Electroanalysis最新文献

The abuse of trichlorfon leading a threat to human health through the food chain, it is great important to establish a selective and sensitive determination method for trichlorfon residual. Herein, a functional molecularly imprinted electrochemical sensor was constructed using CuS/MnS heterojunction and multiwalled carbon nanotubes (MWCNTs). CuS/MnS possesses a highly efficient electron transfer capacity via ion exchange interactions at a given potential, resulting in a favorable signal response. Meanwhile, the signal transmitting efficiency was further promoted by the large specific surface area of MWCNTs. In the preparation of electrochemical sensor, the CuS/MnS was modified on the electrode surface with MWCNTs, and covered by molecularly imprinted layer. The sensor was first incubated into an indicator solution containing potassium ferricyanide, producing a distinct initial signal. Once the target was present, it was identified and captured by the imprinted cavity, which blocked the electron pathway, and the potassium ferricyanide signal subsequently reduced with a measurable level. Under the optimized conditions, the two-stage linear ranges were 1.0–10 and 10–100 nM, with a detection limit of 0.37 nM. In contrast to other complex electrochemical beacons, this work induced heterojunctions and MWCNTs to obtain a satisfactory result via synergistic effect. Furthermore, the recovery rates of 93.70%–105.18% in the real sample assays suggest a prospective application of the proposed sensor in monitoring of pesticide residuals.

This paper describes a novel electrochemical genosensor designed for rapid and simplified detection of Zika virus DNA, using the biological dye safranin as a biomolecular intercalator. The genosensor uses a gold-printed circuit board as electrode, modified with a bilayer formed by cysteamine and graphene quantum dots to immobilize oligonucleotide probes specifically designed for the detection of the Zika virus. The genosensor construction was monitored by scanning electron microscopy (SEM), dynamic force microscope (DFM), and Fourier transform infrared (FTIR). Electrochemical detection was carried out based on differential pulse voltammetry, monitoring the peak current of the DNA intercalator (safranin). The genosensor demonstrated high sensitivity, detecting 1.2 pg mL⁻¹, selectivity against other arboviruses (chikungunya and dengue) and good stability for at least 45 days. These parameters indicate potential for use of this genosensor in medical diagnostic testing for Zika virus, aiming at early screening of patients, especially in epidemic situations.

The abuse of trichlorfon leading a threat to human health through the food chain, it is great important to establish a selective and sensitive determination method for trichlorfon residual. Herein, a functional molecularly imprinted electrochemical sensor was constructed using CuS/MnS heterojunction and multiwalled carbon nanotubes (MWCNTs). CuS/MnS possesses a highly efficient electron transfer capacity via ion exchange interactions at a given potential, resulting in a favorable signal response. Meanwhile, the signal transmitting efficiency was further promoted by the large specific surface area of MWCNTs. In the preparation of electrochemical sensor, the CuS/MnS was modified on the electrode surface with MWCNTs, and covered by molecularly imprinted layer. The sensor was first incubated into an indicator solution containing potassium ferricyanide, producing a distinct initial signal. Once the target was present, it was identified and captured by the imprinted cavity, which blocked the electron pathway, and the potassium ferricyanide signal subsequently reduced with a measurable level. Under the optimized conditions, the two-stage linear ranges were 1.0–10 and 10–100 nM, with a detection limit of 0.37 nM. In contrast to other complex electrochemical beacons, this work induced heterojunctions and MWCNTs to obtain a satisfactory result via synergistic effect. Furthermore, the recovery rates of 93.70%–105.18% in the real sample assays suggest a prospective application of the proposed sensor in monitoring of pesticide residuals.

