This work has applied metal-organic frameworks (MOFs) with high adsorbability and catalytic activity to develop electrochemical sensors to determine free chlorine (free-Cl) concentrations in aqueous media. A zeolitic imidazolate frameworks, Zn(Hmim)2 (ZIF-8) has been synthesized and incorporated with CuO nanosheets to decorate a glassy carbon electrode (GCE) and provide a new sensor for free-Cl determination. The as-prepared ZIF-8 and CuO-ZIF-8 composites have been characterized by FESEM, EDX, XRD, and FT-IR analyses. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) utilized to characterize the CuO-ZIF-8/GC modified electrode electrochemically, demonstrated the ability of the sensor to measure free-Cl concentration. Using differential pulse voltammetry (DPV) and under the optimal conditions, the prepared CuO-ZIF-8/GC modified electrode showed a linear response in the 0.25-60 ppm range with a 12 ppb detection limit (LOD) for free-Cl concentration. Finally, the fabricated sensor was applied to analyze free-Cl from actual swimming pool water samples with promising 97.5 to 103.0% recoveries.

Enantioselective recognition is a fundamental property of chiral linkers in chiral metal-organic frameworks (CMOFs). However, clarifying the efficient enantioselective discrimination tailored by achiral linkers remains challenging to explain the chiral recognition mechanism and efficiency. Here, two CMOFs ([Zn2(l-Phe)2(bpa)2]n and [Zn2(l-Phe)2(bpe)2]n) with the completely different enantioselective recognition are synthesized from different nonchiral ligands and the same chiral ligands. The enantioselective recognition of CMOF is undoubtedly related to l-Phe, which differs in the hydrogen bonding to the Trp enantiomer. However, the electrochemical signals are weak and undifferentiated. [Zn2(l-Phe)2(bpe)2]n produces a flattened coplanar conformation with the -C═C- tether in the achiral ligand. The flattened achiral bpee ligand and its surrounding chiral phenylalanine molecules interact through multiple π-π stacking and hydrogen bonding, which together create a chiral sensor that facilitates the recognition of l-Trp. However, [Zn2(l-Phe)2(bpa)2]n produces a stepped conformation due to the -C-C- tether in the achiral ligand; despite the recognition effect of bpea, the recognition is unsatisfactory. Therefore, the chiral recognition of the two CMOFs stems from the synergistic effect between chiral and achiral ligands. This work shows that nonchiral ligands are also crucial in determining enantiomeric discrimination and opens up a new avenue for designing chiral materials.

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems.

This study investigated the synthesis of cerium oxide (CeO2) nanoparticles (NPs) and composites with reduced graphene oxide (rGO) for the enhanced electrochemical sensing of ammonia. CeO2 NPs were prepared by the focused laser ablation in liquid (LAL) method, which enabled the production of high-purity, spherical nanoparticles with a uniform dispersion and sizes under 50 nm in a short time. The effects of varying irradiation fluence and time on the nanoparticle size, production yield, and dispersion were systematically studied. The synthesized CeO2 NPs were doped with rGO to form CeO2/rGO composites, which were drop casted to modify the glassy carbon electrodes (GCE). The CeO2/rGO-GCE electrodes exhibited superior electrochemical properties compared with single-component electrodes, which demonstrated the significant potential for ammonia detection, especially at a 4 J/cm2 fluence. The CeO2/rGO composites showed uniformly dispersed CeO2 NPs between the rGO sheets, which enhanced the conductivity, as confirmed by SEM, EDS mapping, and XRD analysis. Cyclic voltammetry data demonstrated superior electrochemical activity of the CeO2/rGO composite electrodes, with the 2rGO/1CeO2 ratio showing the highest current response and sensitivity. The CV response to varying ammonia concentrations exhibited a linear relationship, indicating the electrode\'s capability for accurate quantification. These findings highlight the effectiveness of focused laser ablation in enhancing nanoparticle synthesis and the promising synergistic effects of CeO2 and rGO in developing high-performance electrochemical sensors.

