Current Analytical Chemistry - Volume 18, Issue 1, 2022

Background:Modified electrodes have advanced from the initial studies aimed at understanding electron transfer in films to applications in areas such as energy production and analytical chemistry. This review emphasizes the major classes of modified electrodes with mediators that are being explored for improving analytical methodology. Chemically modified electrodes (CMEs) have been widely used to counter the problems of poor sensitivity and selectivity faced in bare electrodes. We have briefly reviewed the organometallic and organic mediators that have been extensively employed to engineer adapted electrode surfaces for the detection of different compounds. Also, the characteristics of the materials that improve the electrocatalytic activity of the modified surfaces are discussed. Objective: Improvement and promotion of pragmatic CMEs have generated a diversity of novel and probable strong detection prospects for electroanalysis. While the capability of handling the chemical nature of the electrode/solution interface accurately and creatively increases, it is predictable that different mediators-based CMEs could be developed with electrocatalytic activity and completely new applications be advanced.

N,N’-dialkylimidazolium-ion liquids are one of the important ionic liquids with a wide range of applications as a conductive electrolyte and in electrochemistry. The modified electrodes create a new view for the fabrication of electroanalytical sensors. Many modifiers have been suggested for modification of electroanalytical sensors since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,N’-dialkylimidazoliumion liquids are the main ionic liquids that have been suggested to modify bare electrodes and especially carbon paste electrodes. Although many review articles have reported on the use of ionic liquids in electrochemical sensors, no review article has specifically introduced so far the advantages of N,N’-dialkylimidazolium ionic liquids. Therefore, in this review paper, we focused on the introduction of recent advantages of N,N’-dialkyl imidazolium ionic liquids in electrochemistry

Background: The rapid and increasing use of the nanomaterials in the development of electrochemiluminescence (ECL) sensors is a significant area of study for its massive potential in the practical application of nanosensor fabrication. Recently, nanomaterials (NMs) have been widely applied in vast majority of ECL studies to remarkably amplify signals owing to their excellent conductivity, large surface area and sometimes catalytic activity. Lanthanides, as f-block-based elements, possess remarkable chemical and physical properties. This review covers the use of lanthanide NMs, focusing on their use in ECL for signal amplification in sensing applications. Methods: We present the recent advances in ECL nanomaterials including lanthanides NMs with a particular emphasis on Ce, Sm, Eu and Yb. We introduce their properties along with applications in different ECL sensors. A major focus is placed upon numerous research strategies for addressing the signal amplification with lanthanide NMs in ECL. Results: Lanthanide NMs as the amplification element can provide an ideal ECL platform for enhancing the signal of a sensor due to their chemical and physical properties. Function of lanthanide NMs on signal amplification remarkably depend on their large surface area to load sufficient signal molecules, high conductivity to promote electron-transfer reaction. Conclusion: ECL as a powerful analytical technique has been widely used in various aspects. As the development of the nanotechnology and nanoscience, lanthanide nanomaterials have shown the remarkable advantages in analytical applications due to their significant physical and chemical properties. We predict that in the future, the demand for ECL sensors will be high due to their potential in a diverse range of applications. Also, we expect the research in nanomaterial-based sensors will still continue intensively and eventually become effectively routine analysis tools that could meet various challenges.

Diagnosis of cancer in the early stages can help treat efficiently and reduce cancerrelated death. Cancer biomarkers can respond to the presence of cancer in body fluids before the appearance of any other symptoms of cancer. The integration of nanomaterials into biosensors as electrochemical platforms offer rapid, sensitive detection for cancer biomarkers. The use of surface- modified electrodes by carbon nanomaterials and metal nanoparticles enhances the performance of electrochemical analysis in biosensing systems through the increase of bioreceptors loading capacity on the surface. In this review, novel approaches based on nanomaterial-modified systems in the point of care diagnostics are highlighted.

Background: Currently, nanotechnology and nanomaterials are considered as the most popular and outstanding research subjects in scientific fields ranging from environmental studies to drug analysis. Carbon nanomaterials such as carbon nanotubes, graphene, carbon nanofibers etc. and non-carbon nanomaterials such as quantum dots, metal nanoparticles, nanorods etc. are widely used in electrochemical drug analysis for sensor development. The main aim of the drug analysis with sensors, is fast development, ease to use and sensitivity. Electroanalytical techniques such as voltammetry, potentiometry, amperometry etc. which measure electrical parameters such as current or potential in an electrochemical cell, are considered economical, highly sensitive and versatile techniques. Methods: Most recent researches and studies about electrochemical analysis of drugs with carbonbased nanomaterials were analyzed. Books and review articles about this topic were reviewed Results: The most significant carbon-based nanomaterials and electroanalytical techniques were explained in detail. In addition to this; recent applications of electrochemical techniques with carbon nanomaterials in drug analysis were expressed comprehensively. Recent researches about electrochemical applications of carbon-based nanomaterials in drug sensing were given in a table. Conclusion: Nanotechnology provides opportunities to create functional materials, devices and systems using nanomaterials with advantageous features such as high surface area, improved electrode kinetics and higher catalytic activity. Electrochemistry is widely used in drug analysis for pharmaceutical and medical purposes. Carbon nanomaterials based electrochemical sensors are one of the most preferred methods for drug analysis with high sensitivity, low cost and rapid detection.

