Capillary electrophoresis in glycosaminoglycan analysis

Glycosaminoglycans (GAGs) are structurally complex, highly acidic polysaccharides that are produced by virtually all animal cells and play essential roles in cell communication, tissue organization, and disease processes. As key components of proteoglycans and as free saccharides, GAGs are abundant on cell surfaces and in the extracellular matrix, where they interact with a wide range of proteins such as growth factors and cytokines. Their interactions with proteins are fine-tuned by extensive structural variations of the polysaccharide chains, most importantly the attachment of sulfate modifications leading to distinct sulfation patterns. The resulting extraordinary structural complexity, however, poses significant challenges to the analysis of GAGs. Capillary electrophoresis (CE) offers distinct advantages for tackling these challenges, including exceptional resolution for charged analytes, low sample requirements, and compatibility with various detection methods. In this review, we highlight recent advances in the application of CE for GAG analysis, addressing key sample preparation steps, derivatization strategies, detection methods, and various CE modes to improve resolution and sensitivity. Challenges and benefits associated with coupling CE to mass spectrometry are addressed explicitly. Selected applications across the GAG families are presented to illustrate the utility of CE in biomedical and glycomic research. Finally, the strengths and current limitations of CE for the wider GAG analysis field are evaluated, and directions for further progress and future developments are outlined.