Differential Pulse Voltammetry Techniques Research Articles

Purpald-functionalized biosensor for simultaneous electrochemical detection of ascorbic acid, uric acid, L-cysteine and lipoic acid

The polymer purpald (4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) film on glassy carbon electrode (p-Purpald@GCE) was fabricated using purpald monomer by electropolymerization method, and the modified electrode was applied as a probe for the simultaneous sensing of ascorbic acid (AA), uric acid (UA), L-cysteine (L-Cys) and lipoic acid (LA). The modified p-Purpald@GCE was well characterized by Scanning electrode microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and Differential Pulse Voltammetry (DPV) techniques. CV, EIS results were confirmed the good electrocatayst nature of p-Purpald@GCE. Independent and simultaneous detection of AA, UA, L-Cys, and LA ware performed by DPV method. For Independent detection, based on the oxidation current changes, we have calculated the limit of detection (LOD) of 392, 137, 341 and 200 nM (LOD) = 3S/m) for AA, UA, L-Cys and LA, respectively. The simultaneous detection of AA, UA, L-Cys, and LA executed and LOD found to be 364, 132, 275 and 192 nM, respectively. The modified electrode shows the high selectivity towards AA, UA, L-Cys and LA even in the presence of high concentration of other interferences. The developed sensor technique will be useful for the sensitive and simultaneous detection of AA, UA, L-Cys, and LA in food and clinical samples.

Design of sonochemical assisted synthesis of Zr-MOF/g-C3N4-modified electrode for ultrasensitive detection of antipsychotic drug chlorpromazine from biological samples.

Therapid fabrication is describedof binary electrocatalyst based on a highly porous metal-organic framework with zirconium metal core (Zr-MOF) decorated over the graphitic carbon nitride (g-C3N4) nanosheets via facile ultrasonication method. It is used for the robust determination of antipsychotic drug chlorpromazine (CLP) from environmental samples. The electrochemical behaviour of 2D Zr-MOF@g-C3N4 was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. The crystalline and porous nature of the composite was characterized by XRD and SEM analysis. The functional groups and surface characteristics were investigated by FT-IR, Raman and XPS. The major electrochemical properties of the Zr-MOF@g-C3N4 composite towards CLP detection were analyzed by CV, chronocoulometric (CC), chronoamperometric (CA) and differential pulse voltammetry (DPV) techniques. The composite exhibits a low detection limit (LOD) of 2.45nM with a linear range of 0.02 to 2.99µM and attractive sensitivity for CLP. The sensor system shows higher selectivity towards the possible interferences of CLP drug and exhibits betterrepeatability and stability. Finally, the fabricated sensor system shows a high recovery range varying from 96.2 to 98.9% towards the real samples. The proposed electrochemical probe might be a promising alternative to the prevailing diagnostic tools for the detection of CLP.

Methanol detection with Au-nanoparticles decorated-PPyC-SnO2 nanocomposites using PEDOT:PSS polymer by differential pulse voltammetry

In this approach, sensitive development of methanol electrochemical sensor based on Au-nanoparticles decorated polypyrrole carbon with tin dioxide nanocomposites (Au NPs-PPyC-SnO2 NCs) were prepared and deposited onto glassy carbon electrode (GCE) to make sensor probe using PEDOT:PSS polymer as a conducting binder. The newly developed Au NPs-PPyC-SnO2 NCs were prepared through wet chemical and photo-reduction techniques in lab-made experimental scales, resulting in a morphology that promotes electrochemical reactions for detecting unsafe methanol under ambient conditions using three-electrode systems by differential pulse voltammetry (DPV). The sensor exhibited higher sensitivity (4.2373 µAµM-1cm−2), lower limit of detection (LOD; 2.39 ± 0.12 µM), and a wide linear detection range (LDR; 30.0 to 300.0 µM), which measured from the slope of the calibration curve from concentration variation analyses by considering the active surface area of the coated GCE. To validate its practical application, the fabricated Au NPs-PPyC-SnO2 NCs/GCE sensor electrode was tested for several real samples. It was found a satisfactory performance in the detection of methanol that was observed by using the electrochemical DPV technique with the recovery approach for the fabricated Au NPs-PPyC-SnO2 NCs/GCE sensor probe. It has introduced a new route for the sensitive detection of target methanol with gold-decorated nanocomposite materials in the protection of environmental and ecological fields using an electrochemical approach on a large scale.

