Bimetallic AuCu nanoparticles coupled with multi-walled carbon nanotubes as ion-to-electron transducers in solid-contact potentiometric sensors

Recent advances in nanomaterial-based solid-contact ion-selective electrodes

Solid-contact ion-selective electrodes (SC-ISEs) are advanced potentiometric sensors with great capability to detect a wide range of ions for the monitoring of industrial processes and environmental pollutants, as well as the determination of electrolytes for clinical analysis. Over the past decades, the innovative design of ion-selective electrodes (ISEs), specifically SC-ISEs, to improve potential stability and miniaturization for in situ/real-time analysis, has attracted considerable interest. Recently, the utilisation of nanomaterials was particularly prominent in SC-ISEs due to their excellent physical and chemical properties. In this article, we review the recent applications of various types of nanostructured materials that are composed of carbon, metals and polymers for the development of SC-ISEs. The challenges and opportunities in this field, along with the prospects for future applications of nanomaterials in SC-ISEs are also discussed.

A Multichannel Screen-Printed Carbon Electrode Based on Fluorinated Poly(3-octylthiophene-2,5-diyl) and Purified Mesoporous Carbon Black Simultaneously Detects Na+, K+, Ca2+, and NO2. ACS OMEGA 2024;9:18238-18248. [PMID: 38680364 PMCID: PMC11044230 DOI: 10.1021/acsomega.3c10471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Preparation of nanocomposites based on fluorinated poly(3-octylthiophene-2,5-diyl) (POTF) and purified mesoporous carbon black (PMCB) as the solid-contact layer of a screen-printed carbon electrode (SPCE) is proposed. POTF is used as a dispersant for PMCB. The obtained nanocomposites possess unique characteristics including high conductivity, capacitance, and stability. The SPCE based on POTF and PMCB is characterized by electrochemical impedance spectroscopy and chronopotentiometry, demonstrating simultaneous detection of Na+, K+, Ca2+, and NO2- ions with detection limits of 10-6.5, 10-6.4, 10-6.7, and 10-6.3 M, respectively. Water layer and anti-interference tests revealed that the electrode has high hydrophobicity, and the static contact angle is >140°. The electrode shows excellent selectivity, repeatability, reproducibility, and stability and is not easily affected by light, O2, or CO2.

Recent Progress on Potentiometric Sensor Applications Based on Nanoscale Metal Oxides: A Comprehensive Review

Electrochemical sensors have been the subject of much research and development as of late, with several publications detailing new designs boasting enhanced performance metrics. That is, without a doubt, because such sensors stand out from other analytical tools thanks to their excellent analytical characteristics, low cost, and ease of use. Their progress has shown a trend toward seeking out novel useful nano structure materials. A variety of nanostructure metal oxides have been utilized in the creation of potentiometric sensors, which are the subject of this article. For screen-printed pH sensors, metal oxides have been utilized as sensing layers due to their mixed ion-electron conductivity and as paste-ion-selective electrode components and in solid-contact electrodes. Further significant uses include solid-contact layers. All the metal oxide uses mentioned are within the purview of this article. Nanoscale metal oxides have several potential uses in the potentiometry method, and this paper summarizes such uses, including hybrid materials and single-component layers. Potentiometric sensors with outstanding analytical properties can be manufactured entirely from metal oxides. These novel sensors outperform the more traditional, conventional electrodes in terms of useful characteristics. In this review, we looked at the potentiometric analytical properties of different building solutions with various nanoscale metal oxides.

Design Criteria for Nanostructured Carbon Materials as Solid Contacts for Ion-Selective Sensors

The ability to miniaturize ion-selective sensors that enable microsensor arrays and wearable sensor patches for ion detection in environmental or biological samples requires all-solid-state sensors with solid contacts for transduction of an ion activity into an electrical signal. Nanostructured carbon materials function as effective solid contacts for this purpose. They can also contribute to improved potential signal stability, reducing the need for frequent sensor calibration. In this Perspective, the structural features of various carbon-based solid contacts described in the literature and their respective abilities to reduce potential drift during long-term, continuous measurements are compared. These carbon materials include nanoporous carbons with various architectures, carbon nanotubes, carbon black, graphene, and graphite-based solid contacts. The effects of accessibility of ionophores, ionic sites, and other components of an ion-selective membrane to the internal or external carbon surfaces are discussed, because this impacts double-layer capacitance and potential drift. The effects of carbon composition on water-layer formation are also considered, which is another contributor to potential drift during long-term measurements. Recommendations regarding the selection of solid contacts and considerations for their characterization and testing in solid-contact ion-selective electrodes are provided.

