Wave Voltammetry Research Articles

Electrodeposition of copper on glassy carbon and palladium from choline chloride - ethylene glycol deep eutectic solvent

Electrodeposition of copper from deep eutectic solvents (DES) based on a mixture of choline chloride and ethylene glycol containing CuCl2·2H2O at 50 °C and 80 °C was studied. Electrochemical reduction/oxidation of Cu(II)/Cu(0) on glassy carbon (GC) and palladium (Pd) electrodes was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) emphasizing that this process takes place through two steps, Cu(II) ↔ Cu(I) and Cu(I) ↔ Cu(0). The CV results showed that in chloride-rich DES electrolytes, the increased presence of chloro ligands raises the overpotential required for Cu electrodeposition. The electrochemical impedance spectroscopy (EIS) results indicate simultaneous electrodeposition of Cu and electrosorption of large cations on electrodeposited Cu on both GC and Pd substrates. Scanning electron microscopy (SEM) results showed that Cu grains of approximately 1 μm were obtained by electrodeposition of Cu on both Pd and GC, whereby better coverage by electrodeposited Cu was obtained on Pd than on GC. Cu electrodeposited on Pd was relatively uniform and smooth, but porous, while Cu electrodeposited on GC was dispersed in small agglomerates. Energy-dispersive X-ray spectroscopy (EDS) of Cu electrodeposited on Pd detected the dominant presence of Cu with the possibility of the formation of CuPd alloy. The presence of CuPd alloy face-centred cubic structures is confirmed by X-ray diffraction (XRD) along with metallic Cu.

PEDOT/CNT Flexible MEAs Reveal New Insights into the Clock Gene's Role in Dopamine Dynamics.

Substantial evidence has shown that the Circadian Locomotor Output Cycles Kaput (Clock) gene is a core transcription factor of circadian rhythms that regulates dopamine (DA) synthesis. To shed light on the mechanism of this interaction, flexible multielectrode arrays (MEAs) are developed that can measure both DA concentrations and electrophysiology chronically. The dual functionality is enabled by conducting polymer PEDOT doped with acid-functionalized carbon nanotubes (CNT). The PEDOT/CNT microelectrode coating maintained stable electrochemical impedance and DA detection by square wave voltammetry for 4 weeks in vitro. When implanted in wild-type (WT) and Clock mutation (MU) mice, MEAs measured tonic DA concentration and extracellular neural activity with high spatial and temporal resolution for 4 weeks. A diurnal change of DA concentration in WT is observed, but not in MU, and a higher basal DA concentration and stronger cocaine-induced DA increase in MU. Meanwhile, striatal neuronal firing rate is found to be positively correlated with DA concentration in both animal groups. These findings offer new insights into DA dynamics in the context of circadian rhythm regulation, and the chronically reliable performance and dual measurement capability of this technology hold great potentialfor a broad range of neuroscience research.

Electrochemical Behavior of Niobium Oxide and Titanium Oxide in NaF–Na3AlF6 Molten Salt

The Bayan Obo ore deposit is a world-renowned polymetallic coexistence mine that integrates important elements, such as rare earths, iron, niobium, and titanium. The chemical properties of niobium and titanium are similar, and the two often coexist in the Bayan Obo deposit as isomorphs, making them difficult to separate. Therefore, the separation of niobium and titanium is crucial for the efficient utilization of niobium resources in the Bayan Obo ore deposit of China. To discuss the feasibility of separating niobium and titanium by selective electrolysis, cyclic voltammetry and square wave voltammetry were used to study the reduction mechanism of niobium oxide and titanium oxide in NaF–Na3AlF6 molten salt. The results revealed significant differences in the diffusion coefficients and reduction steps of Nb5+ and Ti4+ during reduction at a molybdenum cathode. At 950 °C, the diffusion coefficient of Nb5+ during reduction at a molybdenum cathode was 3.57 × 10–6 cm2/s. Also, in the NaF–Na3AlF6 system, Nb5+ underwent a three-step reduction as follows: Nb(V)→Nb(IV)→Nb(I)→Nb. The diffusion coefficient of Ti4+ during reduction at the molybdenum cathode was 9.92 × 10–7 cm2/s, and Ti4+ underwent a two-step reduction in the NaF–Na3AlF6 system: Ti(IV)→Ti(I)→Ti. When Nb2O5 and TiO2 were both present in the NaF–Na3AlF6 system, the deposition potential of niobium metal (−0.64 V) differed from that of titanium metal (−0.77 V). These differences in diffusion coefficient, reduction step, and deposition potential enabled selective electrolytic separation of niobium and titanium.