Enhanced electrocatalytic oxidation activity of platinum-poly(methylene blue) as a sensitive sensor for ammonia–nitrogen detection

To achieve highly effective electrochemical determination of ammonia–nitrogen in the aqueous environment, in this work, based on the great electrocatalytic activities of platinum-poly(methylene blue) (Pt-PMB) composites for ammonia oxidation reaction, one new sensing electrode was constructed based on Pt-PMB for ammonia–nitrogen detection. PMB film was loaded on the surface of Ni foam (NF), and then, Pt film was covered on the PMB film, achieving a self-supported Pt-PMB-NF electrode. Under optimum conditions, prepared Pt-PMB-NF was analyzed via scanning electron microscopy (SEM) and element map and X-ray photoelectron spectroscopy (XPS), and the sensing performances including sensitivity, the limit of detection, selectivity and stability were measured via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques and exhibited great results. In addition, the recovery of real samples indicated that this Pt-PMB-NF electrode showed great potential for practical application.

DFT and electrochemical determination of Hg2+ and Pb2+ in water using polyaniline–quinoxaline composite modified GCE electrode

In this study, we designed and synthesized a new class of donor–acceptor conjugated polymers containing the polyaniline-quinoxaline [Acenaptho [1, 2 -b] quinoxalin-9-amine] (PAni-QUA) composite, and we subsequently utilized it as an electrochemical sensor to detect Hg2+ and Pb2+ ions with good selectivity and sensitivity. Energy dispersive X-ray analysis spectroscopy (EDAX), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and UV–Vis spectroscopy (UV–Vis) were employed to analyze the structural and morphological characteristics of the resulting composite. The electrochemical characteristics of the electrode modifiers were analyzed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Several sensitivity-influencing factors, including chemical and electrochemical parameters like pH and the impact of the supporting electrolyte medium, were also identified to improve the efficiency of the developed sensor. In the presence of different hazardous metal ion species, the interference ability of the proposed sensor was also examined. They were also used to conduct individual and simultaneous sensing studies of various metal ions in different supportive electrolyte media utilizing the differential pulse voltammetry technique (DPV). The PAni-QUA composite modified GCE sensor shows remarkable selectivity and sensitivity towards Hg2+ and Pb2+ ions over the other heavy metal ions in 1 to 20 µM ranges, respectively. The detection limits (3σ/m) were 1.28 nM and 5.91 nM for Hg2+ and Pb2+ ions. Density Functional Theory (DFT) was used in the present study to accomplish the adsorption mechanism of the suggested sensors. The DFT calculation demonstrated that the PAni-QUA composite was formed with a lower band gap energy than QUA and DD PAni. These results showed that the suggested sensor (PAni-QUA) had the lowest detection limit in the acetate buffer medium compared to the specified electrolyte media. Based on these findings, it is possible to use this technology to identify harmful metal ions (Hg2+ and Pb2+) with high sensitivity in real water samples.

High-throughput screening of perovskite-based electrochemical sensor for determination of piroxicam via electrocatalytic oxidation in pharmaceutical and biomedical analysis

Piroxicam is a drug from the oxicam family and is an anti-inflammatory one which is used to relieve pain in humans. In this research work, the electrochemical modifier agents are perovskite nanosheets, graphene oxide (GO) and their effective nanocomposite. The morphology of La(Fe0.7Mn0.3)0.9Pd0.1O3, GO, and La(Fe0.7Mn0.3)0.9Pd0.1O3/GO nanocomposite were examined by SEM, EDX, FTIR, XPS and XRD analysis. The results obtained from the surface analysis of nanocomposite materials represent the compatibility of the intended perovskite structure with the cubic one. Also, GO has affected the main structure of the composite material. According to the results for the perovskite, the porous structure is shown and GO is well placed in the porous structure of the perovskite. Furthermore, the presence of elements in the perovskite structure was confirmed by EDX. Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) techniques were used to investigate the electrochemical behavior of piroxicam and quantification, respectively. The above-mentioned electrode has been utilized to determine the piroxicam. In which, LOD (limit of detection) and the linear range were acquired 0.89 μM and 6–103 μM respectively for piroxicam oxidation process. Eventually, the designed sensing assay was used for the detection and quantification of piroxicam in capsule and human plasma samples. The obtained results from the designed sensor specify acceptable analytical characteristics consisting of low LOD, widespread linear range, and adequate proficiency for the highly sensitive determination of piroxicam. Additionally, La(Fe0.7Mn0.3)0.9Pd0.1O3/GO GCE showed acceptable stability, repeatability, and reproducibility. To investigate the accuracy of the mentioned assay, the recovery index of 96.41% (RSD <5%) indicates the high performance in real samples.

