Facile preparation of tungsten carbide nanoparticles for an efficient oxalic acid sensor via imprinting

Early Detection and Monitoring of Nephrolithiasis: The Potential of Electrochemical Sensors

Nephrolithiasis (kidney stone disease) continues to pose a significant global health challenge, affecting millions of individuals and placing substantial economic pressures on healthcare systems. Traditional diagnostic methods-such as computed tomography (CT), ultrasound, and basic urinalysis-are often limited by issues including radiation exposure, lower sensitivity in detecting small stones, operator dependency, and the inability to provide real-time analysis. In response, electrochemical sensors have emerged as innovative and powerful tools capable of the rapid, sensitive, and specific detection of key biomarkers associated with nephrolithiasis. This review highlights the advances in electrochemical approaches for monitoring oxalate and uric acid, the two primary metabolites implicated in kidney stone formation. We discuss the principles of electrode design and fabrication, including nanomaterial integration, 3D printing, and molecular imprinting, which have markedly improved detection limits and selectivity. Furthermore, we critically evaluate the practical challenges-such as sensor fouling, reproducibility, and stability in complex biological matrices-that currently impede widespread clinical implementation. The potentials for miniaturization and point-of-care integration are emphasized, with an eye toward continuous or home-based monitoring systems that can offer personalized insights into risk of stone formation and progression. By consolidating recent findings and exploring future trends in multi-analyte detection and wearable diagnostics, this review provides a roadmap for translating electrochemical sensors from research laboratories to routine clinical practice, ultimately aiming to enhance early intervention and improve patient outcomes in nephrolithiasis.

Unveiling the PEDOT-polypyrrole hybrid electrode for the electrochemical sensing of dopamine

This study presents the electrochemical sensing of dopamine (DA) using an electrode of polypyrrole/poly(3,4-ethylenedioxythiophene) (PEDOT-PPy) thin film. Electrochemical analyses of the PEDOT-PPy thin film for DA sensing were conducted through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CV analysis demonstrated that PEDOT-PPy exhibited superior electrochemical activity towards DA due to its enhanced conductivity as a high-conducting polymer composite. The DPV results indicated a linear concentration level of 5 nM to 200 µM with a minimal limit of sensing of 5 nM using the PEDOT-PPy electrode material. The fabricated sensor explored the sensitivity of 7.27 µA/µM cm2 at the 5 to 1000 nM DA concentration and the dopamine diffusion coefficient of 1.3 × 10-8 cm2/s. Additionally, the PEDOT-PPy electrode material displayed excellent reproducibility, selectivity, and stability. Therefore, the PEDOT-PPy composite electrode material shows excellent potential for outperforming other electrode materials in detecting DA.

Molecularly Imprinted Polymer-Based Sensors Integrated with Transition Metal Dichalcogenides (TMDs) and MXenes: A Review

Molecularly imprinted polymer (MIP)-based electrochemical sensors have been extensively researched due to their higher sensitivity, quick response, and operational ease. To develop more advanced sensing devices with enhanced properties, MIPs have been integrated with two-dimensional (2D) layered materials such as transition metal dichalcogenides (TMDs) and MXenes. These 2D materials have unique electronic properties and an extended surface area, making them promising sensing materials that can improve the performance of MIPs. In this review article, we describe the methods used for the synthesis of TMDs and MXenes integrated MIP-based electrochemical sensors. Furthermore, we have provided a critical review of a wide range of analytes determined through the application of these electrochemical sensors. We also go over the influence of TMDs and MXenes on the binding kinetics and adsorption capacity which has enhanced binding recognition and sensing abilities. The combination of TMDs and MXenes with MIPs shows promising synergy in the development of highly efficient recognition materials. In the future, these sensors could be explored for a wider range of applications in environmental remediation, drug delivery, energy storage, and more. Finally, we address the challenges and future perspectives of using TMDs and MXenes integrated MIPs. We conclude with a focus on future development and the scope of integrating these materials in sensing technology.

