Electrodeposition in aqueous nanoreactors

One frontier of measurement science is pushing the limit of what is measurable. Nanoelectrochemistry has transformed what is measurable at the nanoscale, elucidating reactivity of single atoms, molecules, and nanoparticles, one by one. The ability to interrogate physicochemical properties of single entities has elucidated new truths of nature that are otherwise averaged out during measurements over many entities (ensemble experiments). Single-entity experiments also give access to the ultimate sensitivity in measurement science: the specific detection of one single entity (not nanomolar quantities, not picomolar quantities—one single unit). One exciting subset of single-entity electrochemistry, and the topic of this review, is the study of reactions in nanoreactors of subfemtoliter (10^?15 L) volumes with a particular focus on nanoparticle synthesis.     

Electrochemistry of complex molecular and biomolecular scale entities

Structural mapping of intermediate size and large molecules and biomolecules at ultra-high resolution using single-crystal electrodes and in situ scanning tunnelling microscopy continues to disclose surprising findings. In situ scanning tunnelling spectroscopy has also recently disclosed new electrochemical conductivity features at the level of the single molecule. We overview briefly elements of this development over the last few years, with focus on three recent discoveries: (1) a new packing mode of a core monolayer target thiol, the amino acid cysteine (Cys) on Au(100)-electrodes, quite different from Cys packing on Au(111)- and Au(110)-electrodes; (2) transition of a core ferrocene in situ scanning tunnelling spectroscopy probe from stochastic single-molecule to macroscopic behaviour, a concept at the heart of nanoscience; and (3) unexpected behaviour of the large molybdenum enzyme sulfite oxidase, when going from macroscopic to single-molecule electrochemistry. We compare these studies with other recent discoveries of single-molecule protein conductivity and molecular scale inorganic nanostructures.     

Development of an electrochemical membrane-based nanobiosensor for ultrasensitive detection of dengue virus

A sensitive membrane-based electrochemical nanobiosensor is developed for the detection of dengue type 2 virus (DENV-2) using nanoporous alumina-modified platinum electrode. Its sensing mechanism relies on the monitoring of electrode's Faradaic current response toward redox probe, ferrocenemethanol, which is sensitive toward the formation of immune complexes within the alumina nanochannels. Anti-DENV-2 monoclonal antibody (clone 3H5, isotype IgG) is used as the biorecognition element in this work. The stepwise additions of antibody, bovine serum albumin (BSA) and DENV-2 are characterized by differential pulse voltammetry (DPV). A low detection limit of 1 pfu mL⁻¹ with linear range from 1 to 10³ pfu mL⁻¹ (R² = 0.98) can be achieved by the nanobiosensor. The nanobiosensor is selective toward DENV-2 with insignificant cross reaction with non-specific viruses, Chikungunya virus, West Nile virus and dengue type 3 virus (DENV-3). Relative standard deviation (RSD) for triplicate analysis of 5.9% indicates an acceptable level of reproducibility. The first direct quantitation of DENV-2 concentration in whole mosquito vector is demonstrated using this electrochemical nanobiosensor.     

化学计量学在电分析化学中的新进展

评述了化学计量学的各种方法,如主成分分析、偏最小二乘、小波分析、人工神经网络等在电分析化学中的进展,主要介绍了这些方法在电分析化学中的应用,并展望了化学计量学在电分析化学中的应用前景。     

Assay of amino acids in individual human lymphocytes by capillary zone electrophoresis with electrochemical detection

Amino acids in individual human lymphocytes were determined by capillary zone electrophoresis with electrochemical detection (ED) at a carbon fiber bundle electrode after on-column derivatization with naphthalene-2,3-dicarboxaldehyde (NDA) and CN⁻. In order to inject cells easily, a cell injector was designed. In this method, a single human lymphocyte and then the lysing/derivatizing buffer were electrokinetically injected into the front end of the separation capillary as a chamber to lyse the lymphocyte and derivatize amino acids in the cell. Four amino acids (serine (Ser), alanine (Ala), taurine (Tau), and glycine (Gly)) in single human lymphocytes have been identified. Quantitation has been accomplished through the use of calibration curves.     