This work, for the first time, investigated and compared electrochemical and thermodynamic properties of kynurenic acid (KYNA) and kynurenine (KYN) in aqueous electrolytes, on glassy carbon electrodes (GCE) and disposable screen-printed carbon electrodes (SPCEs). Both GCE and SPCEs were electrochemically pretreated to activate and functionalize their surfaces. The experiments were performed using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). Overall, the voltammetric data for KYNA on GCE and SPCE were convergent and indicated an irreversible, pH-dependent anodic process, associated with the withdrawal of one electron from the hydroxy group at C4, with the formation of a KYNA^• radical. The KYNA^• radical can polymerize on the electrode, causing passivation of its surface, and/or react with water, leading to the formation of quinone derivatives. The electrooxidation of KYNA occurred at high potentials, and its process was most easily identified by pulse voltammetric techniques. An electrooxidation mechanism of KYNA in aqueous media on carbon electrodes was proposed. The oxidation of KYN at SPCE occurred in a single, irreversible, pH-dependent step, with the removal of one electron from the 2-aminobenzoyl group, forming a cation radical intermediate. The radicals combined to form electroactive dimers. Establishing and comparing the electrochemical properties of KYNA and KYN are important data for understanding their redox reactions, redox stability, and metabolism in biological systems. Electroanalytical methods have been proposed for the detection and quantification of KYNA and KYN on SPCEs. For KYNA, the proposed method used SWV at pH = 7.00 and presented limit of detection (LOD) = 0.782 µmol L⁻¹. For the proposed method for detection and quantification of KYN, DPV was used at pH = 0.30, and a LOD = 0.304 µmol L⁻¹ was obtained.

This work, for the first time, investigated and compared electrochemical and thermodynamic properties of kynurenic acid (KYNA) and kynurenine (KYN) in aqueous electrolytes, on glassy carbon electrodes (GCE) and disposable screen-printed carbon electrodes (SPCEs). Both GCE and SPCEs were electrochemically pretreated to activate and functionalize their surfaces. The experiments were performed using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). Overall, the voltammetric data for KYNA on GCE and SPCE were convergent and indicated an irreversible, pH-dependent anodic process, associated with the withdrawal of one electron from the hydroxy group at C4, with the formation of a KYNA^• radical. The KYNA^• radical can polymerize on the electrode, causing passivation of its surface, and/or react with water, leading to the formation of quinone derivatives. The electrooxidation of KYNA occurred at high potentials, and its process was most easily identified by pulse voltammetric techniques. An electrooxidation mechanism of KYNA in aqueous media on carbon electrodes was proposed. The oxidation of KYN at SPCE occurred in a single, irreversible, pH-dependent step, with the removal of one electron from the 2-aminobenzoyl group, forming a cation radical intermediate. The radicals combined to form electroactive dimers. Establishing and comparing the electrochemical properties of KYNA and KYN are important data for understanding their redox reactions, redox stability, and metabolism in biological systems. Electroanalytical methods have been proposed for the detection and quantification of KYNA and KYN on SPCEs. For KYNA, the proposed method used SWV at pH = 7.00 and presented limit of detection (LOD) = 0.782 µmol L⁻¹. For the proposed method for detection and quantification of KYN, DPV was used at pH = 0.30, and a LOD = 0.304 µmol L⁻¹ was obtained.

Perovskite quantum dots (PQDs) have emerged as a transformative class of nanomaterials for biosensing due to their exceptional optoelectronic properties, including high photoluminescence quantum yield, tunable emission, and efficient charge transport. This review provides a comprehensive overview of recent advances in the synthesis, surface engineering, and integration of PQDs for electrochemical and photoelectrochemical (PEC) detection of cardiovascular disease (CVD) biomarkers such as myoglobin, cholesterol, glutathione, and hypoxanthine. Emphasis is placed on strategies for improving aqueous stability, biocompatibility, and selectivity through encapsulation, ligand functionalization, and heterostructure formation with metal oxides and metal–organic frameworks. Comparative analyses demonstrate PQDs’ superior sensitivity and detection limits compared with traditional quantum dots, alongside discussions of challenges related to toxicity, scalability, and clinical translation. Future perspectives highlight lead-free PQDs, microfluidic integration, and data processing for real-time, multiplexed CVD diagnostics. This review represents an in-depth analysis unifying perovskite quantum dot design principles with their electrochemical and PEC biosensing applications for CVD detection.

Perovskite quantum dots (PQDs) have emerged as a transformative class of nanomaterials for biosensing due to their exceptional optoelectronic properties, including high photoluminescence quantum yield, tunable emission, and efficient charge transport. This review provides a comprehensive overview of recent advances in the synthesis, surface engineering, and integration of PQDs for electrochemical and photoelectrochemical (PEC) detection of cardiovascular disease (CVD) biomarkers such as myoglobin, cholesterol, glutathione, and hypoxanthine. Emphasis is placed on strategies for improving aqueous stability, biocompatibility, and selectivity through encapsulation, ligand functionalization, and heterostructure formation with metal oxides and metal–organic frameworks. Comparative analyses demonstrate PQDs’ superior sensitivity and detection limits compared with traditional quantum dots, alongside discussions of challenges related to toxicity, scalability, and clinical translation. Future perspectives highlight lead-free PQDs, microfluidic integration, and data processing for real-time, multiplexed CVD diagnostics. This review represents an in-depth analysis unifying perovskite quantum dot design principles with their electrochemical and PEC biosensing applications for CVD detection.

