Electroanalysis最新文献

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.

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.

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.

Thin films of the BiSI/Bi₁₃S₁₈I₂ semiconductor compound were synthesized via a simple chemical bath deposition method from solution. The deposition duration significantly affects the morphology, phase composition, and crystallinity of the resulting films. Optimized deposition conditions resulted in homogeneous microstructures with preferred crystallographic orientation and stable chemical composition, as confirmed by Scanning Electron Microscopy (SEM), X-ray diffraction, and Energy-Dispersive X-ray Spectroscopy (EDX) analyses. Photoelectrochemical studies demonstrated that both the composition and pH of the electrolyte markedly influence the photocurrent density, charge transfer efficiency at the semiconductor/electrolyte interface, and the incident photon-to-current conversion efficiency. Comparative photoelectrochemical measurements in different electrolytes containing iodide (I⁻), sulfide (S²⁻), or their combination revealed the synergistic effect of redox-active species on the interfacial charge dynamics and overall device performance. A maximum photocurrent density of 350 μA/cm², a charge transfer efficiency of ≈85%, and an incident photon-to-current efficiency of ≈52% were achieved under monochromatic illumination (λ = 465 nm, 10 mW/cm²) in a mixed electrolyte containing 0.05 M KI and 0.05 M Na₂S in 0.5 M Na₂SO₄. These results confirm the promising potential of BiSI thin films as efficient photoanode materials for use in photoelectrochemical cells, visible-light-driven sensors, and other optoelectronic or solar energy conversion devices.

Thin films of the BiSI/Bi₁₃S₁₈I₂ semiconductor compound were synthesized via a simple chemical bath deposition method from solution. The deposition duration significantly affects the morphology, phase composition, and crystallinity of the resulting films. Optimized deposition conditions resulted in homogeneous microstructures with preferred crystallographic orientation and stable chemical composition, as confirmed by Scanning Electron Microscopy (SEM), X-ray diffraction, and Energy-Dispersive X-ray Spectroscopy (EDX) analyses. Photoelectrochemical studies demonstrated that both the composition and pH of the electrolyte markedly influence the photocurrent density, charge transfer efficiency at the semiconductor/electrolyte interface, and the incident photon-to-current conversion efficiency. Comparative photoelectrochemical measurements in different electrolytes containing iodide (I⁻), sulfide (S²⁻), or their combination revealed the synergistic effect of redox-active species on the interfacial charge dynamics and overall device performance. A maximum photocurrent density of 350 μA/cm², a charge transfer efficiency of ≈85%, and an incident photon-to-current efficiency of ≈52% were achieved under monochromatic illumination (λ = 465 nm, 10 mW/cm²) in a mixed electrolyte containing 0.05 M KI and 0.05 M Na₂S in 0.5 M Na₂SO₄. These results confirm the promising potential of BiSI thin films as efficient photoanode materials for use in photoelectrochemical cells, visible-light-driven sensors, and other optoelectronic or solar energy conversion devices.

The growth of nucleic acid-based diagnostics integrated with electrochemical approaches has fundamentally transformed pathogen detection paradigms, with exponential amplification reaction (EXPAR) and hybridization chain reaction (HCR) emerging as next-generation alternatives to conventional polymerase chain reaction methodologies. EXPAR and HCR have emerged as powerful tools, offering unique biochemical pathways to amplify detection signals for pathogen-derived deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). The key interest in this amplification strategy is due to improved detection signals without the use of sophisticated thermocycling equipment. EXPAR is a potent isothermal amplification technique that employs a mix of polymerases and nicking (specific single-strand breaks) enzymes to rapidly cleave and extend short oligonucleotide sequences and, thereby it results in an exponential growth in the target DNA or RNA. This method is a perfect fit for field-based and point-of-care applications, as it enables extremely quick detection. HCR, on the other hand, employs a regulated, enzyme-free process in which metastable DNA hairpins self-assemble upon hybridization with a target sequence, and resulting in an amplified signal. HCR's programmability and flexibility make it easier to integrate into microfluidic systems and biosensors for real-time pathogen surveillance. Comparative studies suggest that EXPAR generally surpasses HCR in speed and sensitivity, whereas HCR excels in robustness, modularity, and ease of coupling with nanomaterials or aptamer-functionalized probes. This review explores the fundamental principles of EXPAR and HCR, compares their efficiency, sensitivity, and applications in pathogen diagnostics, and discusses their integration with emerging electrochemical sensing technologies. Moreover, this review elaborates on the advances in the use of nanomaterials, aptamer-functionalized probes, and the challenges of multiplexed detection strategies that further enhance their diagnostic potential. Finally, this review provides insights into future directions in next-generation pathogen detection platforms, with an emphasis on their role in the design of rapid, low-cost, and field-deployable diagnostic assays.

Nitrofurazone (NFZ), as an antibiotic, is carcinogenic upon prolonged exposure. Thus, detecting NFZ and its metabolites is essential for ensuring food safety and preventing potential health risks to humans. A dual-signal electrochemical sensor consisting of a composite of carbon nanotubes and an electroactive Schiff base polymer (SBP_Thi-DHA, synthesized from thionine and 2,5-dihydroxyterephthalaldehyde)/carbon nanotubes) enabled highly sensitive detection of nitrofurazolidone (NFZ). The sensor was fabricated using 2,5-dihydroxyterephthalaldehyde (DHA) and electroactive thionine (Thi) monomer as precursors to prepare spherical SBP_Thi-DHA nanomaterials with an average diameter of approximately 2 μm through a Schiff base reaction. The resulting material possessed high surface area, superior electron transport capability, and abundant surface functional groups, which enabled uniform loading of amino-functionalized carbon nanotubes (NH₂-CNT) and significantly enhanced the catalytic performance and detection sensitivity of the sensor. Empirical evidence demonstrated that the ratiometric electrochemical sensor achieved a remarkably low detection of 4.3 nM for NFZ at a reference signal of −0.6 V, with wide linear ranges of 13.1 nM-80 and 80–400 μM. The introduction of ratiometric signals effectively minimized interference caused by electrode surface state variations, electrolyte concentration fluctuations, and temperature changes during detection, significantly improving measurement accuracy and reproducibility. Furthermore, the excellent stability of SBP_Thi-DHA/CNT on the electrode surface endowed the sensor with outstanding reusability.