Advances in capillary electrophoresis: the challenges to liquid chromatography and conventional electrophoresis

In the 1980s, capillary electrophoresis (CE) developed rapidly into a first-class analytical separation technique. Its advances in instrumentation and method development will not only enhance or complement existing mature separation techniques such as liquid chromatography and conventional slab gel electrophoresis, but will also severely challenge these separation methods. A brief overview of the most striking achievements of CE in the 1980s is given. which illustrates the challenges to liquid chromatography and conventional slab gel electrophoresis, and some detailed discussions are presented to highlight the advantages of CE. New developments in CE that can be expected for the 1990s include especially column technology, separation chemistry and instrumentation, which will serve further to diversify and improve the applicability of this technique in areas which are poorly addressed by other separation methods. This paper considers and speculates on the technological advancements that can be expected to emerge for CE in the 1990s.     

微流控芯片毛细管电泳在蛋白质分离分析中的应用研究进展

重点介绍了近年来国内外在微流控芯片毛细管电泳法用于蛋白质分离分析方面的研究进展。按照分离模式的不同,综述了各种应用于蛋白质分离的微流控芯片毛细管电泳系统,讨论了抑制芯片中的蛋白吸附的各种方法,并展望了芯片毛细管电泳系统在蛋白质分离领域的发展前景。引用文献47篇。     

Dynamic Covalent Nanoparticle Building Blocks

Rational and generalisable methods for engineering surface functionality will be crucial to realising the technological potential of nanomaterials. Nanoparticle‐bound dynamic covalent exchange combines the error‐correcting and environment‐responsive features of equilibrium processes with the stability, structural precision, and vast diversity of covalent chemistry, defining a new and powerful approach for manipulating structure, function and properties at nanomaterial surfaces. Dynamic covalent nanoparticle (DCNP) building blocks thus present a whole host of possibilities for constructing adaptive systems, devices and materials that incorporate both nanoscale and molecular functional components. At the same time, DCNPs have the potential to reveal fundamental insights regarding dynamic and complex chemical systems confined to nanoscale interfaces.     

纳米粒子毛细管电泳/微流控芯片新技术及其在手性分离中的应用

纳米粒子因其具有较大的比表面积和良好的生物相容性等特点,已广泛应用于分离科学领域。纳米粒子毛细管电泳/微流控芯片技术是纳米材料技术与毛细管电泳/微流控芯片技术相结合的产物。纳米粒子可以被吸附或键合到毛细管壁作为固定相与被分析物发生相互作用;也可以作为假固定相参与样品在柱内的分配和保留,从而提高柱效,改善分离。手性是自然界的本质属性之一,开发新的快速、高效、灵敏的手性分离分析方法对于对映体的立体选择性合成、药理研究、手性纯度检测和环境检测都具有重要的意义。本文主要综述了近些年来几种不同类型纳米粒子(聚合物纳米粒子、磁性纳米粒子、金纳米粒子、碳纳米管和其他类型纳米粒子)用于毛细管电泳/微流控芯片进行手性分离的现状,并对该领域今后的发展进行了展望。     

Surface sampling capillary electrophoresis–mass spectrometry for a direct chemical characterization of tissue and blood samples

Capillary electrophoresis (CE) is a powerful separation tool for non-targeted analysis of chemically complex samples, such as blood, urine, and tissue. However, traditionally CE requires samples in solution for analysis, which limits information on analyte distribution and heterogeneity in tissue. The recent development of surface sampling CE–mass spectrometry (SS-CE–MS) brings these advantages of CE to solid samples and enables chemical mapping directly from the tissue surface without laborious sample preparation. Here, we describe developments of SS-CE–MS to increase reproducibility and stability for metabolite, lipid, and protein extraction from tissue sections and dried blood spots. Additionally, we report the first electrokinetic sequential sample injection for high throughput analysis. We foresee that the wide molecular coverage from a distinct tissue region in combination with higher throughput will provide novel information on biological function and dysfunction.     

Analysis of drug interactions with serum proteins and related binding agents by affinity capillary electrophoresis: A review

Biomolecules such as serum proteins can interact with drugs in the body and influence their pharmaceutical effects. Specific and precise methods that analyze these interactions are critical for drug development or monitoring and for diagnostic purposes. Affinity capillary electrophoresis (ACE) is one technique that can be used to examine the binding between drugs and serum proteins, or other agents found in serum or blood. This article will review the basic principles of ACE, along with related affinity-based capillary electrophoresis (CE) methods, and examine recent developments that have occurred in this field as related to the characterization of drug–protein interactions. An overview will be given of the various formats that can be used in ACE and CE for such work, including the relative advantages or weaknesses of each approach. Various applications of ACE and affinity-based CE methods for the analysis of drug interactions with serum proteins and other binding agents will also be presented. Applications of ACE and related techniques that will be discussed include drug interaction studies with serum agents, chiral drug separations employing serum proteins, and the use of CE in hybrid methods to characterize drug binding with serum proteins.     

