Differential Pulse Amperometry Research Articles

Intelligent machine learning enabled sensor for acyclovir using NiMnO3 flower-like electrocatalyst

Hierarchical flower-like NiMnO3 was prepared using a hydrothermal route for oxidative detection of acyclovir (ACV), an antiviral pharmaceutical pollutant. The flower-like structure with an electroactive surface area (EASA) of 0.0952 cm2 enables non-revisable oxidation of ACV, with differential pulse voltammetry (DPV) and amperometry confirming its robust analytical capability in both high (15–75 µM) and low (0.1–1.0 µM) concentration ranges, respectively. Using amperometry, the sensor achieved an estimated limit of detection (LOD) of 1.59 nM (S/N=3) with selective oxidation of ACV and a sensitivity of 1.039µA µM−1 cm2 in the presence of other common interferants. The adaptation of machine learning (ML) algorithms like random forest, XGBoost, linear regression, and ANN validated sensors’ performance and confirmed ANN’s superiority in DPV signal interpretation. NiMnO3, as an electrocatalyst for ACV oxidation, validated by ANN modeling, highlights bimetallic oxides’ potential as a cost-effective, versatile platform for detecting pharmaceutical pollutants.

Metal-polymer-clay nanocomposites based electrochemical sensor for detecting hydrazine in water sources

AgNPs embedded polymer-clay (AgNPs@PEI-HNT) nanocomposites were successfully employed to sensitively detect hydrazine in water samples using differential pulse voltammetry (DPV) and amperometry methods. In-situ polymerization was utilized for assembling the polymer-clay composites, which were subsequently coated with AgNPs. PEI improves conductivity and absorbs AgNPs on the surface of HNTs, as evidenced with the help of UV-Visible, IR spectroscopy, XRD, XPS and morphological studies (FE-SEM and TEM). Nanocomposites were coated with GCE, which improved their electrocatalytic performance during hydrazine oxidation. The Tafel plot, Galus and Cottrell equations were used to compute the electron transfer coefficient (0.64), catalytic reaction rate constant (4.81 × 104 M−1s−1) and diffusion coefficient (2.56 × 10−5 cm2/s) of hydrazine at AgNPs@PEI-HNT/GCE. Amperometry technique was used to determine the LOD along with sensitivity of hydrazine, which were 0.22 nm and 116.76 µA µM−1 cm−2. Modified electrode offers enhanced properties for example strong anti-interference capability, good reproducibility, long-term stability, sensitivity, and so on. The designed sensor successfully detects hydrazine in water samples with high recovery rates (R.S.D. < 5 %).

Microneedle electrochemical sensor based on disposable stainless-steel wire for real-time analysis of indole-3-acetic acid and salicylic acid in tomato leaves infected by Pst DC3000 in situ

BackgroundIndole-3-acetic acid (IAA) and salicylic acid (SA), pivotal regulators in plant growth, are integral to a variety of plant physiological activities. The ongoing and simultaneous monitoring of these hormones in vivo enhances our comprehension of their interactive and regulatory roles. Traditional detection methods, such as liquid chromatography-mass spectrometry, cannot obtain precise and immediate information on IAA and SA due to the complexity of sample processing. In contrast, the electrochemical detection method offers high sensitivity, rapid response times, and compactness, making it well-suited for in vivo or real-time detection applications. ResultsA microneedle electrochemical sensor system crafted from disposable stainless steel (SS) wire was specifically designed for the real-time assessment of IAA and SA in plant in situ. This sensor system included a SS wire (100 μm diameter) coated with carbon cement and multi-walled carbon nanotubes, a plain platinum wire (100 μm diameter), and an Ag/AgCl wire (100 μm diameter). Differential pulse voltammetry and amperometry were adopted for detecting SA and IAA within the range of 0.1–20 μM, respectively. This sensor was applied to track IAA and SA fluctuations in tomato leaves during PstDC3000 infection, offering continuous data. Observations indicated an uptick in SA levels following infection, while IAA production was suppressed. The newly developed disposable SS wire-based microneedle electrochemical sensor system is economical, suitable for mass production, and inflicts minimal damage during the monitoring of SA and IAA in plant tissues. SignificanceThis disposable microneedle electrochemical sensor facilitates in vivo detection of IAA and SA in smaller plant tissues and allows for long-time monitoring of their concentrations, which not only propels research into the regulatory and interaction mechanisms of IAA and SA but also furnishes essential tools for advancing precision agriculture.