Background: Over the past few decades, environmental pollution has appeared to be one of the most crucial global problems. The widespread intensification of numerous hazardous pollutants in the environment needs modern researchers to develop viable, reproducible and costeffective determination tools for reliable environmental analysis. The beneficial, as well as perilous, biological compounds, are receiving growing interest due to their variable composition, which produces advantageous and toxic impacts on humans and the environment. Several conventional analytical methods have been established for pharmaceutical and environmental analysis. However, certain drawbacks limited their practices in the modern rapidly growing era of science and technology. The development of electrochemical sensors has emerged as a more beneficial and promising tool against other traditional analytical approaches, in terms of simplicity, cost-effectiveness, sensitivity, stability and reliability. Nonetheless, the over potential and low anodic/cathodic current response are both considered as bottlenecks for the determination of electroactive entities exploiting electrochemical sensors. Interestingly, these problems can be easily resolved by modifying the electrodes with a variety of conductive materials, especially nanostructures. Objective:This review covers different electrochemical methods reported in the literature for environmental and pharmaceutical analysis through simple and cost-effective nanostructures-based sensors. The electrochemical techniques with different modes and the modification of electrodes with highly conductive and prolific polymeric and nanostructured materials used for the determination of different environmental and pharmaceutical samples are the main prominence of this review. Various kinds of nanomaterials, e.g. metal, metal oxide and their composites, have been synthesized for the fabrication of the sensitive electrodes. Conclusion: Nanostructures played a pivotal role in the modification of electrodes, which substantially enhanced the capability and sensitivity of electrochemical sensors. The proper modification of electrodes has materialized the swift detection of electroactive compounds at very low limits and offered the feasible determination procedure without any kind of signal fluctuation and over potential. In crux, due to their enhanced surface area and excellent catalytic properties, nanomaterials recently appeared as the most promising candidates in the field of electrode modification and significantly impacted the detection protocols for various environmental pollutants, viz. pesticides, metal ions and drugs.

Background:Ceramics can reflect ancient technology and art; therefore, it has a very important position in archaeology. However, it is far from enough just to study the shape of pottery and porcelain. It is necessary to use advanced scientific and technological means to conduct a comprehensive analysis of pottery and porcelain, so as to study the information hidden deep in the remains of ceramic objects. Methods: The solid voltammetric method can be used to obtain information about the composition of materials used in ancient ceramics. This new method can be applied to insoluble solids, for example, providing qualitative and quantitative information and structural information with little soluble solids. The method requires only ng-μg sample. Results:In this review, we first describe the development of a solid-state voltammetric method and our work in this field. Then, we describe in detail the application of this method in archaeology, especially in the analysis of ceramics. Finally, we describe the analytical applications of other electrochemical techniques for ceramics analysis. Conclusion: Due to the low demand for samples and the high-cost performance of analytical instruments, this method has been widely studied in Europe. To sum up, we propose to establish a microsampling method for ancient ceramics; a new method for the protection of fine ancient ceramics by the suitable carrier and the fixation on the surface of the electrode. These improvements can enable solid-state electroanalytical chemistry technology to achieve a more comprehensive and accurate quantitative analysis of ancient ceramics particles. We also propose the current challenges and future directions of solid-state electroanalytical chemistry.

Background: Catecholamines are a large group of pharmacological and biological compounds that are widely used in biological systems. These compounds are prepared both naturally and synthetically with many key roles in the human body and its activities. Therefore, many researchers focused on the identification and determination of catecholamines in biological samples. Methods: MgO/SWCNTs were synthesized through the chemical precipitation method. In addition, cyclic voltammetry, differential pulse voltammetry, and chronoamperometric methods were used for the electro-oxidation reaction study of epinine at the surface of the modified electrode. Results: Carbon paste electrode (CPE) modified with MgO/SWCNTs nanocomposite and 1-butyl- 3-methylimidazolium methanesulfonate (BMMS) was used as an electrochemical sensor for the determination of epinine. The results showed a linear dynamic range of 5.0 nM-250 μM with a detection limit of 0.1 nM for epinine determination using MgO/SWCNTs/BMMS/CPE as a sensor. Conclusion: In the present study, a highly sensitive electrochemical sensor was designed and fabricated as an analytical tool for the determination of epinine. MgO/SWCNTs/BMMS/CPE was successfully used for the determination of epinine in water and dextrose saline with an acceptable recovery range of 98.7%-102.72%.

Background:In this research work, a drug sensor (salicylic acid, in this case) was designed . The senor was made by modification of paste electrode (MPE) with CuO-SWCNTs and 1- hexyl-3-methylimidazolium chloride (HMICl). The MPE/CuO-SWCNTs/HMICl showed catalytic activity for the oxidation signal of salicylic acid in phosphate buffer solution Methods:Electrochemical methods were used as a powerful strategy for the determination of salicylic acid in pharmaceutical samples. Aiming at this goal, the carbon paste electrode was amplified with conductive materials and used as a working electrode. Results:The MPE/CuO-SWCNTs/HMICl was used for the determination of salicylic acid in the concentration range of 1.0 nM – 230 μM using the differential pulse voltammetric (DPV) method. At pH=7.0, as optimum condition, the MPE/CuO-SWCNTs/HMICl displayed a high-quality ability for the determination of salicylic acid in urine, pharmaceutical serum, and water samples. Conclusion: The MPE/CuO-SWCNTs/HMICl was successfully used as a new and highperformance working electrode for the determination of salicylic acid at a nanomolar level and in real samples.