Differential Pulse Voltammetric Research Articles

Auramine O amplified glassy carbon electrode for the voltammetric investigation of dihydroxybenzene isomers

• Electropolymerization of Auramine O monomer was achieved. • Exhibits good sensitivity, selectivity and excellent response for individual and simultaneous electroanalysis of CA and HY. • Low detection limit for CA and HY was achieved. • Satisfactory recovery for CA and HY was found. A facile method for the electrochemical analysis of dihydroxybenzene isomers like catechol (CA) and hydroquinone (HY) at poly (Auramine O) modified glassy carbon electrode (poly-AO-MGCE) was examined by cyclic voltammetry (CV) and differential pulse voltammetric (DPV) technique. The constructed electrode depicts low detection limits for CA (0.98 µM) and HY (1.2 µM) with superior current responses due to the inherent catalytic properties of its modifiers. The specific parameters including pH, with speed rate, and concentration variation were carried by electrochemically at designed electrode. The poly-AO-MGCE reveals surface-controlled process and implies high electrocatalytic response for the simultaneous exploring of CA and HY. The proposed electrode expressed superior selectivity and sensitivity. The recovery of CA and HY was achieved in simple method using tap water.

Novel screen-printed sensors with chemically deposited boron-doped diamond and their use for voltammetric determination of attention deficit hyperactivity disorder medication atomoxetine

A novel lab-made disposable screen-printed sensor with chemically deposited boron-doped diamond (LM-SP/BDDE) was characterized by scanning electron microscopy (SEM), Raman spectroscopy, and compared to bulk boron-doped diamond electrode (BDDE) and commercially available screen-printed sensor with BDD working electrode (SP/BDDE). The sensors were applied for the determination of atomoxetine (ATX), a pharmaceutically active ingredient used to treat symptoms of attention deficit hyperactivity disorder (ADHD). Using bulk BDDE and a newly developed differential pulse voltammetric (DPV) method with optimized pre-treatment, DPV parameters, and in Britton-Robinson buffer of pH 2, obtained limit of detection (LOD) was 3.7×10−8 mol L−1. Subsequently, this new method was successfully transferred to the tested SP/BDDE sensors and verified on analysis of an ATX-containing drug Strattera 60MG with excellent repeatability (relative standard deviation (RSD) < 2.5% (n = 5)). Moreover, elimination voltammetry with linear scan (EVLS) uncovered multiple (3-5) diffusion-controlled irreversible oxidation steps at all tested sensors.

Sensitive Detection of Thiourea Hazardous Toxin with Sandwich-Type Nafion/CuO/ZnO Nanospikes/Glassy Carbon Composite Electrodes.

In this research study, we developed a voltammetric electrochemical sensor probe with a copolymer Nafion (Sulfonated Tetrafluoroethylene-based Fluoro-polymer) decorated with hydrothermally prepared sandwich-type CuO/ZnO nanospikes (NSs) onto a glassy carbon electrode (GCE) for reliable thiourea (TU) detection. The detailed characterizations in terms of structural morphology, binding energy, elemental compositions, grain size and crystallinity for synthesized NSs were performed by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis, respectively. The differential pulse voltammetric (DPV) analysis for TU showed good linearity at current-versus-TU concentration on the calibration plot in the 0.15~1.20 mM range, which is defined as a dynamic detection range (LDR) of TU in a phosphate buffer solution. Considering the slope of LDR over the GCE-coated NSs surface area (0.0316 cm2), the TU sensor sensitivity (0.4122 µA µM−1 cm−2) was obtained. Besides this, the low limit (LOD) for TU detection was calculated and found to be 23.03 ± 1.15 µM. The fabricated Nafion/CuO/ZnO NSs/GCE sensor probe was created as a reliable sensor based on reproducibility, interference effect, stability and response time. Real bio-samples were investigated and the results confirm the anticipated reliability of the TU sensor probe. Thus, this is a noble way to develop enzyme-free electrochemical sensors that could be an alternative approach for the detection of chemicals in the field of enzyme-free biosensor development technology.

