Glassy Carbon Electrode Electrode Research Articles

Electrochemical Sensor Based on Electrodeposited Zinc-Aluminium Layered Double Hydroxide Modified Glassy Carbon Electrode for Chlorpromazine Sensing

Chlorpromazine functions as a potent dopamine D2 receptor antagonist, leading to adverse motor-related effects encompassing cataracts, musculoskeletal disorders, alterations in eyelid pigmentation, muscle contractions, and tremors-addressing the need for a reliable analytical tool, an electrodeposited thin film was synthesized on a glassy carbon electrode (GC) surface. This film comprised zinc-aluminium layered double hydroxide (Zn-Al LDH), with nitrate ions intercalated between the LDH layers. The electrocatalytic behavior of the resulting electrode (GC/Zn-Al LDH) in the oxidation and reduction of nitrogen and sulfur atoms within the thiazine ring structure of chlorpromazine was systematically studied using cyclic voltammetry. Evaluation of the electrode’s analytical response through diverse electroanalytical techniques demonstrated that the square wave voltammetry-assisted electrochemical sensor displayed a broad detection range for chlorpromazine (1 × 10−4 to 1 mM), with a sensitivity of 91.86 μA mM−1 and an impressive low detection limit of 16 × 10−6 mM. Furthermore, the performance of the developed electrode was assessed in detecting and quantifying chlorpromazine levels in simulated human urine samples through recovery studies. The results indicated satisfactory recovery rates, affirming the efficacy of the Zn-Al LDH-modified GC electrode. Noteworthy features of the electrochemical sensor included high surface coverage, improved electron transfer rate, reliable repeatability, and exceptional reproducibility. These characteristics collectively contribute to the sensor’s popularity for accurately detecting and quantifying of chlorpromazine in real-world samples.

Selective Electrochemical Determination of L-Cysteine by a Cobalt Carbon Nanotube (CNT)-Modified Glassy Carbon Electrode (GCE)

L-Cysteine is a semi-essential and proteinogenic amino acid, with the formula HO2CCH (NH2) CH2SH. L-cysteine is mostly found in protein-rich foods. In this study, catalysts consisting of cobalt (Co) supported on carbon nanotubes (CNTs) were prepared using the sodium borohydride (NaBH4) reduction method. These catalysts were characterized by means of energy-dispersive x-ray (EDX) with scanning electron microscopy (SEM), temperature-programmed reduction (TPR), and temperature-programmed oxidation (TPO) techniques. Characterization results confirmed the successful preparation of the desired catalyst. After preparing the Co/CNT catalysts, a highly efficient and sensitive electrochemical sensor was developed using a glassy carbon electrode (GCE) modified with the Co/CNT catalysts. The electrochemical behavior of the bare GCE and Co/CNT-modified GCE electrodes was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) in 0.1 M phosphate buffer solution (PBS) + L-cysteine. Electrochemical results showed that the Co/CNT-modified GCE electrode exhibited high sensitivity and selectivity compared to the bare GCE, with sensitivity of 0.0046 µA/µM, limit of detection of 0.2 µM, and limit of quantification of 0.6 µM. Furthermore, this electrode showed higher sensitivity values than those reported in the literature. Further interference studies were performed using CV and EIS to investigate interfering species in the serum environment, such as D-glucose, uric acid, L-tyrosine, and L-tryptophan. In conclusion, the results suggest that the Co/CNT-modified GCE electrode is a promising catalyst for the sensitive detection of L-cysteine.

