Electroanalysis最新文献

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.

Polystyrene (PS), a polymer material renowned for its notable optical and mechanical properties, as well as low cost and ease of processing, stands as one of optimal candidate for flexible electrode substrate materials. However, prevalent modification techniques such as lithography, electron beam evaporation, and plasma etching all entail the requirement for specialized equipment and precise operation, thereby significantly elevating the technical barrier. In this study, we introduce a chemical plating method to fabricate a gold film electrode, coupled with prussian blue (PB) and glucose oxidase (GOx), for the development of a glucose electrochemical biosensor. This process offers simplicity, cost-effectiveness, and feasibility under regular experimental conditions. The electrode surface is covered with numerous gold nanoparticles, effectively augmenting the actual electrode area and enhancing electron transfer efficiency. Remarkably, without the addition of sensitizing agents, the biosensor achieves highly sensitive glucose detection. The proposed biosensor exhibits a broad linear relationship in the concentration range of 0.005–1 mM, with a detection limit of 4.4 μM. Moreover, it exhibits favorable performance in detecting glucose levels in sweat samples, showcasing promising prospects for personal healthcare diagnostics.

Ciprofloxacin (CIP) has been widely used to treat bacterial infections, generating biofluid residues and it endangers health via the food chain; thus, the determination of CIP is essential in food samples. In this work, CPE/ZnO/CQD was prepared from ZnO nanoparticles (ZnO NPs) and carbon quantum dots (CQD) derived from cat hair and modified the graphite carbon paste electrode (CPE); the above electrode sample was further modified by incorporating ionic liquid (IL) to give CPE/ZnO/CQD@IL. The above materials were employed as electrochemical sensors for the recognition of CIP in milk and eggs after the characterization by different analytical techniques (XRD, FT-IR, SEM, TEM, and EDS). The results show that the presence of nanoparticles in the CPE has improved the electrocatalytic properties, giving a greater heterogeneous electron transfer rate constant (k⁰=6.51×10⁻⁴ cm/s) for CPE/ZnO/CQD as compared to unmodified CPE (3.94×10⁻⁴ cm/s), and for CPE/ZnO/CQD/IL, with modification of sample by IL, the rate constant has been further increased to k⁰=8.34×10⁻⁴ cm/s. Thereafter, CPE/ZnO/CQD and CPE/ZnO/CQD@IL were employed for the detection of CIP in food samples such as milk and eggs, observing a maximum oxidation current for CIP at pH 3.0; the limit of detection (LOD) was 0.24, and 0.30 μM for CPE/ZnO/CQD, and CPE/ZnO/CQD@IL, respectively, and those values are much lower than those reported due to the synergistic effect generated by the combination of ZnO/CQD and IL. Furthermore, cell images were developed using ZnO/CQD and ZnO/CQD@IL in real samples like Saccharomyces cerevisiae cells in the presence of CIP.

Carbon composite electrodes often suffer from poor electrocatalytic activity and require complex, expensive, or time-consuming modifications to effectively detect certain analytes such as O₂ and H₂O₂. Thermoplastic electrodes (TPEs) are a new class of composite electrodes, fabricated by mixing commercial graphite with a thermopolymer, that exhibit superior electrochemical properties to typical carbon composite electrodes. This work investigates the properties of TPEs using two thermopolymer binders – polycaprolactone (PCL) and polystyrene (PS) – with sanded and heat-pressed surface treatments. XPS and SEM analysis suggested that sanded TPEs have a higher density of graphitic edge planes and improved electrochemistry as a result. Electrochemical detection of O₂ and H₂O₂ was demonstrated on sanded PS TPEs. Additionally, this work introduces the first use of a 3D-printed TPE template as part of a 3D-printed sensor module that is reversibly sealed with magnets as a proof-of-concept flow-based sensor for detecting H₂O₂.

Salivary thiocyanate is a biomarker of individual health that notably allows for the discrimination between smokers and non-smokers. Recent studies have also demonstrated its potential as a biomarker of cystic fibrosis, thus rendering the development of methods for its determination in saliva of immense importance. In response, we report on the development of graphite screen-printed electrodes (SPE) modified with cobalt(II) phthalocyanine nanosticks (CoPcNst), as low-cost and semi-disposable sensors for the determination of thiocyanate ion (SCN⁻) in human saliva. CoPCNst were synthesized and characterized using scanning electron microscopy, x-ray diffraction, as well as infrared and Raman spectroscopies. The results revealed a structural proximity to the recently identified J-polymorph. Compared with the electrode modified with commercial, beta-structure cobalt(II) phthalocyanine, the CoPc Nst/SPE provided four times better LOD and LOQ (0.49 and 1.62 μM) for thiocyanate determination by differential pulse voltammetry. The response was linear up to 20 μM SCN− (R2=0.996) and it was not affected by excess of common electro active compounds, such as ascorbic and uric acid. The analytical utility of CoPc Nst/SPE in human saliva is demonstrated.

