Differential Pulse Voltammetric Techniques Research Articles

Enhancing Pregnancy Care: Harnessing Label‐Free Immunosensors for Pre‐Eclampsia Detection Using PdNPs/Poly(3,5‐Diaminobenzoic Acid) Modified Glassy Carbon Electrodes

AbstractPlacental Growth factor (PlGF) is one of the biomarkers useful for detecting pregnancy hypertension disorder, Pre‐eclampsia. Herein, we focus on developing a label‐free immunosensor using simple electrochemical methods to detect PlGF antigens for pre‐eclampsia diagnosis. The work includes the electrochemical deposition of Palladium nanoparticles (PdNPs) on the glassy carbon electrode (GCE) surface using amperometry followed by electropolymerization of diaminobenzoic acid (DABA) onto the PdNPs/GCE. Antibody (aPlGF) was covalently immobilized on the pDABA/PdNPs/GCE using EDC/NHS reaction. The interaction of the antibody with the antigen was measured using differential pulse voltammetric technique. The linear range obtained for the immunosensor is 1–25 ng mL−1 with a limit of detection of 53 pg mL−1. The stability and reproducibility of the sensor were obtained in the acceptable range. The developed sensor was used to detect PlGF antigen in artificial blood and urine samples by spike recovery analysis.

A Comparative Analysis of the Interaction between Donepezil and Albumin with and Without a ZnO/Chitosan Quantum Dot Nanocomposite

AbstractIn this study, a nanocomposite of zinc oxide (ZnO) nanoparticles and chitosan‐based carbon quantum dots (ZnO/chQDs) in the presence of bovine serum albumin (BSA) as a promising drug carrier candidate was synthesized and characterized. For this purpose, chitosan and citric acid were used for the synthesis of chQDs and donepezil (DNP) was selected as a model drug. The BSA binding properties of DNP were analyzed by FT‐IR and UV‐Vis techniques, electrochemical methods and molecular docking in the absence and presence of ZnO/chQDs. The thermodynamic parameters and binding constants of DNP with BSA were also evaluated by these methods. The changes in the structural properties of BSA in the presence of DNP, ZnO/chQDs and ZnO/chQDs‐DNP were monitored by ATR‐FTIR spectroscopy. Cyclic and differential pulse voltammetric techniques and electrochemical impedance spectroscopy were applied to investigate the interactions, using methylene blue in electrolyte solution as redox probe, and its redox behaviour was observed to explore the interactions. Molecular docking was carried out on the interaction of DNP with BSA in the absence and presence of the synthesized ZnO/chQDs, and the results were compared with those of the experimental observations. The experimental results were confirmed by molecular docking studies.

Sensitive Voltammetric Detection of Acetaminophen on CuONPs-MWCNTs Modified Glassy Carbon Electrode with Enhancement Effect of Anionic Surfactant

In the present work, a voltammetric method using differential pulse voltammetric technique for the assessment of antipyretic and analgesic drug, acetaminophen was developed. The CuO nanoparticles were prepared and characterized. A glassy carbon electrode (GCE) fabricated with the suspension of CuO nanoparticles (CuONPs) and multi-walled carbon nanotubes (MWCNTs) were used. The modified electrode showed improved anodic peak current by introducing an anionic surfactant sodium dodecyl sulphate in phosphate buffer solution. The consequence of pH of supporting electrolyte, amount of nanoparticles suspension and surfactant concentration was investigated at a physiological pH of 7.4. Using differential pulse voltammetry, the fabricated electrode showed linear dynamic range from 9 to 160 nM of acetaminophen concentration. From the calibration plot, the computed detection limit was 5.06 nM and quantification limit was 16.88 nM. The developed method was checked for its reproducibility and assay during a day and intraday as well. The developed process was fruitfully applied to detect acetaminophen in pediatric oral suspensions administered to infants.

