Emerging Nanoscale Platforms for Precision Glycan Analysis: Molecular Fingerprinting, Nanopore Sensing, and Spatial Readouts.

Glycans present two intrinsic properties that make nanoscale analysis a necessity rather than a refinement: a microheterogeneity that arises from non-templated biosynthesis, and a structural information density that surpasses that of nucleic acids and proteins by orders of magnitude. Both demand readout at the level of the individual molecule, on scales from the chemical bond to the residue to the spatial register. Five emerging platforms now meet these requirements along complementary dimensions. Tip-enhanced Raman spectroscopy reads single glycosidic linkages through vibrational fingerprints. Electrospray ion beam deposition coupled to low-temperature scanning tunneling microscopy resolves connectivity, stereochemistry, and intact glycoconjugate architecture on individual molecules. Engineered nanopores translate single-molecule translocations into linkage- and modification-specific ionic-current signatures in solution. High-resolution cryo-electron microscopy places glycans within hydrated higher-order assemblies as explicit atomic models. Ångström-resolution fluorescence imaging resolves individual glycans on intact cell surfaces. This Review examines each platform from the standpoint of its working principle, the structural variables it resolves, and the methodological boundary it currently defines, with attention to the recurring trade-offs they negotiate across chemistry, physiology, ensemble, and interpretation. The mature contribution of these platforms will be the conversion of glycan structure from inventory into mechanism.