Synthesis and characterization of N-MPG/CuS flower-like/MXene to modify a screen-printed carbon electrode for electrochemical determination of nalbuphine

Nalbuphine (NAL) is a drug with narcotic properties and analgesic effects, and its use has side effects such as drowsiness, nausea, and headache. Excessive use of this drug leads to death. Measuring NAL is important to ensure that the correct dose is administered to the patient and to avoid overdose or underdose. It is also important to monitor the patient's response to the medication and adjust the dosage if necessary. Additionally, measuring nalbuphine levels may be important in cases of suspected overdose or toxicity. In the present research, a very simple and cheap method based on screen-printed carbon electrodes coated with CuS flower-like and N-doped mesoporous graphene and MXene was constructed for the measurement of NAL. At first, the modifier was analyzed by SEM, EDS, and TEM methods. Then, the NAL measurement was done by cyclic and differential pulse voltammetry techniques. Results showed a good ability of the prepared sensor for measurement of NAL in the span of 5–150 μM, which reached a detection limit of 1.6 μM. The prepared sensor showed the capability of NAL measurement in real samples.

Bismuth sulfide micro flowers decorated nickel foam as a promising electrochemical sensor for quantitative analysis of melamine in bottled milk samples

Here, we demonstrate hydrothermally grown bismuth sulfide (Bi2S3) micro flowers decorated nickel foam (NF) for electrochemical detection of melamine in bottled milk samples. The orthorhombic phase of hydrothermally grown Bi2S3 is confirmed by the detailed characterization of x-ray diffraction and its high surface area micro flowers-like morphology is investigated via field emission scanning electron microscope. Furthermore, the surface chemical oxidation state and binding energy of Bi2S3/NF micro flowers is analyzed by x-ray photoelectron spectroscopy studies. The sensor exhibits a wide linear range of detection from 10 ng l−1 to 1 mg l−1 and a superior sensitivity of 3.4 mA cm−2 to melamine using differential pulse voltammetry technique, with a lower limit of detection (7.1 ng l−1). The as-fabricated sensor is highly selective against interfering species of p-phenylenediamine (PPDA), cyanuric acid (CA), aniline, ascorbic acid, glucose (Glu), and calcium ion (Ca2+). Real-time analysis done in milk by the standard addition method shows an excellent recovery percentage of ̴ 98%. The sensor’s electrochemical mechanism studies reveal that the high surface area bismuth sulfide micro flowers surface interacts strongly with melamine molecules through hydrogen bonding and van der Waals forces, resulting in a significant change in the sensor’s electrical properties while 3D skeletal Nickel foam as a substrate provides stability, enhances its catalytic activity by providing a more number /of active sites and facilitates rapid electron transfer. The work presented here confirms Bi2S3/NF as a high-performance electrode that can be used for the detection of other biomolecules used in clinical diagnosis and biomedical research.

An electrochemical voltammetric response of Hg2+ and Pb2+ ions using polyaniline-benzothiazole composite modified GCE electrode: Synthesis, characterization and quantum chemical calculation

An efficient electrochemical sensor based on polyaniline-benzothiazole [(3,5-bis (benzo[d]thiazol-2-yl)-[1,1–biphenyl]-4-ol)] (PAni-BEN) composite was designed and synthesized in this study, and it was employed as an electrochemical sensor to detect Hg2+ and Pb2+ ions with good selectivity and sensitivity. Fourier transform-infrared spectroscopy, UV–Vis spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis spectroscopy were employed to examine the morphology and structure of the produced composite. The electrochemical characteristics of the electrode modifiers were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Also, they were employed to perform both individual and simultaneous sensing studies of various metal ions using the differential pulse voltammetry technique (DPV) in a different supporting electrolyte (acetate buffer (pH 5), phosphate buffer (pH 7), and 0.1 M HCl) mediums. The PAni-BEN composite modified GCE sensor shows remarkable selectivity and sensitivity towards Hg2+ and Pb2+ ions over the other heavy metal ions in 1 to 24.84 µM, respectively. The limits of detection (S/N = 3) were 1 nM and 4.6 nM for Hg2+ and Pb2+ ions. Density Functional Theory (DFT) was used in the present study to accomplish the adsorption mechanism of the suggested sensors. The DFT calculation demonstrated that the PAni-BEN composite was formed with a lower band gap energy than BEN and DD PAni. These findings showed that the suggested sensor (PAni-BEN), which may used to detect Hg2+ and Pb2+ ions, had the lowest detection limit in the acetate buffer medium compared to the proposed electrolyte medium.