Facile synthesis of PEDOT@rGO nanocomposites for novel electrochemical sensor for the determination of 4-chlorophenol in a real water sample

A sensitive electrochemical sensor was developed for the detection of 4-chlorophenol (4-CP) using the nanocomposite based on poly (3,4-ethylenedioxythiophene) and reduced graphene oxide (PEDOT-rGO). The GC electrode modified with the proposed nanocomposite was characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and electrochemical impedance spectroscopy. The Raman analysis confirmed the successful incorporation of PEDOT onto the reduced graphene oxide (rGO) surface. It is also observed in the SEM analysis that PEDOT nanoparticles were spread over the rGO sheet. The lower charge transfer resistance (Rct) values for PEDOT-rGO/GCE compared to PEDOT/GCE in electrochemical impedance spectroscopy confirms the unique conducting properties of rGO and the higher surface area of PEDOT in the proposed composite on the GCE surface. The cyclic voltammetric and differential pulse voltammetric (DPV) results has indicated that the PEDOT-rGO-modified glassy carbon electrode is an excellent electrocatalyst for the detection of 4-CP compared to PEDOT and rGO. This counterpart exhibited a good linear relationship in the range of 5–250 μM, with a detection limit of 12 nM in the DPV technique. This sensor was also employed for the determination of 4-CP in river water samples. The accuracy of the analytical electrochemical sensor for 4-CP was comparatively analyzed using the obtained UV–visible spectral data, indicating a detection limit of 21 nM. Hence, the electrochemical method was successfully employed to obtain a lower detection limit for 4-CP than that for electronic absorption spectral observations. All the observed results were consistent with our expectations and showed that this novel PEDOT-rGO/GCE has good repeatability and stability and without any impactable interference behavior.

Point-of-care dengue detection: polydopamine-modified electrode for rapid NS1 protein testing for clinical samples.

Early diagnosis of dengue infection by detecting thedengue virus non-structural protein 1 (DENV-NS1) is important to the patients to initiate speedy treatment. Enzyme-linked immunosorbent assay (ELISA)-based NS1 detection and RT-PCR are time-consuming and too complex to be employed in remote areas of dengue-endemic countries. Meanwhile, those of NS1 rapid test by lateral flow assay suffer from low detection limit. Electrochemical-based biosensors using screen-printed gold electrodes (SPGEs) have become a reliable detection method to convey both ELISA's high sensitivity and rapid test portability. In this research, we developed an electrochemical biosensor for DENV-NS1 detection by employing polydopamine (PDA)-modified SPGE. The electrodeposition of PDA on the surface of SPGE serves as a bioconjugation avenue for anti-NS1 antibody through a simple and low-cost immobilization procedure. The biosensor performance was evaluated to detect DENV-NS1 protein in PBS and human serum through a differential pulse voltammetric (DPV) technique. The developed sensing platform displayed a low limit of detection (LOD) of 1.63pgmL-1 and a wide linear range of 10pgmL-1 to 1ngmL-1 (R2 ∼ 0.969). The sensing platform also detected DEV-NS1 from four different serotypes in the clinical samples collected from dengue patients in India and Indonesia, with acceptable sensitivity, specificity, and accuracy values of 90.00%, 80.95%, and 87.65%, respectively. This result showcased the facile and versatile method of PDA coating onto the surface of screen-printed gold electrodes for a miniaturized point-of-care (PoC) detection device.

Voltammetric Determination of Phenylephrine Hydrochloride at Poly (Diphenylamine Sulfonic Acid) Electrode

The electrochemical behaviour was studied, and the determination method of phenylephrine hydrochloride (PHE) at wide pH range at poly (Diphenylamine Sulfonic Acid, DPSA), using cyclic voltammetric (CV), differential pulse voltammetric (DPV) techniques. Optimum conditions and optimization of parameters for analytical applications were obtained by DPV technique, this technique was selected for the determination. Using optimized DPV technique, the current was linear within a concentration range between 10–100 nM in pH 6.5 phosphate buffer (PBS). Furthermore, poly (DPSA) electrodes were successfully applied to the determination of PHE in spiked urine and pharmaceutical preparations, rapid and low-cost method. The repeatability, accuracy and precision of the developed technique were checked.

