Differential Pulse Amperometry Research Articles

Rapidly synthesized polyethylene glycol coated cadmium sulphide (CdS) nanoparticles as potential scaffold for highly sensitive and selective lethal cyanide ion sensor

Herein, we report the facile and highly rapid synthesis, characterizations and lethal cyanide sensing applications of polyethylene glycol (PEG) coated cadmium sulphide (CdS) nanoparticles (P-CdS NPs). The P-CdS NPs were synthesized by simple microwave technique and characterized by different techniques which revealed that the nanoparticles are monodisperse spherical shaped and grown in high-density. The synthesized P-CdS NPs were used as efficient electron mediator to fabricate highly sensitive and sensitive chemical sensor. The sensing responses of P-CdS NPs anchored on gold electrode towards cyanide ion have been monitored by three different techniques i.e. differential pulse voltammetry (DPV), cyclic voltammetry (CV) and amperometry. The limits of detection (LOD) of cyanide ions with DPV, CV and amperometry have been found to be ∼9.1×10−9, 4.2×10−6 and 0.9×10−7M, respectively. The detailed sensing results revealed that the DPV is the best method for the detection of cyanide ion using P-CdS NPs. In addition to this, the system has been found to be quite selective for cyanide ion as it gives negligible response towards other anions.

Ruthenium-Modified Sensitive NO Sensors: Quantifying Nitric Oxide in the Pathobiology of Cystic Fibrosis

This is a preliminary work towards preparing a device capable to measure nitric oxide levels in a cystic fibrosis cell line model. It has been found that exhaled NO levels remains unchanged or reduced in cystic fibrosis patients unlike other inflammatory lung diseases like asthma where it increases. However it is not clear whether the lower NO levels in cystic fibrosis correlate with lowered production of this metabolite in the bronchial epithelium. We will present preliminary results of our ruthenium oxide modified combined electrodes and how they can be applied to the study of cystic fibrosis at the cellular level. In this work, we explore the performance of combined reference/working electrodes modified with ruthenium oxide and Poly(3,4-ethylenedioxythiophene) (PEDOT) in the detection of nitric oxide with the goal to measure nitric oxide at the level of single or collective cultured cells. The synergistic effect of the electrocatalytic activity of ruthenium oxide and the enhanced surface area for catalytic activity provided by the polymer greatly enhanced the analytical performance of our sensors in terms of sensitivity, selectivity and stability. With the incorporation of a layer by layer method of electrodeposition we attained a normalized sensitivity of 8.38E-4 pA/nM/μM2 and 1.16E-2 pA/nM/μM2 towards NO in the linear range of 0.2-1.6 mM and 2-16 nM respectively, at an applied potential of 0.8 V vs Ag/AgCl and a detection limit in the vicinity of 500 pM. In order to improve the selectivity of our sensors we coated the surface with nafion and also an ionic liquid composite and lowered the applied to 0.6 V vs. Ag/AgCl. We also measured the response to NO using Differential Pulse Amperometry to further decrease response from biological interferents especially nitrite and ascorbic acid.

Electrocatalytic oxidation of dopamine based on non-covalent functionalization of manganese tetraphenylporphyrin/reduced graphene oxide nanocomposite

In the present work, a reduced graphene oxide (RGO) supported manganese tetraphenylporphyrin (Mn-TPP) nanocomposite was electrochemically synthesized and used for the highly selective and sensitive detection of dopamine (DA). The nuclear magnetic resonance, scanning electron microscopy and elemental analysis were confirmed the successful formation of RGO/Mn-TPP nanocomposite. The prepared RGO/Mn-TPP nanocomposite modified electrode exhibited an enhanced electrochemical response to DA with less oxidation potential and enhanced response current. The electrochemical studies revealed that the oxidation of the DA at the composite electrode is a surface controlled process. The cyclic voltammetry, differential pulse voltammetry and amperometry methods were enable to detect DA. The working linear range of the electrode was observed from 0.3 to 188.8μM, limit of detection was 8nM and the sensitivity was 2.606μAμM−1cm−2. Here, the positively charged DA and negatively charged porphyrin modified RGO can accelerate the electrocatalysis of DA via electrostatic attraction, while the negatively charged ascorbic acid (AA) repulsed by the negatively charged electrode surface which supported for good selectivity. The good recovery results obtained for the determination of DA present in DA injection samples and human pathological sample further revealed the good practicality of RGO/Mn-TPP nanocomposite film modified electrode.

