Electroanalysis最新文献

In this paper, a water-soluble highly electrochemical signal cadmium telluride (CdTe)/cadmium selenide (CdSe)/polyaniline nanocomposite was developed through a fast and convenient method, and then the nanocomposite-modified glassy carbon electrode was prepared for the determination of alpha-fetoprotein (AFP). This aptasensor was constructed by covalently immobilizing NH₂-functionalized AFP-specific aptamer on nanocomposite with plenty of carboxylic groups. This electrochemical biosensor via the layer-by-layer method could evidently increase the steric hindrance of the sensing electrode and effectively depress the electron transfer, leading to obviously decreased current intensity. The ultrahigh sensitivity of this immunoassay is derived from the two primary reasons as follows. First, the CdTe/CdSe multiple-sensitized and cosensitized structure could maximize speed of charge transfer processes between electrodes and the electroactive species, dramatically promote electron transfer, and effectively inhibit the electron–hole recombination, resulting in the significantly enhanced electrochemical current intensity of the sensing electrode. Second, the electrocatalytic oxidation of K₃Fe(CN)₆, which makes the CdTe/CdSe change from a lower-energy to higher-energy states (CdTe/CdSe QDs)*, reduces the activation energy of the reaction and the (CdTe/CdSe QDs)* more likely to oxidize, accelerating the transfer of electrons. Scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy were used to characterize the material. Electrochemical impedance spectroscopy was used to observe the loading process of the material. Differential pulse voltammetry was used as a method of measurement. The immunosensor exhibited a wide linear range from 1.0 to 10.0 μg/mL for target AFP detection, with a low detection limit of 1.0 pg/mL (S/N = 3). To evaluate the analytical reliability, reproducibility, specificity, and stability, the proposed immunosensor was applied to human AFP-spiked serum samples, and acceptable results were obtained, indicating that the method can be readily extended to other bioaffinity assays of clinical or environmental significance.

This study describes the synthesis of a phenyl trisilanol polyhedral oligosilsesquioxane (POSS) employing calcium and its subsequent modification by phosphate and methylene blue for electrochemical applications. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, were employed to characterize the developed material. The obtained POSS was characterized by cyclic coltammetry employing a graphite paste electrode, exhibiting well-defined redox pairs. The modified graphite paste electrode demonstrated an adequate electrocatalytic response for pyridoxine. Regarding catalytic pyridoxine electro-oxidation, the modified electrode exhibited a linear response ranging from 7.0 × 10⁻⁶ to 1.0 × 10⁻³ mol L⁻¹, with a limit of detection of 3.24 × 10⁻⁶ mol L⁻¹. The studied material, therefore, comprises a potential candidate for the development of electrochemical sensors for pyridoxine detection.

Cover picture provided by Dr. Elena Benito-Peña and Dr. Susana Campuzano. Electroanalysis covers all branches of electroanalytical chemistry, including both fundamental and application papers as well as reviews dealing with analytical voltammetry, potentiometry, new electrochemical sensors and detection schemes, nanoscale electrochemistry, advanced electromaterials, nanobioelectronics, point-of-care diagnostics, wearable sensors, and practical applications.

This article uses bis-dihydrazothiazolone derivative called 1,4-xylenyl-spaced bis-thiazole as an ionophore for assessment of trace cobalt(II) ions using an electrochemical potentiometric carbon sensor with tricresyl phosphate as a binder and graphite as base material.The microstructure and morphology were assessed using a scanning electron microscope and energy-dispersive X-ray spectroscopy. In addition, the elemental analyses as well as infrared, mass, and ¹H- and ¹³C-nuclear magnetic resonance were used to determine ionophore structure. The influence of variables such as pH, lifetime, content percentage, and others were modified. Under ideal conditions, it performed an efficient response within 6 s and pH 2.0–7.5 throughout a range from 5.0 × 10⁻³ to 1.0 × 10⁻⁸ M for 69 days with 1.0 × 10⁻⁸ M of the detection limit. Also, cobalt(II) ion was determined in many different samples such as water, fresh and canned fish, rice, mushroom, sesame, and Nigella sativa seed. Atomic absorption spectroscopy was used for the determination of cobalt(II) ions in these samples and provided evidence for the feasibility of the proposed approach as a cobalt(II) ion detection method. The recovery percentages for potentiometric sensor ranged from 98.18% to 99.75% with low relative standard deviation values <5. Statistical validation analysis was reported by analysis of variance (ANOVA) and design expert programs, ANOVA single value, and F- and t-tests at 95% confidence limits.