Simultaneous Analysis of Dopamine and Ascorbic Acid Using Polymelamine/Gold Nanoparticle-Modified Carbon Paste Electrode

Modification of electrode using polymelamine (PM) and gold nanoparticles (AuNPs) has been successfully developed via electropolymerization and electrodeposition onto carbon paste electrode (CPE) using cyclic voltammetry (CV) technique. The modified electrode (AuNPs/PM/CPE) was applied as voltammetry sensors in a simultaneous of dopamine (DA) and ascorbic acid (AA). AuNPs/PM/CPE presented an effective surface area 5 times wider than CPE and demonstrated good electrocatalytic performance in the oxidation of DA and AA in 0.1 M phosphate buffer solution (pH 3) with a scan rate of 100 mV s−1. The differential pulse voltammetry (DPV) technique was chosen as the best method for separating potential peaks of DA and AA. The linear response for determining DA and AA using the DPV technique produced a concentration range of 0.1–13 and 0.4–12 µM with coefficient linearity of 0.9999 and 0.9997, the limit of detection of 0.1405 and 0.2187 µM, the accuracy of 89.62–109.16%, and 83.63–105.08%, and the precision of 0.017–0.701% and 0.066–0.626%, respectively. In addition, this electrode was applied in a real sample of infant urine with a concentration of 1 µM by spike method and found 98.86 and 98.28% as percent recovery of DA and AA, respectively.

A new, fast and selective electrochemical sensor based on Bismuthiol-I for the voltammetric detection of tartrazine, a synthetic food dye, in soft drinks

A new electrochemical sensor (BT-I/GC) was prepared for the determination of tartrazine (TRZ) by modifying the glassy carbon (GC) electrode with 1,3,4-thiadiazoleidine-2,5-dithiol (Bismuthiol I, BT-I). The characterization of the prepared sensor was carried out by some electrochemical techniques and Fourier transform infrared spectroscopy (FT-IR). The rapid and simple determination of TRZ was performed on the surface of the BT-I/GC sensor by differential pulse voltammetry (DPV) technique. Under the optimum experimental conditions, linear working ranges for TRZ detection were found as 38.5 nM-3.72 μM, 3.72 μM-24.10 μM, and 24.10 μM-307 μM, and the value of the limit of detection (LOD) was found as 9.8 nM. The fabricated sensor was used successfully to detect TRZ in soft drink and energy drink samples with recovery values between 95.8 % and 103.8 %.

Fabrication of a noveltantalum boride/vanadium carbidemodified screen-printed carbon electrode for voltammetric determination of pimonidazole in bio-fluids.

For the first time, a tumour hypoxia marker detection has been developedusing two-dimensional layered composite modified electrodes in biological and environmental samples. The concept of TaB2 and V4C3-based MXene composite materials is not reported hitherto using ball-milling and thermal methods and it remains the potentiality of the present work. Thesuccessful formation is confirmed through various characterisation techniques like X-ray crystallography, scanning electron microscopy photoelectron, and impedance spectroscopy. A reliable and repeatable electrochemical sensor based on TaB2@V4C3/SPCE was developed for quick and extremely sensitive detection of pimonidazole by various electroanalytical methods. It has been shown that the modified electrode intensifies the reduction peak current and causesa decrease in the potential for reduction, in comparison with the bare electrode. The proposed sensor for pimonidazole reduction has strong electrocatalytic activity and high sensitivity, as demonstrated by the cyclic voltammetry approach. Under the optimal experimental circumstances, differential pulse voltammetry techniques were utilised for generating the wide linear range (0.02 to 928.51µM) with a detection limit of 0.0072µM. The resultant data demonstrates that TaB2@V4C3/SPCE nano-sensor exhibits excellent stability, reliability, and repeatability in the determinationof pimonidazole. Additionally, the suggested sensor was successfully used to determine the presence of pimonidazole in several real samples, such as human blood serum, urine, water, and drugs.