Optimization of Electrochemical Sensitivity in Anticancer Drug Quantification through ZnS@CNS Nanosheets: Synthesis via Accelerated Sonochemical Methodology

Zinc sulfide/graphitic Carbon Nitride binary nanosheets were synthesized by using a novel sonochemical pathway with high electrocatalytic ability. The as- obtained samples were characterized by various analytical methods such as Transmission Electron Microscopy (TEM), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) to evaluate the properties of ZnS@CNS synthesized by this new route. Subsequently, the electrical and electrochemical performance of the proposed electrodes were characterized by using EIS and CV to establish an electroactive ability of the nanocomposites. The complete properties like structural and physical of ZnS@CNS were analyzed. As-prepared binary nanocomposite was applied towards the detection of anticancer drug (flutamide) by various electrochemical methods such as cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. The glassy carbon electrode modified with a ZnS@CNS composite demonstrates a remarkable electrocatalytic efficiency for detecting flutamide in a pH 7.0 (PBS). The composite modified electrode shows synergistic effect of ZnS and CNS catalyst. The electrochemical sensing performance of the linear range was improved significantly due to high electroactive sites and rapid electron transport pathways. Crucially, the electrochemical method was successfully demonstrated in biological fluids which reveals its potential real-time applicability in the analysis of drug.

Carbon Nanotube Modified Glassy Carbon Electrodes for on‐line and off‐line in vitro Therapeutic Equivalence Assessment of Paracetamol Tablets

AbstractIn vitro bioequivalence assessment of paracetamol tablets was carried out by differential pulse voltammetry (DPV) and amperometry using a multiwalled carbon nanotube modified glassy carbon electrode (GCE/MWCNT). For the DPV developed method, samples were collected from the USP paddle apparatus, while amperometric measurements were carried out in situ. The DPV method was validated in three supporting electrolytes (per in vitro bioequivalence guidelines) by measuring the recovery from standard solutions and paracetamol tablet solutions, while precision was evaluated through the RSD (n=6). In HCl pH 1.2 solution the LOD and LOQ were 48 nM and 160 nM, respectively and the linear range was between 0.18–2.2 μM. In acetate buffer pH 4.5 the LOD and LOQ were 15 nM and 51 nM, respectively and the linear range was between 88 nM–880 nM. And in phosphate buffer pH 6.8 the LOD and LOQ were 4.6 nM and 15 nM, respectively and the linear range was between 88 nM–880 nM. Recovery values were between 95 and 105 % and precision values were less than 5 %. Results showed that both methods were effectively applied for the analysis of samples.

Electrochemical investigation on naproxen sensing and steady-state diffusion analysis using Ni-Fe layered double hydroxide modified gold electrode

Naproxen, a nonsteroidal anti-inflammatory drug commonly used to treat various types of arthritis, including osteoarthritis, juvenile arthritis, and rheumatoid arthritis, has been associated with serious gastrointestinal and kidney complications. To address this issue, a long-lasting electrochemical sensor capable of sensitively and rapidly detecting naproxen has been developed. The sensor was fabricated by electrodepositing nickel–iron layered double hydroxide (NiFe LDH) on the surface of gold electrode, utilizing ferric nitrate and nickel nitrate as precursors. The NiFe LDH thin film serves as an efficient sensing platform for naproxen determination, and its electrochemical performance was characterized using differential pulse voltammetry and amperometry. Impressively, the developed naproxen sensor boasts a wide dynamic detection range (1–307 μM) and a remarkably low limit of detection of 0.32 μM. Additionally, the NiFe LDH/Au electrode exhibited long-term operational stability of 28 days, rapid response time (<80 s), excellent selectivity, and good reproducibility (1.89% RSD). In addition, Hermite wavelet was employed to formulate the relationship between the steady-state concentration of naproxen and the distance from the electrode's surface. With these impressive attributes, the NiFe LDH modified Au electrode is a promising candidate for the development of a long-lasting and reliable naproxen sensor.

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.