Application of Metal Oxide Nanoparticles in the Field of Potentiometric Sensors: A Review

Recently, there has been rapid development of electrochemical sensors, and there have been numerous reports in the literature that describe new constructions with improved performance parameters. Undoubtedly, this is due to the fact that those sensors are characterized by very good analytical parameters, and at the same time, they are cheap and easy to use, which distinguishes them from other analytical tools. One of the trends observed in their development is the search for new functional materials. This review focuses on potentiometric sensors designed with the use of various metal oxides. Metal oxides, because of their remarkable properties including high electrical capacity and mixed ion-electron conductivity, have found applications as both sensing layers (e.g., of screen-printing pH sensors) or solid-contact layers and paste components in solid-contact and paste-ion-selective electrodes. All the mentioned applications of metal oxides are described in the scope of the paper. This paper presents a survey on the use of metal oxides in the field of the potentiometry method as both single-component layers and as a component of hybrid materials. Metal oxides are allowed to obtain potentiometric sensors of all-solid-state construction characterized by remarkable analytical parameters. These new types of sensors exhibit properties that are competitive with those of the commonly used conventional electrodes. Different construction solutions and various metal oxides were compared in the scope of this review based on their analytical parameters.

Ion-Selective Electrodes with Solid Contact Based on Composite Materials: A Review

Potentiometric sensors are the largest and most commonly used group of electrochemical sensors. Among them, ion-selective electrodes hold a prominent place. Since the end of the last century, their re-development has been observed, which is a consequence of the introduction of solid contact constructions, i.e., electrodes without an internal electrolyte solution. Research carried out in the field of potentiometric sensors primarily focuses on developing new variants of solid contact in order to obtain devices with better analytical parameters, and at the same time cheaper and easier to use, which has been made possible thanks to the achievements of material engineering. This paper presents an overview of new materials used as a solid contact in ion-selective electrodes over the past several years. These are primarily composite and hybrid materials that are a combination of carbon nanomaterials and polymers, as well as those obtained from carbon and polymer nanomaterials in combination with others, such as metal nanoparticles, metal oxides, ionic liquids and many others. Composite materials often have better mechanical, thermal, electrical, optical and chemical properties than the original components. With regard to their use in the construction of ion-selective electrodes, it is particularly important to increase the capacitance and surface area of the material, which makes them more effective in the process of charge transfer between the polymer membrane and the substrate material. This allows to obtain sensors with better analytical and operational parameters. Brief characteristics of electrodes with solid contact, their advantages and disadvantages, as well as research methods used to assess their parameters and analytical usefulness were presented. The work was divided into chapters according to the type of composite material, while the data in the table were arranged according to the type of ion. Selected basic analytical parameters of the obtained electrodes have been collected and summarized in order to better illustrate and compare the achievements that have been described till now in this field of analytical chemistry, which is potentiometry. This comprehensive review is a compendium of knowledge in the research area of functional composite materials and state-of-the-art SC-ISE construction technologies.

Unlocking All-Solid Ion Selective Electrodes: Prospects in Crop Detection

This paper reviews the development of all-solid-state ion-selective electrodes (ASSISEs) for agricultural crop detection. Both nutrient ions and heavy metal ions inside and outside the plant have a significant influence on crop growth. This review begins with the detection principle of ASSISEs. The second section introduces the key characteristics of ASSISE and demonstrates its feasibility in crop detection based on previous research. The third section considers the development of ASSISEs in the detection of corps internally and externally (e.g., crop nutrition, heavy metal pollution, soil salinization, N enrichment, and sensor miniaturization, etc.) and discusses the interference of the test environment. The suggestions and conclusions discussed in this paper may provide the foundation for additional research into ion detection for crops.

