Molecularly imprinted polymer-carbon paste electrode (MIP-CPE)-based sensors for the sensitive detection of organic and inorganic environmental pollutants: A review

The rapidly growing existence of a number of contaminants (i.e. heavy metals, dye compounds, explosives and pesticides etc.) in environment is an alarming concern not only due to their harmful impacts for the environment bur also due to their potential high risk for human health. Thus, the careful and sensitive detection of these environmental contaminants is ver crucial. Electrochemical sensors combined with molecularly imprinted polymers (MIPs) become an attractive area for environmental monitoring. Benefiting from their great features such as high chemical and physical stability, cheap preparation process, excellent selectivity, sensitivity and fast response towards the target compound/s.This review paper aims to present and highlight the latest progresses in the design and development of novel electrochemical sensor systems composed of MIPs and carbon paste electrodes (CPEs) for the sensitive detection of pollutants in environmental samples.     

Electrochemical detection based on nanomaterials in CE and microfluidic systems

Electrochemical detection has a great potential in microfluidic systems due to its easy miniaturization without losing analytical performance. In addition, the use of nanomaterials in electroanalysis improves sensitivity, selectivity, and reproducibility. The topic of this review is the use of nanomaterials (nanoparticles, nanotubes, graphene) in electrochemical detection for capillary electrophoresis and microfluidic systems (microchips and paper based analytical devices). This review covers from 2015 up to now and it is a continuation of our previous review, also published in Electrophoresis journal. The following aspects of the surveyed articles are mainly addressed: type of nanomaterial, protocol of working electrode preparation (composite, drop casting and others), advantages of nanomaterial employment and application field (clinical, food, environmental and home security). The use of nanomaterials is still an interesting approach to improve the analytical performance of electrochemical detection based on microfluidic devices. Along the review, readers will find new protocols for working electrode modification, new carbon nanomaterials and promising applications in the aforementioned fields.     

Electrochemical Sensing of Explosives

This article reviews recent advances in electrochemical sensing and detection of explosive substances. Escalating threats of terrorist activities and growing environmental concerns have generated major demands for innovative field‐deployable tools for detecting explosives in a fast, sensitive, reliable and simple manner. Field detection of explosive substances requires that a powerful analytical performance be coupled to miniaturized low‐cost instrumentation. Electrochemical devices offer attractive opportunities for addressing the growing explosive sensing needs. The advantages of electrochemical systems include high sensitivity and selectivity, speed, a wide linear range, compatibility with modern microfabrication techniques, minimal space and power requirements, and low‐cost instrumentation. The inherent electroactivity of nitroaromatic, nitramine and nitroester compounds makes them ideal candidates for electrochemical detection. Recent activity in various laboratories has led to the development of disposable sensor strips, novel electrode materials, submersible remote sensors, and electrochemical detectors for microchip (‘Lab‐on‐Chip’) devices for on‐site electrochemical detection of explosive substances. The attractive behavior of these electrochemical monitoring systems makes them very promising for addressing major security and environmental problems.     

Nanomaterials based non-enzymatic electrochemical and optical sensors for the detection of carbendazim: A review

Carbendazim sensors with high sensitivity and selectivity have become imperative for the welfare of the food industry, agriculture, aquaculture, and forestry. The design and development of sensors with high sensitivity and selectivity require deeper insights into the chemistry of nanomaterials. Driven by these needs, we intend to offer a concise discussion of diverse materials and various analytical techniques employed for carbendazim detection. This review focuses on interpreting the performance of well-recognized techniques integrated with keenly engineered nanomaterials, critical discussions on the drawbacks of the available sensors, and subsequent advances in nano-tailored materials. This review also provides constructive ideas for the requirement of maiden electrochemical and optical sensors, as well as existing challenges and future prospects.     

New advances in electrochemical biosensors for the detection of toxins: Nanomaterials,magnetic beads and microfluidics systems. A review

The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised.     

Application of molecularly imprinted polymers for electrochemical detection of some important biomedical markers and pathogens

The determination of biomedical markers and pathogens using electrochemical sensors is a well-established technique in which the transducer and the recognition element are used to detect the target molecule. There is a growing interest in molecularly imprinted polymer (MIPs) applications as promising recognition elements. The use of MIPs as recognition elements in electrochemical sensors offers the advantages of being fast, low cost, and, at the same time, provides accurate and selective results compared with other commonly applied routine methods for biomedical markers and pathogen detection. Compared with other nanomaterials and aptamer-based biosensors, MIP-based sensors offered excellent selectivity for low-priced reagents to be used. The aim of the current review is to discuss the most recent applications of MIP-based electrochemical sensors (2019–2021) as promising detection devices for some important biomarkers, enzymes, and pathogens, such as viruses, bacteria, and toxins.     