Crumpled MXene nanosheets for sensing of ascorbic acid in food, biological fluids, and erythrocytes in-vitro microenvironment

In this work, a simple and facile method was developed to achieve controlled oxidation and enhance the surface area of MXene nanosheets and their utilization in the efficient sensing of ascorbic acid (AA or vitamin C). After etching of MAX phase to MXene via the MILD technique, controlled flash oxidation was carried out in the open air environment for 1.5 h, followed by flocculation of oxidized MXene nanosheets by using H2SO4, consequently achieving crumpled MXene possessing anatase phase, porosity, and improved surface area as revealed and confirmed by SEM, TEM, Raman, and BET analysis results. The as-prepared crumpled MXene was coated over a glassy carbon electrode (GCE) and used to determine AA successfully via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) with a linear concentration range of 300 μM to 0.005 μM with a detection limit (LOD) of 2 nM (2.8 % RSD and S/N = 3). The developed electrochemical sensor was used to determine the AA in various actual samples such as juice, urine, serum, and erythrocytes spiked with AA with excellent recoveries in the 94-103 % range. The sensor also demonstrated excellent reproducibility (~1 % RSD for five repetitive assays) and a shelf life of nearly one month with a negligible decrease in response. Furthermore, it lost only 10 % of its response for the next ten days. It also showed satisfactory selectivity toward AA in the presence of other similar compounds, including uric acid (UA), dopamine (DA), and glucose.

Picomolar or beyond Limit of Detection Using Molecularly Imprinted Polymer-Based Electrochemical Sensors: A Review

Over the last decades, molecularly imprinted polymers (MIPs) have emerged as selective synthetic receptors that have a selective binding site for specific analytes/target molecules. MIPs are synthetic analogues to the natural biological antigen-antibody system. Owing to the advantages they exhibit, such as high stability, simple synthetic procedure, and cost-effectiveness, MIPs have been widely used as receptors/sensors for the detection and monitoring of a variety of analytes. Moreover, integrating electrochemical sensors with MIPs offers a promising approach and demonstrates greater potential over traditional MIPs. In this review, we have compiled the methods and techniques for the production of MIP-based electrochemical sensors along with the applications of reported MIP sensors for a variety of analytes. A comprehensive in-depth analysis of recent trends reported on picomolar (pM/10^-12 M)) and beyond picomolar concentration LOD (≥pM) achieved using MIPs sensors is reported. Finally, we discuss the challenges faced and put forward future perspectives along with our conclusion.

An edible molecularly imprinted material prepared by a new environmentally friendly deep eutectic solvent for removing oxalic acid from vegetables and human blood

A novel deep eutectic solvent-magnetic molecularly imprinted polymer (DES-MMIP) for the specific removal of oxalic acid (OA) was prepared by an environmentally friendly deep eutectic solvent, consisting of betaine, citric acid, and glycerol, which acted as the functional monomer for polymerization. The structure and morphology of DES-MMIPs were studied by X-ray diffraction, scanning and transmission electron microscopy, thermal gravimetric analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. DES-MMIPs had a core-shell structure, with magnetic iron oxide as the core, and showed good thermal stability and high adsorption capacity (18.73 mg/g) for OA. The adsorption process of OA by DES-MMIPs followed the pseudo-second-order kinetic model and Langmuir isotherm model. DES-MMIPs had significant selectivity for OA and their imprinting factor was 3.26. When applied to real samples, high performance liquid chromatography analysis showed that DES-MMIPs could remove OA from both spinach and blood serum. These findings provide potential methods for removal of OA from vegetables and for specific removal of OA in renal dialysis.

The Selectivity of Molecularly Imprinted Polymers

The general claim about novel molecularly imprinted polymers is that they are selective for their template or for another target compound. This claim is usually proved by some kind of experiment, in which a performance parameter of the imprinted polymer is shown to be better towards its template than towards interferents. A closer look at such experiments shows, however, that different experiments may differ substantially in what they tell about the same imprinted polymer's selectivity. Following a short general discussion of selectivity concepts, the selectivity of imprinted polymers is analyzed in batch adsorption, binding assays, chromatography, solid phase extraction, sensors, membranes, and catalysts. A number of examples show the problems arising with each type of application. Suggestions for practical method design are provided.