Electrochemical sensing of aniline based on bio-inspired cauliflower shaped tin-oxide nanoparticle using Solanum trilobatum leaf extract

The quantitative detection and determination of aniline (AN) in water samples are of significant importance due to its potential to induce adverse effects in humans and other livestock when consumed in excess. Therefore, it is the need of the hour to develop a highly sensitive conductive matrix for the electrochemical detection and quantification of AN in-water samples. In this regard, tin oxide nanoparticles (SnO2 NPs) were synthesized using Solanum trilobatum leaf extract for the first time. Upon conducting structural analysis of the synthesized SnO2 NPs, aggregates of spherical nanoparticles were observed, resulting in the formation of a cauliflower-like structural morphology. Subsequently, the cauliflower-shaped SnO2 nanoparticles were drop-casted onto the surface of a screen-printed carbon electrode using nafion as a binder, thereby developing an electrochemical sensing platform for the detection of AN. Later, differential pulse voltammetry technique was employed to detect AN over a concentration range of 2.0–14.0 nM, with a limit of detection of 0.897 nM based on the signal-to-noise ratio (S/N = 3). Importantly, the sensing of AN remained unaffected by tested interfering species from various pollutants, as confirmed by recovery values (99.2–101.0%) in water samples. These results collectively demonstrate that the newly designed sensor exhibits good selectivity, sensitivity, and reproducibility for the detection of AN.

The development of electrochemical DNA biosensor based on woolen ball-shaped La3+/TiO2 nanostructure coating: Nanomolar detection of Vinorelbine

Although Vinorelbine (VOB) is a powerful anticancer medication, it inevitably has a number of adverse effects. Therefore, identifying this medication in biological samples is crucial for assessing both its effectiveness and negative effects. In this study, a new DNA biosensor was created to analyze VOB within biological samples. Moreover, the sensor has been created though the modification of a pencil graphite electrode (PEG) with polypyrrole (PP), a woolen ball-shaped La3+/TiO2 nanostructure (WB–S La3+/TiO2-NS) (enhancing the conductivity of electricity), along with ds-DNA (calf thymus) (ds-DNA/PP/WB-S La3+/TiO2-NS/PGE). Alterations in electrode signal has been then utilized to determine whether VOB is present. Under optimized condition, the differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques were adopted for electrochemical sensing of VOB. With a 0.37 nM detection limit, ds-DNA/PP/WB-S La3+/TiO2-NS/PGE demonstrated remarkable sensitivity for VOB at concentrations between 0.001 and 150.0 μM by DPV method. In addition, the calibration curve shows a linear range between 5.0 and 100.0 μM vanillin with a detection limit of about 0.76 μM by EIS method. Theoretical docking investigation was used to analyze the contacts among VOB and ds-DNA bases for future assessments, and the results supported the intercalation of VOB with guanine bases ds-DNA's intercalations. VOB was examined using the ds-DNA/PP/WB-S La3+/TiO2-NS/PGE method in actual samples.

Electrochemical sensor for sensitive detection of an anticancer drug Capecitabine by modified carbon paste electrode with tetrahydrodipyrazolo pyridine derivative and Cu-MCM-41 nanoparticles

In this work, the electrochemical performance of the modified carbon paste electrode with tetrahydrodipyrazolo pyridine derivative as an organic modifier, and Cu-MCM-41 nanoparticles have been investigated to determine Capecitabine (CAP), an anticancer drug. CAP has been used for treating some cancers such as rectal, stomach, breast, pancreatic, and colon cancer. It works by inhibiting cancer cells growth. Herein, an organic modifier was prepared using a green biocatalyst in a biomimetic synthesis, a simple method was used for synthesis of Cu-MCM-41 nanoparticles. The electrochemical parameters such as the transfer coefficient and the number of electrons and protons involved in the redox reaction of the modifier were calculated using cyclic voltammetry (CV). Also, an electrocatalytic reaction was observed for CAP oxidation on the modified electrode surface as a result of a reduction in the CAP species oxidation overvoltage. To measure the CAP species by the modified electrode, some optimizations were performed. The Tafel curve was used to determine the transfer coefficient between the CAP and modifier, which was determined as 0.9. The chronoamperometric experiment was also investigated to obtain the numerical value of the CAP diffusion coefficient (D = 7.67 × 10–6 cm2 s−1). The calibration curve was drawn by the differential pulse voltammetry technique (DPV), and linear ranges of 2.0–80.0 µM and 80.0–800.0 µM, and the detection limit (LOD = 0.144 µM) were obtained. To evaluate the efficiency of the proposed sensor for CAP determination, measurement was done on a real blood serum sample. The proposed sensor displayed good selectivity, repeatability, and stability.

