Determination of inorganic phosphate by electroanalytical methods: A review

Determination of inorganic phosphate is of very high importance in environmental and health care applications. Hence knowledge of suitable analytical techniques available for phosphate sensing for different applications becomes essential. Electrochemical methods for determining inorganic phosphate have several advantages over other common techniques, including detection selectivity, stability and relative environmental insensitivity of electroactive labels. The different electrochemical sensing strategies adopted for the determination of phosphate using selective ionophores are discussed in this review. The various sensing strategies are classified based on the electrochemical detection techniques used viz., potentiometry, voltammetry, amperometry, unconventional electrochemical methods etc., The enzymatic sensing of phosphate coupled with electrochemical detection is also included. Various electroanalytical methods available in the literature are assessed for their merits in terms of selectivity, simplicity, miniaturisation, adaptability and suitability for field measurements.     

Crystal Channel Engineering for Rapid Ion Transport: From Nature to Batteries

Ion transport behaviours through cell membranes are commonly identified in biological systems, which are crucial for sustaining life for organisms. Similarly, ion transport is significant for electrochemical ion storage in rechargeable batteries, which has attracted much attention in recent years. Rapid ion transport can be well achieved by crystal channels engineering, such as creating pores or tailoring interlayer spacing down to the nanometre or even sub-nanometre scale. Furthermore, some functional channels, such as ion selective channels and stimulus-responsive channels, are developed for smart ion storage applications. In this review, the typical ion transport phenomena in the biological systems, including ion channels and pumps, are first introduced, and then ion transport mechanisms in solid and liquid crystals are comprehensively reviewed, particularly for the widely studied porous inorganic/organic hybrid crystals and ultrathin inorganic materials. Subsequently, recent progress on the ion transport properties in electrodes and electrolytes is reviewed for rechargeable batteries. Finally, current challenges in the ion transport behaviours in rechargeable batteries are analysed and some potential research approaches, such as bioinspired ultrafast ion transport structures and membranes, are proposed for future studies. It is expected that this review can give a comprehensive understanding on the ion transport mechanisms within crystals and provide some novel design concepts on promoting electrochemical ion storage capability in rechargeable batteries.     

Electrochemical sensing of gases based on liquid collection interfaces

Although many electrochemical gas sensors have been reported, electrochemical gas sensors based on liquid collection constitute a smaller subset. Minimally, a liquid interface based electrochemical gas sensor is composed of two electrodes and an ion conducting electrolyte. There is a large number of possible arrangements of these parts, and many choices exist for their composition and preparation methods. This results in a diverse and rich technology now available for gas sensing. The measurement of some analyte gases of interest, notably ozone, nitrogen oxides, hydrogen peroxide, formaldehyde, ammonia, sulfur dioxide and hydrogen sulfide are specifically discussed. Finally, the recent reviews that are likely to be the most relevant to the further development of electrochemical detection approaches for gases with a liquid collection interface are cited and discussed.     

Electrochemical strategies for the label-free detection of amino acids, peptides and proteins

Electrochemical methods for the detection of amino acids, peptides, and proteins in a variety of media are reviewed. Label-free strategies in which the detection is based on the inherent electrochemical properties of the analyte are discussed. Various processes such as direct or mediated (in solution or immobilised) redox processes and interfacial ion transfers have been employed for the electrochemical detection and determination of the target analytes. The various methods covered encompass voltammetry at uncoated and modified electrodes and at immiscible liquid-liquid interfaces, potentiometry at polymer membrane electrodes and electrochemical impedance spectroscopy. The determination of the target analytes in complex biological matrices is discussed. The various approaches highlighted here illustrate the rich capabilities of electrochemical methods as simple, low-cost, sensitive tools for the determination of these important biological analytes at trace and ultra-trace levels.     

Nanopore‐Based Sequencing and Detection of Nucleic Acids

Nanopore‐based techniques, which mimic the functions of natural ion channels, have attracted increasing attention as unique methods for single‐molecule detection. The technology allows the real‐time, selective, high‐throughput analysis of nucleic acids through both biological and solid‐state nanopores. In this Minireview, the background and latest progress in nanopore‐based sequencing and detection of nucleic acids are summarized, and light is shed on a novel platform for nanopore‐based detection.     

