Electroanalysis最新文献

Glutamate is a critical neurotransmitter in the central nervous system that plays a key role in numerous physiological processes and neurological disorders. Traditional methods of glutamate detection have low spatiotemporal resolution, while electrochemical methods are limited due to glutamate not being readily redox active at unmodified carbon electrode surfaces. This study presents the development of a glutamate oxidase-modified microelectrode for the sensitive, real-time detection of glutamate using fast-scan cyclic voltammetry (FSCV) with a triangle waveform. Here, we employed a chitosan-hydrogel coating to immobilize glutamate oxidase onto carbon-fiber microelectrodes, enabling selective metabolism of glutamate to hydrogen peroxide. The metabolism to hydrogen peroxide facilitates indirect detection with high sensitivity across a concentration range relevant to physiological concentrations. We utilized FSCV for detection, which enhanced temporal resolution and chemical selectivity, allowing for the codetection of glutamate with other neurotransmitters such as dopamine and norepinephrine. We performed proof-of-concept validation and testing utilizing both biological fluids and complex food samples, demonstrating the enzyme-modified microelectrode's broad applicability in clinical diagnostics and food quality assessment. The sensor showed excellent stability, resistance to fouling, and retained over 90% of its initial response after multiple uses. This work highlights the potential of this biosensor as a versatile tool for minimally invasive, biocompatible, rapid, and accurate glutamate measurement in a wide variety of samples for a diverse set of applications.

Single entity electrochemistry (SEE) finds exciting application in analytical chemistry. Multiple methodologies have been tailored to measure conventional quantities such as concentration and size for a large variety of particles. Intense effort is also dedicated to investigation of chemical dynamics in electro-catalysis. This mini-review will focus its attention to the analysis of motion of particles at the interface and near the interface. The velocity of particles and types of motion (lateral, transversal, and rotational) will be discussed for a wide range of particles including solid metal and polystyrene particles as well as soft liquid droplets and gas bubbles. A new perspective on motion in SEE will be given by discussing the motion of phase boundaries within solid particles as well as soft liquid droplets and gas bubbles.

The detection of pharmaceutical contaminants, such as Ceftriaxone (CTRX), in water sources is a critical environmental and public health concern. Conventional detection methods often suffer from limited sensitivity and stability, making the accurate quantification of low CTRX concentrations challenging. To overcome these limitations, a novel amperometric sensor was developed using a carbon paste electrode (CPE) modified with gold and bismuth nanoparticles (Au-BiNPs). The synergistic electrocatalytic properties of these nanoparticles significantly enhance the sensitivity and stability of CTRX detection in complex environments. The Au-BiNPs-modified CPE (Au-BiNPs/CPE) exhibited excellent electrocatalytic activity toward the oxidation of CTRX, achieving a low detection limit of 0.267 µM and a high sensitivity of 25.9 μA/μM cm². The sensor was optimized to operate at pH 4.0 using Britton–Robinson buffer, following a mixed adsorption–diffusion reaction mechanism. Furthermore, the electrode demonstrated remarkable reproducibility (relative standard deviation [RSD] = 3.0%) and repeatability (RSD = 1.5%). Stability and corrosion resistance were confirmed through Tafel polarization studies, underscoring the sensor's durability and long-term performance. Additionally, density functional theory calculations provided molecular-level insights into the CTRX oxidation mechanism, complementing the experimental findings and further validating the sensor's design. This study presents the first Au-BiNPs-modified CPE for the sensitive detection of CTRX, integrating experimental optimization with theoretical insights. The significant outcomes of this work lay the foundation for advanced sensor development, offering a reliable and efficient platform for the detection of antibiotics in environmental and clinical settings.

The consumption of illicit drugs is spread worldwide and remains a challenge for concerned authorities. Hence, it is vital to develop effective and precise methods for detecting these types of compounds in biological fluids, seized street samples, and wastewaters. Electrochemical sensors are extensively used for analysis in many fields and represent an exclusive prospect to permit inexpensive, fast, and accurate monitoring and detection simultaneously. Electrochemical approaches are mainly open to forensic investigation because of their high performance in turbid and complex matrices. In this minireview, recent electrochemical strategies applied to the detection of illicit drugs in different samples have been presented.

The abnormal expression of hydrogen peroxide (H₂O₂) in living cells is closely related to the occurrence and development of tumor diseases. It is a kind potential marker for tumor diagnosis and treatment of tumor diseases. Therefore, it is very meaningful to develop high selective and sensitive method for real-time detecting H₂O₂ released from cancer cells. Herein, an AgCl cube/porous carbon nanotube composite nanomaterials was successfully fabricated and employed to construct a non-enzymatic electrochemical H₂O₂ sensor. Test results showed that the proposed sensor displayed the high sensitivity with the detection limit of 5.3 × 10⁻⁹ mol/L (S/N = 3). Importantly, it can accurately analyze H₂O₂ in milk samples and achieve real-time determination of H₂O₂ secreted from living cancer cells. In addition, the established sensor exhibited good stability and anti-interference ability. This strategy offers a potential way to diagnose tumor diseases.

Nitrite indicates nitrogen availability in aquatic ecosystems, with primary productivity and ecological balance implications. However, excessive nitrite accumulation poses significant risks to aquatic life, necessitating reliable detection methods. Electrochemical approaches offer flexibility and adaptability crucial for varied research needs, and nanoporous electrode surface modification emerges as a promising strategy to enhance sensitivity and precision in nitrite detection. In this study, a sensitive sensor is developed utilizing gold microelectrodes modified with nanoporous gold to detect nitrite. At optimized conditions, the sensor has a linear response (R² = 0.994) in the nitrite concentration range from 50 to 1 mmol L⁻¹ and a detection limit of 8.9 nmol L⁻¹ following the 3σ/s method. The results show that the proposed sensor can perform electrochemical detection with high repeatability (relative standard deviation (RSD) = 2%, n = 7) and reproducibility (RSD = 2%, n = 8). The concentration of nitrite in tap water and microalgae-growing media samples was determined, and the results agreed with those from the Griess method. These findings challenge conventional surface area, sensitivity, and detection limit assumptions, highlighting the nuanced relationship between electrode surface morphology and detection limit and presenting some evidence that the highest sensitivity does not always reflect on the lowest detection limit.

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.