A highly sensitive electrochemical sensor for Cr6+ ions detection using Ag NPs/rGO/quercetin modified glassy carbon electrode for water applications

Heavy metals possess some serious hazardous influence on the environment as well as on human health. Monitoring of Cr6+ ions using the electrochemical sensing method proves to be an effective analytical tool and has an edge over the other conventional technologies. The glassy carbon electrode used in this study has its surface modified with highly sensitive silver nanoparticles, conductive 2-dimensional carbon material, and a metal chelating bio-compound prepared to significantly impact the selectivity and sensing of metal ions in the electrochemical determination. Applying the green chemistry principle, Graphene Oxide is reduced and functionalized simultaneously using a natural flavonoid called quercetin. Turkevich method was used to synthesis Silver nanoparticles. A novel composite is prepared by taking these compounds in a 1:1:2 ratio. The working electrode's surface was modified using this Ag NPs/Q-rGO composite and used in the analysis of Cr6+ ions. The physio-chemical characterization of the synthesized Ag NPs/quercetin-rGO composite was carried out. The surface morphology of the novel composite was observed. The cyclic voltammetry technique was used for electrochemical characterization. The monitoring of the Cr6+ metal ions using the Ag NPs/Q-rGO electrode was done with differential pulse voltammetry technique. The cyclic voltammogram for the Ag NPs/Q-rGO showed two anodic peaks at Epa1 = 0.28 V, Epa2 = 0.38 V, and one cathodic peak was seen at Epc = 0.14 V. Analytical parameters like the effect of electrolytes and the effect of pH were optimized. The results obtained from DPV experiments showed that the Ag NPs/Q-rGO electrode is efficient enough to sense the Cr6+ ions. Interpretation from the Linear plot helped in determining the LOD and LOQ of Cr6+ ions in the system which was found to be 0.07 μgL−1 and 0.224 μgL−1 respectively.

Sensitive determination of 4,6-dinitro-o-cresol based on a glassy carbon electrode modified with Zr-UiO-66 metal-organic framework entrapped FMWCNTs.

A DNOC electrochemical sensor has been developed by using a composite of Zr-UiO-66 and FMWCNTs on a glassy carbon electrode (GCE) and using the differential pulse voltammetry technique. The synthesized materials were physico-chemically characterized by BET, PXRD, FTIR, TGA, EDX, and FESEM. Cyclic voltammetry showed that DNOC has three oxidation peaks at 0.03 V (RSD: 0.23%), 0.42 V (RSD: 0.21%), and 1.32 V (RSD: 0.32%) and three reduction peaks at - 0.20 V (RSD: 0.15%), - 0.82 V (RSD: 0.26%), and - 1.14 V (RSD: 0.19%) which follow a diffusion-controlled mechanism. Different parameters were optimized using differential pulse voltammetry and good linear ranges were found for the simultaneous detection of the three reduction peaks. For a specific concentration range of 0.1-50 μM, a limit of detection of 0.119 μM based on 3Sb/m was obtained. The interfering effects of five non-phenolic pesticides and five heavy metals were evaluated to highlight the selectivity of the developed sensor. It is the first report of an electrochemical DNOC sensor in which all three oxidation peaks are prominently visible. Ethion and chloropyriphos were found to inhibit the redox process of DNOC on the developed sensor platform Zr-UiO-66/FMWCNT/GCE. The sensor was successfully applied to DNOC determination in spiked potato samples and the results showed a standard deviation of less than 3%. The proposed method is expected to provide a novel platform for the quantitative determination of DNOC pesticides in vegetables.

Ruthenium complex based nanocomposite film with enhanced and selective electrochemical sensing of bifenthrin pesticide.