A novel composite electrode was developed based on graphene oxide (GO)/MnO₂:h-MoO₃ nanocomposite for sensitive and selective voltammetric detection of acetaminophen (ACP). The composite electrode materials were characterized using X-Ray photoelectron spectroscopy (XPS), X-Ray Diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetric (CV) techniques. In the optimum conditions, the oxidation peak current (I_pa) of ACP was increased linearly with its concentration over two linear ranges from 0.06 to 10.0 μmol L⁻¹ and 20.0 to 80.0 μmol L⁻¹ with a detection limit of 0.0133 μmol L⁻¹. Due to its higher selectivity and long term stability, the composite electrode was applied to the detection of ACP in pharmaceutical formulations.

Herein we report the use of electrochemical faradaic spectroscopy in biosensors, with application on a commercially used first-generation glucose biosensor manufactured by Zimmer and Peacock. The mechanism for the glucose sensor was explained and approximated as an EC’ mechanism, where E is for electron transfer step, whereas C’ signifies catalytical chemical step. Experimental chronoamperograms in electrochemical faradaic spectroscopy are compared to chronoamperometry, where it was found that the sum component in electrochemical faradaic spectroscopy gives higher response, resulting in better sensitivity of the sensor. Theoretical simulations give an insight of the response in electrochemical faradaic spectroscopy for an EC’ mechanism and its dependence on different parameters (dimensionless electrode kinetic parameter, mid potential, dimensionless chemical kinetic parameter). For some specific set of parameters (large electrode and catalytic reaction kinetics), theoretical chronoamperograms in electrochemical faradaic spectroscopy can become similar to the experimental. The property of the sum component to have higher response in EC’ mechanism for specific parameters is not limited only for electrochemical faradaic spectroscopy. Exemplified with square-wave voltammetry, it is shown that other pulse techniques for an EC’ mechanism can also result with higher sum component. Hence, for better sensitivity in quantitative analysis in EC’ mechanism, one should quantify the sum component.

The successful application of bioelectrochemical systems in the future depends on the improving of electrode performance while decreasing material costs. This study explores the use of chitosan supported on different kinds of carbon materials to modify graphite electrode for the electricity generation performance of Geobacter sulfurreducens. The novel hierarchically carbon composites modified electrodes were obtained by a simple and environment-friendly method. Among the proposed composites, the optimal composite CS/CB (5 h) possessed a better performance for the promotion of electrochemically active biofilm (EAB) growth and enhancing current generation compared with other composites. Based on morphological, chemical, and electrochemical evidences, we conclude that the CB was coated on the surface of CS to form the CS/CB decorated graphite electrode, and CS/CB (5 h) electrode exhibited significant load-bearing capacity for bacteria colonization and enhanced the contact between bacteria and electrode, which improved the direct electron transfer process. The microbial three-electrode system equipped CS/CB (5 h) device delivered a high current density of 1457±69 μA/cm². The current density was increased to 3 times higher than that of the unmodified electrode. The use of this CS/CB (5 h) composite can substantially improves EAB growth and enhance power production of bioelectrochemical systems.

Given the high solubility and mobility of hexavalent chromium in the environment and edible plants, the development of a suitable method for the screening and quantification of Cr(VI) is highly desirable. Herein, a selective and sensitive sensing method for detecting Cr(VI) in food grains was established, using an electrodeposited gold-palladium bimetallic nanoparticles (BNPs) based electrochemical sensor and a microwave digestion procedure for chromium dissolution. The sensor interface was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and cyclic voltammetry. The results indicate that the fabricated sensor has a larger active surface area and an enhanced electrocatalytic effect compared to the monometallic modification, leading to a significant increase in the electrochemical reduction current of Cr(VI) as a consequence of synergistic effects. Using square wave anodic stripping voltammetry, the sensor demonstrates a wide linear range (5–3000 μg L⁻¹) and a low detection limit of 2.7 μg L⁻¹ for Cr(VI), as well as considerable repeatability and stability. Satisfactory selectivity towards Cr(VI) was also demonstrated, even in the presence of 500-fold Cr(III) and 100-fold common heavy metal ions like Cd(II), Pb(II), and Hg(II). The proposed sensing method offers a promising alternative for rapidly identifying toxic Cr(VI) in water and food grains.