First electrochemical investigation and determination of non-steroidal anti-inflammatory drug etofenamate using disposable pencil graphite electrode with voltammetric techniques

In this study, the electrochemical properties of etofenamate, an active ingredient belonging to the non-steroidal anti-inflammatory drug group, were investigated using cyclic voltammetry (CV) and square wave voltammetry (SW) techniques on a disposable pencil graphite electrode (PGE). With the CV technique, reversible voltammetric waves of around +0.470 V and irreversible voltammetric waves of around +1.02 V were produced on the PGE. An environmentally friendly, selective and highly sensitive SW voltammetric method was developed using disposable PGE. This voltammetric method gave very good analytical working range on PGE in PBS (pH = 3.0) medium at concentrations ranging from 0.017 μM to 0.306 μM. The LOD value of this analytical method in PBS (pH = 3.0) medium was calculated as 0.0011 μM (0.406 μg L−1). The developed voltammetric method was successfully applied to urine and drug samples. The results of the voltammetric method were compared with the results of the spectrophotometric method. The results were found to be compatible with each other.

Novel TiO2 nanoparticle-based sensor for xanthate quantification in mineral flotation samples

A voltammetric method for xanthate quantification was developed by fabricating a new electrode based on TiO2 nanoparticles (TiO2 NPs). The nanomaterial in the anatase phase was synthesized by a simple sol-gel method followed by a thermal treatment (9 h at 500 °C). The nanoparticles have a spheroidal morphology with an average size of 20.61 ± 6.01 nm. The band gap energy (3.7 eV) was determined by means of UV–visible spectroscopy from the absorption band at 335 nm. The TiO2 based sensor was employed as working electrode (electroactive area: 0.02248 cm2) in a cyclic voltammetry study, and a greater peak current was observed for the electrooxidation of isopropyl xanthate at pH 10 as compared to the unmodified electrode. The electrode optimization showed that the percentage of TiO2 and the amount of mineral oil in the electrode have a significant influence on the electrochemical response, with 18.4 % of TiO2 NPs, 0.74 mL of mineral oil, and 18 h of electrode rest before the first use as optimal conditions. In the polarization studies, the charge transfer reaction occurred through a lower overpotential with respect to the open circuit potential. The exchange current density was three times higher for the modified electrode. Electrochemical impedance spectroscopy indicated the detection of xanthate with lower charge transfer resistance than when the unmodified electrode was used. The electrochemical sensor allows the quantification of xanthate from 5 μmol/L to 10 mmol/L by cyclic voltammetry and the square wave technique. For the cyclic voltammetry calibration, the limits of detection and quantification were 40.6 μmol/L and 135 μmol/L, respectively. The limit of detection by square wave voltammetry was 2.4 μmol/L, and the limit of quantification was 7.9 μmol/L. The repeatability of the method showed a relative dispersion of 3.1 % at 0.51 mmol/L. The electroanalytical response of the sensor was reproducible up to 30 days. The recoveries of xanthate in real flotation samples were 91.9 % and 94.6 % for concentrations of 0.55 and 1.1 mmol/L, respectively. No statistically significant differences were found between the quantification using the sensor and the UV spectrophotometric method. Dicresyl dithiophosphate showed statistically significant interference with the xanthate oxidation signal.

MCNTs/ZnO nanocomposite-fabricated nanosensor for 1-naphthyleacetic acid electroanalysis and its applications

