Decoding of Carbohydrates With Monosaccharide-Level Resolution Using Tip-Enhanced Raman Scattering.

We report a tip-enhanced Raman spectroscopy (TERS) platform integrated with nanopillar-assisted glycan trapping for high-sensitivity, label-free analysis of oligosaccharides. Mechanical confinement of glycans generates localized plasmonic hot spots, enabling highly reproducible and structurally informative vibrational spectra. The system resolves subtle structural differences such as β(1→3) vs. β(1→4) glycosidic linkages, and allows semi-quantitative estimation of chain length based on H-C-H deformation signatures. The azido tag provides an internal reference, supporting signal normalization from trace sample volumes. The platform also tracks enzymatic glycosylation reactions in real time, including the emergence of α1→2 fucosylation linkages. This approach distinguishes single-bond differences and monitors biosynthetic progression with high molecular specificity. This work establishes TERS as a powerful tool for glycan sequence analysis and dynamic monitoring of carbohydrate synthesis.