Highly efficient and reliable voltammetry food sensor for Tartrazine dye using a nanocomposite reformed electrode

Monitoring synthetic dyes in foodstuffs holds significant importance owing to their adverse effects on human health. A modified Sol-gel process was used for synthesizing mixed metal (Copper, Iron, and Nickel oxides) nanocomposites (NCs). Ternary metal NCs were characterized using FT-IR, FE-SEM, UV–Vis, and X-ray diffraction (PXRD and GID) studies. NCs (Cu/Fe/NiO) modified working electrode was fabricated for Voltammetric detection of Tartrazine dye in soft drinks. A wide concentration range (0–500 µM) was used for the Voltammetric sensing of Tartrazine dye. Voltammetric techniques like Linear Sweep Voltammetry (LSV), Differential Pulse Voltammetry (DPV), and Cyclic Voltammetry (CV) were used for the electrochemical characterization of dye. The sensor shows a good electrochemical oxidation peak in 0.1 M sodium phosphate buffer solution (pH 6.0) as a supporting electrolyte at a scan rate of 0.01 mV s−1. The impedance spectroscopy (IS) technique was applied to examine the working electrode–electrolyte interface and film resistance. A comparative study of the sensor was done with a bare glassy carbon electrode (GCE), and a Cu-wire electrode using the CV technique. The NCs modified working electrode shows a higher oxidative peak in comparison to bare GCE and Cu-wire electrodes for sensing dye. The effect of pH and scan rate on the electrochemical oxidation of Tartrazine was also examined. The lowest detection limit of Tartrazine was 0.010 µM. The fabricated working electrode shows high sensing capability for Tartrazine dye in natural and synthetic samples. The developed sensor proved to be cost-effective, and reliable for detecting food preservatives, additives, and coloring agents.

Hg2+ Ions Sensor: Single Walled Carbon Nanotubes Incorporated Zn-Metal Organic Framework

In the present work, zinc benzene 1,4 dicarboxylate (ZnBDC) metal organic framework (MOF) and its composite with single-walled carbon nanotubes (SWNTs), we called as SWNTs@ZnBDC, has been synthesized by traditional solvothermal method. The synthesized materials have been evaluated with various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction (XRD), thermogravimetric-differential thermal analysis, Brunauer–Emmett–Teller surface area analysis, cyclic voltammetry, and electrochemical impedance spectroscopy. The sensor has been fabricated by depositing SWNTs@ZnBDC MOF on a glassy carbon electrode (GCE). The SWNTs@ZnBDC/GCE electrode shows excellent sensing behaviour in terms of selectivity towards Hg2+ ions only at pH = 5 and does not show any sensing response towards Pb2+, Cr2+, Cd2+, Cu2+, and Ni2+ ions at a concentration of 1 μM. For the Hg2+ ions, the sensor shows a high sensitivity of 0.86 μA/nM with a limit of detection of 6.74 nM and a limit of quantification of 5 nM.

Simultaneous voltammetric determination of female hormones using different carbonaceous electrodes in a non-aqueous environment

An undemanding electroanalytical method for the simultaneous determination of estrogens, namely 17β-estradiol (E2) or synthetic 17α-ethinylestradiol (EE2), with dienogest (DGN) has been developed for the analysis of oral contraceptives and hormone replacement therapy products. This approach is based on their anodic oxidation at carbonaceous electrode materials in pure acetonitrile using square-wave voltammetry. The electrochemical behaviour of these hormones at a glassy carbon electrode (GCE) in a nonaqueous environment was investigated using cyclic voltammetry to verify their reaction mechanisms. As part of the optimisation, commercially available GCE and boron-doped diamond electrodes were found to provide similar analytical performance, characterized by a wide linear range (>100 μmolL−1) with limits of quantification approximately 1.6 μmolL−1 for each hormone. A satisfactory precision (relative standard deviation < 4%) has been achieved for a mixture of 10 μmolL−1 E2 and DGN. Finally, the developed electroanalytical method was applied to the determination of female hormones present in pharmaceutical preparations and the results acquired were comparable to those obtained by a reference method employing reversed-phase high-performance liquid chromatography coupled to a diode array detector, which confirmed the practical use of this method in routine pharmaceutical analysis.