Amperometric determination of salivary thiocyanate using electrochemically fabricated poly (3, 4-ethylenedioxythiophene)/MXene hybrid film

Thiocyanate (SCN) is a hazardous byproduct of the detoxification of cyanide. Even in minute quantity, the SCN has a negative impact on health. Although there are several ways for SCN analysis, an efficient electrochemical procedure has hardly ever been attempted. Here, the author reports the development of a highly selective and sensitive electrochemical sensor for SCN utilizing Poly (3, 4-Ethylenedioxythiophene) incorporated MXene (PEDOT/MXene) modified screen-printed electrode (SPE). The Raman, X-ray photoelectron (XPS), and X-ray diffraction (XRD) analyses support the effective integration of PEDOT on the MXene surface. Further, scanning electron microscopy (SEM) is employed to demonstrate the formation of MXene and PEDOT/MXene hybrid film. In order to specifically detect SCN in phosphate buffer media (pH 7.4), the PEDOT/MXene hybrid film is grown on the SPE surface via the electrochemical deposition method. Under the optimized condition, the PEDOT/MXene/SPE-based sensor provides a linear response against SCN from 10 to 100 µM and 0.1 μM to 1000 μM with the lowest limit of detections (LOD) of 1.44 μM and 0.0325 μM by differential pulse voltammetry (DPV) and amperometry, respectively. For accurate detection of SCN, our newly created PEDOT/MXene hybrid film-coated SPE demonstrates excellent sensitivity, selectivity, and repeatability. Ultimately, this novel sensor can be used to detect SCN precisely in environmental and biological samples.

Two dimensional architectures of graphitic carbon nitride with the substitution of heteroatoms for bifunctional electrochemical detection of nilutamide

The exploration of graphitic carbon nitride (g-C3N4), a two-dimensional (2D) metal-free polymer semiconducting material, is largely discussed due to its large specific surface area, high electrical conductivity, thermal stability, and adaptable electronic structure. The adaption of sulfur (S) and phosphorous (P) atoms into the layers of g-C3N4 increases the electrochemical performance of detecting nilutamide (NT). The aggregation severity can be decreased by integrating S/P into g-C3N4, thereby improving surface area and electrical conductance. The g-C3N4, S/gC3N4, P/g-C3N4, and S/P/g-C3N4 were studied with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Ultraviolet visible spectroscopy (UV), Thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET). The well-assigned S/P/g-C3N4 exhibited a good crystalline structure with more active sites for improved electron transfer toward NT detection. Both differential pulse voltammetry (DPV) and amperometry (IT) was studied for NT detection. The electrochemical studies were done with a linear range of 0.019–1.17 μM to 5.36–1891.98 μM in DPV and 0.01 μM–158.3 μM in IT technique. The attained limit of detection in DPV analysis was 3.2 nM and with IT analysis 2.4 nM. The nanocomposite S/P/g-C3N4 shows good selectivity towards NT. The fabricated electrode showed excellent repeatability, reproducibility, and stability, with a significant recovery range in real sample analysis.

Static and dynamic analysis of sulfamethoxazole using GO/ZnO modified glassy carbon electrode by differential pulse voltammetry and amperometry techniques.

Surface water contamination of sulfamethoxazole (SMX) has tremendously affected the ecosystem. A primary study was performed to develop an electrochemical sensor for the determination of SMX. Overcoming the demerit associated with the conventional techniques, an electrochemical method was developed using GO/ZnO nanocomposite modified electrode to detect SMX in 0.1M phosphate buffer (pH-5.5) buffer solution. The GO, ZnO and GO/ZnO nanocomposite were prepared using modified Hummer's, precipitation and sonochemical methods, respectively. Physico-chemical properties of all the materials and its modified electrode were analysed. Comparison was made by studying the SMX sensing performance of electrodes modified with GO, ZnO and GO/ZnO nanocomposites. Out of which GO/ZnO nanocomposite exhibited excellent sensing performance with the concentration range from 0.10×10-6 to 1.5×10-6M with the limit of detection (LOD) 28.9nM. The parameters such as electrolyte, effect of pH, scan rate were optimized for effective sensing performance. From the optimized results 0.1M phosphate buffer was found to be a suitable electrolyte and the pH 5.5 was found to be appropriate to sense SMX at the scan rate 50mVs-1. Under optimized condition, the Differential Pulse Voltammetry (DPV) and Amperometry techniques were adopted for electrochemical sensing of SMX under static and hydrodynamic condition. The developed method was successfully tested for real time analysis for the samples collected from waste water treatment plant.