This article uses bis-dihydrazothiazolone derivative called 1,4-xylenyl-spaced bis-thiazole as an ionophore for assessment of trace cobalt(II) ions using an electrochemical potentiometric carbon sensor with tricresyl phosphate as a binder and graphite as base material.The microstructure and morphology were assessed using a scanning electron microscope and energy-dispersive X-ray spectroscopy. In addition, the elemental analyses as well as infrared, mass, and ¹H- and ¹³C-nuclear magnetic resonance were used to determine ionophore structure. The influence of variables such as pH, lifetime, content percentage, and others were modified. Under ideal conditions, it performed an efficient response within 6 s and pH 2.0–7.5 throughout a range from 5.0 × 10⁻³ to 1.0 × 10⁻⁸ M for 69 days with 1.0 × 10⁻⁸ M of the detection limit. Also, cobalt(II) ion was determined in many different samples such as water, fresh and canned fish, rice, mushroom, sesame, and Nigella sativa seed. Atomic absorption spectroscopy was used for the determination of cobalt(II) ions in these samples and provided evidence for the feasibility of the proposed approach as a cobalt(II) ion detection method. The recovery percentages for potentiometric sensor ranged from 98.18% to 99.75% with low relative standard deviation values <5. Statistical validation analysis was reported by analysis of variance (ANOVA) and design expert programs, ANOVA single value, and F- and t-tests at 95% confidence limits.

Vonoprazan fumarate (VPZ), a potent potassium-competitive acid blocker, has gained prominence recently for its efficacy in acid-related disorders, surpassing traditional proton pump inhibitors in acid suppression. Combining molecular modeling simulations with electrochemical sensors represents a cutting-edge approach in analytical chemistry. Molecular docking guided the selection of calix[8]arene as the optimal ionophore due to its superior affinity for VPZ, supported by robust docking scores and hydrophobic interactions. The final sensor configuration, incorporating calix[8]arene, sodium tetraphenylborate, and dioctyl phthalate, exhibited outstanding electroanalytical characteristics, including improved slope, enhanced potential stability, and rapid response times. Notably, the developed solid-contact sensors demonstrated a Nernstian response with a slope of 58.587 over a concentration range of 1 × 10⁻⁸–1 × 10⁻² M, achieving an impressive low detection limit of 3.09 × 10⁻⁹ M. The developed method offers a cost-effective and environmentally sustainable solution for precise monitoring of VPZ, promising significant advancements in pharmaceutical quality control.

Vonoprazan fumarate (VPZ), a potent potassium-competitive acid blocker, has gained prominence recently for its efficacy in acid-related disorders, surpassing traditional proton pump inhibitors in acid suppression. Combining molecular modeling simulations with electrochemical sensors represents a cutting-edge approach in analytical chemistry. Molecular docking guided the selection of calix[8]arene as the optimal ionophore due to its superior affinity for VPZ, supported by robust docking scores and hydrophobic interactions. The final sensor configuration, incorporating calix[8]arene, sodium tetraphenylborate, and dioctyl phthalate, exhibited outstanding electroanalytical characteristics, including improved slope, enhanced potential stability, and rapid response times. Notably, the developed solid-contact sensors demonstrated a Nernstian response with a slope of 58.587 over a concentration range of 1 × 10⁻⁸–1 × 10⁻² M, achieving an impressive low detection limit of 3.09 × 10⁻⁹ M. The developed method offers a cost-effective and environmentally sustainable solution for precise monitoring of VPZ, promising significant advancements in pharmaceutical quality control.