Construction of a novel sensor based on activated nanodiamonds, zinc oxide, and silver nanoparticles for the determination of a selective inhibitor of cyclic guanosine monophosphate in real biological and food samples

In the present work, we developed a highly sensitive and selective method for the determination of sildenafil (SIL) using a modified glassy carbon electrode (GCE) with activated nanodiamonds, zinc oxide, and silver nanoparticles nanocomposite (AND@ZnO-Ag/GCE). Various voltammetric techniques, including CV, DPV, and EIS, were employed to investigate the electrochemical process of SIL on the modified electrode. The resulting AND@ZnO-Ag/GCE electrode exhibited enhanced electron transfer between the electrode and the analyte, resulting in an excellent electrocatalytic performance for SIL oxidation under optimized conditions. The analytical performance of the AND@ZnO-Ag/GCE sensor demonstrated two linear responses within the concentration range of 0.01–0.08 μM and 0.08–14.6 μM, with a remarkably low detection limit of 7.08 nM. Moreover, the modified sensor (AND@ZnO-Ag/GCE) exhibited high selectivity and anti-interference capacity. It successfully detected trace amounts of SIL in biological and food samples, yielding satisfactory results. Furthermore, this work provides insights into the potential adulteration of energy drinks with sildenafil, addressing an area that has received limited attention in previous research.

Designing hybrid nanocubes-like cobalt stannate with appliance of MWCNT's nano composite for electrochemical detection of dopamine in bio-clinical samples

In this work, Co2SnO4 having nanocubes like structure synthesized via simple co-precipitation method and the nano-composite was prepared with appliance of multi-walled carbon nanotubes (MWCNT's) and employed for the determination of neuro-transmittance of dopamine (DA) in biological sample. The Co2SnO4 nanocubes and Co2SnO4@MWCNTs are characterized through distinct spectroscopic and microscopic methods, such as Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction spectroscopy (XRD), Raman spectroscopy, Filed emission scanning electron microscopy (FE-SEM), and electron spectroscopy for chemical analysis (ESCA) and as well as electrocatalytic activity was examined by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry techniques. Under optimal circumstances, the nano composite exhibited better activity over bare GCE. Moreover, Glassy carbon electrode (GCE) modified with Co2SnO4@MWCNTs was high sensitive and selective towards the determination of DA in presence of common interfering biomolecules. The electro analytical parameters via wide linear range (50–350 nM), low detection limit of 10.3 nM, sensitivity 0.043 nM mAcm−2 obtained by DPV analysis. The reliability of the Co2SnO4@MWCNTs/GCE electrode confirmed by real sample analysis of human urine sample and dopamine hydrochloride injection shows favor recovery percentage.

Bio-inspired polynorepinephrine based nanocoatings for reduced graphene oxide/gold nanoparticles composite for high-performance biosensing of Mycobacterium tuberculosis

Polydopamine (PDA) has established itself as a promising grafting and coating material, particularly for functional group-deprived electrochemically active nanomaterials such as graphene, MXene, CNT, metal nanoparticles, and so on, and has proven its extensive applicability in the design and development of electrochemical biosensor devices. However, polynorepinephrine (PNE), a sister compound of PDA, having additional –OH groups and greater coating uniformity and biocompatibility, has never been studied in the field of biosensors. Herein, we investigated PNE as a coating material for reduced graphene oxide (RGO) and gold nanoparticles (Au) in order to build an electrochemical genosensor for Mycobacterium tuberculosis (MTB) detection. Biotin-Avidin chemistry was used to covalently immobilize probe DNA (ssDNA) specific to MTB to the nanocomposite surface on glassy carbon electrode (GCE) in order to construct biosensing electrodes. The formation of RGO/PNE and RGO/PNE/Au nanocomposite as well as the immobilization of ssDNA onto the bioelectrodes are both corroborated by UV–Visible, Raman, and XRD studies with FE-SEM and HR-TEM analysis. The electrochemical studies performed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) showed the significant enhancement in charge transfer kinetics of RGO/PNE/GCE and RGO/PNE/Au/GCE electrode compared to GO/GCE electrode. The biosensing investigations performed using ssDNA/avidin/RGO/PNE/Au/GCE bioelectrode showed high sensitivity (2.3 × 10−3 mA μM−1), low detection limit (0.1 × 10−7 μM), broad detection range (0.1 × 10−2 to 0.1 × 10−7 μM) with good selectivity and low response time (5 s) of the developed sensor. In comparison to the analogous RGO/PDA/Au material system, RGO/PNE/Au demonstrated increased enzyme loading, improved electrochemical responsiveness, and superior biosensing performance.

