A copper metal-organic framework-based electrochemical sensor for identification of glutathione in pharmaceutical samples

CuSeO3@f-CNFs: A superoxide nanozyme for the selective nanomolar determination of the key cardiovascular biomarker, Glutathione

Nanocomposites that mimic the characteristics of enzymes, commonly as nanozymes, can function as an efficient sensing material with high selectivity towards the targeted biological macromolecule. These nanozymes overcome of the challenges that arise when using natural enzymes as sensing material. This study presents a novel nanozyme, Copper Selenite (CuSeO3) nanoparticles mounted on f-CNF, to electrochemically determine a potential cardiovascular biomarker, Glutathione (GSH). The choice of this material is due to the well-known ability of GSH to form a complex with copper. When a Cu ion enters a healthy cell, it quickly forms a complex with GSH, which then moves to another storage molecule: either a metalloprotein or a chelator. CNF was functionalized using acid to generate functionalized-CNF to enhance biocompatibility and boost conductivity. This was done to provide many active sites for effective integration of CuSeO3 in the nanocomposite preparation. The glassy carbon electrode (GCE) surface was enhanced by introducing CuSeO3@f-CNF nanocomposite, resulting in a significant increase in the current response for GSH in comparison to prior research. CuSeO3@f-CNF/GCE sensor has shown excellent sensing properties, like enhanced stability, selectivity, sensitivity, and reproducibility, for detecting and quantifying GSH. The sensor demonstrated an extensive linear detection range from 62.5 nM to 7785.0 μM, signifying one of the most comprehensive ranges documented to date. It attained a remarkable detection limit (LOD) of 17.6 nM. The sensor's performance was further tested by analyzing genuine biological fluid samples. The nanozyme-modified GCE demonstrated exceptional electrocatalytic efficiency for GSH detection, making it extremely appropriate for real-time monitoring applications.

Cu-MOFs/GO composite-based electrochemical sensor for the simultaneous measurement of xanthine, hypoxanthine and caffeine at trace levels

Copper-MOFs were prepared via a simple solvothermal route using copper metal ion as the source and trimesic acid as the linker molecule at room temperature. The composite was then prepared by mixing the copper-MOFs with graphene oxide and used as a modifier for the simultaneous measurement of xanthine derivatives, such as xanthine, hypoxanthine and caffeine. The composite was characterised by X-ray diffraction, infrared spectroscopy, thermogravimetry and BET surface area studies. The electrochemical behaviour of the composite was studied through cyclic voltammetry, impedance and square wave voltammetry. The analytical signal responses for all three analytes were linear in the concentration range of 1-400 μM, with limits of detection of 0.045, 0.052 and 0.02 μM for xanthine, hypoxanthine and caffeine, respectively. The sensor exhibited wide linearity, good stability and reproducibility and was successfully applied to measure target analyte molecules from real sample matrices at trace levels, even in the presence of common interferants. The fabricated sensor can be utilised as an alternative method for the simultaneous measurement of xanthine, hypoxanthine and caffeine in complex sample matrices at low concentration levels.

Electrochemical detection of per- and polyfluoroalkyl substances: A review

Per- and poly-fluoroalkyl substances (PFASs) are recognised for their environmental persistence and bioaccumulation, necessitating a dependable detection technology. Traditional methods examine multiple facets. Electrochemical sensors represent a preferable alternative due to their reliability, real-time detection capabilities, and potential for on-site analysis. Metal-organic frameworks (MOFs) and molecularly imprinted polymers (MIPs) exhibit remarkable properties in analysis, including high sensitivity and selectivity, rapid response and efficient electron transfer capabilities. Nonetheless, the stability of MOFs occasionally poses issues in aquatic conditions. Utilising a microfluidic channel between interdigitated microelectrodes (IDμE) in a MOF-based electrochemical sensor for PFASa detection offers numerous advantages. It possesses a minimal limit of detection (LOD), comparable to cutting-edge ex-situ methodologies. The molecular interactions of the capture probes provide effective electrochemical transduction, while the nanoporous morphology of the materials and IDμE significantly enhance the signal-to-noise ratio. Extended diffusion durations impede detection abilities and limit molecular interactions between PFAS and electrode surfaces. The selectivity challenges involve differentiation problems and complex matrices. Accurately identifying PFAS compounds in samples is problematic, especially those with similar carbon chain lengths, and existing sensors are hindered by interference from non-fluorinated surfactants. Improvements in electrode design can be realised by the use of nonplanar interdigitated microelectrode arrays (NP-IDμE), the application of nanoporous and capacitive electrode technologies, and the incorporation of electrode nano-porosity to minimise non-specific adsorption. Improvements in signal and sensitivity can optimise the detection process. Signal increases can be attained by decoupling sensitivity and selectivity using force as a tuning parameter, employing ambient oxygen as a mediator molecule instead of expensive ferrocene, and utilising electrochemical impedance spectroscopy (EIS) for improved sensitivity. Integrating IoT with EC PFAS sensors indicates a promising future for environmental monitoring.