Zinc oxide nanoparticles and multiwalled carbon nanotubes were mixed to create a novel carbon paste electrode known as MCNTs/ZnO/CPE—a substance that stimulates plant growth. This electrode was designed to investigate the effects of NAA. Various techniques, including cyclic voltammetry (CV) and square wave voltammetry (SWV), were employed to assess the stability and electrochemical properties of the MCNTs/ZnO/CPE electrode. The study aimed to examine the electrochemical behavior of NAA on MCNTs/ZnO/CPE to investigate its potential application in plant development. The experiment results provided valuable insights into the complementary effects of NAA and the electrode materials, paving the way for future advances in plant bioelectrochemistry. At a pH of 3.0, the more significant peak current indicates the effective electron transfer between the PB solution and the MCNTs/ZnO/CPE sensor. The sensor's outstanding catalytic activity at this pH further suggests its potential for various electrochemical applications. Actual samples, such as water, fruits, vegetables, and soil, were analyzed using the SWV method. ZnO/CPE, bare CPE, MCNTs/CPE, and MCNTs/ZnO/CPE all had peak currents of 4.044 µA, 10.40 µA, 12.91 µA, and 16.52 µA, respectively. The peak potentials for bare CPE, ZnO/CPE, MCNTs/CPE, and MCNTs/ZnO/CPE were all found to be 1.19 V, 1.19 V, 1.18 V, and 1.15 V, respectively. All the experiments were carried out at 25 s of optimum accumulation time. The detection limit was determined to be 1.1 nM, and the linear range is 0.2 × 10−8 to 7.0 × 10−6 M. The surface area of the unmodified CPE was determined to be 0.04 cm2, whereas the surface area of the modified CPE was determined to be 0.13 cm2. The mean value of the rate constant (ks) for the anodic reaction was 2.8 × 10−3 cm s−1. In addition to electro-kinetic factors like the effect of temperature and the heterogeneous rate constant, the electro-oxidation of NAA was examined about several parameters, including electron contribution, accumulation duration, pH, energy of activation, scan rate, and transfer coefficient.

Electrochemical formation and characterization of Ni-Sc intermetallic compounds in LiF-CaF2 eutectic melt

The present investigation aimed to examine the cathodic behavior of Sc(III) on a reactive nickel electrode within a fluoride molten salt system. The electrochemical formation process of Ni-Sc alloy in LiF-CaF2 eutectic melt was investigated using cyclic voltammetry and square wave voltammetry electrochemical techniques. The formation of Ni-Sc intermetallic compounds induces a depolarization phenomenon, hence promoting the underpotential deposition of scandium onto the Ni electrode. The standard Gibbs free energy of formation for Ni-Sc intermetallic compounds were calculated by the use of open-circuit chronopotentiometry measurements. Furthermore, Ni-Sc alloys were fabricated via potentiostatic and galvanostatic electrolysis methods and subsequently characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The results indicated that a sequential emergence of Ni5Sc, Ni2Sc, and combined NiSc+NiSc2 intermetallic compounds escalates as the cathodic polarization potential. Multifarious Ni-Sc intermetallic compounds can be synthesized by controlling the electrolysis conditions, providing new insights for the preparation of Ni-Sc alloy and establishing a theoretical foundation for the synthesis of Ni-Sc intermediate alloy for solid-state reactive cathodes.

Simultaneous determination of environmental endocrine disruptors bisphenol A and 4-nitrophenol bleached from food-contacting materials using the spin-ladder compound La2Cu2O5 modified glassy carbon electrode

Environmental endocrine-disrupting chemicals, Bisphenol A (BPA) and 4-Nitrophenol (4-NP), pose significant risks to reproductive health in both animals and humans. Here, we introduce the first utilization of the 4-leg spin ladder compound La2Cu2O5 as an electrode material for electrochemical sensor. Nanostructured La2Cu2O5 was synthesized via a straightforward Sol-Gel method and thoroughly characterized using X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and powder X-ray diffraction. La2Cu2O5 nanoparticles modified glassy carbon electrode (GCE) exhibited a significant electrocatalytic activity towards the oxidation of BPA and 4-NP in phosphate buffer saline (pH 7.0). Square wave voltammetry studies revealed lowest detection limits of 3 nM for BPA and 2.6 nM for 4-NP over a wider concentration range of 0.01–500 μM. Notably, this study marks the first utilization of La2Cu2O5 for simultaneous electrochemical detection of BPA and 4-NP, demonstrating its potential in this field. Furthermore, the sensor exhibited good sensitivity, reproducibility, and selectivity towards BPA and 4-NP, even in the presence of similar potential organic and inorganic interferents. Additionally, the newly developed sensor enabled simultaneous quantification of BPA and 4-NP in real samples such as packaged milk, river water, and plastic bottles, achieving recovery rates above 95%. Importantly, our results underscore the leaching of BPA into water from thin and thick plastics at elevated temperatures (40 °C–80 °C), emphasizing the utility of the proposed sensor for rapid and simultaneous detection of BPA and 4-NP in environmental and food matrices.