Electrochemical determination of nitroaromatic explosives using glassy carbon/multi walled carbon nanotube/polyethyleneimine electrode coated with gold nanoparticles

The on site/in field detection of explosives has become a rising priority for homeland security and counter−terrorism measures. This work presents the sensitive detection of nitroaromatic explosives using glassy carbon/multi−walled carbon nanotubes/polyethyleneimine (GC/MWCNTs/PEI) electrode coated with gold nanoparticles (AuNPs). MWCNTs and PEI could be well dispersed in ethanol/water solution, giving rise to a thin and homogeneous film on GCE. The GC/MWCNTs/PEI electrode was electrochemically modified with AuNPs and used for the differential pulse voltammetric (DPV) detection of nitroaromatics. The enhanced detection sensitivities were achieved through π–π and charge-transfer (CT) interactions between the electron-deficient nitroaromatic explosives and donor amine groups in PEI to which gold nanoparticles were linked, providing increased analyte affinity toward the modified GCE. Calibration curves of current intensity versus concentration were linear in the range of 0.05–8 mg L−1 for TNT, 0.2–4 mg L−1 for 2,4-dinitrotoluene (DNT), 1–20 mg L−1 for 2,4-dinitrophenol (2,4-DNP), 0.25–10 mg L−1 for picric acid (PA), and 0.05–4 mg L−1 for 2,4,6-trinitrophenyl-N-methylnitramine (tetryl) with detection limits (LOD) of 15 μg L−1, 45 μg L−1, 135 μg L−1, 30 μg L−1, and 12 μg L−1, respectively. The proposed method was successfully applied to the analysis of nitroaromatics in synthetic explosive mixtures and military composite explosives (comp B and octol). The electrochemical method was not affected by possible interferents of electroactive camouflage materials and common soil ions. Method validation was performed against the reference LC−MS method on TNT and PA−contaminated clay soil samples separately.

Integrated-electrochemical Approaches Powered by Photovoltaic Energy for Detecting and Treating Hydroxychloroquine in Water

Hydroxychloroquine (HCQ), a derivative of 4-aminoquinolone, is prescribed as an antimalarial prevention drug and to treat diseases such as rheumatoid arthritis, and systemic lupus erythematosus. Recently, the treatment of Coronavirus (COVID-19) was authorized by national and international medical organizations in certain hospitalized patients by chloroquine and hydroxychloroquine. However, its use for treating COVID-19 is only an unproven hypothesis still being investigated. Consequently, the high risk of natural water contamination due to the large production and utilization of HCQ is a key issue to overcome urgently. For this reason, the monitoring its concentration in water and the treatment of polluted effluents with HCQ are needed to minimize its hazardous effects. Then, in this study, an electrochemical measuring device and electrochemical water treatment are integrated for their environmental application on HCQ control. In the former, raw cork-graphite electrochemical sensor was prepared and a simple differential pulse voltammetric (DPV) method was developed for the quantitative determination of HQC. Meanwhile, the degradation of HCQ was carried out with BDD anode by applying 15, 30, and 60 mA cm-2 over 90 min of treatment, in the latter. The decay and degradation of HCQ were monitored by DPV, and HPLC measurements. Results indicated that, the electrochemical device exhibited a clear current response, allowing to quantify the analyte in the 2.5–25 ppm range. Alternatively, BDD-electrolysis demonstrated to be an efficient process for removing organic matter from the drug compound effluent via the production of strong oxidizing species. Lower HCQ concentrations were detected, using the electrochemical sensor, when higher current densities and sulfate concentrations were used in BDD-electrolysis, demonstrating the applicability of integrated-technologies. The evolution of short-carboxylic acids (oxalic, formic, oxamic, maleic, acetic, and glycoxylic) was observed at 15 mA cm-2 but all of them were eliminated after 120 min. Inorganic ions (NH4 + and NO3 -) were also detected under these experimental conditions, confirming that the pollutant was mineralized. Finally, lower energy requirements were estimated for all experimental conditions; however, solar photovoltaic (PV) renewable energy has been utilized to power these electrochemical technologies, decreasing the investment cost.

Simple sonochemical synthesis of flake-ball shaped bismuth vanadate for voltammetric detection of furazolidone