Electrochemical in-vivo sensors using nanomaterials made from carbon species,noble metals,or semiconductors

Electrochemical analytical methods have the advantages of simplicity, direct measurements, and ease of miniaturization which pave the way for real time detection and sensing. However, the complexity of living systems usually requires electrochemical sensors to display high selectivity, sensitivity, accuracy, biocompatibility and stability over time. Nanomaterials possess attractive properties in terms of surface modification, catalysis, and functionality. These open new avenues with respect to electrochemical enzymatic determination of neurochemicals such as dopamine, serotonin and ascorbate, biological small molecules such as H₂O₂ and metal ions such as copper(II) in-vivo. Three properties of nanomaterials make their use particularly attractive, namely the larger surface-to-volume ratio area, their unique surface, and the ease of electron transfer between enzymes and electrodes. These properties make them more sensitive, selective and stable. The article is subdivided into sections that cover applications of the following materials: carbonaceous materials (mainly carbon nanotube), noble metal particles (mainly gold and platinum particles), and semiconductor (mainly metal oxide) nanomaterials. A conclusion and outlook section addresses current chances and limitations. The review contains 99 references. Figure

Three attractive properties of nanomaterials: the larger surface-to-volume ratio area, unique surface, and facilitating the electron transfer between enzyme and electrode, can improve the analytical performance of electrode, fulfilling the requirements in sensitivity, selectivity and stability for in vivo electrochemistry.     

Role of carbon nanotubes in electroanalytical chemistry: a review

This review covers recent advances in the development of new designs of electrochemical sensors and biosensors that make use of electrode surfaces modification with carbon nanotubes. Applications based on carbon nanotubes-driven electrocatalytic effects, and the construction and analytical usefulness of new hybrid materials with polymers or other nanomaterials will be treated. Moreover, electrochemical detection using carbon nanotubes-modified electrodes as detecting systems in separation techniques such as high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) will be also considered. Finally, the preparation of electrochemical biosensors, including enzyme electrodes, immunosensors and DNA biosensors, in which carbon nanotubes play a significant role in their sensing performance will be separately considered.     

Electrochemical Detection of Pathogenic Bacteria—Recent Strategies,Advances and Challenges

Bacterial infections represent one of the leading causes of mortality worldwide, nevertheless the design and development of rapid, cost‐efficient and reliable detection methods for pathogens remains challenging. In recent years, electrochemical sensing methods have gained increasing attention for the detection of pathogenic bacteria, due to their increasingly competitive sensitivity. However, combining sensitivity with cost efficiency, high selectivity and a facile working procedure in a portable device is difficult. The presented review provides a summary of biosensing strategies for bacteria, published since 2015, by covering significant achievements towards custom‐designed portable point‐of‐care devices. Herein, the direct chemical recognition of bacteria via enzyme activity or secretion products, as well as their detection at various electrode surfaces and materials, such as nanomaterials, indium tin oxide or paper‐based immunosensors, is discussed. Furthermore, newly established hyphenated sensing principles, incorporated into lab‐on‐a‐chip and microfluidic devices, are presented and remaining technical challenges and limitations are considered.     

Shielded molecularly imprinted polymers prepared with a selective surface modification

Uniformly sized, molecularly imprinted polymers (MIPs) of bisphenol A (BPA), one of many potential endocrine disruptors, were prepared by selective surface modification and immobilized at intervals of functional monomers with 4,4′‐methylenebisphenol as a pseudotemplate. MIPs for BPA were prepared with 4‐vinyl pyridine immobilized at the most effective interval and with ethylene glycol dimethacrylate monomer as a functional crosslinker. The prepared MIPs were surface‐modified with both polar and ionic monomers with different modification methods and then evaluated to reveal their selectivity and retention characteristics. Some of the modified MIPs showed significant selectivity for BPA retention when they were used as high‐performance liquid chromatography (HPLC) stationary phases, in comparison with ordinary MIPs. This effect of molecular imprinting was retained even after the surface modification of MIPs. The MIPs employed as pretreatment media for a column‐switching HPLC system provided a detection limit as low as 1 ng/L (ppt) by electrochemical detection. Actual samples, including Suwannee River natural organic matter (NOM), were analyzed for BPA, and BPA was quantitatively detected in NOM even with the combination with widely used UV detection because of the effective removal of interference afforded by an effective surface modification of the MIPs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2048–2060, 2005     