Applications of microfabrication techniques in electrochemical sensor development

Electrochemical sensors have been used either as a whole or as an integral part of a chemical and biological sensing device. Microfabrication technology has been used in the development of electrochemical sensors. The recent advancement of micromachining techniques adds new impetus to electrochemical sensor development. Most noticable is the application of anisotropic chemical etching, plasma etching, sacrificial layer methods, and high aspect ratio X-ray lithography to enhance the opportunity to produce scientifically and commercially viable electrochemical sensors. Examples will be used to illustrate the potential of microfabrication and micromachining techniques in electrochemical sensor development.     

Emerging trends in miniaturized and microfluidic electrochemical sensing platforms

Electrochemical sensing has established a strong presence in diverse areas. The conventional electrochemical sensing approach consumes large sample volumes and reagents and requires bulky potentiostat, macro-electrodes, and other equipment. The synergistic integration of electrochemical sensing systems with miniaturized or microfluidic electrochemical devices and microelectrodes in a single platform provides rapid analysis with a disposable, reusable, and cost-effective platform for multiplexed point-of-care detections. Such microdevices have created scope for using several materials as electrodes and sensing platforms by using appropriate fabrication techniques. One of the most recent advancements in miniaturized devices includes the integration of automation and Internet of Things to realize fully automated and robust electrochemical microdevices. The review summarizes the emerging trends in fabrication methods of miniaturized and microfluidic devices, their multiple applications in real-time, integration of Internet of Things, automation, identifying research gaps with strategies for bridging these gaps, future outlook, and recent approaches to intelligent electrochemical sensing.     

Electrochemical sensing of heavy metals in biological media: A review

Trace metals are required in the body as they play a significant role in several biochemical processes. Moreover, certain heavy metals are beneficial at appropriate levels. Copper (Cu), for example, is essential for red blood cell formation, bone strength, and infant growth. Despite these fundamental roles, Cu can become toxic at high levels. Other heavy metals such as lead (Pb), cadmium (Cd), manganese (Mn), and mercury (Hg), have been identified to cause acute and chronic health complications. For these reasons, rapid, real-time quantification of such metals in biological media is of interest to improving human health outcomes. Electrochemical methods offer numerous advantages, such as portability, capability to be miniaturized, low cost, and ease-of-use. In this review, we examine recent developments in electrochemical sensing for the detection of heavy metals in biological media. To meet the requirements for inclusion in this review, the electrochemical sensor must have been evaluated in biological media (blood, serum, sweat, saliva, urine, brain tissue/cells). Several applications are explored to examine recent advancements in electrochemical sensing within these matrices. Addressing the challenges through materials, device, and system innovations, it is expected that electrochemical sensing of heavy metals in biological media will facilitate future diagnoses and treatments in healthcare.     

Techniques for recording reconstituted ion channels

This review describes and discusses techniques useful for monitoring the activity of protein ion channels in vitro. In the first section the biological importance and the classification of ion channels are outlined in order to justify the strong motivation for dealing with this important class of membrane proteins. The expression, reconstitution and integration of recombinant proteins into lipid bilayers are crucial steps to obtain consistent data when working with ion channels. In the second section recording techniques used in research are presented. Since this review focuses on analytical systems bearing reconstituted ion channels the industrial most important patch-clamp techniques of cells are only briefly mentioned. In section three, artificial systems developed in the last decades are described while the emerging technologies using nanostructured supports or microfluidic systems are presented in section four. Finally, the remaining challenges of membrane protein analysis and its potential applications are briefly outlined.     

Biological applications of amide and amino acid containing synthetic macrocycles

ABSTRACT

Amino acid derived macrocycles with elaborate well-defined stereochemistry are a unique class of compounds that have been isolated from natural sources. Macrocycles like cyclosporine, octreotide, and valinomycin have been used in multiple applications, like drugs or ion sensors. Chemists have long been fascinated by the unique molecular recognition capabilities of these macrocycles and tried to design synthetic analogs with similar functions. This article is focused on reviewing current research on amide and amino acid containing macrocycles that have been developed in research laboratories for biological recognition, specifically for anion sensing, ion transport, carbohydrate sensing, and peptide sensing.     