Gold structures on 3D carbon electrodes as highly active nanomaterials for the clean energy conversion of crude glycerol

The electrochemical stability of gold nanomaterials and their ability to oxidize C2 and C3 polyols makes them suitable electrocatalysts for the oxidation of biofuels like crude glycerol. In this work, Au nanomaterials were electrodeposited by differential pulse amperometry (named as Au DPA 1&2) and cyclic voltammetry (Au CV 1&2) onto 3D porous carbon paper electrodes. X‒ray diffraction patterns indicated that DPA promoted the abundance of Au with {100} surface domains (Au DPA 2), and it was attributed to the formation of 3D hierarchical structures known to be rich in surface/crystalline defects. While, CV allowed to obtain hemispheres with small particle sizes. For the crude glycerol oxidation, Au DPA 2 was the most active material, displaying 56.2 mA cm−2 at 0.5 M crude glycerol + 3 M KOH at 20 mV s−1, and onset potential of −0.13 V vs. NHE (only 70 mV more positive than monometallic Pd). According to impedance studies, this activity was attributed to the decrease of the resistances to charge transfer (Rct) at different steps of the electrocatalytic process, suggesting a better renewal of actives sites, and a better tolerance to poisoning by intermediates. Differential pulse voltammetry (DPV) curves demonstrated that the abundance of {100} surface sites enhanced the OH− adsorption to form Au(OH)ads species lowering the potentials to start the reaction, boosting the activity and durability.

Electrochemical Dopamine Detection using a Fe/Fe3O4@C Composite derived from a Metal‐Organic Framework

AbstractIn this paper, a novel composite of Fe/Fe3O4@C is synthesized by taking a Fe‐metal‐organic framework (Fe‐MOF) as precursor template. Different treating temperature (450, 550, 650 and 750 °C) were carried out to investigate the composite of calcined products. The Fe/Fe3O4@C‐650 modified glassy carbon electrode (Fe/Fe3O4@C‐650GCE) shows good electrocatalytic activity towards dopamine (DA) oxidation. Three electrochemical measuring methods of cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry i‐t are adopted to investigate the sensing behaviors of Fe/Fe3O4@C‐650/GCE. The results show that: the sensors based on CV and DPV technology exhibit excellent advantages in the aspect of sensitivity and linear range thanthose of the sensor based on amperometry i‐t technology. Meanwhile, the sensor based on CV method shows good selectivity for dopamine, and can resist the influence of various sugars, uric acid, ascorbic acid, as well as Na+ and K+. The sensor also shows good stability and repeatability in the sensing process. In addition, the Fe/Fe3O4@C‐650/GCE could be successfully applied in the DA detection in the human serum.

2D MXene/graphene nanocomposite preparation and its electrochemical performance towards the identification of nicotine level in human saliva

The quantitative analysis of neurological drugs is critical since the kinetics of body fluids is strongly dependent on the dosage of the drug levels. Thus, the study of neurological medicines is significant because of the major diseases connected to it, for instance, Alzheimer's and Parkinson's diseases. Herein, a 2D hybrid MXene/graphene (MX/Gr) film was synthesized through a top-down approach and utilized to prepare an electrochemical transducer for the electrochemical sensing of nicotine. The X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of MX with Gr sheets. The high-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (TEM) have been used to confirm the formation of MX, graphene sheets and the MX/Gr hybrid film. Furthermore, the MX/Gr hybrid film composite modified glassy carbon electrode (GCE) was prepared to selectively detect the nicotine in phosphate buffer medium (0.1 M PBS, pH~7.4). Under the optimized condition, the MX/Gr/GCE based sensor provided a linear response against nicotine from 1 to 55 µM and 30 nM – 600 nM with the lowest limit of detections (LOD) of 290 nM and 0.28 nM by differential pulse voltammetry (DPV) and amperometry, respectively. This newly developed MX/Gr hybrid film modified electrode displayed a remarkable selectivity, sensitivity, and reproducibility for accurate detection of nicotine. Finally, this new sensor was applied to detect nicotine in human/artificial saliva samples with high accuracy.