Transition metal vanadates have an enhanced number of active sites and performance in the electrocatalytic activity due to the synergic effect. The present work demonstrated a facile synthesis of bismuth vanadate (BiVO4) flake-ball shaped microstructure by sonochemical approach for excellent selective voltammetric detection of furazolidone (FZD). The prepared material was studied through various spectroscopic and microscopic techniques to confirm the crystal phase, compositional, and morphological profile of the flake-ball shaped BiVO4. Based on the results, the crystallite size has been measured to be ~ 18.89 nm using the Debye-Scherer equation. The flake-ball shaped structure and material formation was confirmed by morphology, crystal phase, chemical structural, and valence state analyses. For the electrochemical evaluation, synthesized BiVO4 was drop cast on screen-printed carbon electrode (SPCE) and scrutinized their electrochemical performance towards the detection of FZD. The electrochemical investigation of the modified electrode was studied using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and differential pulse voltammetric (DPV) techniques. In addition, the modified electrode displayed a lower detection limit (LOD) of 0.016 µM and respectable sensitivity of 0.75 µA µM–1 cm–2, which surpassed the several earlier reported FZD sensors. Furthermore, the proposed sensor act as a promising electrode for real sample investigation of biological samples of human blood serum and urine with satisfactory recovery rates of 96.6–99.8%. Thereby, the developed sensor exhibits long cycling stability, excellent repeatability, reproducibility, and selectivity.

Ultrasound assisted synthesis of silver titanate for the differential pulse voltammetric determination of antibiotic drug metronidazole

Highly electroactive transition metal oxides have been received great potential in antibiotic drug electrochemical sensors due to excellent features including ease of preparation, a large number of active sites, good conductivity , high stability, and selectivity . In this work, the perovskite-type silver titanate (Ag 2 TiO 3 ) was synthesized by ultrasound-assisted coprecipitation method. The structural and morphology were examined using typical analytical techniques such as X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FT-IR), Raman spectrometry , field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) analyzes confirmed the purity and the chemical composition of as-prepared Ag 2 TiO 3 . The Brunauer−Emmett−Teller analysis (BET) of as-synthesized Ag 2 TiO 3 displayed a specific surface area of 48.485 m 2 g −1 resulted in improved charge transfer resistance (R ct ) of 695 Ω. The cyclic voltammetry (CV) analysis revealed the superior electrochemical performance of Ag 2 TiO 3 than other electrodes towards metronidazole (MTZ) detection. Under optimized differential pulse voltammetric (DPV) studies, the modified electrode exhibits a wide linear range of 0.1–104.3 μM with the lowest detection limit of 0.011 μM and a sensitivity of 0.371 μA μM −1 cm −2 . Furthermore, the fabricated sensor displayed excellent cyclic stability, reproducibility, repeatability, and noticeable selectivity in potentially effective interfering compounds for the detection of MTZ. The constructed electrode delivered good sensitivity to MTZ in urine and tablet with acceptable recoveries. Schematic diagram of as-synthesized Ag 2 TiO 3 towards electrochemical sensing of MTZ. • Perovskite-type Ag 2 TiO 3 was prepared by a simple ultrasonication method. • The as-synthesized Ag 2 TiO 3 modified electrode was optimized for the loading catalyst, pH, scan rate, peak current, and peak potential at the electrochemical determination of MTZ. • The fabricated sensor shows an extensive linear response from 0.1 to 104.3 μM with a low detection limit of 0.011 μM. • MTZ was successfully applied in real samples with good sensitivity and appropriate results.

Novel enzymatic graphene oxide based biosensor for the detection of glutathione in biological body fluids

In this work, we report a novel enzymatic biosensor based on glutathione peroxidase (GSH-Px), graphene oxide (GO) and nafion for the electrochemical sensing of glutathione (GSH) in body fluids. GSH-Px was immobilized covalently via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) onto modified glassy carbon electrode (GCE) decorated with GO and nafion and successfully used for sensing of GSH in the presence of H2O2 as catalyst with Michaelis-Menten constant about 0.131 mmol/L. The active surface are of GCE improve from 0.183 cm2 to 0.225 cm2 after modification with GO. The introduced biosensor (GSH-Px/GO/nafion/GCE) was used for monitoring of GSH over the range 0.003–370.0 μM, with a detection limit of 1.5 nM using differential pulse voltammetric (DPV) method. The GSH-Px/GO/nafion/GCE was successfully applied to the determination of GSH in real samples.

Green Composite Sensor for Monitoring Hydroxychloroquine in Different Water Matrix.