Electroanalytical Determination of Trimetazidine in Pharmaceuticals and Synthetic Urine Using an Anodically Treated Boron-Doped Diamond (BDD) Electrode and Square Wave Voltammetry (SWV)

Trimetazidine dihydrochloride is an anti-ischemic agent widely used in the treatment of coronary artery disease, more specifically in the treatment of angina. Here is reported a simple and sensitive electroanalytical methodology for quantifying trimetazidine in pharmaceutical and synthetic urine samples using square-wave voltammetry. The influence of anodic and cathodic treatments on boron-doped diamond (BDD) was evaluated. The best results for trimetazidine were obtained using a BDD treated anodically at +3.0 V versus Ag(s)/AgCl(s)/Cl-(aq., saturated KCl) for 300 s in 0.1 mol L−1 H2SO4. The determination of trimetazidine was carried out in Britton-Robinson buffer at pH 3. Trimetazidine oxidation reveals two well-defined irreversible oxidation peaks. A calibration relationship was obtained from 0.35 mg L-1 to 2.6 mg L−1 (R2 = 0.997). Limits of detection and quantification for trimetazidine were 5.63 x 10−9 and 1.88 x 10−8 mol L−1, respectively. Recovery values were between 97 and 101 % and 96.8 and 99.8 % in pharmaceutical and synthetic urine.

Paper-based electrochemical immunosensor for highly sensitive detection of chicken anemia virus

Chicken anemia virus (CAV) is one of the primary causes of morbidity and mortality in young chickens. Given the importance of timely detection for maintaining livestock quality, there is a pressing need for rapid and field-deployable diagnostic tools. This study introduces a highly sensitive paper-based electrochemical immunosensor (PEI) for the detection of the 60 amino acid N-terminally truncated viral protein 1 (Δ60VP1), a derivative of the CAV capsid (VP1). A custom antibody was produced for precise immunoassay detection, with results obtainable within 30 min using Square Wave Voltammetry (SWV). The underlying mechanism involves an immunocomplex in the sample zone that hinders the electron transfer of redox species, thereby reducing the current signal in proportion to the Δ60VP1 concentration. Under optimal conditions, the detection linearity for Δ60VP1 ranged from 80 to 2500 ng/mL, with a limit of detection (LoD) of 25 ng/mL. This device was then successfully applied to detect VP1 in 29 chicken serum samples, achieving 91.6% sensitivity and 94.1% selectivity. In conclusion, the PEI device presents a promising solution for rapid, sensitive, and disposable detection of chicken pathogens, potentially revolutionizing productivity and quality assurance in chicken farming.

Voltammetric measurement of catechol-O-methyltransferase inhibitor tolcapone in the pharmaceutical form on the boron-doped diamond electrode.

This study presents an electroanalytical approach to measure the catechol-O-methyltransferase (COMT) inhibitor tolcapone (TOL) using a boron-doped diamond (BDD) electrode. The application of cyclic voltammetry (CV) technique revealed that TOL exhibited a distinct, diffusion-controlled, irreversible anodic peak at a potential of approximately +0.71 V (vs. Ag/AgCl) in a 0.1 mol L-1 phosphate buffer solution (PBS) with a pH of 2.5. The oxidation of TOL is highly dependent on the pH and supporting electrolytes. Based on the data obtained from the pH investigation, a proposed mechanism for the electro-oxidation of TOL is suggested. Using the square wave voltammetry (SWV) technique, a satisfactory linear relationship was observed at approximately +0.66 V in a 0.1 mol L-1 PBS with a pH of 2.5. The presented method exhibited linearity within the concentration range between 1.0-50.0 μg mL-1 (3.7 × 10-6-1.8 × 10-4 mol L-1), with a limit of detection (LOD) of 0.29 μg mL-1 (1.1 × 10-6 mol L-1). The BDD electrode demonstrated good selectivity against inorganic ions and filler materials interference. Finally, the suitability of the developed approach was assessed by measuring TOL in tablet formulations, resulting in favorable recoveries ranging from 103.4% to 106.2%.

