Electroanalysis最新文献

In this work, a novel electrochemical DNA biosensor was developed for the quantitative detection of 4-nonylphenol (NPh) based on its ability to damage DNA. The surface of a carbon-based screen-printed electrode (SPE) was modified with magnetite (Fe₃O₄) and cerium (IV) oxide (CeO₂) nanoparticles (NPs) to form a nanocomposite platform for enhanced electron transfer. Fish-sperm DNA (fsDNA) was immobilized on the CeO₂–Fe₃O₄ NPs/SPE surface to construct the fsDNA/CeO₂–Fe₃O₄ NPs/SPE biosensor. The analytical response was evaluated using guanine (Gu) and adenine (Ad) oxidation signals, which decreased in proportion to NPh-induced DNA damage. The biosensor exhibited linear response ranges for NPh of 0.022–3.0 nM based on Gu and 0.017–3.0 nM based on Ad signals, with detection limits of 0.007 and 0.005 nM, respectively. The binding constant (K_b) of the fsDNA–NPh complex was calculated as approximately 10⁸ M⁻¹, indicating a strong interaction. The biosensor's applicability was demonstrated in food samples, yielding recoveries of 97.85% and 101.37%.

In this article, a solid-phase preconcentration method using the multicomponent oxide SiO₂/TiO₂/Sb₂O₅ as a chelating agent-free solid-phase extractor for the determination of Pb²⁺ at trace levels, employing a portable 3D-printed electrochemical cell, was developed. The optimization of the preconcentration parameters was carried out using a 2^4–1 fractional factorial design. The most effective conditions were pH 5.0, elution volume 600 µL, eluent (H₂SO₄) concentration 1.5 mol L⁻¹, and preconcentration flow rate 6.0 mL min⁻¹ of 20.0 mL of the sample. Electrochemical parameters were also optimized, establishing ideal values for deposition time (60 s), deposition potential (–1.5 V), potential step (6 mV), pulse amplitude (60 mV), and frequency optimal (10 Hz). The developed method exhibited high precision and sensitivity, with limits of detection and quantification of 0.98 and 3.30 µg L⁻¹, respectively, and showed tolerance to different metal ions (Ca²⁺, Mg²⁺, Ni^2+, and Co²⁺). When applied to real samples, such as mineral and tap water, as well as Korean ginseng, the method demonstrated satisfactory recovery values (90%–108%), attesting to the method's applicability and accuracy without interference.

Cryptosporidium (Crypto) is a microscopic parasite that leads to diarrhea and gastroenteritis in humans. The oocysts of Crypto present a significant risk to water supplies because they are highly resistant to common disinfectants. To prevent potential outbreaks, it is essential to monitor and detect this pathogen at trace levels. In this work, a manganese-carbon quantum dot titanium ternary composite (CQD-TiO₂–MnO₂) is proposed as a material for immobilizing the aptamer on the electrode surface. Various techniques, including X-ray spectroscopy, high-resolution transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy, were employed to confirm the synthesis of the materials. The techniques revealed a uniform distribution of nanomaterials, and the ternary composite contains oxygen-containing groups that facilitate electron movement and ensure the stable attachment of the aptamer. The electrochemical tests demonstrated that the GCE-CQD-TiO₂–MnO₂-Apt₁-BSA electrode exhibited enhanced electrochemical kinetics and conductivity. The study achieved a low detection limit of 0.0012 ng mL^−1, a limit of quantification of 0.005 ng mL⁻¹, a linear range of 0.0055–0.0070 ng mL⁻¹, and a sensitivity of 0.197 mA µM⁻¹. The developed aptasensor showed excellent performance in both dam and river water, with recoveries ranging from 75% to 96%.