Pickering‐Emulsion Inversion Strategy for Separating and Recycling Nanoparticle Catalysts

With the recent advances in nanoscience and nanotechnology, more and more nanoparticle catalysts featuring high accessibility of active sites and high surface area have been explored for their use in various chemical transformations, and their rise in popularity among the catalysis community has been unprecedented. The industrial applications of these newly discovered catalysts, however, are hampered because the existing methods for separation and recycling, such as filtration and centrifugation, are generally unsuccessful. These limitations have prompted development of new methods that facilitate separation and recycling of nanoparticle catalysts, so as to meet the burgeoning demands of green and sustainable chemistry. Recently, we have found that Pickering‐emulsion inversion is an appealing strategy with which to realize in situ separation and recycling of nanoparticle catalysts and thereby to establish sustainable catalytic processes. We feel that at such an early stage, this strategy, as an alternative to conventional methods, is conceptually new for readers but that it has potential to become a popular method for green catalysis. This Concept article aims to provide a timely link between previous efforts and both current and future research on nanoparticle catalysts, and is expected to facilitate further investigation into this strategy.     

A decade of capillary electrophoresis

Since the introduction of the first commercial capillary electrophoresis (CE) instrument a decade ago, CE applications have become widespread. Today, CE is a versatile analytical technique which is successfully used for the separation of small ions, neutral molecules, and large biomolecules and for the study of physicochemical parameters. It is being utilized in widely different fields, such as analytical chemistry, forensic chemistry, clinical chemistry, organic chemistry, natural products, pharmaceutical industry, chiral separations, molecular biology, and others. It is not only used as a separation technique but to answer physicochemical questions. In this review, we will discuss different modes of CE such as capillary zone electrophoresis, micellar electrokinetic chromatography, capillary gel electrophoresis, capillary isoelectric focusing, and capillary electrochromatography, and will comment on the future direction of CE, including array capillary electrophoresis and array microchip separations.     

Recent Advances in Polyurethane/POSS Hybrids for Biomedical Applications

Advanced organic-inorganic materials-composites, nanocomposites, and hybrids with various compositions offer unique properties required for biomedical applications. One of the most promising inorganic (nano)additives are polyhedral oligomeric silsesquioxanes (POSS); their biocompatibility, non-toxicity, and phase separation ability that modifies the material porosity are fundamental properties required in modern biomedical applications. When incorporated, chemically or physically, into polyurethane matrices, they substantially change polymer properties, including mechanical properties, surface characteristics, and bioactivity. Hence, this review is dedicated to POSS-PU composites that have recently been developed for applications in the biomedical field. First, different modes of POSS incorporation into PU structure have been presented, then recent developments of PU/POSS hybrids as bio-active composites for scaffolds, cardiovascular stents, valves, and membranes, as well as in bio-imaging and cancer treatment, have been described. Finally, characterization and methods of modification routes of polyurethane-based materials with silsesquioxanes were presented.     

Analytical separation and detection methods for flavonoids

Flavonoids receive considerable attention in the literature, specifically because of their biological and physiological importance. This review focuses on separation and detection methods for flavonoids and their application to plants, food, drinks and biological fluids. The topics that will be discussed are sample treatment, column liquid chromatography (LC), but also methods such as gas chromatography (GC), capillary electrophoresis (CE) and thin-layer chromatography (TLC), various detection methods and structural characterization. Because of the increasing interest in structure elucidation of flavonoids, special attention will be devoted to the use of tandem-mass spectrometric (MS/MS) techniques for the characterization of several important sub-classes, and to the potential of combined diode-array UV (DAD UV), tandem-MS and nuclear magnetic resonance (NMR) detection for unambiguous identification. Emphasis will be on recent developments and trends.     

