Analytical & Bioanalytical Electrochemistry
Volume:16 Issue: 4, Apr 2024

In this study, Fe-oxide-based NPs (Fe2O3 NPs) were prepared via precipitation strategy, and characterized by transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), X-ray photo-reduction spectroscopy (XPS), cyclic voltammetry (CV). The characterization data indicated that prepared Fe-based NPs possessed α-Fe2O3 phase with 50-60 nm diameter. Next, the CV technique was employed to test the ability of the prepared Fe2O3 NPs toward electrochemical oxidation of salicylaldehyde at a glassy carbon electrode (3 mm diameter) in an alkaline electrolyte. The results demonstrated that the electrochemical oxidation of salicylaldehyde followed first-order kinetics with a hydroxyl-radical aided process, requiring 18.4 kJ/mol activation energy at ambient temperature.

Electrochemical method is used for glycated hemoglobin (HbA1c) detection using a new configuration of working electrodes coated by ZnO nanorods. HbA1c reflects the average plasma glucose over two months. In this work, HbA1c is directly detected electrochemically without any proteolytic digestion for the first time. ZnO nanorods modify the working electrode to increase the surface of sensing, leading to amplifying the electrochemical signal and providing a stable enzyme bed for GOx immobilization. The limit of detection (LOD) is 0.32 μg/μl which can be achieved in 40 seconds as the sensor's response time. The range of detection is 0.32 µg/µl (0.21% of HbA1c)-22.4 µg/µl (14.93% of HbA1c) that covers the standard diagnosis range. Due to embedded nanostructures, a small amount of about 2 μl GOx solution and 50 nl of blood is required for detection. The low response time makes this sensor suitable for fast tests such as diabetic population enumeration and screening.

The present work aimed at comparing the capabilities and efficiency of symmetric and asymmetric electrodes for potentiometric detection of Cu2+. Initially, we synthesized N-(benzothiazol-2-ylcarbamothioyl)benzamide, and 1H-NMR, 13C-NMR, and FT-IR spectroscopy approaches were used for characterization. Subsequently, it was employed as an ionophore to fabricate asymmetric electrodes of coated wire (CWE) and solid-state (SSE) and symmetric electrodes with liquid internal electrolyte (LIE). The best liquid membrane was prepared with an Ionophore: DBP: PVC: NaTPB ratio of 12:56:30:2. All electrodes exhibited Nernstian responses. The detection limits for SSE (1×10-9 mol/L) and CWE (1×10-7 mol/L) were superior to LIE (2×10-6 mol/L). Moreover, all three electrodes demonstrated very short response times (approximately 6 seconds) and exhibited large selectivity coefficient values for different cations. Asymmetric electrodes displayed longer lifetimes (SSE: 13 weeks and CWE: 12 weeks) compared to the symmetric electrode (LIE: 10 weeks). Finally, the electrodes were utilized for potentiometric titration of Cu2+ with ethylenediaminetetraacetic acid.

A sensitive electrochemical genosensor was introduced and developed for a tumor suppressor gene, p53, detection. An Au screen-printed electrode coated with polyaniline film and ceria nanoparticles decorated on reduced graphene oxide was employed. To generate the genosensor, a suitable ssDNA probe sequence was immobilized on the modified surface of a glassy carbon electrode without re-quiring any labeling or tagging moieties. The surface properties of the resulting electrodes were evaluated through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Hy-bridization phenomena of the probe and its target sequence were followed by differential pulse voltammetric signal of tris(bipyridine) ruthenium(II) chloride as an electrochemical probe. The detection limit was found to be 1 fM, and the DPV current was pro-portional to the logarithm of the p53 ssDNA concentration from 10 fM to 0.1 nM. The proposed genosensor showed excellent sen-sitivity, high selectivity, and reasonable reproducibility, which can be useful in future cancer di-agnosis microdevice development.

This article is focused on the development of a sensitive voltammetric electrode for sulfadiazine using nanoparticles of Tb2(WO4)3 to modify a carbon paste electrode (CPE). The behaviour of the modified-CPE was evaluated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and fast Fourier transform square wave voltammetry (FFTSWV). The results revealed an irreversible sulfadiazine oxidation peak around 0.85 V vs. the Ag/AgCl reference electrode. The physicochemical properties of the nano-material were investigated using scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Some effective parameters such as, pH, percentage of modifier, amplitude and frequency on sensor sensitivity were studied and optimized. The analytical curve was then obtained in the concentration ranges of 0.01–1.0 μM and 1.0–100 μM with a detection limit of 4.10 nM by fast fourier transform square wave voltammetry. Also the electron transfer coefficient (α) was determined as a value 0.66 for the sulfadiazine oxidation. The drug analysis in pharmaceutical formulation was also carried out and recovery percentages in the range of 97–102% were recorded. The sensor presented a good reproducibility and repeatability with acceptable RSD values (3.8%, 1.02% respectively) and long-term stability (almost one month).

Wearable potentiometric ion sensors (WPISs) have emerged as exciting analytical platforms that combine chemical, material, and electronic advancements to provide physiological information during various human activities. The real possibility of wearing an analytical device with diverse configurations, such as sweatbands, patches, or garments, without disturbing the wearer's comfort has enabled potentiometric ion sensors to serve as both healthcare monitoring and improve the performance of athletes.