Fabrication of high-performance cell-imprinted polymers based on AuNPs/MXene composites via metal-free visible light-induced ATRP.

Cell-imprinted polymers (CIPs) for yeasts were fabricated via metal-free visible-light-induced atom transfer radical polymerization (MVL ATRP) on the surface of a glassy carbon electrode (GCE) which had been modified with gold nanoparticles (AuNPs)/MXene (Ti3C2Tx) composites. Here, the AuNPs/Ti3C2Tx composites form a macroporous structure, which could improve the electron transfer rate of the materials and facilitate the leaving or rebinding of cells. Methacrylic acid (MAA) and N,N'-methylene bis-acrylamide (MBA) were selected as the functional monomer and cross-linker of CIPs, because they could form efficient hydrogen bonding with mannan from yeast cell walls. The obtained electrode (CIPs/AuNPs/Ti3C2Tx/GCE) was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Further experiments indicated that the CIPs/AuNPs/Ti3C2Tx/GCE electrode could be utilized as an electrochemical biosensor to determine yeast cells by differential pulse voltammetry (DPV). The linear response range was 1.0 × 102 to 1.0 × 109 cells per mL and the detection limit was 20 cells per mL (S/N = 3). The CIPs/AuNPs/Ti3C2Tx/GCE electrode also showed good selectivity, repeatability, reproducibility, and regeneration. Finally, the proposed sensor was used to detect yeast cells in commercial samples of Saccharomyces boulardii sachets by a standard addition method. The obtained recovery was from 96.9 to 104.8% showing its potential applications in clinical and diagnostic research.

SnO2QDs Deposited on GO/PPy-Modified Glassy Carbon Electrode for Efficient Electrochemical Hydrogen Peroxide Sensor.

In this present work, we demonstrate an efficient electrochemical sensor for the detection of hydrogen peroxide (H2O2) using a glassy carbon electrode (GCE) modified with a ternary nanocomposite of tin oxide QDs/GO/PPy (SGP2). An in situ chemical oxidative polymerization method was used to create the SGP2 nanocomposite. FTIR, XRD, HR TEM, CV, DPV, and impedance analysis were used to characterize the nanocomposite. The SGP2 nanocomposite modified GCE can be used to create an effective H2O2 electrochemical sensor with high sensitivity and a low detection limit (LOD). With SGP2 modified GCE, the electrochemical detection test for H2O2 was carried out using cyclic voltammetry (CV) and amperometric methods. The SGP2 modified GCE shows improved sensing capabilities, resulting in considerable sensitivity of 11.69 µA mM cm-2 and a very low limit of detection (LOD) of 0.758 µM for a broad linear range of H2O2 concentration from 0.1 mM to 0.8 mM with a correlation coefficient R2 = 0.9886. Additionally, the performance of the SGP2-modified GCE electrode is on par with or nonetheless superior to that of the other functional materials that have been reported for H2O2. As a result, our findings suggest that combining conductive polymer with metal oxide may be a useful method for producing sophisticated and affordable electrochemical sensors.