The widespread usage of levofloxacin (LVF) intake is executed for several urinary and respiratory systems infections in human. But, its over intake leads to severe damage to humans and the environment by its exposure. Hence the detection of LVF is concerned and we herein developed an electrocatalyst, strontium tungsten oxide nanospheres and later decorated onto the functionalized multiwall carbon nanotubes (SrWO4/f-MWCNT) to perform effective electrochemical recognition of LVF in aquatic and biological samples. Binary metal oxide with carbon composite SrWO4/f-MWCNT was developed due to its specific features as nanostructures. Various methods of investigation have been examined to identify the physiochemical characteristics like X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and morphological characteristics including field emission scanning electron microscopy, and transmission electron microscopy. The synthesized SrWO4/f-MWCNT sample crystalline size was around 32.9 nm. The SrWO4/f-MWCNT modified glassy carbon electrode (GCE) has been subjected to electrochemical investigation with a wide linear range of 0.049 μM-574.73 μM with good sensitivity 2.86 μA μM-1 cm2, the limit of detection at 14.9 nM for LVF sensing. Furthermore, the designed LVF detection exhibited excellent anti-interference, stability, reproducibility, and repeatability. The as-developed sensor\'s electrochemical outcomes indicate the superior performance inherent in the developed composite.

Background In recent years, significant advancements have been made in various scientific sectors, particularly in healthcare and pharmaceutical research. This progress has been driven by the development of enhanced sensing materials and methodologies. Electrochemical sensing has become an important tool in detecting and analyzing drug molecules due to its high sensitivity, specificity, and rapid response times. Among various drugs, paracetamol, also known as acetaminophen, is widely used for its analgesic and antipyretic properties. Accurate detection of paracetamol is crucial due to its widespread use and potential for overdose, which can lead to severe liver damage. Copper molybdate (CuMoO4) is a transition metal oxide that has garnered attention for its excellent electrical conductivity and electrochemical stability. These properties make it a promising candidate for use in electrochemical sensors. The ability of CuMoO4 to act as a sensor material is enhanced by its unique structural and morphological characteristics, which can be tailored during synthesis. Aim This study aimed to synthesize CuMoO4 and investigate its electrochemical sensing capability for the detection of drug molecules, specifically paracetamol. Materials and method CuMoO4 was synthesized using a precipitation method that did not involve any surfactants. This approach was chosen to simplify the synthesis process and avoid potential contamination from surfactants. The morphology of the synthesized CuMoO4 nanoparticles was investigated using a field emission scanning electron microscope (FE-SEM). Energy-dispersive X-ray spectroscopy (EDX) confirmed the purity of the CuMoO4 nanomaterial. Structural analysis was performed using X-ray diffraction (XRD). To evaluate the electrochemical sensing capability of CuMoO4 for paracetamol, Differential pulse voltammetry (DPV) was employed. DPV is a sensitive electrochemical technique that can detect changes in current response corresponding to the presence of analytes. Results The synthesized CuMoO4 exhibited a rock-like structure, as revealed by FE-SEM imaging. This morphology is advantageous for electrochemical applications due to the increased surface area available for interaction with analytes. EDX confirmed the purity of the CuMoO4 nanomaterial, showing no significant impurities. XRD analysis indicated that the CuMoO4 nanoparticles were crystalline in nature, which is beneficial for consistent and reproducible electrochemical behavior. The DPV analysis demonstrated that the CuMoO4 sensor exhibited a linear increase in current response with increasing concentrations of paracetamol. This linear relationship indicates that CuMoO₄ is capable of detecting paracetamol effectively, with a strong and quantifiable signal response. Conclusion The CuMoO4 nanomaterial was successfully synthesized using a simple precipitation method and was characterized by its rock-like morphology and crystalline structure. Electrochemical testing using DPV showed that CuMoO4 has excellent sensing capabilities for detecting paracetamol, with a clear and linear current response. These findings suggest that CuMoO4 is a promising electrochemical sensing material for drug detection, potentially offering a reliable and efficient method for monitoring paracetamol and possibly other pharmaceuticals in various settings.

Zeolitic Imidazolate (metal organic) Frameworks (ZIFs) and Prussian Blue Analogues (PBAs) are promising materials in electrochemical sensing due to their unique properties. In this study, a composite material comprising NiFe-PBA and ZIF-67 was synthesized and made to form a uniform layer onto a glassy carbon electrode (GCE) to enhance electrochemical performance for furazolidone (FZD) detection. The synthesized NiFe-PBA/ZIF-67 composite exhibited excellent sensitivity, selectivity, and stability towards FZD detection, with a low limit of detection (LOD). The electrochemical behaviour of FZD on the NiFe-PBA/ZIF-67/GCE electrode was investigated, revealing a diffusion-controlled process. Differential pulse voltammetry (DPV) analysis demonstrated the synergetic effect of the PBA/MOF core-shell structure in enhancing FZD electro-reduction. The sensor exhibited exceptional LOD of 0.007 μM. Selectivity studies confirmed the sensor\'s ability to distinguish FZD from potential interferents. Extensive evaluations demonstrated the sensor\'s reproducibility, repeatability, and long-term stability, affirming its practical utility. Real sample analysis further validated the sensor\'s excellent analytical capabilities in diverse matrices.