Trouble Free Dopamine Sensing by Palladium Nanoparticles Fabricated Poly(3,4-ethylenedioxythiophene) Functionalized Graphene

An electrochemical sensor based on poly(3,4-ethylenedioxythiophene) functionalized reduced graphene oxide with palladium nanoparticles (Pd/PEDOT/rGO) has been constructed for electrochemical determination of dopamine (DA) in presence of ascorbic acid (AA) at high concentration. The structural features of the catalyst were characterized using several instrumental methods. The transmission electron microscopy (TEM) analysis suggests a well dispersed spherical PdNPs set successfully onto PEDOT/rGO film. Electrochemical determination of DA in presence of AA was investigated on modified glassy carbon electrode in 0.1 M phosphate buffer solution at pH 7.4 using cyclic voltammetry, differential pulse voltammetry (DPV) and amperometry techniques. A wider linear analytical range for DA detection (1–200 μM) and comparatively lower limit of detection (LOD) 0.14 μM were obtained using DPV technique, while LOD increases up to 0.16 μM in the presence of five times higher AA. Also, no significant interference was observed from similar biomolecule species such as norepinephrine, epinephrine, uric acid and AA. This DA-sensor retained 85.6% of its initial response up to 15 days.

Design of a Portable Potentiostat with Dual-microprocessors for Electrochemical Biosensors

In this paper, we design and implement a portable potentiostat by using dual-microprocessors for the signal processing of electrochemical biosensors. In our design approach, one of the microprocessors is used to design the programmable waveform generator, and the other microprocessor is used to measure the current of biosensors. The proposed potentiostat can perform general electrochemical analysis functions, including cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry, amperometry, and potentiometry. In the experiment, we adopt a commercial screen printed electrode immersed in potassium ferricyanide solution to test the performance of the proposed potentiostat and compare the proposed potentiostat's measured results with a commercial potentiostat's (CH Instrument Model: CHI1221) under the same test condition. The experimental results show that the proposed potentiostat has the merits of good accuracy, low cost, low power consumption, and high portability.

Simultaneous determination of dopamine, uric acid and nitrite using carboxylated graphene oxide/lanthanum modified electrode

A bare glassy carbon electrode (GCE) was reformed by carboxylated graphene oxide/lanthanum, and the modified electrode, called GO-COOLa/GCE, was fabricated for simultaneously detecting dopamine (DA), uric acid (UA) and nitrite (NO2−) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. Several factors which affected the electrocatalytic activity of the GO-COOLa/GCE electrode, such as the effect of pH, scan rate and concentration were studied. Due to the combination of carboxylated graphene oxide and lanthanum ions, the GO-COOLa/GCE sensor showed rapid response, excellent selectivity and high catalytic performance toward the electrooxidation of DA, UA and NO2−. In optimized conditions, two linear response ranges for determining DA were obtained over ranges of 0.01-1.96×102μM and 1.96×102-1.23×103μM with detection limit of 0.018μM (S/N=3). And the responses of the GO-COOLa/GCE electrode for UA and NO2− were linear in the region of 1-1.53×103μM and 1-2.75×103μM with detection limits of 0.058μM and 0.070μM, respectively. Furthermore, this reformed electrode was successfully used to the detection of DA, UA and NO2− in real urine and serum samples, showing its promising application in the electroanalysis of real samples.

A novel third generation uric acid biosensor using uricase electro-activated with ferrocene on a Nafion coated glassy carbon electrode

A new uric acid biosensor was constructed using ferrocene (Fc) induced electro-activated uricase (UOx) deposited within Nafion (Naf) on glassy carbon electrode (GCE). Electro-activation of UOx was successfully achieved by cyclic voltammetry through the electrostatic interaction of Fc with Trp residues within the hydrophobic pockets in UOx. The Naf/UOx/Fc composite was characterised by AFM, FTIR and EDX to ensure proper immobilisation. The interaction of Fc with the enzyme was analysed by Trp fluorescence spectroscopy and the α-helicity of the protein was measured by CD spectropolarimetry. The charge transfer resistance (Rct), calculated from electrochemical impedance spectroscopy, for the modified sensor was lowered (1.39kΩ) and the enzyme efficiency was enhanced by more than two fold as a result of Fc incorporation. Cyclic voltammetry, differential pulse voltammetry and amperometry all demonstrated the excellent response of the Naf/UOx/Fc/GCE biosensor to uric acid. The sensor system generated a linear response over a range of 500nM to 600μM UA, with a sensitivity and limit of detection of 1.78μAμM−1 and 230nM, respectively. The heterogeneous rate constant (ks) for UA oxidation was much higher for Naf/UOx/Fc/GCE (1.0×10−4cms−1) than for Naf/UOx/GCE (8.2×10−5cms−1). Real samples, i.e. human blood, were tested for serum UA and the sensor yielded accurate results at a 95% confidence limit.