Cryptosporidium (Crypto) is a microscopic parasite that leads to diarrhea and gastroenteritis in humans. The oocysts of Crypto present a significant risk to water supplies because they are highly resistant to common disinfectants. To prevent potential outbreaks, it is essential to monitor and detect this pathogen at trace levels. In this work, a manganese-carbon quantum dot titanium ternary composite (CQD-TiO₂–MnO₂) is proposed as a material for immobilizing the aptamer on the electrode surface. Various techniques, including X-ray spectroscopy, high-resolution transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy, were employed to confirm the synthesis of the materials. The techniques revealed a uniform distribution of nanomaterials, and the ternary composite contains oxygen-containing groups that facilitate electron movement and ensure the stable attachment of the aptamer. The electrochemical tests demonstrated that the GCE-CQD-TiO₂–MnO₂-Apt₁-BSA electrode exhibited enhanced electrochemical kinetics and conductivity. The study achieved a low detection limit of 0.0012 ng mL^−1, a limit of quantification of 0.005 ng mL⁻¹, a linear range of 0.0055–0.0070 ng mL⁻¹, and a sensitivity of 0.197 mA µM⁻¹. The developed aptasensor showed excellent performance in both dam and river water, with recoveries ranging from 75% to 96%.

Dopamine (DA) and uric acid (UA) are small biomolecules involved in various physiological and pathological processes in the human body. The simultaneous and accurate detection of these two substances is of great significance for the early diagnosis and monitoring of disease conditions such as Parkinson's disease and gout. In this study, we proposed a portable electrochemical platform based on the gold-coated screen-printed electrode (Au-SPE) for parallel detection of DA and UA and explored the mechanism behind the enhanced performance of Au-SPE. Both DA and UA possess electrochemical activity and display different oxidation peaks in electrochemical detection. Differential pulse voltammetry results show that the Au-SPE-based electrochemical biosensor can simultaneously detect the oxidation reactions of DA and UA at different potential value. Compared with the carbon-modified electrode, Au-SPE exhibits superior signal responses and linear ranges toward DA and UA. Density functional theory and Gibbs free energy analysis revealed that the AuNPs coating enhanced electron transfer and adsorption and made the oxidation reactions more thermodynamically favorable. The Au-SPE-based sensor exhibits good linear responses in the concentration range of 0.05–10 and 10–300 μM, with a detection limit of 0.02 and 4.12 μM in the parallel detection of DA and UA. In addition, the biosensor shows good selectivity for UA and DA and favorable recovery rate in artificial sweat, laying a certain foundation for the development of portable and easy-to-use electrochemical biosensors.

The increasing heavy metal pollution in marine environments has highlighted the urgent need for rapid, on-site detection methods. In this study, a reduced graphene oxide (rGO) and carboxylated multiwalled carbon nanotube (MWCNTs-COOH)-modified screen-printed electrode (SPE) was coupled with a portable electrochemical workstation for on-site detection of Pb²⁺ and Cd²⁺ in seawater. The key influencing factors involved in the detection process, such as deposition potential, deposition time, and pH value, have been systematically optimized. The response surface methodology (RSM) was applied to refine the portable electrochemical workstation parameters, including step potential, frequency, and pulse amplitude. The detection capability for heavy metals was significantly enhanced by using square wave stripping voltammetry (SWASV) with in situ Hg-Bi film plating, achieving detection limits of 0.4 μg/L for Pb²⁺ and 0.8 μg/L for Cd²⁺. Finally, the portable workstation together with rGO/MWCNTs-COOH/SPE showed recovery rates of 101.33 ± 3.42% ~ 115.85 ± 3.50% for Pb²⁺ and 101.32 ± 2.23% ~ 102.00 ± 2.00% for Cd²⁺ in real seawater. The results were in good agreement with those obtained by inductively coupled plasma mass spectrometry (ICP-MS), thereby validating the detection accuracy of this platform.