Rapid and efficient extraction of cerium by forming Al-Ce alloys in LiCl-KCl molten salts

The extraction of lanthanides in spent fuel reprocessing plays a key role in the development of nuclear energy. In this work, the extraction of the typical fissionable cerium elements has been studied by electrolytic co-reduction of Al(III) and Ce(III) in LiCl-KCl-CeCl3 molten salts assisted by KAlCl4. The electrochemical behavior of the reduction of Al(III) and Ce(III) on a molybdenum electrode was studied by cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit chronopotentiometry (OCP), and specific peaks of five Al-Ce intermetallic compounds were detected. After 2.7 h of galvanostatic electrolysis at a current density of 0.064 A cm-2, the extraction efficiency and current efficiency of Ce(III) reached 99.9 % and 91.3 % respectively. Potentiostatic electrolysis is slightly more efficient, with 99.9 % Ce(III) extraction in 3.5 h at a current efficiency of 97.8 %. The products of electrolysis are rod-shaped alloys (Al11Ce3, Al3Ce, Al2Ce), and the molten salts purified by electrolytic separation are free of impurity signals and can be reused for electrolytic refining.

Electrochemical biosensor for the evaluation of monoclonal antibodies targeting the N protein of SARS-CoV-2 virus

The emergence of COVID-19 caused by the coronavirus SARS-CoV-2 has prompted a global pandemic that requires continuous research and monitoring. This study presents a design of an electrochemical biosensing platform suitable for the evaluation of monoclonal antibodies targeting the SARS-CoV-2 nucleocapsid (N) protein. Screen-printed carbon electrodes (SPCE) modified with gold nanostructures (AuNS) were applied to design a versatile and sensitive sensing platform. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), were used to investigate the interactions between immobilised recombinant N (rN) protein and several monoclonal antibodies (mAbs). The electrochemical characterisation of SPCE/AuNS/rN demonstrated a successful immobilisation of rN, enhancing the electron transfer kinetics. Affinity interactions between immobilised rN and four mAbs (mAb-4B3, mAb-4G6, mAb-12B2, and mAb-1G5) were explored. Although mAb-4B3 showed some non-linearity, the other monoclonal antibodies exhibited specific and well-defined interactions followed by the formation of an immune complex. The biosensing platform demonstrated high sensitivity in the linear range (LR) from 0.2 nM to 1 nM with limits of detection (LOD) ranging from 0.012 nM to 0.016 nM for mAb-4G6, mAb-12B2, and mAb-1G5 and limits of quantification (LOQ) values ranging from 0.035 nM to 0.139 nM, as determined by both EIS and SWV methods. These results highlight the system's potential for precise and selective detection of monoclonal antibodies specific to the rN. This electrochemical biosensing platform provides a promising route for the sensitive and accurate detection of monoclonal antibodies specific to the rN protein.

Core-Shell Nanocables Decorated with Carbon Spherical Shells and Silver Nanoparticles for Sensing Ethinylestradiol Hormone in Water Sources and Pills.

The selective, rapid detection of low levels of hormones in drinking water and foodstuffs requires materials suitable for inexpensive sensing platforms. We report on core-shell Ag@C nanocables (NCs) decorated with carbon spherical shells (CSSs) and silver nanoparticles (AgNPs) by using a hydrothermal green approach. Sensors were fabricated with homogeneous, porous films on screen-printed electrodes, which comprised a 115 nm silver core covered by a 122 nm thick carbon layer and CSSs with 168 nm in diameter. NCs and CSSs were also decorated with 10-25 nm AgNPs. The NC/CSS/AgNP sensor was used to detect ethinylestradiol using square wave voltammetry in 0.1 M phosphate buffer (pH 7.0) over the 1.0-10.0 μM linear range with a detection limit of 0.76 μM. The sensor was then applied to detect ethinylestradiol in tap water samples and a contraceptive pill with recovery percentages between 93 and 101%. The high performance in terms of sensitivity and selectivity for hormones is attributed to the synergy between the carbon nanomaterials and AgNPs, which not only increased the sensor surface area and provided sites for electron exchange but also imparted an increased surface area.

Electrochemical determination of riboflavin in pharmaceuticals using unmodified screen printed carbon electrodes.