Synthesis of Tin oxide nanoparticles using Nelumbo nucifera leaves extract for electrochemical sensing of dopamine

In this investigation, SnO2 nanoparticles are prepared through environmental benign method using Nelumbo nucifera (lotus leaf) leaves extract as a reducing agent without any other reagents. The phase formation and the morphology of the as-synthesized SnO2 nanoparticles are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The nanoparticle size is obtained using selected area diffraction patterns of transmission electron microscope (TEM). The synthesized material modified glassy carbon electrode (GCE) is used for electrochemical detection of the dopamine (DA). In cyclic voltammetry (CV), the modified GCE shows effective electrochemical sensing performance than the bare GCE electrode. The limit of detection (LOD) and limit of quantification (LOQ) of DA were calculated by differential pulse voltammetry (DPV). Aforementioned material has high sensitivity and selectivity towards DA oxidation through electrochemical sensing.

Direct electrochemical detection of Cu(Ⅱ) ions in juice and tea beverage samples using MWCNTs-BMIMPF6-Nafion modified GCE electrodes

Due to a small amount of Cu (Ⅱ) ions being beneficial and too much being harmful, it is necessary to establish a rapid and direct detection method. Herein, we reported a platform based on multiwalled carbon nanotubes (MWCNTs), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), and Nafion solution-modified glassy carbon electrode (GCE) for the direct electrochemical detection of Cu (II) ions. We used differential pulse anodic stripping voltammetry, including the electrodeposition of Cu (Ⅱ) ions on the modified GCE and subsequent anodic stripping. Under the optimum conditions, the linear range was 20 μg·L−1 ∼ 950 μg·L−1, the limit of detection (LOD) was 16 μg·L−1, and the limit of quantification (LOQ) was 54 μg·L−1 for Cu (II). We realized the quantitative detection of Cu (Ⅱ) ions in juice and tea beverage without tedious pretreatment. The result showed that the sensor had good anti-interference and practicability for actual food samples.

An Efficient Voltammetric Sensor Based on Graphene Oxide-Decorated Binary Transition Metal Oxides Bi2O3/MnO2 for Trace Determination of Lead Ions

Herein we present a facile synthesis of the graphene oxide-decorated binary transition metal oxides of Bi2O3 and MnO2 nanocomposites (Bi2O3/MnO2/GO) and their applications in the voltammetric detection of lead ions (Pb2+) in water samples. The surface morphologies, crystal structures, electroactive surface area, and charge transferred resistance of the Bi2O3/MnO2/GO nanocomposites were investigated through the scanning electron microscopy (SEM), power X-ray diffraction (XRD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques, respectively. The Bi2O3/MnO2/GO nanocomposites were further decorated onto the surface of a glassy carbon electrode (GCE), and Pb2+ was quantitatively analyzed by using square-wave anodic stripping voltammetry (SWASV). We explored the effect of the analytical parameters, including deposition potential, deposition time, and solution pH, on the stripping peak current of Pb2+. The Bi2O3/MnO2/GO nanocomposites enlarged the electroactive surface area and reduced the charge transferred resistance by significant amounts. Moreover, the synergistic enhancement effect of MnO2, Bi2O3 and GO endowed Bi2O3/MnO2/GO/GCE with extraordinary electrocatalytic activity toward Pb2+ stripping. Under optimal conditions, the Bi2O3/MnO2/GO/GCE showed a broad linear detection range (0.01–10 μM) toward Pb2+ detection, with a low limit of detection (LOD, 2.0 nM). The proposed Bi2O3/MnO2/GO/GCE electrode achieved an accurate detection of Pb2+ in water with good recoveries (95.5–105%).

Detection of Axitinib Using Multiwalled Carbon Nanotube-Fe2O3/Chitosan Nanocomposite-Based Electrochemical Sensor and Modeling with Density Functional Theory.

