Electroanalysis最新文献

This study proposed a new method for the direct and reagent-free fabrication of laser-induced graphene (LIG)-gold (Au–LIG) nanocomposite electrodes on a polyimide (PI) film using a commercially available, low-cost do-it-yourself (DIY) blue laser system for the first time. The one-step fabrication of Au–LIG nanocomposite was achieved by simply irradiating a PI film previously covered with gold leaves using a blue laser. Surface analysis and electrochemical oxidation of glucose revealed the formation of Au–LIG nanocomposites on the electrodes. Electrochemical sensitivity of the Au–LIG electrode against glucose in the concentration range from 0.1 to 50 mM was 153.4 µA/cm²/mM-glucose, and its limit of detection was 45.5 µM. This simple and cost-effective DIY blue laser system is expected to significantly contribute to the low-cost mass production of high-performance chemical sensors.

Bacterial infections represent a major public health challenge due to treatment difficulties and resistance spread. Antimicrobial peptides (AMPs) offer innovative applications in biosensors, since their interaction with microbial membranes can be detected by electrochemical changes. This study developed a nanostructured sensor using multiwalled carbon nanotubes (MWCNTs) and the antimicrobial peptide Temporin-PTA (T-PTA), derived from Hylarana picturata skin secretion. MWCNTs were electrodeposited on electrodes via cyclic voltammetry (CV) in acidic dispersion, improving electron kinetics and enabling chemical immobilization of T-PTA. The system was applied to detect Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus in a label-free electrochemical assay. Electrochemical impedance spectroscopy (EIS) and CV confirmed sensor assembly and interaction with different bacterial concentrations. Complementary analyses with atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FTIR) evaluated gradual adhesion of platform components. The biosensor detected concentrations from 10¹ to 10⁵ CFU/mL within only 5 min. Notably, the electrochemical signal was stronger for Gram-negative bacteria, particularly P. aeruginosa, consistent with T-PTA's affinity for electronegative surfaces. This system demonstrated rapid, sensitive, and selective detection, distinguishing Gram-negative from Gram-positive species. Such characteristics highlight its potential as a valuable complement to gold-standard microbiological methods.

Bacterial infections represent a major public health challenge due to treatment difficulties and resistance spread. Antimicrobial peptides (AMPs) offer innovative applications in biosensors, since their interaction with microbial membranes can be detected by electrochemical changes. This study developed a nanostructured sensor using multiwalled carbon nanotubes (MWCNTs) and the antimicrobial peptide Temporin-PTA (T-PTA), derived from Hylarana picturata skin secretion. MWCNTs were electrodeposited on electrodes via cyclic voltammetry (CV) in acidic dispersion, improving electron kinetics and enabling chemical immobilization of T-PTA. The system was applied to detect Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus in a label-free electrochemical assay. Electrochemical impedance spectroscopy (EIS) and CV confirmed sensor assembly and interaction with different bacterial concentrations. Complementary analyses with atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FTIR) evaluated gradual adhesion of platform components. The biosensor detected concentrations from 10¹ to 10⁵ CFU/mL within only 5 min. Notably, the electrochemical signal was stronger for Gram-negative bacteria, particularly P. aeruginosa, consistent with T-PTA's affinity for electronegative surfaces. This system demonstrated rapid, sensitive, and selective detection, distinguishing Gram-negative from Gram-positive species. Such characteristics highlight its potential as a valuable complement to gold-standard microbiological methods.

Electrocatalysts for the oxygen evolution reaction (OER) must be effective, inexpensive, and long-lasting if electrochemical water splitting technologies are to advance. In this study, screen-printed electrodes containing ZIF-67—a zirconium-based metal–organic framework (Zr-MOF) composed of trimesic acid, carbon quantum dots (CQDs), and graphene nanoplatelets (GNPs)—were created using a layer-by-layer modification process. Increased number of active sites, increased surface area, and improved electron transport were demonstrated in structural and electrochemical testing of hybrid electrocatalyst systems. In comparison to reported electrodes, the ZIF/MOF/GNP-modified screen-printed carbon electrode (SPCE) performed significantly better at OER, with a reduced overpotential of 280 mV at 10 mA cm⁻² and a Tafel slope of 40 mV dec⁻¹. Electrochemical impedance spectroscopy (EIS) confirms a significant reduction in charge transfer resistance due to the improved interfacial conductivity. After 18 h of operation, the system displayed excellent performance with little drift, according to chromatopotentiometry testing. Because the MOF framework was made more conductive by the combined effects of conductive GNPs and CQDs, EIS revealed a reduction in charge transfer resistance. These findings suggest that a hybrid system consisting of ZIF, MOF, and GNP might be an effective electrocatalyst for cost-effective, scalable, and environmentally friendly water splitting applications. They additionally demonstrate that this SPCE-based layer modification method may be utilized for extensive, cost-effective water-splitting applications.

