] pyramidal units into [PbO4] tetrahedral units by doping with high dopant levels, yielding to the apparition of the PbO2 crystalline phase. The observed electron paramagnetic resonance (EPR) spectra confirm three signals located on the gyromagnetic factor, g~2, 2.2 and 8 assigned to the nickel ions in higher oxidation states as well as the metallic nickel nanoparticles. This compositional evolution can be explained by considering a process of the drastic reduction in nickel ions from the superior oxidation states to metallic nickel. The linewidth and the intensity of the resonance lines situated at about g~2, 2.17, 4.22 and 7.8 are attributed to the Co+2 ions from the EPR data. The best reversibility of the cyclic voltammograms was highlighted for the samples with x = 10 mol% of NiO and 15 mol% of Co3O4, which are recommended as suitable in applications as new electrodes for the lead acid battery.