Recent Advances in Electrochemical Sensors Based on Molecularly Imprinted Polymers and Nanomaterials

This review focuses on the recent achievement during period of 2013–2018 related to the electrochemical sensors based on molecularly imprinted polymers (MIPs) combined with nanomaterials for various kinds of applications. MIPs based electrochemical sensors have found a great interest due to their high stability, short time required for electropolymerization, and high specificity towards the target analyte. The sensitivity is considered as one of the important parameter in electrochemical sensing strategies that should be improved by the combination of highly conductive nanomaterials with selective MIPs. In general, the most employed nanomaterials are magnetic nanoparticles, gold nanoparticles (AuNPs), carbon nanotubes and graphene. This review discusses the main current achievement as well as the current challenges regarding the development of biomimetic sensors in electroanalysis.     

Laser-induced breakdown spectroscopy for detection of explosives residues: a review of recent advances, challenges, and future prospects

In this review we discuss the application of laser-induced breakdown spectroscopy (LIBS) to the problem of detection of residues of explosives. Research in this area presented in open literature is reviewed. Both laboratory and field-tested standoff LIBS instruments have been used to detect explosive materials. Recent advances in instrumentation and data analysis techniques are discussed, including the use of double-pulse LIBS to reduce air entrainment in the analytical plasma and the application of advanced chemometric techniques such as partial least-squares discriminant analysis to discriminate between residues of explosives and non-explosives on various surfaces. A number of challenges associated with detection of explosives residues using LIBS have been identified, along with their possible solutions. Several groups have investigated methods for improving the sensitivity and selectivity of LIBS for detection of explosives, including the use of femtosecond-pulse lasers, supplemental enhancement of the laser-induced plasma emission, and complementary orthogonal techniques. Despite the associated challenges, researchers have demonstrated the tremendous potential of LIBS for real-time detection of explosives residues at standoff distances. Figure This review discusses the application of laser-induced breakdown spectroscopy (LIBS) to the problem of explosive residue detection. LIBS offers the capability for real-time, standoff detection of trace amounts of residue explosives on various surfaces     

Recent advances in electrochemical sensors for antibiotics and their applications

The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution,which in turn will affect human health.Therefore,it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields.Compared with traditional detection methods,electrochemical sensors have received extensive attention due to their advantages such as high sensitivity,low detection limit,and good selectivity.In this mini review,we summarized the latest developments and new trends in electrochemical sensors for antibiotics.Here,modification methods and materials of electrode are discussed.We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields.In addition,the existing problems and the future challenges ahead have been proposed.We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.     

Electrical,electrochemical, and thermometric sensors for the detection of explosives

The main analytical characteristics of electrical, electrochemical, and thermometric sensors in the detection of vapors and traces of explosives and accompanying substances are compared. The limits of detection, sensitivity, sensor setting time (response speed) and, recovery time after exposure to analytes, and the selectivity of sensors are discussed. The efficiency of using nanodimensional structures in the sensing elements of sensors is investigated.     

Zn Nanoparticles Modified Screen Printed Carbon Electrode as a Promising Sensor for Insulin Determination

Screen printed carbon electrodes (SPCEs) modified by a combination of chitosan, multi walled carbon nanotubes (MWCNTs) and zinc nanoparticles (ZnNPs) were studied for the first time as a suitable candidate for non-enzymatic insulin determination. In an effort to find the most suitable modification for electrochemical insulin determination, the stability, analytical characteristics, and selectivity were determined. The results confirmed that the ZnNPs/chitosan-MWCNTs prepared with the Zn deposition time of 45 s displayed the best electrocatalytic activity towards insulin oxidation in a wide linear concentration range (0.5 μM to 5 μM), with low limit of detection and high sensitivity.     