Bifenthrin (BF), a widely used pyrethroid pesticide in farming, lacks highly sensitive and selective sensors despite its extensive application. Ruthenium complexes are very effective for selective sensing applications but suffer from structural instability at elevated conditions, electrochemical activity, and the use of costly electrolytes. This work improves their electrochemical activity and mechanical strength by incorporating silver nanowires and replacing the costly electrolyte with abundant KCl + PBS, resulting in enhanced signal performance. Herein, a ruthenium complex containing composite film was immobilized on a platinum (Pt) electrode using Langmuir Blodgett technique. The fabricated sensor has been characterized by differential pulse voltammetry (DPV) based electrochemical technique. The BF pesticide sensing parameters, including the limit of detection (LOD), linear range (LR), and sensitivity, were evaluated using SWV, DPV, and CV techniques. Among these, the DPV technique demonstrated the best performance, achieving a sensitivity of 0.648 μA cm-2 μM-1, a LR of 1-10 μM, and a LOD of 1 μM. The relative standard deviation (RSD) values using DPV are found to be 6.3% (repeatability study), 3% (reproducibility study), 8% (metal ion interference), 5% (organic species interference), and 2% (real sample study), which are much lesser than the World Health Organization (WHO) recommendation of RSD value on the pesticide (i.e. 20%). The BF sensor demonstrated a selectivity of 2× difference of peak height response compared to similar pesticides. The reported pesticide sensor will open new options for sensor research using metal complex-based LB film nanocomposite.

A portable label-free electrochemical DNA biosensor for rapid detection of Salmonella Typhi.

A highly accurate, rapid, portable, and robust platform for detecting Salmonella enterica serovar Typhi (S. Typhi) is crucial for early-stage diagnosis of typhoid to avert and control the outbreaks of this pathogen, which threaten global public health. This study presents a proof-of-concept for our developed label-free electrochemical DNA biosensor system for S. Typhi detection, which employs a printed circuit board gold electrode (PCBGE), integrated with a portable potentiostat reader. Initially, the functionalized DNA biosensor and target detection were characterized using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) methods using a benchtop potentiostat. Interestingly, the newly developed DNA biosensor can identify target single-stranded DNA concentrations ranging from 10 nM to 20 μM, achieving a detection limit of 7.6 nM within a brief 5 minute timeframe. Under optimal detection conditions, the DNA biosensor exhibits remarkable selectivity, capable of distinguishing a single mismatch base pair from the target single-stranded DNA sequence. We then evaluated the feasibility of the developed DNA biosensor system as a diagnostic tool by detecting S. Typhi in 50 clinical samples using a portable potentiostat reader based on the DPV technique. Remarkably, the developed biosensor can distinctly distinguish between positive and negative samples, indicating that the miniaturised DNA biosensor system is practical for detecting S. Typhi in real biological samples. The developed DNA biosensor device in this work proves to be a promising point-of-care (POC) device for Salmonella detection due to its swift detection time, uncomplicated design, and streamlined workflow detection system.

Electrospun cobalt-doped 2D-MoSe2/polypyrrole hybrid-based carbon nanofibers as electrochemical sensing platforms

A novel cobalt-doped two-dimensional molybdenum diselenide/polypyrrole hybrid-based carbon nanofiber (Co/MoSe2/PPy@CNF) was prepared using the hydrothermal method followed by electrospinning technique. The structural and morphological properties of the 2D-TMD@CNF-based hybrids were characterized through X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and transmission electron microscopy (TEM). The Co-MoSe2/PPy@CNF exhibited large surface area, porous structure, and improved active sites due to the synergistic effect of the components. The electrochemical and electrocatalytic characteristics of the 2D-TMD@CNF-modified electrodes were also investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The Co/MoSe2/PPy@CNF electrode was used as an electrochemical sensor for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) and showed enhanced catalytic activity and sensitivity. Using DPV measurements, the Co/MoSe2/PPy@CNF demonstrated wide linear ranges of 30–3212 μM for AA, 1.2–536 μM for DA, and 10–1071 μM for UA with low detection limits of 6.32, 0.45, and 0.81 μM, respectively. The developed sensor with the Co/MoSe2/PPy@CNF-modified electrode was also applied to a human urine sample and gave recoveries ranging from 94.0 to 105.5% (n = 3) for AA, DA, and UA. Furthermore, the Co/MoSe2/PPy@CNF-based sensor exhibited good selectivity and reproducibility for the detection of AA, DA, and UA.Graphical abstract