Electrochemical Sensing of Arsenic Ions Using a Covalently Functionalized Benzotriazole‐Reduced Graphene Oxide‐Modified Screen‐Printed Carbon Electrode

AbstractHerein,Tecoma stans(TS) flower extract was used as an efficient green reducing agent for graphene oxide (GO) to produce reduced graphene oxide (rGO) for the first time. The organic heterocyclic benzotriazole (BTA) was incorporated onto the rGO surface through a nucleophilic substitution reaction to produce covalently bonded BTA‐rGO. The prepared materials were analyzed by UV‐visible spectroscopy, powder X‐ray diffraction measurements (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and Scanning Electron Microscopy (SEM). A screen‐printed carbon electrode (SPCE) was modified with BTA‐rGO. The fabricated electrode was electrochemically analyzed by using K3[Fe (CN)6] as a redox probe. To evaluate the sensing ability of BTA‐rGO/SPCE electrode towards arsenic ions using differential pulse voltammetry (DPV) and amperometry techniques. The BTA functional was play the major role in significant improving the conductivity and sensitivity of the designed electrode. The BTA‐rGO/SPCE modified electrode demonstrates voltammetric determination of As3+ions with a limit of detection, high sensitivity, and linear range values of 2.89 nM, 1.8 μA nM−1, and 2–40 nM, respectively. Furthermore, all of these impressive results indicate that BTA‐rGO can be used as an electrode‐material with capability for electrochemical arsenic sensors. The fabricated sensors showed repeatability and reproducibility in this study.

Hemin-Modified Halloysite Nanotube as Electrocatalyst for the Enhanced Electrochemical Determination of Nitrite

Halloysite is naturally occurring nanotubular clay with a phyllosilicate structure and widely used as solid support to modify various redox mediators. We prepared a hemin modified halloysite (Hemin/HNT) by a simple impregnation method, in which a known amount of halloysite was dispersed in ethanolic solution of 1% hemin and reacted for 12 h. The resulting pure Hemin/HNT was employed as electrocatalyst for the electrochemical oxidation of nitrite by cyclic voltammetry. The coverage of hemin molecule over the nanotubular halloysite was confirmed by TGA, FT-IR, XRD and XPS studies. The electron transfer behavior of Hemin/HNT was studied by CV and EIS. It was noted that hemin/HNT modified GCE showed two-fold enhanced oxidation peak current for nitrite with a peak potential of + 0.8 V vs Ag/AgCl in 0.1 M PBS. For a quantitative electrochemical analysis of nitrite ion at the trace levels the differential pulse voltammetry (DPV) and amperometry methods were used based on hemin/HNT modified GCE. A linear calibration plot was constructed by plotting the peak current against the concentrations of nitrite in the ranges of 0.6 × 10−6 M to 24.6 × 10−5 M, (R2 = 0.9968) and 0.6 × 10−8 to 43.3 × 10−7 M (R2 = 0.9996) and the detection limit was found to be 42 and 43 nM with a sensitivity of 23.55 and 22.96 μA.μM−1.cm−2 by DPV and amperometry, respectively. The repeatability of the proposed sensor evaluated in terms of relative standard deviation of 1.7% for 5 measurements (3.3 × 10−6 M) nitrite. The inference effect of various anions and cations on nitrite oxidation peak current was studied by amperometry method. A stable and reliable current response was obtained for nitrite analysis in water samples.

Electrochemical Dopamine Sensor Based on Gold Nanoparticles Electrodeposited on a Polymer/Reduced Graphene Oxide-Modified Glassy Carbon Electrode

A novel electrochemical dopamine (DA) sensor based on Au nanoparticles (AuNPs) electrochemically loaded on poly([2,2′;5′,2″]-terthiophene-3′-carbaldehyde)/reduced graphene oxide (poly(TTP)/rGO) improved glassy carbon electrode (GCE) was fabricated. The Au@poly(TTP)/rGO/GCE was evaluated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), amperometry, and electrochemical impedance spectroscopy (EIS). The optimized Au@poly(TTP)/rGO/GCE sensor had a wide electroactive surface area and exhibited good selectivity. The linear determination range of the sensor was from 0.02 to 232 µM with a sensitivity of 315 µA/mM/cm2. The limit of detection (LOD) was estimated to be 11.5 nM using signal-to-noise (S/N) ratio of 3. Additionally, the sensor displayed excellent selectivity, satisfactory response time from 4.5 to 6 s, replicability with a relative standard deviation (RSD) of 2.31%, reproducibility with a RSD of 3.67%, and storage stability with 92.57% of its initial current response for 37 days. The Au@poly(TTP)/rGO/GCE was employed to estimate DA in injection samples.