Electrochemical water treatment: Review of different approaches

The continued development in agriculture, the rapid growth of industrialization, and last but not least, the increase in the global population adversely affects the environment. The availability of drinking water decreases every year with the rise in water pollution, which is the consequence of the failure of conventional approaches to the water treatment process. This review will provide a comprehensive and detailed analysis of the electrochemical water treatment processes, as these techniques have several benefits over conventional methods, such as being cost-effective, easily applicable, selective, and broad applicability. This review starts by discussing the traditional methods. It explains their limitations and finishes the introductory part by presenting all the benefits of the electrochemical method over the conventional method for water treatment. Then, the discussion will be carried out on the individual electrochemical method with their detailed analysis of the selected approach, selected material, and optimized parameters for analysis. The elaborative study was targeted, and the different coupled systems, their analysis parameters, and derived removal efficiencies were given in tabular form. In the last section of the article, the conclusive statements present the prospects of the electrochemical method for water treatment.

An iron metal-organic framework-based electrochemical sensor for identification of Bisphenol-A in groundwater samples

Bisphenol A (BPA) is an endocrine disruptor that leaches into food and is significantly employed in food and beverage storage, and source water cycles. To ensure an outstanding and sustainable biosphere while safeguarding human health and well-being, BPA detection is essential, necessitating an efficient detection methodology. Here, we describe an easy-to-use, inexpensive, and overly sensitive electrochemical detector that uses Fe-MOF nanotextures for identifying BPA in groundwater. This sensing electrode device combines the excellent guest interaction potential of organic ligands with the substantial surface area of metal. Using various analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (XRD), the structural and physicochemical behaviors of the as-synthesized material were evaluated. Electrochemical BPA detection was enabled by a diffusion-controlled oxidation procedure with a comparable number of both protons and electrons. With a 0.1 μM detection limit, the sensor displayed a linear sensitivity of around 0.1 μM and 15 μM. Additionally, the sensors demonstrated an outstanding recovery with actual water samples as well as a repeatable and steady performance over the course of a month exhibiting minimal interference from typical inorganic and organic species. Due to its notable sensitivity, inexpensive cost, robust selectivity, excellent repeatability, and reuse ability, the electroanalytical possibilities of the Fe-MOF-modified GCE suggest that the device can be implemented into real-world applications in its primed condition.

MnO2-based dual channel surface plasmon resonance fiber sensor for trace glutathione and refractive index detection

Glutathione (GSH) plays vital role in human biological systems, so its rapid and sensitive detection is necessary for health condition monitoring. In this work, a simple structure for dual channel GSH and refractive index (RI) detection is proposed. By introducing Au-MnO2 thin film coating on the fiber surface for the first time, GSH solution would lead to the dissolution of MnO2, the change in GSH levels could be monitored over a short period in channel 2. For channel 1, ITO-Ag thin film is applied for RI change detection. After optimization, the GSH detection sensitivity reached about -2.361 nm/mM in the range of 0.005-50 mM, and the RI sensitivity reached 1704.252 nm/RIU in the range of 1.331-1.3895 RIU. Channel 1 could also put into GSH detection in the high concentration scale to enlarge the sensor's range and 0.095 nm/mM of sensitivity is acquired within the range of 50-600 mM. With the presence of MnO2 film, the detection sensitivity increased 25.663 times. Neither channel interferes with the operation of the other. Proposed sensor provides stability, high selectivity and elevation in GSH detection sensitivity, which shows great potential for environmental and biological detection field and their applications.