DNA linearization through confinement in nanofluidic channels

Stretching DNA has emerged as a vital process for studying the physical and biological properties of these molecules. Over the past decade, there has been increasing research interest in utilizing nanoscale fluidic channels to confine and stretch single DNA molecules. Nanofabricated systems for linearizing DNA have revealed new and important insights into the conformation changes of DNA molecules. They also have emerged as innovative techniques for efficiently separating DNA molecules based on size and for physically mapping genetic information along the genome. This review describes physical theories of DNA linearization, current DNA stretching techniques based on nanofabricated channels, and breakthroughs resulting from the use of nanofluidic channels for DNA linearization.     

金属锗酸盐微纳米材料的研究进展

金属锗酸盐微纳米材料是一类非常重要的功能材料,展现出特殊的物理与化学性质,近年来已引起国内外学者浓厚的研究兴趣。迄今为止,人们已经利用多种合成方法制备了不同尺寸和形貌的锗酸盐微纳米材料。本文综述了目前这些材料制备方面的研究现状,简单比较了各种方法的优缺点;介绍了金属锗酸盐微纳米材料在光催化、重金属离子吸附、电化学传感、锂离子电池负极材料和光学器件等领域的应用,并展望了可能的发展趋势。     

Optical-facilitated single-entity electrochemistry

Single-entity electrochemistry focusing on the study of transient electrochemical process at the confined interface, has become a promising field that addresses questions from multi-disciplines such as cellular biology, material chemistry, organic chemistry, etc. It offers the fruitful information hidden in bulk electrochemical measurements. As the optical techniques improve in spatial and temporal resolution, the combination of electrochemistry with optical microspectroscopy provides more comprehensive information of single-entity electrochemistry. Herein, we review recent progress made in optical–electrochemical measurements covering three aspects from the precise localization and temperature measurements of single compartments, to the in-situ tracking of dynamic behaviors of single nanoparticles in electrochemical process, and to the monitoring confinement-controlled electrochemistry at the single molecule/ion level. The review demonstrates how these optical methods are innovatively integrated with single-entity sensing. It also reveals how these optical–electrochemical combinations push single-entity electrochemistry forward.     

Unmodified silver nanoparticles based multisensor for Ni (II) ions in real samples

This article report microwave assisted green method for the synthesis of silver nanoparticle from Brassica oleracea var. Italica (BI) extract. The synthesized silver nanoparticle (AgNP-BI) was characterized by various analytical techniques. Here we are reporting three methods for the sensing of Ni (II) from the synthesized AgNP-BI. First one is the detection of Ni (II) ion based on changes in the absorbance resulting from the complex formation of the Ni (II) ion with AgNP-BI. The second one is the fluorescent sensing of Ni (II) ion using AgNP-BI by the changes in the fluorescence intensity. The third one is the electrochemical sensing of Ni (II) ion in which silver nanoparticle attached to the platinum electrode surface. The above-mentioned methods exhibit outstanding selectivity towards Ni (II) ion. The practical application of the AgNP-BI was also carried out for the trace determination of Ni (II) ions. The limit of detection was found to be 0.932 µM using differential pulse voltammetry (DPV).     

