Precision Synthesis of Polysaccharides: Unlocking the Sugar Code for Tailored Biological Functions

As vital biomacromolecules, polysaccharides play pivotal roles in biological processes, including cell recognition, immune modulation, and signal transduction. Their bioactivities hinge on the precise "sugar code", comprising monosaccharide composition, glycosidic linkages, chain length, branching, and modifications. However, natural extraction faces challenges, including yield variability, low purity, and batch inconsistencies, which impede research and applications. Thus, synthetic approaches have emerged as an essential strategy for producing well-defined polysaccharides. This review summarizes recent progress in polysaccharide synthesis across chemical, enzymatic, and chemoenzymatic approaches. Framing the "structure-synthesis-function" nexus, it elucidates the design principles and application potential of bioactive polysaccharides, traces their evolution from fundamental research to industrial implementation, and offers strategic insights for drug discovery, biomaterials engineering, and functional food development.