Hydroxychloroquine (HCQ), a derivative of 4-aminoquinolone, is prescribed as an antimalarial prevention drug and to treat diseases such as rheumatoid arthritis, and systemic lupus erythematosus. Recently, Coronavirus (COVID-19) treatment was authorized by national and international medical organizations by chloroquine and hydroxychloroquine in certain hospitalized patients. However, it is considered as an unproven hypothesis for treating COVID-19 which even itself must be investigated. Consequently, the high risk of natural water contamination due to the large production and utilization of HCQ is a key issue to overcome urgently. In fact, in Brazil, the COVID-19 kit (hydroxychloroquine and/or ivermectin) has been indicated as pre-treatment, and consequently, several people have used these drugs, for longer periods, converting them in emerging water pollutants when these are excreted and released to aquatic environments. For this reason, the development of tools for monitoring HCQ concentration in water and the treatment of polluted effluents is needed to minimize its hazardous effects. Then, in this study, an electrochemical measuring device for its environmental application on HCQ control was developed. A raw cork–graphite electrochemical sensor was prepared and a simple differential pulse voltammetric (DPV) method was used for the quantitative determination of HCQ. Results indicated that the electrochemical device exhibited a clear current response, allowing one to quantify the analyte in the 5–65 µM range. The effectiveness of the electrochemical sensor was tested in different water matrices (in synthetic and real) and lower HCQ concentrations were detected. When comparing electrochemical determinations and spectrophotometric measurements, no significant differences were observed (mean accuracy 3.0%), highlighting the potential use of this sensor in different environmental applications.

Screen-printed amalgam electrodes

Silver amalgam screen-printed electrodes (AgA-SPEs) were designed, prepared and tested for the first time as perspective representatives among SPEs that allow measuring at high negative potentials. For this purpose, the precise electrochemical (coulometric) preparation procedure for mercury deposition at the silver working electrode surface of the commercial silver-SPE was developed and a universal method of preparing amalgam electrodes from different metal-SPEs was described. An optimal electrolyzer construction for the mercury deposition, electrolyte composition, electrolysis potential, and a way to activate the electrode surface for its uniform coverage by mercury were proposed. The effect of the mercury content in amalgam on the potential of hydrogen evolution (PHE) at AgA-SPEs was investigated. The maximum PHE value (−1979 ± 4 mV; RSD = 0.17 %; N = 5) was found on AgA-SPE with 50 % (w/w) of Hg content in 0.1 mol L−1 NaOH, which is more negative than in the case of the original silver-SPE for 387 mV (−1592 ± 12 mV; RSD = 0.69 %; N = 5). Determination of the iodine content in iodinated table salt was used for the AgA-SPEs practical testing. Measurement parameters were optimized for three electrochemical cell arrangements: i) the electrodes area of AgA-SPE was covered by 50 μL of the sample solution and differential pulse voltammetric (DPV) measurements were carried out; ii) 3-electrode batch arrangement with only working electrode from AgA-SPE connected with an analyzer for DPV-measurements; iii) amperometric measurements in a flow system. The results of iodine analysis by all three methods were consistent with the manufacturer declared values.

Highly selective voltammetric detection of antipsychotic drug thioridazine hydrochloride based on NiO@Gd2O3 modified screen printed carbon electrode

• NiO@Gd 2 O 3 was synthesized via the facile co-precipitation method. • Modified sensor were studied by CV and DPV techniques for TRH detection. • NiO@Gd 2 O 3 electrode displayed WLR, low LOD, and excellent sensitivity. • The fabricated sensor shows good selectivity in MT, DA, UA, and CPZ towards TRH. The construction of mixed metal oxides matrix acts as highly active electrode materials in the field of an electrochemical sensor, owing to high conductivity, a large number of active sites, fast kinetics, and superior sensing activity. In this study, the spherical-like NiO@Gd 2 O 3 (NGO) microstructures were successfully synthesized by a simple co-precipitation method and employed for the selective electrochemical detection of thioridazine hydrochloride (TRH). The as-prepared NGO-500 material was confirmed with suitable spectrometric techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy, Brunauer–Emmett–Teller (BET) method, field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrometry (XPS) analyses. The electrocatalytic performance of TRH on modified screen-printed carbon electrode (NGO-500/SPCE) was investigated through cyclic voltammetric (CV), and differential pulse voltammetric (DPV) methods. As a result, the proposed electrode demonstrated a wide linear response of 0.04–151.6 µM, a low detection limit of 0.004 µM with an excellent sensitivity of 3.09 µA µM −1 cm −2 . Besides, the modified electrode establishes outstanding selectivity in the presence of the various interfering compounds towards TRH detection. The fabricated electrode displayed notable repeatability, reproducibility, acceptable cyclic and storage stability. The feasibility of the NGO-500 electrode was used to sense TRH in urine and serum samples with satisfactory results.