This study explores a carbon-based electrode alternative of conventional gold-thiolate monolayers for high-throughput biosensor development. We investigate the functionalization of glassy carbon electrodes (GCEs) with aptamers to create biosensing interfaces. The modification process of carbon involves three main steps: (1) electrografting of 4-aminobenzoic acid (ABA) onto the electrode surface to introduce carboxyl (–COOH) groups, (2) –COOH groups activation using EDC/NHS chemistry, and (3) coupling 5^′-amine-terminated aptamers for tobramycin (apt-TOB). Surface modification of the resulting GCE/ABA/aptamer was characterized rigorously using cyclic voltammetry (CV), water contact angle, electrochemical impedance spectroscopy (EIS), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The obtained interface exhibits an exceptional surface coverage of ≈170 pmol cm⁻², exceeding that of conventional gold-thiolate monolayers. As a proof of concept, we demonstrate the impedimetric detection of tobramycin using the GCE/ABA/aptamer-modified electrodes. The range of detection achieved was 1 nM–10 μM and a LOD of 1 nM. This work aims to evaluate the feasibility of using ABA (via carbodiimide chemistry) as a linker for aptamer immobilization on GCE, like a practical alternative to gold for high-performance aptamer-based sensors in clinical, ambiental, and alimentary analyses.

This study explores a carbon-based electrode alternative of conventional gold-thiolate monolayers for high-throughput biosensor development. We investigate the functionalization of glassy carbon electrodes (GCEs) with aptamers to create biosensing interfaces. The modification process of carbon involves three main steps: (1) electrografting of 4-aminobenzoic acid (ABA) onto the electrode surface to introduce carboxyl (–COOH) groups, (2) –COOH groups activation using EDC/NHS chemistry, and (3) coupling 5^′-amine-terminated aptamers for tobramycin (apt-TOB). Surface modification of the resulting GCE/ABA/aptamer was characterized rigorously using cyclic voltammetry (CV), water contact angle, electrochemical impedance spectroscopy (EIS), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The obtained interface exhibits an exceptional surface coverage of ≈170 pmol cm⁻², exceeding that of conventional gold-thiolate monolayers. As a proof of concept, we demonstrate the impedimetric detection of tobramycin using the GCE/ABA/aptamer-modified electrodes. The range of detection achieved was 1 nM–10 μM and a LOD of 1 nM. This work aims to evaluate the feasibility of using ABA (via carbodiimide chemistry) as a linker for aptamer immobilization on GCE, like a practical alternative to gold for high-performance aptamer-based sensors in clinical, ambiental, and alimentary analyses.

The application of electrochemical impedance spectroscopy (EIS) for electrode characterization and biosensor development has become challenging due to the overlapping or superimposed semicircles and features on the Nyquist plot and numerous possible equivalent circuits. This study aimed to apply an EIS analysis workflow consisting of data validation using the Kramers–Kronig Model, distribution of relaxation times (DRT) analysis, and equivalent circuit model (ECM) parameterization using the recently available pyDRTtools and the Python package “impedance.py”. The effect of modifying the electrode with a metal organic framework – Cu-BTC, graphite, and gold nanoparticles (AuNP) was studied by calculating the effective capacitance (C_eff) and electrochemically active surface area (ECSA) from the ECM parameters. 60% Cu-BTC mixed with graphite (v/v) showed the highest increase in the C_eff and therefore the ECSA from 0.18 to 12.72 cm². Electrodeposition of AuNP reduced this value to 0.31 cm² due to in-between particle agglomeration. The final hybrid nanomaterial was composed of DNA tagged with ferrocene and thiol, AuNP, and a 60% Cu-BTC and graphite mixture assembled on a glassy carbon electrode. DRT analysis was used to propose the data-driven ECMs. Based on the root mean square error of each model circuit and the percent standard error for each parameter, the transmission line model has the best fit mathematically. However, a Randles circuit with a constant phase element and a custom circuit composed of two RC in series between a resistor and a Warburg element are practical to use for further biosensor development using this electrode assembly.