Electrochemical Sensing of Nitrite Ions Using Tin‐Submicroparticles Modified Glassy Carbon Electrodes

AbstractThe applicability of tin submicroparticles modified glassy carbon electrodes for sensing of nitrite ions is demonstrated. Tin submicroparticles have been electrodeposited on a glassy carbon electrode using constant potential deposition. The detection of nitrite ions is carried out with differential pulse voltammetry, amperometry and electrochemical impedance spectroscopy. The lowest detection limit of 0.5 µM with a linear range of 5 µM–1000 µM is inferred from the differential pulse voltammetry. The interference from different compounds such as urea, glucose and nitrate ions is also analyzed.

Effect of Au Content in Aupd Electro-Synthesized Mixtures Toward Formic Acid/Formate Electro-Oxidation

AuPd mixtures were electrochemically synthesized using pulse potential techniques such as differential pulse amperometry, square wave voltammetry and second harmonic AC voltammetry in order to modify the metal content of the mixtures. Pure Au and Pd were electrochemical synthesized for comparison purposes. The metal proportions of 90:10, 60:40, 50:50, 35:65 and 15:85 Au-Pd were obtained according to EDS and XRF analyses. Formic acid/formate was worked in 0.3 M KOH (as electrolyte) in order to preserve the presence of formate. At low Formic acid/formate concentration (0.01 and 0.1 M) pure-Pd material exhibited good electrocatalytic activity in terms of current density. Pure-Au material showed no response for formic acid/formate electrooxidation at low concentrations. On the other hand, AuPd mixtures exhibited different behavior as function of the bimetallic content. At low concentrations (0.01 and 0.1 M) mixtures enriched with Au exhibited a poor electrocatalytic activity. Meanwhile, Pd-enriched mixtures content showed low current density than pure-Pd. However, when the formic acid concentration was increase to 0.3 and 0.5 M, pure-Pd showed higher CO-poisoning effect than Pd-enriched AuPd mixtures.

An electrocatalytic oxidation and voltammetric method using a chemically reduced graphene oxide film for the determination of caffeic acid

The present work describes the characterization of a chemically reduced graphene oxide (CRGO) modified glassy carbon electrode (GCE) for electrochemical investigation of caffeic acid (CA). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), amperometry, and electrochemical impedance spectroscopy (EIS) techniques were used to characterize the properties of the electrode. There was an obvious enhancement of the current response and a decreased over potential for the oxidation of CA. The interfacial electron transfer rate of CA was studied by EIS. Under optimal conditions, the CRGO displayed a linear response range of 1×10−8 to 8×10−4M and the detection limit was 2×10−9M (S/N=3), with a sensitivity of 192.21μAmM−1cm−2 at an applied potential of +0.2V (vs. Ag/AgCl reference), which suggests that the CRGO is a promising sensing materials for the electrochemical investigation of CA. The results showed the good sensitivity, selectivity and high reproducibility of the CRGO modified electrode. Moreover, this modified electrode was further applied to investigate the CA in real samples of wine with satisfactory results.

Controlled growth of single-crystalline nanostructured dendrites of α-Fe2O3 blended with MWCNT: a systematic investigation of highly selective determination of l-dopa

α-Fe2O3 dendritic nanostructures were prepared by simple hydrothermal method and then blended with MWCNT (multiwall carbon nanotubes) to construct a novel biosensor for the determination of L-dopa. The structure of the new material was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and the electrochemical behavior of L-dopa was also studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry in phosphate buffer solution (PBS) at pH 7.2. The experimental results suggested that α-Fe2O3 blended MWCNT composite showed 3-fold increase of the oxidation peak current compared to that of the bare electrode. The DPV current responses of L-dopa were increased linearly in the range from 5.0 × 10−8 to 3.8 × 10−6 M with a lower detection limit of 30 nM (3σ). Finally, the proposed sensor was demonstrated for the sensitive determination of L-dopa in pharmaceutical samples and the obtained results were quite promising.