Electrochemical Detection of 2-Nitrophenol Using a Glassy Carbon Electrode Modified with BaO Nanorods.

Here, an electrochemical detection approach (differential pulse voltammetry) was employed to develop a 2-nitrophenol (2-NP) sensor probe using a glassy carbon electrode (GCE) coated by wet-chemically synthesized nanorods (NRs) of BaO. The prepared BaO NRs were characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD) analysis. The peak currents by differential pulse voltammetric (DPV) analysis of 2-NP are plotted against the concentration to obtain the calibration curve of the 2-NP detection. It was found to be linear from 1.5 to 9.0 μM, defined as the dynamic range (LDR) for 2-NP detection in phosphate buffer solution. The sensor sensitivity was calculated from the slope of LDR by considering the active surface area of NRs coated on GCE (0.0316 cm2 ) and found as 17.6 μAμM-1 cm-2 . The limit of detection (LOD) was calculated as 0.50±0.025 μM from the signal/noise (S/N) ratio of 3. Moreover, the sensor analytical parameters such as reproducibility, long-term performing ability (stability), response time and validity in real environmental samples were found acceptable and to give satisfactory results. The development of a nanomaterial-based electrochemical chemical sensor might be an effective approach to sensor technology to detect carcinogenic and hazardous toxins for environmental safety and healthcare fields in a broad scale.

Enhanced response of sensor on serotonin using nickel-reduced graphene oxide by atomic layer deposition

Atomic layer deposition (ALD) is a promising method for preparing nanomaterials. The thickness and uniformity of nanomaterials can be precisely controlled. Hence, the uniform Ni nanoparticles (Ni NPs) deposited on reduced graphene oxide (rGO) by ALD and got the optimal combination interface. The morphology, structure, and electrochemical behavior of Ni NPs-rGO nanocomposite are investigated. By experiment results, the Ni NPs could occupy some active surface of rGO, resulting in high conductivity and large specific surface area of Ni NPs-rGO nanocomposite. The Ni NPs-rGO nanocomposite exhibits high electrocatalytic activity for serotonin and speeds up the electron transfer between the surface of the electrode and the solution. Therefore, the sensor is prepared by Ni NPs-rGO nanocomposite modified glassy carbon electrode (GCE) and used to sensitive detection of serotonin. By differential pulse voltammetric, the Ni NPs-rGO/GCE enhanced the current responses and showed a wide linear range of 0.02–2 μM with a low detection of 0.01 μM for serotonin (S/N = 3). The Ni NPs-rGO/GCE exhibited good stability, selectivity, and anti-interference ability that can be used for real sample detection. According to these results, the Ni NPs-rGO nanocompositeis successfully prepared by ALD. The properties of Ni NPs-rGO nanocomposite make it an attractive material for potential applications in sensors and catalysis.

Simultaneous electrochemical sensing of dihydroxy benzene isomers at cost-effective allura red polymeric film modified glassy carbon electrode

BackgroundA simple and simultaneous electrochemical sensing platform was fabricated by electropolymerization of allura red on glassy carbon electrode (GCE) for the interference-free detection of dihydroxy benzene isomers.MethodsThe modified working electrode was characterized by electrochemical and field emission scanning electron microscopy methods. The modified electrode showed excellent electrocatalytic activity for the electrooxidation of catechol (CC) and hydroquinone (HQ) at physiological pH of 7.4 by cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques.ResultsThe effective split in the overlapped oxidation signal of CC and HQ was achieved in a binary mixture with peak to peak separation of 0.102 V and 0.103 V by CV and DPV techniques. The electrode kinetics was found to be adsorption-controlled. The oxidation potential directly depends on the pH of the buffer solution, and it witnessed the transfer of equal number of protons and electrons in the redox phenomenon.ConclusionsThe limit of detection (LOD) for CC and HQ was calculated to be 0.126 μM and 0.132 μM in the linear range of 0 to 80.0 μM and 0 to 110.0 μM, respectively, by ultra-sensitive DPV technique. The practical applicability of the proposed sensor was evaluated for tap water sample analysis, and good recovery rates were observed.Graphical abstractElectrocatalytic interaction of ALR/GCE with dihydroxy benzene isomers.