Electrochemical determination of sorafenib by chronopotentiometry and ASDPV based on novel molecularly imprinted polymer and their applications in oncology patients

A promising selective and sensitive biosensor was fabricated for the first time to monitor trace amounts of sorafenib (SORF), a multi-target kinase inhibitor, based on the electropolymerization of pyrrole on a carbon paste electrode (CPE). To prepare a modified CPE, the prepared metal organic framework (NH2-MIL-101(Fe)) was mixed with graphite powder in the presence of an appropriate amount of paraffin oil before it was packed into a plastic tube containing a copper wire. Computational studies appreciate the use of pyrrole as the functional monomer for electropolymerization at the CPE surface using chronopotentiometry in the presence of SORF as a template. After the leaching of SORF, the imprinted sensor was characterized using FT-IR, SEM, and AFM, while NH2-MIL-101(Fe) was investigated by XRD, XPS, and SEM analysis. Under optimum conditions, SORF was detected using anodic stripping differential pulse voltammetric and chronopotentiometric techniques. High sensitivity (6.40 × 10−12 mol/L), excellent selectivity, and a wide linear range (4.20 × 10−11–7.10 × 10−3 mol/L) were recorded. Furthermore, the proposed sensor exhibited good repeatability (RSD = 2.40 % for n = 7) and high lifetime stability (∼7 weeks). Based on the above-mentioned merits, the designed electrochemical sensor was properly utilized for SORF determination in different oncology patients with satisfactory results (recovery = 94.40–99.90 %).

Nanomolar detection of essential amino acid in dairy products using a novel electrochemical sensor based on zinc cobaltite nanoflowers embedded porous 3D reduced graphene oxide

L-tryptophan (L-Trp) is a vital amino acid that sways neuronal function, immunity, and gut homeostasis, and its accurate detection in food samples is crucial. The aim of this study is to integrate zinc cobaltite (ZCO) nanoparticles and 3D porous reduced graphene oxide (rGO) on a screen-printed carbon electrode (SPCE) surface for building a novel electrochemical sensor to sensitively detect L-Trp in food products. A low-temperature aqueous solution method was employed in ZCO nanoflower synthesis and a hydrothermal approach was utilized to prepare 3D rGO. SEM, elemental mapping, XRD, Raman spectroscopy, XPS, and EIS characterizations were performed on the prepared nanocomposite, ZCO/3DrGO. Electrochemical experiments conducted with the cyclic and differential pulse voltammetric techniques were used for effectively assessing the catalytic power of ZCO/3DrGO/SPCE. With a low detection limit of 3 nM, high sensitivity of 19.53 μAμM−1cm−2, and a broad linear range of 0.08–5.93; 5.93–87.18 μM, the sensor demonstrated promising electrocatalytic activity towards L-Trp. Further, the reliability of the sensor was proved by analyzing its stability, repeatability, reproducibility, and selectivity towards L-Trp. The successful detection of L-Trp in dairy products (yogurt, milk, and cottage cheese) using the proposed sensor evinced its practical feasibility with high recovery of 98.16%–101.16% and low RSD of 2.8%.

Eco-friendly electrochemical sensor for determination of conscious sedating drug “midazolam’’ based on Au-NPs@Silica modified carbon paste electrode