In this study, axitinib (AXI), a potent and selective inhibitor of vascular endothelial growth factor receptor (VEGFR) tyrosine kinase and used as a second-generation targeted drug, was investigated electrochemically under optimized conditions using multiwalled carbon nanotubes/iron(III) oxide nanoparticle–chitosan nanocomposite (MWCNT/Fe2O3@chitosan NC) modified on the glassy carbon electrode (GCE) surface. Characterization of the modified electrode was performed using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The adsorptive stripping differential pulse voltammetric (AdSDPV) technique was used for the sensitive, rapid, and precise detection of AXI. The current peak obtained with the MWCNT/Fe2O3@chitosan NC modified electrode was 23 times higher compared to the bare electrode. The developed modified electrode showed excellent electrocatalytic activity in AXI oxidation. Under optimized conditions, the effect of supporting electrolyte and pH was investigated, and 0.1 M H2SO4 was chosen as the electrolyte with the highest peak current for the target analyte. In the concentration range of MWCNT/Fe2O3@chitosan NC/GCE, 6 × 10–9 and 1 × 10–6 M, the limit of detection (LOD) and limit of quantification (LOQ) values were calculated to be 0.904 and 0.0301 pM, respectively. Tablet and serum samples were used for the applicability of the developed sensor, relative standard deviation (RSD) values for all samples were below 2%, and the recovery results were 99.23 and 101.84%, respectively. The MWCNT/Fe2O3@chitosan NC/GCE designed to determine AXI demonstrated the applicability, selectivity, precision, and accuracy of the sensor. The mechanism of electron transfer from the modified GCE surface to the analyte solution is studied via modeling the modified GCE surface by the density functional theory (DFT) method at B3LYP/6-311+g(d,p) and M062X/6-31g(d,p) levels. We observed that the iron oxide nanoparticles play an important role in channeling electron flow from the analyte solution to the MWCNT-coated GCE electrode surface. Adsorption of the nanocomposite material onto the GCE surface occurs via strong electrostatic interactions, including ionic and hydrogen bond formations. During the adsorption-controlled oxidation process of the axitinib, the electrons are transferred via the highest occupied molecular orbital (HOMO) localized on the iron oxide moiety to the lowest unoccupied molecular orbital (LUMO) of the MWCNT/GCE surface.

Comparative study on sensing and optical properties of carbazole linked novel zinc(II) and cobalt (II) phthalocyanines

In the current work, symmetrically carbazole linked Zn(II) and Co(II) phthalocyanines (Pcs) have been succesfully synthesized and characterized through Fouirer Transform Infrared (FT-IR), Ultraviolet–visible (UV–vis) spectroscopies, Matrix-assisted laser desorption - ionisation-time of flight mass spectrometry (MALDI-TOF MS) along with proton and carbon Nuclear Magnetic Resonance (1H and 13C- NMR) spectroscopies. The electrochemical performance of the targeted metallo- phthalocyanines was demonstrated with cyclic voltammetry (CV), and square wavevoltammetry (SWV). The final phthalocyanines were used as hybrid materials for the preparation of the modified glassy carbon electrode (GCE). The hybrid materials were then deposited on GCE via an electropolymerization or electrodeposition method. The surface morphologies of the hybrid electrodes were investigated using scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDX). IR, UV–vis and Raman spectroscopies were carried out to evaluate the surface of the hybrid electrodes. The N-ethylcarbazole moiety and redox active Zn(II), Co(II) metal centers were employed in order to improve the sensing performance of targeted compounds. Furthermore, hybrid material-graphene modified GCEs have been designed to compare and rise the analytical activity. The sensing properties of the designed electrodes was investigated to detect electrochemically active biomolecules namely, dopamine (DA), ascorbic acid (AA), and uric acid (UA) in both phosphate buffered saline (PBS) and tap water sample. The Grp/ Ply(Car-CoPc)/GCE electrode was only detected DA with a limit of detection (LOD) of 16 nM. On the other hand, LOD values of Grp(Car-CoPc)/GCE were determined by voltammetric analyses as 3.38 μM and 0.62 μM for AA and UA, respectively. Sensing performances of the designed electrodes were eximined for the concurrently determination of DA and UA using differential pulse voltammetry (DPV) method.