The analytical solution has been expanded to describe the circuit parameters of a redox couple with a charge of +1 and 0 for electrochemical reaction in the presence of supporting electrolyte as a potential application in lithium-ion battery. The Gouy–Chapman–Stern theory has been developed to comprehend the capacitance behavior as a function of the difference in electrical potential between the solution and metal parameters (E_eq variable). Finite-element simulations have been employed to explore various electrochemical system configurations, enhancing electrical storage energy by engineering the types of metal electrode and concentration heterocharge redox couple and supporting electrolyte. The initial guess for the Randles circuit parameters has been implemented by Matlab code developing, deriving them from the electrical current response versus time in a frequency-dependent sinusoidal wave function. Subsequently, the optimization problem regarding fitting of the circuit parameters has been performed through open-source Python code for electrochemical impedance spectroscopy using the initial Randles circuit parameter guess. The semianalytical method revealed a minimum in capacitance behavior near the zero value of the E_eq variable. Additionally, the numerical method showed that the capacitance behavior regarding the E_eq variable remains constant for high concentrations of the supporting electrolyte. The charge transfer coefficient demonstrated a monotonic behavior versus E_eq for all electrochemical reactions occurring on the parallel microdisk. A simulation result regarding general trend for capacitance versus E_eq variable is consistent with the available experimental data.

The analytical solution has been expanded to describe the circuit parameters of a redox couple with a charge of +1 and 0 for electrochemical reaction in the presence of supporting electrolyte as a potential application in lithium-ion battery. The Gouy–Chapman–Stern theory has been developed to comprehend the capacitance behavior as a function of the difference in electrical potential between the solution and metal parameters (E_eq variable). Finite-element simulations have been employed to explore various electrochemical system configurations, enhancing electrical storage energy by engineering the types of metal electrode and concentration heterocharge redox couple and supporting electrolyte. The initial guess for the Randles circuit parameters has been implemented by Matlab code developing, deriving them from the electrical current response versus time in a frequency-dependent sinusoidal wave function. Subsequently, the optimization problem regarding fitting of the circuit parameters has been performed through open-source Python code for electrochemical impedance spectroscopy using the initial Randles circuit parameter guess. The semianalytical method revealed a minimum in capacitance behavior near the zero value of the E_eq variable. Additionally, the numerical method showed that the capacitance behavior regarding the E_eq variable remains constant for high concentrations of the supporting electrolyte. The charge transfer coefficient demonstrated a monotonic behavior versus E_eq for all electrochemical reactions occurring on the parallel microdisk. A simulation result regarding general trend for capacitance versus E_eq variable is consistent with the available experimental data.

Ionic rectifiers/diodes are devices with potential applications in water treatment (desalination) and sensors. Diode preparation sometimes involves expensive processes such as laser drilling and thus the need for simpler and low-cost methods. We developed a low-cost cation rectifying hybrid membrane ionic rectifier where a microporous sulfonated poly-(2,6-dimethyl phenylene oxide) (SPPO) was asymmetrically attached to a microhole region in a polypropylene adhesive tape substrate. Contact angle measurements showed that SPPO is hydrophilic with a 62° angle. In comparison, the polypropylene adhesive tape and SPPO within it are hydrophobic with angles of 101° and 87°, respectively, contributing to the diode's stability in water. Zeta potential measurements confirmed the negative charge of the SPPO surface in all electrolyte solutions. Scanning electron microscopy revealed that the punctured tape substrate has a 3–4 µm microhole and a thickness of about 25 µm. The SPPO membrane is ≈29 µm thick with a smooth cross-sectional surface. The effects of electrolyte, ionic strength and microhole diameter on ionic diode performance were investigated using cyclic voltammetry and chronoamperometry in a 4-electrode measurement cell. The reported ionic rectifier is simple to fabricate, and it shows good rectification even in high ionic strength media.