Benzodiazepines (BZDs) are a group of drugs prescribed for their sedating effect. Their misuse and addictive properties stipulate different authorities for developing simple, fast and accurate analytical methods for instantaneous detection. Differential pulse voltammetric technique (DPV) was utilized for the selective assay of midazolam hydrochloride (MDZ) in the pure, parenteral dosage forms and plasma samples. A chemically modified carbon paste electrode (CPE) was implemented during the study. The method depended on the electroreduction of MDZ on the surface of the electrode over a potential range of 0.0 V to −1.6 V. The electrode was fabricated using silica nanoparticles (Si-NPs) which were incorporated into the composition of the CPE and used to enhance the electrode performance. Then, to enhance the sensitivity of the method, a chronoamperometric modification step was applied for depositing gold nanoparticles (Au-NPs) on the carbon paste electrode surface. Modification with Au-NPs showed a higher reduction current peak for MDZ with well-defined peaks. Various parameters such as pH of the media and measurements scan rate were investigated and optimized to enhance the sensor sensitivity. The sensor showed a dynamic linear response over a concentration range of 4.0 × 10−7 M to 2.9 × 10−4 M of MDZ with a LOD of 2.24 × 10−8 M using 0.1 M acetate buffer (pH 5.6). The sensor was validated in accordance with the ICH guidelines regarding accuracy, precision and specificity for the selective assay of MDZ in the presence of excipients. A greenness evaluation was performed using three different assessment tools, namely, the “Green Analytical Procedure Index” (GAPI), the “Analytical Greenness metric” (AGREE) and the “Whiteness Analytical Chemistry tool” (WAC) using the RGB12 model.

Voltammetric Determination of Trace Amounts of Lead With Novel Graphite/Bleaching Earth Modified Electrode

Modified composite electrodes have gained considerable interest in the detection of heavy metal ions due to their excellent sensitivity, selectivity, stability, and rapid response. Generally, these sensors consist of binder, conductive substance, and modifier. This study examined into the performance of a novel modified electrode that used a graphite–bleaching earth (BE-MCPE) composite performed while detecting trace amounts of Pb(II) using a differential pulse voltammetric technique (DPASV). In order to investigate the properties of BE-MCPE, we employed several analytical techniques, including SEM, SEM-EDX, FTIR, and XRD. These techniques were used to characterize the physical, chemical, and elemental properties of BE-MCPE, as well as its Pb(II) adsorption capacity, providing a comprehensive understanding of its composition and structure. The electrochemical results showed that the modified electrode demonstrated superior sensitivity and selectivity, in detecting Pb(II) ions, with a linear response range of 2.10-7 M to 10.10-7 M, limit of detection (LOD) of 4,89x10-8 mol.L-1, and limit of quantification (LOQ) of 1,63x10-7 mol.L-1. This novel modified electrode can achieve the sensitive detection of trace amounts of Pb(II) in a wide range of wastewater applications.

ELECTROCHEMICAL INVESTIGATION OF OTILONIUM BROMIDE USING BORON-DOPED DIAMOND AND GLASSY CARBON ELECTRODES

Objective: Using cyclic (CV) and differential pulse (DPV) voltammetric techniques, the electrochemical research of otilonium bromide (OTB) was carried out over a wide pH range (0.3–12) at glassy carbon electrodes (GCE) and boron-doped diamond electrodes (BDDE). The typical electrochemical behavior of OTB was identified as being dependent on the type of working electrode and pH. This research aims to provide a brand-new electroanalytical technique for measuring OTB in buffer solutions. Material and Method: All experiments employed the typical three-electrode cell of 10 ml capacity in conjunction with a platinum wire counter electrode, a BDDE and GCE working electrode, and an Ag/AgCl reference electrode. NOVA 1.8 software and an AUTOLAB 204 potentiostat/galvanostat were used for electrochemical measurements. Result and Discussion: The electrochemical behavior of OTB, which belongs to a class of drugs called 'antispasmodics' (spasm and cramps reliever), primarily used to treat irritable bowel syndrome (IBS), and other gastrointestinal conditions characterized by motility problems, painful bowel spasms and distension (swelling and bloating in the belly area), was examined in 0.1 M H2SO4 at BDDE and GCE. The electrooxidation mechanism was also investigated by conducting CV investigations at various pH levels throughout a broad pH range (pH 0.3-12.0). Understanding the mechanism was aided by scan rate investigations, which revealed that diffusion was controlled for both electrodes. The proposed technique was successfully used to determine OTB under optimal conditions.