毛细管电泳的原理及应用(第五讲)毛细管电泳在医药领域中的应用

简单介绍了毛细管电泳在医药领域中的应用，包括药物分析、中药成分分析、手性对映体分离分析和临床化学、法医及单细胞分析等。药物分析中包括主药成分分析、相关杂质检测、药物计量离子配比测定和定量分析等。中药成分分析中包括各类药效成分、中药材中主要成分及中药复方制剂成分分析。手性对映体分离中包括机理研究、新型手性选择剂。临床化学中包括临床疾病诊断、临床蛋白分析、临床药物监测、药物代谢研究和分子生物学测定。法庭科学中包括毒物分析、枪击残余物分析、炸药分析、笔迹墨水分析。单细胞分析中包括神经细胞分析、红细胞分析和胚胎细胞分析。     

Capillary electrophoretic methods in the development of metal-based therapeutics and diagnostics: new methodology and applications

In recent years, capillary electrophoresis (CE) has matured to a standard method in medicinal inorganic chemistry. More and more steps of the drug discovery process are followed by CE. However, not only the number of applications has steadily increased but also the variety of used methodology has significantly broadened and, as compared to a few years ago, a wider scope of separation modes and hyphenated systems has been used. Herein, a summary of the newly utilized CE methods and their applications in metallodrug research in the timeframe 2006-2011 is presented, following related reviews from 2003 and 2007 (Electrophoresis, 2003, 24, 2023-2037; Electrophoresis 2007, 28, 3436-3446). Areas covered include impurity profiling, quality control of pharmaceutical formulations, lipophilicity estimation, interactions between metallodrugs and proteins or nucleotides, and characterization and also quantification of metabolites in biological matrices and real-world samples.     

毛细管电泳用于药物分析的研究进展

药物分析是毛细管电泳（CE）的重要应用领域,所有CE分离模式与检测方法都在各种药物及其不同形式样品的分离分析中显示出特色和应用能力。该文从药品分析领域中的小分子药物（包括手性药物）及其有关物质、中药与天然产物、体内药物分析、生物制品药物分析等几个方面,综述了近几年CE在这些传统药物分析领域应用的研究进展。限于篇幅,未包括现代药物分析研究比较活跃的理化常数测定、亲和毛细管电泳与结合常数研究（药物与受体间的相互作用等）、临床生物标志物分析、代谢组学和微流控芯片CE分析等方面的内容。根据目前传统药物分析领域的发展,该文关注到近期CE在顺应药物分析的法规需求、电容耦合非接触电导检测（CE-C⁴ D）、改进检测灵敏度与精密度、CE-十二烷基硫酸钠（SDS）毛细管电泳、全柱成像毛细管等电聚焦（icIEF）、抗体分析等方面的新进展。该文结合文献,讨论了目前传统药物分析领域的需求,以及CE在其中的地位、挑战和机遇。对目前CE主要作为互补分析方法在化学药和中药分析中的应用研究提出了一些针对性的建议,期待CE在生物制品分析中的特色和能力得到进一步的发挥,同时提出CE-MS和对CE分析重复性改进等新进展可能对未来CE应用领域的大幅度扩展。该综述主要涉及近3年（2017年1月到2020年2月）及部分2016年的相关文献。     

Recent developments in the separation of inorganic and small organic ions by capillary electrophoresis

Which method should I use for ion analysis, ion chromatography (IC) or capillary electrophoresis (CE)? In terms of actual theoretical plates CE has a clear-cut advantage. The separation ability of IC is adequate for many sample types, and many separation scientists feel that IC offers greater reliability and confidence than CE. However, IC is a more mature technique and there has been more time to solve problems such as peak tailing and to improve reproducibility. The two techniques should be viewed as complementary. A number of recent developments in ion analysis by CE are discussed. These include some simple ways to control electroosmotic flow and improve reproducibility, separation of isotopes, improved methods of indirect photometric detection, a new contactless conductivity detector, separation of ions at low pH, and in solutions of high salt content. Progress in a new technique called IC-CE will be described in which a soluble ion-exchange polymer is added to the capillary electrolyte to separate anions based on differences in both electrophoretic mobility and ion-exchange interactions.     

Thermoset polyester as an alternative material for microchip electrophoresis/electrochemistry

Microchip CE coupled with electrochemical detection (MCE-EC) is a good method for the direct detection of many small molecule analytes because the technique is sensitive and readily miniaturized. Polymer materials are being increasingly used with MCE due to their affordability and ease of fabrication. While PDMS has become arguably the most widely used material in MCE-EC due to the simplicity of microelectrode incorporation, it suffers from a lack of separation efficiency, lower surface stability, and a tendency for analyte sorption. Other polymers, such as poly(methylmethacrylate) (PMMA) and poly(carbonate) (PC), have higher separation efficiencies but require more difficult fabrication techniques for electrode incorporation. In this report, thermoset polyester (TPE) was characterized as an alternative material for MCE-EC. TPE microchips were characterized in their native and plasma oxidized forms and after coating with polyelectrolyte multilayers (PEMs). TPE provides higher separation efficiencies when compared to PDMS microchips, while still using simple fabrication protocols. In this work, separation efficiencies as high as 295,000 N/m were seen when using TPE MCE-EC devices. Furthermore, the EOF was higher and more consistent as a function of pH for both native and plasma-treated TPE than PDMS. Finally, TPE is amenable to modification using simple PEM coatings as another way to control surface chemistry and surface charge.     

