Capillary electrophoresis of carbohydrates: from monosaccharides to complex polysaccharides (Volpi N. Editor)

Capillary electrophoresis (CE) encompasses a range of related separation techniques that use narrow-bore fused-silica capillaries to separate a complex array of large and small molecules. Due to its high resolving power and sensitivity, CE has been applied in the analysis of simple and complex carbohydrates, such as intact oligosaccharides and glycosaminoglycans-derived oligosaccharides and disaccharides providing concentration and structural characterization data essential for understanding their biological functions. Simple carbohydrates and complex oligosaccharides and polysaccharides are a class of ubiquitous (macro)molecules exhibiting a wide range of biological functions. The recent advent of enhanced enzymatic, chemical and analytical tools for the study of these sugars has triggered a genuine explosion in the field of glycomics. In particular, the study of complex oligosaccharides and heteropolysac¬charides has led to deeper insight into how specific sugar structures modulate cellular phenotypes. An increased understanding of the structure-function relationship has led to the discovery of new pharmaceuticals for the treat¬ment of serious diseases, such as cancer. This area of research is rapidly expanding and is expected to have a major impact on future therapeutic regimens.This Volume on the capillary electrophoresis of carbohydrates provides the reader with the latest break-throughs and improvements in CE and CE techniques applied to monosaccharides up to complex oligo- and polysaccharides. Chapter 1 presents an overview on the application of CE and CE- mass spectrometric (MS) in the analysis of simple carbohydrates without any previous derivatization step. Various detection techniques such as spectrophotometric detection, electrochemical detection, MS but also less common techniques are discussed. Finally, a wide-ranging list of CE and CE-MS applications in the field of carbohydrate analysis published during the last decade is reported. Chapter 2 covers all the currently used derivatization procedures, by means of chromophore or fluorophore incorporation, their mechanistic details and the merits attributed to each approach with the aim of enhancing sensitivity and also of improving analyte separation. Chapter 3 focuses on CE, CE-MS and tandem MS, on the separation and characterization of lipopolysaccharides along with some acidic polysaccharides and derived oligosaccharides and disaccharides, which are important (macro)molecules belonging to bacteria. Chapter 4 gives an outline of microchip-based CE analysis of complex natural heteropolysaccharides, known as glycosaminoglycans, which affords rapid analysis on a time scale of seconds. This technology has great potential as a tool for routine assessment of pharmaceutical preparations and for clinical diagnosis. Chapter 5 discusses the use of CE as an analytical approach for the detection of biofilm positivity in particular microorganisms, as well as for the separation of biofilm-positive and -negative strains, considering that the biofilm-positive surfaces are usually covered with specific extracellular polysaccharide substances that play a key role in biofilm formation and function. Chapter 6 illustrates the capacity of CE in the structural characterization of polysaccharide mono- and oligomer constituents, surveying several applications on chemically and enzymatically degraded polysaccharides. Furthermore, CE was also demonstrated to be highly reliable for the determination of polysaccharides in biological samples, due to the possibility of analyzing rather complex matrices even without any pre-treatment, a distinctive feature with respect to other separation strategies. In relation to this versatility, Chapter 7 features a survey on the more recent applications and developments of CE to study reactions involving saccharide-bearing molecules, such as strategies applied to monitoring the synthesis of carbohydrate based-molecules, or research channeled towards the investigation of the action of enzymes on carbohydrates, or studies showing how CE has been recently applied to investigate naturally occurring processes pursuing the ultimate goal of monitoring single cell reactions. Chapter 8 investigates “biopharmaceuticals”, a term commonly employed to define therapeutic proteins produced by biotechnology and specifically via genetic engineering. Many of the biopharmaceuticals currently produced are glycoproteins in which the oligosaccharide chains can impact markedly on bioactivity and several other properties. It is therefore mandatory to control glycoproteins by robust methods capable of providing adequate details regarding minor modifications. CE has proved its usefulness not only for the characterization of glycoprotein pharmaceuticals but also as a quality control tool enabling accurate quantitation. Following this topic, Chapter 9 highlights recent developments in the analysis of proteins glycosylated at the amino groups of asparagine residues by CE and CE-MS. The analysis of intact glycoproteins is reviewed followed by a detailed analysis of N-glycans released from glycoproteins through chemical or enzymatic reactions. Furthermore, in order to obtain detailed structural information, the advantages and limitations of various methodological approaches and techniques, as well as MS instrumentation, are discussed specifically in the context of glycan analysis. Finally, Chapter 10 evaluates CE as a powerful analytical method to effectively and accurately determine the monosaccharide composition of glycoproteins and glycolipids in biological and biomedical samples also in relation to its potential application in the diagnosis or prognosis of diseases.As the editor of this Volume, I would like to thank all the contributors for their first-rate articles, which will certainly impact the area of CE separation of carbohydrates by providing a better understanding of the underlying analytical phenomena and by widening the scope of their possible applications. Acknowledgement is due to Springer Editors for their assistance in bringing this issue to publication.