Electrochemical behavior of protein oxidation biomarkers meta-, ortho- and 3-chloro-tyrosine on carbon electrodes: A comparative study with para-tyrosine and phenylalanine

The anodic behavior of the isomers meta-, ortho- and para-tyrosine (m-, o-, p-Tyr) and of phenylalanine in aqueous support electrolytes, with different pH values, on the glassy carbon electrode (GCE), were investigated and compared using cyclic and differential pulse voltammetry. The electrochemical behavior of 3‑chloro-tyrosine (3-Cl-Tyr) in different aqueous media was also investigated on a GCE and boron-doped diamond electrode (BDDE). The results showed that all tyrosines undergo oxidation at the phenolic group, with the removal of one electron and one proton, forming one intermediate radical, Tyr●. The reactivity of this radical in aqueous medium, however, is clearly conditioned by its position in the tyrosine structure. The m-Tyr● reaction occurs with the formation of polymers and with water to form one quinone derivative. The o-Tyr● radical reacts preferentially with water leading to formation of two electroactive quinone derivatives and p-Tyr● preferentially follows the polymerization. The electrochemical results of the 3-Cl-Tyr electro-oxidation were very similar in relation to p-Tyr. There was little influence of the substituent -Cl, occurring in the phenolic group with predominantly polymer formation. On the other hand, unlike the other tyrosines, one irreversible and pH-dependent cathodic peak for 3-Cl-Tyr was detected, associated to the electro-reduction of the chloro group attached at C3. Using differential pulse voltammetry (DPV), experimental optimizations were also performed for quantification of 3-Cl-Tyr with low detection limit. These were carried out with a carbon working electrode (GCE or BDDE), support electrolyte composition and pH and considering possible interferents. Thus, electroanalytical methods for detection and quantification of 3-Cl-Tyr at carbon electrodes were also developed and proposed.

Colloidal synthesis of perovskite-type lanthanum aluminate incorporated graphene oxide composites: Electrochemical detection of nitrite in meat extract and drinking water.

A novel electrochemical method has been developed for determination of nitrite using La-based perovskite-type lanthanum aluminate nanorod-incorporated graphene oxide nanosheets (LaAlO3@GO). Morphological and structural analyses of the prepared perovskite-type electrocatalyst, with and without a glassy carbon electrode (GCE) surface, were performed using various techniques, including transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry, Raman spectroscopy, and electrochemical impedance spectroscopy. Under optimal conditions, the LaAlO3@GO composite-modified GCE (LaAlO3@GO/GCE) exhibited excellent electrocatalytic performance toward the electrooxidation of nitrite (pH = 7.0), with a significant increase in anodic peak currents compared with the bare GCE. Using amperometry, the fabricated sensor exhibited a wide nitrite determination range from 0.01 to 1540.5µM, with a detection limit of 0.0041µM. Notably, the proposed LaAlO3@GO/GCE electrode demonstrated a good nitrite detection performance in different meat and water samples. In addition, the LaAlO3@GO/GCE electrode displayed excellent selectivity, repeatability, reproducibility, storage, and operational stability toward nitrite detection.

Novel Electrochemical Sensor for Rifampicin based on Ionic Liquid Functionalised TiO2 Nanoparticles