UNASSIGNED: Erectile dysfunction is a common issue among adult males involving difficulty in maintaining an erection, and it is often treated with fast-acting, low-side-effect drugs like avanafil (AVN), among other phosphodiesterase-5 inhibitors. Hence, developing fast, simple, and sensitive methods to detect AVN is crucial.
UNASSIGNED: This study conducts an electroanalytical inquiry and provides a new voltammetric method for accurately analyzing AVN utilizing a boron-doped diamond (BDD) electrode without any modifications.
UNASSIGNED: In the Britton-Robinson buffer (BR, 0.04 mol L-1, pH 4.0), cyclic voltammetry showed a clearly defined and irreversible anodic peak at around +1.44 V relative to Ag/AgCl. The pH of the solution was shown to have an impact on the voltammetric signals of the oxidation peaks. A good linear response for AVN quantification was achieved using square-wave voltammetry. This was done in a 0.04 mol L-1 BR (pH 4.0) solution at a potential of +1.33 V (vs. Ag/AgCl). The method exhibited a wide dynamic range of 0.5 to 30.0 μg mL-1 (1.0 to 62 μmol L-1) and a low limit of detection of 0.14 μg mL-1 (0.29 μmol L-1). The method proposed demonstrated suitability for determining AVN content in pharmaceutical formulations. The accuracy of the approach was demonstrated by comparing the results obtained using the developed method with those achieved using the UV-Vis spectrometry method.
UNASSIGNED: Our method simplifies the analytical process by eliminating the need for electrode modification, reducing both time and resource requirements while enhancing overall feasibility.

The treatment of wound inflammation is intricately linked to the concentration of reactive oxygen species (ROS) in the wound microenvironment. Among these ROS, H2O2 serves as a critical signaling molecule and second messenger, necessitating the urgent need for its rapid real-time quantitative detection, as well as effective clearance, in the pursuit of effective wound inflammation treatment. Here, we exploited a sophisticated 3D Cu2- x Se/GO nanostructure-based nanonzymatic H2O2 electrochemical sensor, which is further decorated with evenly distributed Pt nanoparticles (Pt NPs) through electrodeposition. The obtained Cu2- x Se/GO@Pt/SPCE sensing electrode possesses a remarkable increase in specific surface derived from the three-dimensional surface constructed by GO nanosheets. Moreover, the localized surface plasma effect of the Cu2- x Se nanospheres enhances the separation of photogenerated electron-hole pairs between the interface of the Cu2- x Se NPs and the Pt NPs. This innovation enables near-infrared light-enhanced catalysis, significantly reducing the detection limit of the Cu2- x Se/GO@Pt/SPCE sensing electrode for H2O2 (from 1.45 μM to 0.53μM) under NIR light. Furthermore, this biosensor electrode enables in-situ real-time monitoring of H2O2 released by cells. The NIR-enhanced Cu2- x Se/GO@Pt/SPCE sensing electrode provide a simple-yet-effective method to achieve a detection of ROS (H2O2、-OH) with high sensitivity and efficiency. This innovation promises to revolutionize the field of wound inflammation treatment by providing clinicians with a powerful tool for accurate and rapid assessment of ROS levels, ultimately leading to improved patient outcomes.

An electrochemical sensor sensitive to coenzyme A (CoA) was designed using a CoA-responsive polyallylamine-manganese oxide-polymer dot nanogel coated on the electrode surface to detect various genetic models of osteoarthritis (OA). The CoA-responsive nanogel sensor responded to the abundance of CoA in OA, causing the breakage of MnO2 in the nanogel, thereby changing the electroconductivity and fluorescence of the sensor. The CoA-responsive nanogel sensor was capable of detecting CoA depending on the treatment time and distinguishing the response towards different OA genetic models that contained different levels of CoA (wild type/WT, NudT7 knockout/N7KO, and Acot12 knockout/A12KO). The WT, N7KO, and A12KO had distinct resistances, which further increased as the incubation time were changed from 12 h (R12h = 2.11, 2.40, and 2.68 MΩ, respectively) to 24 h (R24h = 2.27, 2.59, and 2.92 MΩ, respectively) compared to the sensor without treatment (Rcontrol = 1.63 MΩ). To simplify its application, the nanogel sensor was combined with a wireless monitoring device to allow the sensing data to be directly transmitted to a smartphone. Furthermore, OA-indicated anabolic (Acan) and catabolic (Adamts5) factor transcription levels in chondrocytes provided evidence regarding CoA and nanogel interactions. Thus, this sensor offers potential usage in simple and sensitive OA diagnostics.