In this study, we have devised an efficient and rapid approach to detect riboflavin (also known as Vitamin B2 or VB2) utilizing an unaltered screen-printed carbon electrode (SPCE). The unmodified screen-printed electrodes are created within the laboratory, where carbon ink is applied to a ceramic substrate. All experiments pertaining to the investigation of electrochemical behavior and the fine-tuning of crucial experimental parameters were conducted through cyclic voltammetry (CV). For quantitative assessments, square wave voltammetry (SWV) was employed. The findings indicate that unaltered SPCEs exhibit robust current signals during the riboflavin redox reaction. Riboflavin displays a distinct oxidation peak at -0.136V (vs. Ag/AgCl, 3.0M KCl) in a Britton-Robinson buffer solution (BRBS) at pH 2, which was employed for quantification. The electrode demonstrates a broad linear range from 0.05 to 10µM, boasting a detection limit of 0.03µM. Repeatability stands at 1.45%, while reproducibility is 6.61%. Testing the influence of common interfering compounds yielded negligible results. The sensor effectively determines riboflavin content in pharmaceutical formulations without any prior treatment. This method presents an economical, modifier-free sensor with exceptional sensitivity and cost-effectiveness, making it suitable for rapid riboflavin quantification.

NFC-enabled potentiostat and nitrocellulose-based metal electrodes for electrochemical lateral flow assay

Rapid detection of pathogens at the point-of-need is crucial for preventing the spread of human, animal and plant diseases which can have devastating consequences both on the lives and livelihood of billions of people. Colorimetric, lateral flow assays consisting of a nitrocellulose membrane, are the preferred format today for low-cost on-site detection of pathogens. This assay format has, however, historically suffered from poor analytical performance and is not compatible with digital technologies. In this work, we report the development of a new class of digital diagnostics platform for precision point-of-need testing. This new versatile platform consists of two important innovations: i) A wireless and batteryless, microcontroller-based, low-cost Near Field Communication (NFC)-enabled potentiostat that brings high performance electroanalytical techniques (cyclic voltammetry, chronoamperometry, square wave voltammetry) to the field. The NFC-potentiostat can be operated with a mobile app by minimally trained users; ii) A new approach for producing nitrocellulose membranes with integrated electrodes that facilitate high performance electrochemical detection at the point-of-need. We produced an integrated system housed in a 3D-printed phone case and demonstrated its use for the detection of Maize Mosaic Virus (MMV), a plant pathogen, as a proof-of-concept application.

Commercial ink-coated PVC: No longer abrading conventional PVC surfaces for electrode fabrication using pencil drawing

Using pencil drawing, a rapid “do-it-yourself” approach is reported to fabricate electrochemical sensors on commercial ink-coated polyvinyl chloride (PVC) substrates. Unlike conventional PVC, the ink-coated substrates have a rougher surface, enabling graphite deposition without a mechanical pretreatment step and simplifying the fabrication method. Three-electrode electrochemical sensors were designed with 2B, 6B, and 8B graphite pencils. Regardless of the pencil type, the fabrication process was conducted with the same number of pencil movements while a commercial multimeter monitored the graphite trails’ electrical resistance. 8B graphite pencils exhibited superior performance due to their softness. Such a feature facilitated the graphite exfoliation and deposition, producing continuous conductive trails and enhancing the sensors' electrochemical responses. Similarly to conventional glassy carbon electrodes, the proposed sensors showed a diffusion-controlled electrochemical behavior for the hexaammineruthenium, requiring only 80 µL of solution for electrochemical measurements. The sensors also exhibited repeatability and reproducibility. Additionally, the sensors’ mechanical stability was demonstrated through bending tests, demonstrating robustness. Under optimized conditions, the analytical performance of the sensors was initially evaluated for analytes with forensic and food interest, such as cocaine-free base (COC) and caffeic acid (CA). As a proof of concept, caffeic acid was successfully quantified in tea samples using square wave voltammetry, achieving a low detection limit of 0.37 μmol L-1. Therefore, this work brings a straightforward alternative to fabricating electrochemical sensors using cheap daily-use materials and showcases the resulting device's utility for antioxidant sensing in tea samples.