Aim::The main strategy of this study is to develop a novel ionic liquid functionalised metal nanocomposite based electrochemical sensor with potential applications for the sensitive electrochemical detection of rifampicin.Background::Tuberculosis (TB) is a widespread disease that is caused by the gram-positive Mycobacterium tuberculosis (MTB). In addition, for several decades TB has become a constant threat to human health, however due to the accessibility of broad-spectrum antibiotics (rifampicin, pyrazinamide, isoniazid, and ethambutol), which are active against the bacterium, the social and economic burden for sufferers from the illness remains to be huge. Specially, in countries, like India and sub Saharan Africa, it is one of the common diseases affecting members from all age groups. So, this work is aimed at developing a novel electrochemical sensor for the determination of rifampicin (RIF) in pharmaceutical samples.Objective::To synthesis and characterization of the novel liquid functionalised metal nanocomposite. Fabrication of glassy carbon electrode with potent electrode modifiers whose applicability as electro catalysis agents towards rifampicin is investigated.Method::In this work, a nanocomposite based on trihexyltetradecylphosphonium-bis-(2,4,4-trimethylpentyl)-phosphinate ([P14, 6, 6, 6] [(C8H17)2 PO2)]) ionic liquid functionalised titanium oxide nanoparticles (TiO2NPs) and multiwalled carbon nanotubes (MWCNTs) were used in the modification of a highly sensitive electrochemical sensor for quantification of rifampicin in pharmaceutical formulations. The modified glassy carbon electrode (GCE) were characterised by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD).Results::The electrochemical behaviour of RIF was studied on the modified electrode by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. At pH 6.0 in phosphate buffer solution (PBS), the anodic peak current value of RIF obtained with the fabricated electrode is 7 times greater than with the bare GCE electrode. The anodic peak current value and concentration of RIF showed a good linear relationship in the range of 0.015–2.8 μM, with the limit of detection (LOD) of 0.0218 μM and limit of quantification (LOQ) 0.3120 μM respectively.Conclusion::Under the optimal conditions, the IL-f-TiO2NPs-MWCNTs-GCE provided a relatively lower detection limit and wider linear range compared to other previous procedures. The proposed electrochemical sensor had potent catalytic activity for RIF oxidation and provided important quantitatively reproducible analytical performance. Finally, this modified electrode was successfully applied to the determination of RIF in real pharmaceutical samples.

Determination of Uric Acid Using TiO2 Nanoparticles Modified Glassy Carbon Electrode

In the present study, the electrochemical behavior of uric acid (UA) was evaluated using a titania nanoparticle (TiO2) coated glassy carbon electrode (GCE). TiO2 nanoparticles are synthesized and characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX) techniques. The electrochemical behavior of uric acid on both bare GCE and Titania coated GCE electrodes were studied through differential pulse voltammetry. Titania-coated GCE showed a higher current at the lower potential for the oxidation of uric acid when compared to bare GCE. The sensor's improved electrocatalytic activity was observed to detect uric acid in a 0.1 M phosphate buffer saline (PBS) solution at pH 7.0. A good linear relationship was observed between electrical response and the concentration of uric acid in the range of 1 to 9 μM. Under optimized experimental conditions, the limit of detection (LOD) was found as 0.764 μM. The sensor has expressed considerable sensitivity towards UA detection without interference and is successfully used to determine UA in human urine samples.

Synthesis of B-RGO-MWCNT/CuFeO2 Composite for Efficient Hydrogen Evolution Reaction

The key to utilizing renewable energy is the development of promising new materials for electrocatalytic water splitting. Boron doped reduced graphene oxide/multiwalled carbon nanotubes (B-RGO-MWCNT) composite decorated with CuFeO2 complex modified glassy carbon electrode (GCE) was applied to the water electrolysis (HER). The B-RGO-MWCNT composite was prepared using the hydrothermal method and the CuFeO2 delafossite material was synthesized by a glycine nitrate process. Moreover, the material structures of B-RGO-MWCNT/CuFeO2 composite were identified by different spectroscopic and microscopic measurements. The B-RGO-MWCNT/CuFeO2 composite was structurally well-formed with an active surface area. The GCE electrode decorated with B-RGO-MWCNT/CuFeO2 composite was applied to HER and exhibited an outstanding electrocatalytic response with low over-potential and a small Tafel slope of 54 mV·dec−1 at 10 mA.cm−2 over potential with high stability. Moreover, the small Tafel slope suggests a promising electrocatalyst suitable for practical use. Furthermore, the obtained B-RGO-MWCNT/CuFeO2 electrode was correlated with Pt/C and exhibited superior electrocatalytic performance toward the HER in acidic media. The electrochemical response is credited to the active sites and effective electron transport between CuFeO2 and B-RGO-MWCNT. As a result, the B-RGO-MWCNT/CuFeO2 composite looks to be an effective catalyst for the electrocatalytic reaction of HER and has the potential to produce clean energy.