Recent advances in the analysis of polysialic acid from complex biological systems

[Display omitted] •Polysialic acid is of significant interest due its roles in biology and disease.•First systematic review of approaches for extraction and characterisation of polysialic acids from biological matrices.•Approaches to analysis of the degree of polymerisation of polysialic acid evaluated.•Quantitation considered, including accuracy and limit of detection. Polysialic acid (polySia) is a unique, well-characterised carbohydrate polymer highly-expressed on the cell surface of neurons in the early stages of mammalian brain development. Post-embryogenesis, it is also re-expressed in a number of tumours of neuroendocrine origin. It plays important roles in modulating cell-cell, and cell-matrix adhesion and migration, tumour invasion and metastasis. Techniques for structural and quantitative characterisation of polySia from tumours and cancer cells are thus essential in exploring the relationship between polySia expression levels and structural and functional changes associated with cancer progression and metastasis. A variety of techniques have been developed to structurally and quantitatively analyse polySia in clinical tissues and other biological samples. In this review, analytical approaches used for the determination of polySia in biological matrices in the past 20 years are discussed, with a particular focus on chemical approaches, and quantitative analysis.