Comparative DNA-/BSA-binding, DNA cleavage, and cytotoxic properties of copper(II) amino/salicyl-phenolate Schiff bases (phen) complexes that induce generation of phenoxyl radicals

A series of mixed-ligand Cu(II) complexes of the type [Cu(L1-5)(diimine)(H2O)](ClO4) (1–5) and [Cu(L6)(diimine)](ClO4) (6), where HL1-HL4 are aminophenolate Schiff base ligands viz., 2-(benzylideneamino)phenol (HL1, 1), 2-(4-fluorobenzylideneamino)phenol (HL2, 2), 2-(4-chlorobenzylideneamino)phenol (HL3, 3), and 2-(4-nitrobenzylideneamino)phenol (HL4, 4) whereas HL4 and HL5 are salicyl-phenolate Schiff base ligands viz.,2-((phenylimino)methyl)phenol (HL5, 5) and (E)-2-(((2-(dimethylamino)ethyl)imino)methyl)phenol (HL6, 6) as primary ligands and the diimine 1,10-phenanthroline (phen) as co-ligand have been isolated. TheSchiffbaseligandsand their mixedligandchelates were characterizedby spectral techniques (UV–Visible, IR, mass, 1H, and 13C NMR), elemental analysis, cyclic voltammetry (CV), and differential pulse voltammetric (DPV) techniques. The molecular structure of 6, which alone formed appreciable crystals, was determined by single-crystal X-ray studies, and two crystallographically independent molecules (a and b) existed in square pyramidal distorted trigonal bipyramidal (SPDTBP) geometry. The complexes 1–4 showed a reversible (ΔEp for 3; 64), quasi-reversible (2; 105 and 4; 115), and irreversible (1; 181 mV) oxidation waves discernible at E1/2 ranging from + 0.035 V to −0.120 V (DPV) which are attributed to the formation of copper(II)-phenoxyl radical species. Among them, 2 and 3 showed a well-defined reversible phenoxyl radical formation in CV and DPV. Also, these two complexes exhibited more stable phenoxyl radical in the presence of CAN (cerium ammonium nitrate). The DNA binding studies revealed that the fluoro- and chloro-substituted complexes 2 and 3 exhibited higher DNA binding propensity than the other complexes. All the complexes displayed moderate to high oxidative DNA cleavage property in the presence of H2O2, wherein complexes 2 and 3 exhibited higher DNA cleavage than the others. Interestingly, complex 3 exhibited less AC50 value (18.26 µM) than complex 2 (43.3 µM). The mechanistic study led to the inference that the DNA cleavage is possibly mediated via copper(II)-bound phenoxyl-radical. The cytotoxicity of complexes 1–6 was investigated in A549 non-small cell lung carcinoma cell. The amino-phenolate complexes 2 (IC50 = 3.52 µM) and 3 (IC50 = 3.4 µM) brought about higher cytotoxicity and ≈ 3.8-times more potency than cisplatin. The complex 3 showed to be 47-times less toxic to non-cancerous peripheral blood mononuclear cells (PBMC). Fluorescent staining assay revealed that the complexes 1–6 induced apoptotic cell death with some degree of necrosis. JC-1 staining assay revealed that complex 3 efficiently depolarized the mitochondrial membrane potential. Put together, the results substantiate that amino-phenolate-containing copper(II) mixed ligand complexes are more cytotoxic than salicyl-phenolate-containing copper(II) complexes.

Bioresource-derived multifunctional carbon quantum dots as a fluorescence and electrochemical sensing platform for picric acid and noncytotoxic food storage application

