Capillary electrophoresis has emerged as a powerful approach for carbohydrate analyses since 2014. The method provides high resolution capable of separating carbohydrates by charge-to-size ratio. Principle applications are heavily focused on N-glycans, which are highly relevant to biological therapeutics and biomarker research. Advances in techniques used for N-glycan structural identification include migration time indexing and exoglycosidase and lectin profiling, as well as mass spectrometry. Capillary electrophoresis methods have been developed that are capable of separating glycans with the same monosaccharide sequence but different positional isomers, as well as determining whether monosaccharides composing a glycan are alpha or beta linked. Significant applications of capillary electrophoresis to the analyses of N-glycans in biomarker discovery and biological therapeutics are emphasized with a brief discussion included on carbohydrate analyses of glycosaminoglycans and mono-, di-, and oligosaccharides relevant to food and plant products. Innovative, emerging techniques in the field are highlighted and the future direction of the technology is projected based on the significant contributions of capillary electrophoresis to glycoscience from 2014 to the present as discussed in this review.

This report covers advances in capillary electrophoresis (CE) from January 2018 through September 2019. A summary of the literature during this time period is insightful. A search performed using the SciFinder Scholar® database for journal reports (limited to English) using the term capillary electrophoresis returned approximately 1,800 publications. Further analysis of this list, depicted in Figure 1, provided a snapshot of activity in biomolecular research. Classes of biomolecules most frequently associated with CE publications were proteins, drugs, DNA and metabolites. Another measure of the impact of CE is the translation of this technology into society. A search of patent activity illustrating this process of CE technology transfer returned 346 patents published in all languages, with a substantial contribution reported only in Chinese (198 patents) or English (98 patents). The versatility of CE for biological systems is exemplified by the rise of the technique in several areas. Metabolomics research involving measurements of large sets of molecules with subtle structural differences benefits from rapid separations achieved with high peak capacity and automated instruments. Single cell and sub-cellular analyses continue to progress in CE because of the size compatibility of the technique with the sample. Other examples of areas utilizing CE that are accelerating include portable and printable instrumentation, affinity interaction, as well as proteomics. As an established analytical tool, CE instrumentation and methods have been designed to be accessible and easily adopted by researchers with expertise in areas beyond the field of separations. Generally, publications including CE measurements either outline innovations in the technique or they are compelling applications of a mature analytical approach. The goal of this review, which is limited to 180 citations, is

Capillary electrophoresis provides a rapid, cost-effective platform for enzyme and substrate characterization. The high resolution achievable by capillary electrophoresis enables the analysis of substrates and products that are indistinguishable by spectroscopic techniques alone, while the small volume requirement enables analysis of enzymes or substrates in limited supply. Furthermore, the compatibility of capillary electrophoresis with various detectors makes it suitable for KM determinations ranging from nanomolar to millimolar concentrations. Capillary electrophoresis fundamentals are discussed with an emphasis on the separation mechanisms relevant to evaluate sets of substrate and product that are charged, neutral, and even chiral. The basic principles of Michaelis-Menten determinations are reviewed and the process of translating capillary electrophoresis electropherograms into a Michaelis-Menten curve is outlined. The conditions that must be optimized in order to couple off-line and on-line enzyme reactions with capillary electrophoresis separations, such as incubation time, buffer pH and ionic strength, and temperature, are examined to provide insight into how the techniques can be best utilized. The application of capillary electrophoresis to quantify enzyme inhibition, in the form of KI or IC50 is detailed. The concept and implementation of the immobilized enzyme reactor is described as a means to increase enzyme stability and reusability, as well as a powerful tool for screening enzyme substrates and inhibitors. Emerging techniques focused on applying capillary electrophoresis as a rapid assay to obtain structural identification or sequence information about a substrate and in-line digestions of peptides and proteins coupled to mass spectrometry analyses are highlighted.

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Stoichiometry, the ideal gas law, and the concept of limiting reagent are challenging principles for students to conceptualize in introductory chemistry. These topics are fundamental to successfully mastering other chemistry content. Therefore, a handheld microfluidic device was designed as a new tool to visualize these principles. Using food-grade baking soda, vinegar, and carbonated water as reagents, the students were engaged in a hands-on learning experience. The baking soda and vinegar were the source of sodium bicarbonate and acetic acid which were combined in a 1:1 mol ratio to form carbon dioxide gas which was then quantified using the device, thereby illustrating the ideal gas law. Experiments were devised to support learning outcomes that involved using the ideal gas law to interconvert moles and volume, balancing chemical equations, quantifying the amount of product generated from a known amount of reactant, conveying measurement uncertainty, and postulating sources of experimental error. The microfluidic device is a fast and cost-effective tool to teach stoichiometry. Moreover, the use of food-grade reagents makes the activity accessible as well as safe enough to be conducted outside of a traditional laboratory setting.