Glycans are important components of mammalian cells, which exists extensively in eukaryocytes. Glycans are mainly consisted of monosaccharides, oligosaccharides and polysaccharides. They are connected to proteins or lipids through glycosylation, which constitute glycoconjugates. Glycosylation is one of the most important post-modifications of proteins, which mediate a wide variety of biological processes, including cell growth and differentiation, cell-cell communication, immune response, pathogen interaction, and intracellular signaling events. Because of the complex marshalling sequences, diversiform connection types and multiple branch structures, glycans are endowed with various structures. The diversity of glycan structure brings glycoconjugates with abundant information of cellular function. Among all the factors, human diseases act as an important ingredient which can induce unnatural glycosylation process. Glycoconjugates have been chosen as an efficient biomarker in the area of disease surveillance and targeted drug therapy. Thus, analysis of secreted glycans is of great importance for monitoring the states of cells or diseases in clinical diagnosis and treatment. Based on recent research of extracellular glycans, this review introduces the types of glycans in cellular secretion and their biological functions or significances, summarizes the identification or detection techniques of the secreted glycans, including lectin identifications, chemical covalent identifications and glycan metabolic marker techniques. Detection technologies of cell secretory glycan have been emphatically introduced in this review, which mainly contain spectrophotometry techniques, chromatography techniques, mass-spectrography techniques, fluorescence methods, electrochemical processes, enzyme linked immunosorbent assay techniques and western blot methods. After summarizing the progresses in this field during the past few decades, we outlook the future development of the analysis of cell secretory glycans. As far as we concern, in situ identification and quantitative detection will be the most challenging but meaningful topic of this field. We hope this review can be provided as a useful guidance for the investigating of glycosylation or glycan-related biological processes.

Key words: glycoconjugate, secreted glycan, glycan recognition, glycan detection