Excessive oligomeric Amyloid-β (AβOs) in the brain induces strong neurotoxicity and are a major causative marker of Alzheimer's disease (AD). Herein, an exemplary electrochemiluminescence (ECL) aptasensor for AβOs that coupled a triple-helix switchable system (THSS) with gold-doped Ru(bpy)₃²⁺/copper luminescent-nanospheres (RuCu@AuLNs) was successfully developed. In brief, the anti-AβOs aptamer (Apt) with two symmetric arms and RuCu@AuLN-marked signal transduction DNA (RuCu@AuLNs-ST) perfectly constructed the THSS on a gold electrode surface via hybridization reaction. At this point, the THSS was closed, and a strong initial ECL signal (I_ECL0) output was generated. Once AβOs appeared, they specifically bound with Apt and opened the THSS, releasing RuCu@AuLNs-ST from electrode surface, and degressive ECL signal (I_ECL1) was obtained. Thus, the aptasensor detected AβOs-dependent I_ECL1 change (ΔI_ECL1 = I_ECL0 − I_ECL1) with a concentration range of 1 fM to 1 pM with a low detection limit of 0.5 fM, and demonstrated good reliability and practicality in human serum. Additionally, the reconfigurability of the sensor allows it to be continuously reused up to 5 times at a concentration of 1 fM AβOs. The developed ECL aptasensor could be used as a cost-effective tool for early diagnosis of AD. Moreover, the strategy has promising application in the bioassays of various analytes.

Dopamine (DA) and uric acid (UA) are small biomolecules involved in various physiological and pathological processes in the human body. The simultaneous and accurate detection of these two substances is of great significance for the early diagnosis and monitoring of disease conditions such as Parkinson's disease and gout. In this study, we proposed a portable electrochemical platform based on the gold-coated screen-printed electrode (Au-SPE) for parallel detection of DA and UA and explored the mechanism behind the enhanced performance of Au-SPE. Both DA and UA possess electrochemical activity and display different oxidation peaks in electrochemical detection. Differential pulse voltammetry results show that the Au-SPE-based electrochemical biosensor can simultaneously detect the oxidation reactions of DA and UA at different potential value. Compared with the carbon-modified electrode, Au-SPE exhibits superior signal responses and linear ranges toward DA and UA. Density functional theory and Gibbs free energy analysis revealed that the AuNPs coating enhanced electron transfer and adsorption and made the oxidation reactions more thermodynamically favorable. The Au-SPE-based sensor exhibits good linear responses in the concentration range of 0.05–10 and 10–300 μM, with a detection limit of 0.02 and 4.12 μM in the parallel detection of DA and UA. In addition, the biosensor shows good selectivity for UA and DA and favorable recovery rate in artificial sweat, laying a certain foundation for the development of portable and easy-to-use electrochemical biosensors.

A unitized reversible fuel cell (URFC) is a promising technology that combines the functions of hydrogen production and electricity generation in a single device. However, the insufficient corrosion resistance of the bifunctional oxygen electrode significantly limits the large-scale implementation of this technology. This work investigates the influence of different architectures of the catalytic layer (CL) (layered and mixed loading of electrocatalysts, as well as the application of a titanium carbonitride (TiCN) sublayer) on the efficiency and durability of the oxygen electrode in fuel cell (FC) and water electrolyzer (WE) modes. A protocol for assessing electrode durability is proposed, involving cyclic recording of i–V curves in FC/WE modes, followed by testing the electrode in a potentiostatic mode at 1.65 V and 80°C for 30 min. The use of an electrode with a TiCN sublayer deposited by magnetron sputtering between platinum and iridium electrocatalysts doubled the device's service life compared to using a mixed loading of electrocatalysts. This effect is attributed to the reduced rate of Ir conversion to its oxidized form (IrO_x) due to the competitive oxidation of titanium in the sublayer, which also inhibits further corrosion processes.

This study investigates the electrochemical behavior of uric acid (UA) in the presence of ascorbic acid (AA) using differential normal pulse voltammetry (DNPV), aiming to establish a rapid and reliable method for UA detection without electrode modification. In DNPV, interference from AA was effectively suppressed by its pre-oxidation during the initial potential pulse. A systematic evaluation of pulse parameters revealed that a first-pulse width of 1000 ms and a pulse amplitude (ΔE) of 0.15 V provided optimal conditions, under which AA was almost completely depleted and the current response was dominated by UA oxidation. Under these optimized conditions, UA could be selectively quantified over the range of 0–300 μM, even in the presence of 100 μM AA. Application to human urine samples demonstrated good agreement with results obtained from enzymatic colorimetric assays, validated through the standard addition method after 100-fold dilution.