非酶葡萄糖传感器电极材料构建策略

电化学传感器因具有灵敏度高、检测限低等优点而得到广泛应用,将非酶电化学传感器应用于葡萄糖浓度的检测具备重要的研究价值。以金属有机骨架、碳材料和导电聚合物为基底与金属及其衍生物复合,构建的纳米复合材料修饰电极对于葡萄糖的检测具有极高的灵敏度、较低的检测限和快速响应的能力,可应用于实际样品的检测。本文综述了近年来非酶葡萄糖电化学传感器的研究进展,通过对纳米复合材料的性能比较,为非酶葡萄糖传感器的构建提供思路。     

Virus‐Based Chemical and Biological Sensing

Viruses have recently proven useful for the detection of target analytes such as explosives, proteins, bacteria, viruses, spores, and toxins with high selectivity and sensitivity. Bacteriophages (often shortened to phages), viruses that specifically infect bacteria, are currently the most studied viruses, mainly because target‐specific nonlytic phages (and the peptides and proteins carried by them) can be identified by using the well‐established phage display technique, and lytic phages can specifically break bacteria to release cell‐specific marker molecules such as enzymes that can be assayed. In addition, phages have good chemical and thermal stability, and can be conjugated with nanomaterials and immobilized on a transducer surface in an analytical device. This Review focuses on progress made in the use of phages in chemical and biological sensors in combination with traditional analytical techniques. Recent progress in the use of virus–nanomaterial composites and other viruses in sensing applications is also highlighted.     

Increased electrochemical detector sensitivity by electrode surface modification

Summary Electrode surface modification by electrochemical pretreatment of glassy carbon electrodes was shown to enhance significantly the sensitivity of the electrodes for the detection of timolol and oxprenolol, but reduce slightly the sensitivity to prenalterol. This method may permit the detection of exprenolol and timolol with increased sensitivity, or may allow their detection at lower applied potentials than is presently possible. Electrode surface modification may prove to be a valuable aid to the detection of compounds that are considered to be outside the practical limits of electrochemical detection.     

Fullerene Black Modified Screen Printed Electrodes for the Quantification of Acetaminophen and Guanine

Fullerene Black (FB) and Extracted Fullerene Black (EFB) were used in modified screen‐printed electrodes producing electrochemical transducers (FB‐SPEs and EFB‐SPEs). A complete electrochemical study was performed and the best results are obtained working with FB‐SPEs, especially in terms of: 1. improved electron‐transfer kinetic mechanisms and 2. sensitivity and selectivity toward Acetaminophen (Ac) and Guanine (G). These latter represent two important electro‐active targets to quantify in medicine field application, because: Ac is a preferred alternative (as analgesic‐antipyretic agent) to aspirin, particularly for patients who cannot tolerate aspirin; the oxidation signal of G is useful for the fabrication of emerging analytical tools, such as DNA chipsand user‐friendly diagnostic devices. Ac and G are quantify by using FB‐SPEs electrochemical devices, with an extended linearity (1–300 μM for Ac; 0.1–300 μM for G), an excellent sensitivity (2.82 μA μM⁻¹ cm⁻² in the case of Ac; and 0.183 μA μM⁻¹ cm⁻² in the case of G), a low detection limit (0.01 μM for Ac; 0.005 μM for G), a very good reproducibility (both: intra‐; inter‐electrodes reproducibility RSD % ranging from 0.3–0.5 for Ac; and 0.50–0.85 for G) and a very fast response time (6 s for Ac; 5 s in the case of G). In addition, high selectivity is obtained at FB‐SPEs, meaning that the FB‐SPEs electrochemical transducers are suitable to simultaneously quantify Ac and G in real samples, having several different (highly concentrated) interference.     

Molecularly imprinted polymers for sample preparation: A review

In spite of the huge development of analytical instrumentation during last two decades, sample preparation is still nowadays considered the bottleneck of the whole analytical process. In this regard, efforts have been conducted towards the improvement of the selectivity during extraction and/or subsequent clean-up of sample extracts. Molecularly imprinted polymers (MIPs) are stable polymers with molecular recognition abilities, provided by the presence of a template during their synthesis and thus are excellent materials to provide selectivity to sample preparation. In the present review, the use of MIPs in solid-phase extraction and solid-phase microextraction as well as its recent incorporation to other extraction techniques such as matrix-solid phase dispersion and stir bar sorptive extraction, among others, is described. The advantages and drawbacks of each methodology as well as the future expected trends are discussed.