This work deals with the synthesis of facile, water-soluble, and blue-emitting carbon quantum dots (CQDs) from Plumbago indica leaves by a hydrothermal method with a quantum yield of 16 %. The biomass Plumbago indica leaves exhibit several advances such as easy availability, cost-effectiveness, non-toxic, green source, and not requiring any sophisticated techniques to develop the sensor. The optical, morphological, structural, and compositional properties of the CQDs were confirmed by various characterization methods. As a fluorescent probe, CQDs exhibited good linear response to picric acid (PA) with a limit of detection (LOD) of 18 nM. The sensing mechanism involves a combination of static quenching and fluorescence resonance energy transfer (FRET). In the electrochemical sensing method, the differential pulse voltammetric (DPV) technique was performed using a CQD-modified gold electrode with a LOD of 0.35 nM for PA. Using fresh carrots as a model sample, the antioxidant activity of PVA, CQD, and a PVA-CQD mixture was qualitatively determined. The in vitro cytotoxicity analysis of CQDs by MTT assay using the L6 cell line confirmed its non-toxic behaviour. This work is noteworthy because it offers a new attempt to identify toxic PA from biomass-derived precursor material and finds future applications in the food industry.

Electrochemical Monitoring of Acyclovir in Plasma Samples Using Fe3O4/SiO2 Doped Cu Metal-Organic Framework Sensor

In the world of medicine, the discovery of acyclovir, an antiviral medication often used to treat herpes infections, is very important. Accurate and sensitive detection are essential for patient safety since acyclovir is recognized for its possible adverse effects and toxicity at high dosages. A Cu metal-organic framework (MOF) doping with Fe3O4/SiO2 was prepared by direct Co-precipitation method. This binary Fe3O4-SiO2/Cu-MOF was analysis by scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD), and this MOF was used to modify the glassy carbon electrode (GCE) surface. Modified GCE was used for the electrochemical monitoring of Acyclovir in the plasma samples. Acyclovir’s electro-oxidation behavior was assessed using cyclic and differential pulse voltammetric techniques. A redox mechanism was postulated based on the effect of the potential scanning rate and solution pH on the voltammetric response of Acyclovir oxidation. A 0.03 μM limit of detection was acquired for Acyclovir analysis with a linear response in the range of 1–60 μM. Finally, acyclovir quantification in the blood serum samples was successfully performed.

Eutectic solvent-mediated synthesis of manganese molybdate nanosheets: Rapid and real-time electrochemical detection of p-methylaminophenol sulfate(metol)

The present study explores the design of MnMoO4 modified sensing platform for the electrochemical detection of metol. The green synthesis of MnMoO4 nanosheets was accomplished by a low-temperature deep eutectic solvents (DES) assisted hydrothermal protocol. According to structural and electrochemical studies, the large surface area and pore volume of the MnMoO4-based working electrode assembly provided a conduit for the anchoring of the target analytes. Under optimized electrochemical conditions, the modified sensor demonstrated an exceptionally low detection limit (LOD = 0.98 nM) with a sensitivity of 88.8 μA μM−1 cm−2 within a substantial linear working range from 0.01 to 375.6 μM by differential pulse voltammetric (DPV) technique. Benefiting from the significantly improved stability, sensitivity, and reproducibility, the proposed MnMoO4 electrocatalyst showed amplified current responses of metol. The possibility of metol detection without any foreign interference and % recovery between ±99.20–99.90 % opens up new prospects for the efficacious on-site detection of metol.

Poly(3,4-ethylenedioxythiophene):Polystyrene Sulfonate-Modified Electrode for the Detection of Furosemide in Pharmaceutical Products.

Furosemide (4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoyl benzoic acid) is a widely used, FDA-approved drug prescribed for several symptoms associated with heart, kidney, liver failure, or chronic high blood pressure. In this work, a glassy carbon working electrode modified with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is developed to detect furosemide (FURO) with high sensitivity and precise selectivity. The modified electrode was also characterized using field emission scanning electron microscopy, attenuated total reflectance-Fourier transform infrared, and cyclic voltammetry. Here, an efficient and cost- and time-efficient technique to study the furosemide mechanism of reaction in an acidic liquid medium is presented. An electrochemical oxidation of loop diuretic furosemide was investigated in a supporting electrolyte, 0.01 M of phosphate buffer (at a pH level of 4.0) at 25 ± 0.1 °C using a differential pulse voltammetric (DPV) technique. Under optimized parameters, the developed sensor displays a wide detection range of furosemide concentrations of 6.0 × 10-6 to 1.0 × 10-4 M with a detection limit of 2.0 × 10-6 M using DPV. The presented sensor offers a robust and high-precision technique with an excellent reproducibility to detect furosemide in as a real sample such as urine and pharmaceutical products.