New Construction of Functionalized CuO/Al2O3 Nanocomposite-Based Polymeric Sensor for Potentiometric Estimation of Naltrexone Hydrochloride in Commercial Formulations

Electrically conductive polymeric nanocomposites with nanoparticles are adaptable types of nanomaterials that are prospective for various applications. The extraordinary features of copper oxide (CuO) and aluminium oxide (Al₂O₃) nanostructures, encourages extensive studies to prospect these metal oxide nanocomposites as potential electroactive materials in sensing and biosensing applications. This study suggested a new CuO/Al₂O₃ nanocomposite-based polymeric coated wire membrane sensor for estimating naltrexone hydrochloride (NTX) in commercial formulations. Naltrexone hydrochloride and sodium tetraphenylborate (Na-TPB) were incorporated in the presence of polymeric polyvinyl chloride (PVC) and solvent mediator o-nitrophenyloctyl ether (o-NPOE) to form naltrexone tetraphenylborate (NTX-TPB) as an electroactive material. The modified sensor using NTX-TPB-CuO/Al₂O₃ nanocomposite displayed high selectivity and sensitivity for the discrimination and quantification of NTX with a linearity range 1.0 × 10^-9-1.0 × 10^-2 mol L^-1 and a regression equation E_mV = (58.25 ± 0.3) log [NTX] + 754.25. Contrarily, the unmodified coated wire sensor of NTX-TPB exhibited a Nernstian response at 1.0 × 10^-5-1.0 × 10^-2 mol L^-1 and a regression equation E_mV = (52.1 ± 0.2) log [NTX] + 406.6. The suggested modified potentiometric system was validated with respect to various criteria using the methodology recommended guidelines.

A Review of Nanocomposite-Modified Electrochemical Sensors for Water Quality Monitoring

Electrochemical sensors play a significant role in detecting chemical ions, molecules, and pathogens in water and other applications. These sensors are sensitive, portable, fast, inexpensive, and suitable for online and in-situ measurements compared to other methods. They can provide the detection for any compound that can undergo certain transformations within a potential window. It enables applications in multiple ion detection, mainly since these sensors are primarily non-specific. In this paper, we provide a survey of electrochemical sensors for the detection of water contaminants, i.e., pesticides, nitrate, nitrite, phosphorus, water hardeners, disinfectant, and other emergent contaminants (phenol, estrogen, gallic acid etc.). We focus on the influence of surface modification of the working electrodes by carbon nanomaterials, metallic nanostructures, imprinted polymers and evaluate the corresponding sensing performance. Especially for pesticides, which are challenging and need special care, we highlight biosensors, such as enzymatic sensors, immunobiosensor, aptasensors, and biomimetic sensors. We discuss the sensors' overall performance, especially concerning real-sample performance and the capability for actual field application.

High Capacity Nanocomposite Layers Based on Nanoparticles of Carbon Materials and Ruthenium Dioxide for Potassium Sensitive Electrode

This work presents the new concept of designing ion-selective electrodes based on the use of new composite materials consisting of carbon nanomaterials and ruthenium dioxide. Using two different materials varying in microstructure and properties, we could obtain one material for the mediation layer that adopted features coming of both components. Ruthenium dioxide characterized by high electrical capacity and mixed electronic-ionic transduction and nano-metric carbon materials were reportedly proved to improve the properties of ion-selective electrodes. Initially, only the materials and then the final electrodes were tested in the scope of the presented work, using scanning and transmission electron microscope, contact angle microscope, and various electrochemical techniques, including electrochemical impedance spectroscopy and chronopotentiometry. The obtained results confirmed beneficial influence of the designed nanocomposites on the ion-selective electrodes' properties. Nanosized structure, high capacity (characterized by the electrical capacitance value from approximately 5.5 mF for GR + RuO₂ and CB + RuO₂, up to 14 mF for NT + RuO₂) and low hydrophilicity (represented by the contact angle from 60° for GR+RuO₂, 80° for CB+RuO₂, and up to 100° for NT + RuO₂) of the mediation layer materials, allowed us to obtain water layer-free potassium-selective electrodes, characterized by rapid and stable potentiometric response in a wide range of concentrations-from 10^-1 to 10^-6 M K⁺.