Electrocatalysts for the oxygen evolution reaction (OER) must be effective, inexpensive, and long-lasting if electrochemical water splitting technologies are to advance. In this study, screen-printed electrodes containing ZIF-67—a zirconium-based metal–organic framework (Zr-MOF) composed of trimesic acid, carbon quantum dots (CQDs), and graphene nanoplatelets (GNPs)—were created using a layer-by-layer modification process. Increased number of active sites, increased surface area, and improved electron transport were demonstrated in structural and electrochemical testing of hybrid electrocatalyst systems. In comparison to reported electrodes, the ZIF/MOF/GNP-modified screen-printed carbon electrode (SPCE) performed significantly better at OER, with a reduced overpotential of 280 mV at 10 mA cm⁻² and a Tafel slope of 40 mV dec⁻¹. Electrochemical impedance spectroscopy (EIS) confirms a significant reduction in charge transfer resistance due to the improved interfacial conductivity. After 18 h of operation, the system displayed excellent performance with little drift, according to chromatopotentiometry testing. Because the MOF framework was made more conductive by the combined effects of conductive GNPs and CQDs, EIS revealed a reduction in charge transfer resistance. These findings suggest that a hybrid system consisting of ZIF, MOF, and GNP might be an effective electrocatalyst for cost-effective, scalable, and environmentally friendly water splitting applications. They additionally demonstrate that this SPCE-based layer modification method may be utilized for extensive, cost-effective water-splitting applications.

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.

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.

A novel multiple-pair-electrode detection system for high-performance liquid chromatography was developed using track-etched membrane electrodes arranged in series along the eluent flow. The system generates distinct anodic and cathodic response combinations from each electrode pair, individually polarized at specific potentials, effectively reflecting the electrochemical reaction reversibility of each component. These detection behaviors offer robust support for peak identification in complex chromatograms. The effectiveness of the proposed system was demonstrated through the identification and quantification of several phenolic compounds in commercially available coffee and green tea beverages.

3D printing has been benefiting electroanalysis due to the quick and low-cost manufacture of cells and sensors. For this production, the choice of eco-friendly materials is welcome due to the agreement to the principles of sustainability, green chemistry, and circular economy. In this work a novel 3D-printed sensor modified with biochar (BC) from coffee husk residues is proposed for the determination of the fungicide carbendazim in natural waters using square wave voltammetry (SWV). The sensor was prepared through the coating of an insulating ring-shaped 3D-printed substrate (Acrylonitrile Butadiene Styrene/ABS) with a BC-modified conductive ink (acetone, ABS, graphite, and BC). Using the optimized sensor (10% wt. of BC) in 0.1 mol L⁻¹ phosphate buffer (pH 2.0) and optimized SWV parameters (E_s = 2 mV, f = 15 Hz and A = 120 mV), the detectability of carbendazim was 50% higher than unmodified, and a linear range (LR) from 0.25 to 15.00 µmol L⁻¹ (R² = 0.998) and a limit of detection (LOD) (S/N = 3) of 50 nmol L⁻¹ were obtained. Good inter-electrode (RSD = 6.21%; n = 6) and inter-day (RSD = 6.96%; n = 10) reproducibility and accuracy (recovery between 92.71% and 96.43% in water samples) were obtained. This alternative sensor is simpler than those fabricated using BC-modified filaments, being promising for the trace level analysis of environmental pollutants.

3D printing has been benefiting electroanalysis due to the quick and low-cost manufacture of cells and sensors. For this production, the choice of eco-friendly materials is welcome due to the agreement to the principles of sustainability, green chemistry, and circular economy. In this work a novel 3D-printed sensor modified with biochar (BC) from coffee husk residues is proposed for the determination of the fungicide carbendazim in natural waters using square wave voltammetry (SWV). The sensor was prepared through the coating of an insulating ring-shaped 3D-printed substrate (Acrylonitrile Butadiene Styrene/ABS) with a BC-modified conductive ink (acetone, ABS, graphite, and BC). Using the optimized sensor (10% wt. of BC) in 0.1 mol L⁻¹ phosphate buffer (pH 2.0) and optimized SWV parameters (E_s = 2 mV, f = 15 Hz and A = 120 mV), the detectability of carbendazim was 50% higher than unmodified, and a linear range (LR) from 0.25 to 15.00 µmol L⁻¹ (R² = 0.998) and a limit of detection (LOD) (S/N = 3) of 50 nmol L⁻¹ were obtained. Good inter-electrode (RSD = 6.21%; n = 6) and inter-day (RSD = 6.96%; n = 10) reproducibility and accuracy (recovery between 92.71% and 96.43% in water samples) were obtained. This alternative sensor is simpler than those fabricated using BC-modified filaments, being promising for the trace level analysis of environmental pollutants.