Fabrication of RuNPs/TBA/PGE and its application for the electrochemical determination of trace amounts of acyclovir

In this work, a pencil graphite electrode modified by ruthenium nanoparticles and thiobarbituric acid (RuNPs/TBA/PGE) was used to measure the acyclovir (ACV) using a sensitive adsorptive differential pulse voltammetric technique)AdDPV). Field emission scanning electron microscopy (FESEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the modified electrode. Some concentration and instrumental factors affecting the electrode response in the ACV measurement were optimized, and ACV was determined under optimized conditions in two concentration ranges: 3.0 to 30.0 and 30.0 to 3000.0 nM. The detection limit was also determined to be 0.8 nM. Finally, the proposed method was used to measure ACV in tablet and urine samples, and the results showed that the proposed method has the necessary accuracy and precision.

Electrochemical preparation and the characterizations of poly(3,5-diamino 1,2,4-triazole) film for the selective determination of pyridoxine in pharmaceutical formulations.

The online version contains supplementary material available at 10.1007/s11696-023-02777-5.

Fabrication of a novel electrochemical biosensor based on easy and efficient modifications of a glassy carbon electrode for sensitive and selective determination of morphine

In this study, a selective and sensitive electrochemical determination of morphine at low concentration was carried out using electropolymerization of 3-methyl-1-phenyl-pyrazole-5-one (MPP) at the surface of a glassy carbon electrode (GCE) which was further modified by electrodeposition of cobalt nanoparticles (Co NPs) onto its surface. The electrochemical studies of morphine were performed using cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques. Modification of the electrode surface increased its response to morphine which yielded a relatively wide linear range (2 to 100 μM) and a low limit of detection of 0.12 μM. The analytical characteristics of the sensor towards determination of the morphine were investigated which confirmed a good analytical performance for the sensor. Finally, the sensor was used for monitoring morphine in serum and urine samples as real matrices whose performance was both acceptable and admirable which motivated us to introduce it as a reliable method for determination of morphine in biological fluids.

Synergetic effects of Mo2C sphere/SCN nanocatalysts interface for nanomolar detection of uric acid and folic acid in presence of interferences

Till to date, the application of sulfur-doped graphitic carbon nitride supported transition metal carbide interface for electrochemical sensor fabrication was less explored. In this work, we designed a simple synthesis of molybdenum carbide sphere embedded sulfur doped graphitic carbon nitride (Mo2C/SCN) catalyst for the nanomolar electrochemical sensor application. The synthesized Mo2C/SCN nanocatalyst was systematically characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with elemental mapping. The SEM images show that the porous SCN network adhered uniformly on Mo2C, causing a loss of crystallinity in the diffractogram. The corresponding elemental mapping of Mo2C/SCN shows distinct peaks for carbon (41.47%), nitrogen (32.54%), sulfur (1.37%), and molybdenum (24.62%) with no additional impurity peaks, reflecting the successful synthesis. Later, the glassy carbon electrode (GCE) was modified by Mo2C/SCN nanocatalyst for simultaneous sensing of uric acid (UA) and folic acid (FA). The fabricated Mo2C/SCN/GCE is capable of simultaneous and interference free electrochemical detection of UA and FA in a binary mixture. The limit of detection (LOD) calculated at Mo2C/SCN/GCE for UA and FA was 21.5 nM (0.09 – 47.0 μM) and 14.7 nM (0.09 – 167.25 μM) respectively by differential pulse voltammetric (DPV) technique. The presence of interferons has no significant effect on the sensor’s performance, making it suitable for real sample analysis. The present method can be extended to fabricate an electrochemical sensor for various molecules.