Synthesis and Application of Graphdiyne Oxide-Polyurethane Nanocomposite Yield a Highly Sensitive Non-Enzyme Glucose Sensor

Graphdiyne is a new carbon nanomaterial after graphene. It has excellent electrical properties and can be chemically modified. Here, a graphdiyne oxide-polyurethane nanocomposite (GDYO-PU) was synthesized by chemical coupling and characterized with Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). A GDYO-PU modified glassy carbon electrode (GCE) was applied as a non-enzymatic glucose electrode. The electrochemical property of the GDYO-PU electrode was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry in the presence of [Fe(CN)6]3−/4− in 0.1 M NaOH alkaline solution and at the bias potential of 0.2 V. Fast electro-deposition was observed for the electrochemical deposition of Fe(CN)6 3−/4− on the GDYO-PU electrode surface. Under the optimized conditions, the calibration curve of the nano electrode is linear over the concentration range of 0.2 to 6.4 μM, with high sensitivity of 377 μAmM−1cm−2 as well as a low detection limit (LOD) of 0.1 μM (S/N = 3). The GDYO-PU nanocomposite based non-enzyme glucose electrode is therefore promising for analysis of tiny volume of biological samples, which meets the requirement of minimal invasive measurement in clinic and family care.

Voltammetric determination of alpha lipoic acid using chitosan-based polyurethane membrane electrode

In this study, chitosan-based polyurethane (PU) membrane modified electrodes were prepared for sensitive, practical and fast measurement of α-lipoic acid (ALA), which is an important biomolecule. PU membranes were synthesized using hexamethylene diisocyanate, chitosan, caffeic acid and polyethylene glycol compounds. Chemical structure, thermal stability and morphological properties of the prepared PU membranes were determined with different instrumental techniques. Surface morphology, wettability and hydrophilicity of synthesized chitosan-based PU membranes were investigated. Gold electrode was modified by these PU membranes with different film thicknesses. The bare and PU membrane coated electrodes were used for deduction of ALA by cyclic voltammetry, differential pulse voltammetry and amperometry techniques. In addition, sensitivity, linearity, repeatability and deduction limit of PU modified electrodes were investigated. Modified electrodes showed wide linear detection range (5–200 µmolL−1), low detection limit (4.931 µmolL-1) and short response time. Results show that polyurethane modified electrodes are good alternative for ALA determination.

Fortified electrochemical activity of Au@Fe3O4@rGO decorated GCE for sensing of acetaminophen

In this work, the decoration of a GCE with an Au@Fe3O4@rGO nanocomposite material and its benefit as a sensor for the detection of acetaminophen (AP) in a phosphate buffer solution (PBS) with (pH = 7) are analysed. The nanocomposite mixture was prepared by a simple co-precipitation method and characterized by different surface analytical techniques. The electrochemical characteristics of the modified nanocomposite electrode were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. The Au@Fe3O4@rGO/GCE nanocomposite showed good electrochemical sensitivity and performance towards AP. The peak current obtained by amperometry gradually increased with an increase in the AP concentration in the hiatus ranging from 0.01 to 0.28 μM (R2 = 0.99) with a calculated low limit of detection (LOD) and good sensitivity of 5 nM and 0.11 μA μM−1 respectively revealing a good rapid response. The proposed sensor was assessed for the determination of AP in human urine sample and in the unknown concentration of AP with good recoveries suggesting that the modified electrode can effectively sense AP in human urine sample.

Fabrication of disposable electrochemical dopamine sensor using photoluminescent graphene oxide

Graphene oxide (GO) with photoluminescent property was prepared by modifiedHummer’s method. Spectroscopic and morphological studies were carried out using photoluminescence spectroscopy, UV-Vis absorption spectroscopy, FT-IR, XRD and FE-SEM. Electrochemical dopamine sensor was fabricated by drop casting GO onto screen printed carbon electrodes (SPCE). Cyclic voltammogram, differential pulse voltammogram and amperometry were performed to test the fabricated sensor. The sensor exhibits wide detection range of 12.5 μM to 1 mM dopamine concentrations in 0.1 M PBS of pH 7.4. The major interferents such as ascorbic acid shown negligible current response compared to dopamine.