Staircase and pulse potential electrochemical techniques for the facile and rapid synthesis of Pt and PtAg materials

Electrochemical synthesis is an attractive option for the synthesis of materials because electrocrystallization is faster (microseconds), easier (fewer variables influence structure) and more cost-effective (only requiring an ion source and electrolyte) than traditional chemical methods. Pt and PtAg materials were synthesised using electrochemical techniques, including staircase cyclic voltammetry (CV). Differential pulse amperometry (DPA), square wave voltammetry (SWV) and second harmonic AC voltammetry (2nd H AC V) were employed as pulse potential techniques. Characterisation was conducted using X-ray diffraction, field emission scanning electron microscopy, X-ray fluorescence, cyclic voltammetry in acidic and basic media and by assessing the behaviour of the synthesised materials in oxygen reduction reaction (ORR). For the cyclic voltammetry and DPA techniques, a decrease in the interfacial electrode/solution concentration resulted in the formation of semi-spherical nanoparticles with dendritic nanosheet growth. Semi-spherical Pt nanoparticles with small crystal sizes were obtained using SWV and 2nd H AC V due to the enhancement of the Pt seed growth by the low-time pulse potential period. Silver incorporation allowed the formation of well-defined cubic-shaped and flower-like PtAg nanoparticles without the need for surfactants and/or reductants. Silver acted both as a silver ion source and an additive, due to its passivation of the particle surfaces.

Simultaneous electrochemical determination of dopamine and paracetamol on multiwalled carbon nanotubes/graphene oxide nanocomposite-modified glassy carbon electrode

In the present study, multiwalled carbon nanotubes (MWCNT)/graphene oxide (GO) nanocomposite was prepared by homogenous dispersion of MWCNT and GO and used for the simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA). The TEM results confirmed that MWCNT walls were wrapped well with GO sheets. The MWCNT/GO nanocomposite showed superior electrocatalytic activity towards the oxidation of DA and PA, when compared with either pristine MWCNT or GO. The major reason for the efficient simultaneous detection of DA and PA at nanocomposite was the synergistic effect between MWCNT and GO. The electrochemical oxidation of DA and PA was investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The nanocomposite modified electrode showed electrocatalytic oxidation of DA and PA in the linear response range from 0.2 to 400 µmol L(-1) and 0.5 to 400 µmol L(-1) with the detection limit of 22 nmol L(-1) and 47 nmol L(-1) respectively. The proposed sensor displayed good selectivity, sensitivity, stability with appreciable consistency and precision.

Electrocatalytic Reduction of Metronidazole on Bismuth Modified Pencil‐lead Electrode

AbstractWe report a new and simple approach based on an experimental design method for the preparation of pencil‐lead electrode modified with bismuth thin film. The fabrication process consists of reduction of bismuth on the surface of electrode with potentiostate method. Response surface methodology was developed as experimental strategies for modeling and optimization of the influence of some variables on the performance of modified electrode. The electrocatalytic behavior of this modified electrode was exploited as a sensitive detection system for the mercury‐free reduction and determination of metronidazole in pharmaceutical and biological samples by using differential pulse voltammetry and amperometry methods.

Electrochemical synthesis of flower-like Pd nanoparticles with high tolerance toward formic acid electrooxidation

Flower-like nanoparticles exhibit unique properties due to the presence of edge and corner atoms, ad-atoms, pits and other collection of defects. In this work, flower-like Pd nanoparticles were obtained by surfactantless and additiveless square wave voltammetry as an electrochemical method of synthesis. Furthermore, other well-defined Pd shapes with dendritic growth such as spinous flower-like, cone and coral reef-like shapes were obtained by electrochemical methods using cyclic voltammetry, differential pulse amperometry and second harmonic AC voltammetry. Crystal sizes were calculated through the X-ray diffraction patterns for the spinous flower-like, cone, flower and coral reef-like palladium architectures resulting in sizes of 33, 56, 44 and 47 nm, respectively. SEM and cross-section TEM images confirmed that the architectures were composed of micro and nanostructures with dendritic growths. Cyclic voltammetry in acidic medium confirmed the presence of certain facets and terraces in both, flower-like Pd and the dendritic growths. The electrocatalytic properties of the palladium architectures were evaluated to the formic acid electrooxidation at 0.1, 0.5 and 1 M. The flower-like Pd architectures exhibited the highest tolerance to CO poisoning due to the process being carried out by a direct pathway and can be related to the effect of the unique flower-like shape which due to its nature exhibits a high presence of terraces and defects.