Recent developments in electrokinetically driven analysis on microfabricated devices

This review is devoted to the rapid developments in the field of microfluidic separation devices in which the flow is electrokinetically driven, and where the separation element forms the heart of the system, in order to give an overview of the trends of the last three years. Examples of microchip layouts that were designed for various application areas are given. Optimization of mixing and injection strategies, designs for the handling of multiple samples, and capillary array systems show the enormous progress made since the first proof-of-concept papers about lab-on-a-chip devices. Examples of functional elements for on-chip preconcentration, filtering, DNA amplification and on-chip detection indicate that the real integration of various analytical tasks on a single microchip is coming into reach. The use of materials other than glass, such as poly(dimethylsiloxane) and polymethylmethacrylate, for chip fabrication and detection methods other than laser-induced fluorescence (LIF) detection, such as mass spectrometry and electrochemical detection, are described. Furthermore, it can be observed that the separation modes known from capillary electrophoresis (CE) in fused-silica capillaries can be easily transferred to the microchip platform. The review concludes with an overview of applications of microchip CE and with a brief outlook.     

Ionic liquids in separation techniques

The growing interest in ionic liquids (ILs) has resulted in an exponentially increasing production of analytical applications. The potential of ILs in chemistry is related to their unique properties as non-molecular solvents: a negligible vapor pressure associated to a high thermal stability. ILs found uses in different sub-disciplines of analytical chemistry. After drawing a rapid picture of the physicochemical properties of selected ILs, this review focuses on their use in separation techniques: gas chromatography (GC), liquid chromatography (LC) and electrophoretic methods (CE). In LC and CE, ILs are not used as pure solvents, but rather diluted in aqueous solutions. In this situation ILs are just salts. They are dual in nature. Too often the properties of the cations are taken as the properties of the IL itself. The lyotropic theory is recalled and the effects of a chaotropic anion are pointed out. Many results can be explained considering all ions present in the solution. Ion-pairing and ion-exchange mechanisms are always present, associated with hydrophobic interactions, when dealing with IL in diluted solutions. Chromatographic and electrophoretic methods are also mainly employed for the control and monitoring of ILs. These methods are also considered. ILs will soon be produced on an industrial scale and it will be necessary to develop reliable analytical procedures for their analysis and control.     

Recent developments and applications of EMMA in enzymatic and derivatization reactions

This review provides systematic coverage of examples in the field of in-capillary electrophorecially mediated microanalysis (EMMA). The recent developments and applications in the time period up to mid 2011 have been described, as well as relevant older papers. The basic principles and modes of in-capillary assays have been demonstrated. An overview is also given of the various injection, separation and detection modes implemented in combination with EMMA. The review is presented in two parts mainly dealing with (i) enzymatic and (ii) derivatization or chemical reactions. Finally, the future trends of CE in performing and monitoring reactions have been drawn.     

毛细管电泳新型手性分离体系研究进展

在现代分离科学中,手性化合物的分离分析一直是研究的重点和难点。相比于高效液相色谱（HPLC）、气相色谱（GC）等传统色谱分析方法,毛细管电泳（CE）技术凭借其高效率、低消耗、分离模式多样化等诸多优势,已经发展成为手性分离研究领域最有应用前景的分析方法之一。近年来,研究人员在CE手性分析方法的构建过程中,基于毛细管电动色谱（EKC）、配体交换毛细管电泳（LECE）、毛细管电色谱（CEC）等各种基础电泳模式,不断地对传统手性分离体系进行优化和改造,构建出了许多高性能的新型手性CE分离体系。如利用各类功能化离子液体以"手性离子液体协同拆分""手性离子液体配体交换""离子液体手性选择剂"等模式设计出多种基于离子液体的CE手性分离体系;利用纳米材料独特的尺寸效应、多样性、可设计性等特点,直接或与传统手性选择剂有机结合构建CE手性分离体系。此外,金属有机骨架材料修饰、低共熔溶剂修饰、非连续分段式部分填充等各式新颖的CE手性分离体系也都被研究人员成功开发,并表现出较大的发展潜力。该综述将对近年来（尤其是2015~2019年）此类新型CE手性分离体系的发展状况进行梳理,并结合相应的手性识别机理研究和手性CE方法实际应用情况,对该领域存在的问题及发展前景进行分析和展望。