现场侦检装备在应对化学威胁中的应用与发展

近年来,国内外不断发生的化学恐怖袭击和化学事故仍然是当今人类生存、国家安全所面临的重大威胁。化学侦检是防化应急处置与救援的眼睛,熟练掌握和正确使用侦检装备是应对化学威胁、降低损失和伤亡的关键因素。基于化学传感等技术的侦检装备具有响应快速、智能便携的特点,并且在远程监测和实时值守等方面具有优势。该文针对涵盖电化学传感器、质量敏感型传感器、红外传感器、拉曼传感器、离子迁移谱仪、火焰光度检测器、光致电离检测器、远程遥测传感装备等在内的现场侦检装备,从原理、性能、优势和不足等方面进行了概述,重点阐述了侦检装备在应对化学威胁方面的最新进展,并对其发展趋势、应用前景进行了展望,以期为化学侦检装备在应对化学威胁中的深入研究与应用提供参考。     

Electrochemical Sensing of Flutamide Contained in Plasma and Urine Matrices Using NiFe2O4/rGO Nanocomposite,as an Efficient and Selective Electrocatalyst

In this article, we report on the synthesis and new employment of magnetic nickelferrite oxide nanoparticles decorated reduced graphene oxide (NiFe₂O₄/rGO) to electrochemically sensing of flutamide. The preparation of this electrocatalyst was first assessed using various analytical instrumental techniques including FT‐IR spectroscopy, X‐ray diffraction spectroscopy, energy‐dispersive X‐ray spectroscopy, and field emission scanning and transmission electron microscopy. Besides, its electrochemical performance was investigated utilizing some electrochemical methods such as cyclic and differential pulse voltammetry, and also electrochemical impedance spectroscopy. The findings of this research are especially relevant for sensing flutamide in aqueous and biological samples. At the optimized conditions, the electrochemical sensor showed a linear range of 0.24–40.0 μmol L^?1, the detection limit of 0.05 μmol L^?1 flutamide, calibration sensitivity of 1.016 μA/μmol L^?1, and repeatability and reproducibility of 1.7 % and 4.1 %, respectively. The selectivity of the method was investigated in the presence of ions, and species can generally exist in the biological medium. The resulting data of the present work represented that this type of magnetic nanocomposites is suitable for selective detection of flutamide in real samples of plasma and urine. The recoveries obtained for flutamide analyses represented lower than 5.0 percent of relative error in these real samples.     

Detection of single ion channel activity on a chip using tethered bilayer membranes

Membrane-bound ion channels are promising biological receptors since they allow for the stochastic detection of analytes at high sensitivity. For stochastic sensing, it is necessary to measure the ion currents associated with single ion channel opening and closing events. However, this calls for stability, high reproducibility, and long lifetimes. A critical issue to overcome is the low stability of the ion channel environment, that is, the bilayer membrane. A promising technique to surmount this is to connect the lower part of the membrane to a surface forming a tethered bilayer membrane. By reconstituting the synthetic ion channel, gramicidin A, into a tethered bilayer as part of a microchip design, we have been able to record the activity of single ion channels. The observed activity was compared with that obtained by a conventional electrophysiology method, tip dipping, to confirm its authenticity. These findings allow for the construction of stable biosensors based on ion channels and provide a novel technique for the characterization of ion channel activity.     

Electrochemistry on Paper‐based Analytical Devices: A Review

Even though they were introduced less than a decade ago, electrochemical paper‐based devices (ePADs) have attracted widespread attention because of their inherent advantages in many applications. ePADs combine the advantages of microfluidic paper‐based devices (low cost, ease of use, equipment free pumping, etc.) for sample handling and processing with the advantages of sensitive and selective detection provided by electrochemistry. As a result, ePADs provide simplicity, portability, reproducibility, low cost and high selectivity and sensitivity for analytical measurements in a variety of applications ranging from clinical diagnostics to environmental sensing. Herein, recent advances in ePAD development and application are reviewed, focusing on electrode fabrication techniques and examples of applications specially focused on environmental monitoring, biological applications and clinical assays. Finally, a summary and prospective directions for ePAD research are also provided.     

微纳电化学传感界面的构建及其用于单细胞实时监测

细胞是生物体形态结构和生命活动的基本单位.常规检测群体细胞的方法往往会掩盖细胞间的个体差异,因此亟需发展高效的单细胞分析策略,深入研究细胞生命活动过程,揭示疾病发生发展机制,推动个体化诊疗.超微电化学传感器具有尺寸小、灵敏度高、时空分辨率高等特点,在单细胞实时动态监测方面发挥了非常重要的作用.目前,微纳电化学传感器在电...