Analyzing and modifying sialic acid at the glycan end: Systematic review of methods and functional outcomes

Sialic acid, a nine-carbon monosaccharide at the termini of glycan chains, is intricately linked to tumor progression and disease, necessitating highly sensitive analytical methods for accurate disease monitoring. This review elucidates advancements in the analysis of sialic acid, emphasizing methodologies including electrochemistry, mass spectrometry, fluorescence, and Raman scattering. Special attention is devoted to fluorescence-based techniques for the analysis of sialic acid within living cells, covering global, cell-specific, region-specific, and protein-specific strategies. Notably, variations in sialic acid abundance are connected to critical biological processes like tissue homeostasis, cell migration, and immune responses. This review also examines the wide-ranging applications of sialic acid, particularly in modulating cellular behavior through both internal and external glycan editing techniques. By systematically summarizing strategies for sialic acid analysis and regulation, and highlighting its dual influence, this review serves as a valuable resource for researchers aiming to deepen their understanding in this field.