Development of an electroanalytical sensor for γ-hexachlorocyclohexane based on a cellulose acetate modified glassy carbon electrode

A simple, reproducible, environmentally friendly cellulose acetate modified glassy carbon electrode was prepared and used for the direct reduction of lindane in aqueous alcoholic medium. This modified electrode offers a high sensing current with a lower reduction potential for lindane. The lowest adsorption of pesticide molecules was observed on the cellulose acetate modified electrode when compared with a bare glassy carbon electrode which enhances the sensitivity of the sensor. This modified electrode is highly stable with respect to time, so that the single electrode can be used for the multiple analysis of the lindane sample. Cyclic voltammetry, differential pulse voltammetry and amperometry were used as the sensing techniques. The reduction potential of lindane on this modified electrode is −1.5 V whereas the reduction potential of nitropesticides is around −0.600 V. This wide difference in reduction potential can be used to estimate lindane even in the presence of nitropesticides by cyclic voltammetry and differential pulse voltammetry. The analytical utility of the proposed method was checked with a commercial lindane lotion and drinking water samples. An amperometric instrument, interfaced with the cellulose acetate modified glassy carbon electrode was designed and tested for the sensing of lindane. The performance of this instrument was assessed.

Nanosilver/surfactant modified glassy carbon electrode for the sensing of thiamethoxam

Abstract A simple, stable and reproducible nanosilver/SDS modified glassy carbon electrode was developed as a sensing probe for the electrochemical determination of thiamethoxam. The electrode offers very low reduction potential for thiamethoxam compared to other modified electrodes reported in the literature. A linear relationship between the peak current and the concentration was obtained from differential pulse voltammetry in the range from 0.1 to 9 μM with the detection limit of 0.1 μM. The modified electrode is highly stable over time; one time modified electrode can be used for seven measurements for the sensing of thiamethoxam. The cheap stabilizing agent, SDS was used for the preparation of silver nanoparticles. The analytical utility of the proposed sensor was tested with the potato samples. Real sample analysis was also carried out by using this electrode. The results show good agreement with the HPLC method. Cyclic voltammetry, differential pulse voltammetry and amperometry were used as sensing techniques. This electrode can be used for the sensing of thiamethoxam under field conditions.

Direct electrochemistry of hemoglobin immobilized in chitosan–room temperature ionic liquid film and application in its interaction with 3,4′-bis-(4-hydro-3-xycoumarin)-2,5-hexanediol

The direct electrochemistry of hemoglobin (Hb) and application in its interaction with 3,4′-bis-(4-hydro-3-xycoumarin)-2,5-hexanediol (HCH) based on the Hb immobilized in chitosan–room temperature ionic liquid film were investigated by means of cyclic voltammetry, differential pulse voltammetry and amperometry. The binding ratio m and binding constant between HCH and Hb were estimated as 2 and 3.46M−1, respectively. The amperometric response showed a linear dependence on the concentration of HCH with the detection limit of 0.06μM. In addition, the amperometry was a novel method in the field of binding studies and might be taken into account for future binding studies. At last a sensitive and convenient electrochemical method was proposed for the determination of HCH.

Characterization of Novel Microelectrode Geometries for Detection of Neurotransmitters

In this paper, a microelectrode array is introduced and characterized using differential pulse voltammetry (DPV), amperometry and fast scan cyclic voltammetry with norepinephrine as a model neurotransmitter. Twenty-one sensor geometries were evaluated with DPV to determine optimal electrode configurations. Next, electrode responses were characterized for the best electrode geometry using an onboard platinum pseudo-reference electrode, whose reliability is established.

Gold nanoparticle–polypyrrole composite modified TiO2 nanotube array electrode for the amperometric sensing of ascorbic acid

Titanium dioxide (TiO2) nanotubes were fabricated by anodisation of titanium foil in 0.15 M ammonium fluoride in an aqueous solution of glycerol (90 % v/v). Electropolymerisation of pyrrole and deposition of gold nanoparticles on to the TiO2 nanotube array electrode were carried out by cyclic voltammetry (CV). Electrochemical characterization of the sensor was performed by CV and electrochemical impedance spectroscopy. The morphology of the electrode was studied after every step of modification using field emission scanning electron microscope and atomic force microscope. The sensor was tested for AA and other biomolecules in phosphate buffered saline solution of pH 7 using CV, differential pulse voltammetry and amperometry. The sensor exhibited very high sensitivity of 63.912 μA mM−1 cm−2 and excellent selectivity to ascorbic acid (AA) in the presence of other biomolecules such as uric acid, dopamine, glucose and para-acetaminophen. It also showed very good linearity (R = 0.9995) over a wide range (1 μM–5 mM) of detection. The sensor was tested for AA in lemon and found its concentration to be 339 mg ml−1.