Revolutionizing HPV Detection: Unveiling a Novel Electrochemical Immunosensor for Ultra-Sensitive HPV16 E7 Oncoprotein Detection Based on Gold-Graphitic Carbon Nitride Nanocomposite

Cervical cancer (CC), a significant contributor to the mortality of females globally, manifests an annual incidence of 500,000 cases and is predominantly linked to the human papillomavirus (HPV) infection. The pressing demand for affordable and user-friendly assays for CC detection is highlighted by the limited availability and dependability of diagnostic screening tools, especially in developing countries. In response to the critical need for enhanced cervical cancer diagnostics, we present an innovative electrochemical immunosensor designed for the selective detection of the HPV 16-E7 oncoprotein. The immunosensing platform is constructed from a gold-graphitic carbon nitride (Au-g-C3N4) nanocomposite, with antibodies immobilized through a physical adsorption process onto the sensing platform. Employing Square Wave Voltammetry (SWV), we systematically evaluated the antigen-antibody interaction, achieving ultrasensitive detection of E7 with ferric/ferrocyanide. The linear detection range of the proposed sensor for E7 antigen is 0.01 fg ml−1 to 1 ng ml−1, assuming ideal conditions and an impressive Limit of Detection (LOD) of 0.0065 fg ml−1. The accuracy of the proposed immunosensor was effectively evaluated in contrast to Enzyme linked immunosorbent assay (ELISA). Finally, the proposed immunosensor exhibited favourable selectivity, sensitivity, and reproducibility upon introduction to clinical samples, thereby validating its potential suitability for point-of-care testing aimed at the timely detection of CC.

Electrochemical and theoretical studies of the interaction between anticancer drug ponatinib and dsDNA

In this study, electrochemical and theoretical studies were performed to explain the interaction mechanism between ponatinib (PNT), a third generation tyrosine kinase inhibitor, and dsDNA. The electrochemical part was conducted in phosphate-buffered saline (PBS) at physiological pH of 7.4 and in acetate buffer with a pH of 4.7, using square wave voltammetry. A boron-doped diamond electrode was used in a bulk-incubated solution. The theoretical part was investigated using computational methods, such as the semiempirical method PM7 and density functional theory (DFT). Significant differences in the electrochemical behavior of PNT in the presence of DNA confirmed the occurrence of interactions. The results obtained in the acetate buffer strongly suggested the preferential interaction of PNT with guanine residues. However, at physiological pH, it can be concluded that PNT interacts with dGua and dAdo in the dsDNA molecule. These results are consistent with outcomes from the theoretical studies, where quantum-chemical calculations showed that both electrochemically detectable nucleobases form hydrogen bonds with the drug. These bonds appeared to be stronger with guanine than with adenine. According to the computational studies, the dsDNA major groove is the energetically preferred site for the complexation of PNT.

Electrochemical immunosensors for 2,4-dichlorophenoxyacetic acid based on 3-aminopropyltrimethoxysilane modified electrodes

A novel electrochemical immunosensor prepared by direct coating of small molecular hapten on glassy carbon electrode (GCE) is reported for the detection of 2,4-dichlorophenoxyacetic acid (2,4-D). The glassy carbon electrodes were activated by electrochemical method and then were further treated with 3-aminoprpyltriethoxysilane (APS) to functionalize the GCE surface with amino groups for covalent linkage to small molecular hapten of 2,4-D with carboxyl groups. The electrodes were characterized by X-ray photoelectron spectroscopy (XPS). The principle of this immunoassay is based on an indirect competitive immunoassay. Analytes of 2,4-D and hapten of 2,4-D immobilized on glassy carbon electrode (GCE) compete for 2,4-D antibodies labeled by horseradish peroxidase (HRP-anti-2,4-D). After complete immunoreaction, the GCE attached HRP-anti-2,4-D tracers was transferred to a substrate solution containing hydroquinone (QH2) and hydrogen peroxide for square wave voltammetry (SWV) detection. Determination conditions were optimized. The SWV anodic peak current decreased linearly with the increase of 2,4-D concentration over the range from 0.10 to 15.0 mg/L 2,4-D with a detection limit of 0.01mg/L. The performance of this electrochemical immunoassay was successfully evaluated with river water spiked with 2,4-D, indicating that this convenient, rapid, and sensitive technique offers great prospect for the monitoring of trace 2,4-D in environment.