Comparative studies on electrochemical activity of graphene nanosheets and carbon nanotubes

This study compares the electrochemical activity of four kinds of carbon materials, i.e. single-walled carbon nanotubes (SWNTs), pristine graphene oxide nanosheets (GONs), chemically reduced GONs, and electrochemically reduced GONs, with potassium ferricyanide (K₃Fe(CN)₆), β-nicotinamide adenine dinucleotide (NADH) and ascorbic acid (AA) as the redox probes. Cyclic voltammetry (CV) results demonstrate that the electron transfer kinetics of the redox probes employed here at the carbon materials essentially depend on the kind of the materials, of which the redox processes of the probes at SWNTs and electrochemically reduced GONs are faster than those at the pristine and chemically reduced GONs. The different electron transfer kinetics for the redox probes at the carbon materials studied here could be possibly ascribed to the synergetic effects of the surface chemistry (e.g., C/O ratio, presence of quinone-like groups, surface charge, and surface cleanness) and conductivity of the materials. This study could be potentially useful for understanding the structure/property relationship of the carbon materials and, based on this, for screening and synthesizing advanced carbon materials for electrochemical applications.     

电分析化学中的化学计量学方法及其应用进展

本文综述了电分析化学领域中化学计量学方法的应用进展，引用文献65篇。     

Detection of catechin based on its electrochemical autoxidation

Catechins are strong autoxidant to produce steady intermediate in alkali solution. In present work, we, for the first time, developed a electrochemical method based on ruthenium tris (2, 2′) bipyridyl (Ru(bpy)₃³⁺) modified boron-doped diamond (BDD) electrode to investigate the electrochemical reduction of catechin autoxidation intermediate with its existence verified by the electron spin resonance (ESR). The reduction peak potential was observed at −855.5 mV, not appearing either in acid solution (pH 2) containing catechins or in oxidized catechin solution (pH 12). Moreover, the effects of pH, ascorbic acid, Cu²⁺, Fe²⁺ and autoxidation time are investigated, demonstrating the reduction peak being really the reduction of catechin autoxidation intermediate. It is found that the peak current is proportional to scan rate, indicative of a surface confined reduction process. Sensitive amperometric response was obtained covering linear range from 0.3268 μM to 0.1591 mM. The determination of catechin in commercial preparations using this method shows satisfactory results comparable with those of the traditional methods.     

A 1,2,3,4,5-pentaphenylferrocene-stoppered rotaxane capable of electrochemical anion recognition

The chloride anion templated synthesis of an electrochemical anion sensory interlocked host system, prepared by the integration of redox-active 1,2,3,4,5-pentaphenylferrocene stopper groups into the structure of a rotaxane capable of binding anionic guests is described. Extensive (1)H NMR and electrochemical titration investigations were used to probe the anion recognition and sensing properties of the rotaxane, compared to the axle and model system components. A characteristic electrochemical response was observed for chloride binding by the rotaxane, which was attributed to the topologically constrained cavity of the interlocked host molecule.     

半微分伏安法间接测定农药甲基1605的研究

利用半微分阴极扫描伏安法,对农药甲基1605中的游离和易水解的产物对硝基苯酚、总对硝基苯酚的测定进行了研究。发现在室温下,pH6.4的磷酸氢二钠和柠檬酸底液中,在-0.9V处对硝基苯酚有一灵敏对称的还原峰,在3.0×10~(-7)～3.0×10~(-5)mol·dm~(-3)浓度范围内,峰高与浓度有很好的线性关系,其相关系数在0.999以上。检测限为3.0×10~(-5)mol·dm~(-3)。并对实样进行了测定,结果满意。     

扫描电化学显微镜在电催化表面反应分析中的现代应用

能源和环境问题成为制约未来可持续发展的关键问题之一,因此,针对不同电催化反应设计电催化剂变得越来越重要.电催化剂因其能量效率高、制备简单和易操作等优点,而应用于可再生能源的相关反应(如水分解和人工光合作用)中.明确不同反应电催化剂的设计原理,深入理解其在相关反应中的催化机理,可进一步优化催化剂性能.本文综述了扫描电化学显微镜(SECM)应用于电催化反应的历程、关键方法以及一些代表性的工作,阐明了电催化剂的工作机理以推进电催化剂的设计.本文还介绍了为提高SECM的空间分辨率而尝试的纳米尺寸电极方面的新进展,分享了纳米电极在以前研究无法涉及的单一催化实体方面的应用.     

多变量校正方法在电分析化学多组分同时测定中的应用

评述了多变量校正方法在电分析化学中的应用进展,着重介绍了多变量校正方法的原理及其在电分析化学多组分同时测定中的应用。