Quantum chemical studies and electrochemical investigations of pyrogallol red modified carbon paste electrode fabrication for sensor application

In order to develop a sensing platform, it is very important to understand the sensing mechanism of the modified electrode by locating the redox reactive sites of the modifier, for this better understanding we used the density functional theory (DFT)-based quantum chemical modelling to explain the redox reactive sites of the pyrogallol red molecule. The pyrogallol red was later used to modify the carbon paste electrode by electropolymerisation technique for sensing applications. The real analytical applicability of the proposed sensor was evaluated by employing it to the analysis of pharmaceutical sample and a good recovery results were obtained. According to the experimental results, a high reactivity performance is observed at the fabricated electrode for the paracetamol (PRM) electro-oxidation involving the transfer of identical number of electrons and protons. The lower limit of detection (LOD) was 0.11 μM by differential pulse voltammetric (DPV) method in the linear range of 5.0 µM − 45.0 µM was obtained. The real analytical applicability of the proposed method is valid for the pharmaceutical analysis in presence of possible excipients suggested that the fabricated electrode is a promising sensing platform. The methodology adopted in the present work can be extended to construct the electrochemical sensor for other electroactive molecules also.

Flex Printed Circuit Board Implemented Graphene-Based DNA Sensor for Detection of SARS-CoV-2.

Since the COVID-19 outbreak was declared a pandemic by the World Health Organization (WHO) in March 2020, ongoing efforts have been made to develop sensitive diagnostic platforms. Detection of viral RNA provides the highest sensitivity and specificity for detection of early and asymptomatic infections. Thus, this work aimed at developing a label-free genosensor composed of graphene as a working electrode that could be embedded into a flex printed circuit board (FPCB) for the rapid, sensitive, amplification-free and label-free detection of SARS-CoV-2. To facilitate liquid handling and ease of use, the developed biosensor was embedded with a user-friendly reservoir chamber. As a proof-of-concept, detection of a synthetic DNA strand matching the sequence of ORF1ab was performed as a two-step strategy involving the immobilization of a biotinylated complementary sequence on a streptavidin-modified surface, followed by hybridization with the target sequence recorded by the differential pulse voltammetric (DPV) technique in the presence of a ferro/ferricyanide redox couple. The effective design of the sensing platform improved its selectivity and sensitivity and allowed DNA quantification ranging from 100 fg/mL to n}{}1~mu text{g}n/mL. Combining the electrochemical technique with FPCB enabled rapid detection of the target sequence using a small volume of the sample (5-n}{}20~mu text{L}n). We achieved a limit-of-detection of 100 fg/mL, whereas the predicted value was ~33 fg/mL, equivalent to approximately n}{}5times 10^{5}n copies/mL and comparable to sensitivities provided by isothermal nucleic acid amplification tests. We believe that the developed approach proves the ability of an FPCB-implemented DNA sensor to act as a potentially simpler and more affordable diagnostic assay for viral infections in Point-Of-Care (POC) applications.

Poly(glutamic acid) Modified Pencil Graphite Electrode for Voltammetric Determination of Bisphenol A

Bisphenol A (BPA), which is an endocrine-disrupting substance, is often utilized as beverage and food packing material, and it may accumulate in nutrition and water sources, which is why it is important to monitor. In this study, for the determination of bisphenol A, electro-polymerization of glutamic acid (GA) was performed on a pencil graphite electrode (PGE). The performance of the sensor (PGA/PGE) for determining bisphenol A was examined utilizing the cyclic voltammetric (CV) and differential pulse voltammetric (DPV) methods. Electrochemical characterization process of the PGA/PGE was carried out by the electrochemical impedance spectroscopy (EIS) and CV methods. The morphological property of the PGA/PGE was investigated by scanning electron microscopy (SEM). The presence of functional groups in the PGA/PGE composition was characterized by Fourier transform infrared spectroscopy (FTIR). The electrochemical behavior of BPA was observed with the bare PGE and the PGA/PGE. Based on the findings, the response of BPA was considerably raised with PGA/PGE. With the optimized parameters and based on the findings from DPV, the BPA oxidation current was linear in a concentration interval of 1.0 to 100 μM (R=0.9992), and the detection limit was found to be 0.37 μM. Detection of BPA in the plastic bottled drinking water sample using PGA/PGE was performed successfully, and the recoveries were in the range of 89.3 to 104.7%. This strategy can provide several prospects in electrochemically determining BPA in practical applications.

Comparative Studies of CPEs Modified with Distinctive Metal Nanoparticle-Decorated Electroactive Polyimide for the Detection of UA.

In this present work, an electrochemical sensor was developed for the sensing of uric acid (UA). The sensor was based on a carbon paste electrode (CPE) modified with electroactive polyimide (EPI) synthesized using aniline tetramer (ACAT) decorated with reduced nanoparticles (NPs) of Au, Pt, and Ag. The initial step involved the preparation and characterization of ACAT. Subsequently, the ACAT-based EPI synthesis was performed by chemical imidization of its precursors 4,4′-(4.4′-isopropylidene-diphenoxy) bis (phthalic anhydride) BPADA and ACAT. Then, EPI was doped with distinctive particles of Ag, Pt and Au, and the doped EPIs were abbreviated as EPIS, EPIP and EPIG, respectively. Their structures were characterized by XRD, XPS, and TEM, and the electrochemical properties were determined by cyclic voltammetry and chronoamperometry. Among these evaluated sensors, EPI with Au NPs turned out the best with a sensitivity of 1.53 uA uM−1 UA, a low limit of detection (LOD) of 0.78 uM, and a linear detection range (LDR) of 5–50 uM UA at a low potential value of 310 mV. Additionally, differential pulse voltammetric (DPV) analysis showed that the EPIG sensor showed the best selectivity for a tertiary mixture of UA, dopamine (DA), and ascorbic acid (AA) as compared to EPIP and EPIS.

E-MagnetoMethyl IP: a magnetic nanoparticle-mediated immunoprecipitation and electrochemical detection method for global DNA methylation.

The quantification of global 5-methylcytosine (5mC) content has emerged as a promising approach for the diagnosis and prognosis of cancers. However, conventional methods for the global 5mC analysis require large quantities of DNA and may not be useful for liquid biopsy applications, where the amount of DNA available is limited. Herein, we report magnetic nanoparticles-assisted methylated DNA immunoprecipitation (e-MagnetoMethyl IP) coupled with electrochemical quantification of global DNA methylation. Carboxyl (-COOH) group-functionalized iron oxide nanoparticles (C-IONPs) synthesized by a novel starch-assisted gel formation method were conjugated with anti-5mC antibodies through EDC/NHS coupling (anti-5mC/C-IONPs). Anti-5mC/C-IONPs were subsequently mixed with DNA samples, in which they acted as dispersible capture agents to selectively bind 5mC residues and capture the methylated fraction of genomic DNA. The target-bound Anti-5mC/C-IONPs were magnetically separated and directly adsorbed onto the gold electrode surface using gold-DNA affinity interaction. The amount of DNA adsorbed on the electrode surface, which corresponds to the DNA methylation level in the sample, was electrochemically estimated by differential pulse voltammetric (DPV) study of an electroactive indicator [Ru(NH3)6]3+ bound to the surface-adsorbed DNA. Using a 200 ng DNA sample, the assay could successfully detect differences as low as 5% in global DNA methylation levels with high reproducibility (relative standard deviation (% RSD) = <5% for n = 3). The method could also reproducibly analyze various levels of global DNA methylation in synthetic samples as well as in cell lines. The method avoids bisulfite treatment, does not rely on enzymes for signal generation, and can detect global DNA methylation using clinically relevant quantities of sample DNA without PCR amplification. We believe that this proof-of-concept method could potentially find applications for liquid biopsy-based global DNA methylation analysis in point-of-care settings.

Electrochemical Detection and Degradation of Carbendazim at Poly (Vat Violet 2r) Modified GCE

To increase the electrochemical activity of the working electrode, vat violet 2R dye was electro-polymerized on the GCE surface i.e., poly (VVR)/GCE. Utilizing various voltammetric techniques including such cyclic voltammetric (CV), differential pulse voltammetric (DPV), and square wave voltammetric (SWV) technique, the fabricated glassy carbon electrode demonstrated excellent electrocatalytic behaviour against the electro-oxidation of carbendazim (CBM) in a 0.2 M PBS 3.0 pH. There has been observed a well resolution peak of the CBM with enhancement in the current for the developed GCE. The impact of electroanalytical parameters such as accumulation time, temperature variation, pH, heterogeneous rate, transfer coefficient, sweep rate, activation energy, as well as total count of electrons and protons have been evaluated in the CBM electro-oxidation mechanism. The real samples like water and soil samples were investigated using voltammetric techniques. The developed sensor is sensitive for the investigation of fungicide CBM by the determination of detection and quantification limit of CBM.