In addition, we used this platform to directly analyze intact glycoproteins. Protein glycosylation analysis typically requires tedious sample preparation, such as enzymatically releasing glycans from glycoproteins and chemically labeling glycans for detection . Direct analysis of intact glycoproteins will speed up the analysis procedure and benefit the glycobiology community. We evaluated the feasibility of quantifying sialylation levels of fetuin/asialofetuin mixture. The collective spectra once again demonstrated superior quantification performance, with R 2 and normalized mean square error (NMSE) values of 0.9941 and 0.005912, respectively. Moreover, we evaluated the sensor performance in distinguishing glycosylic linkages of sialic acids. Sialic acid is an important monosaccharide for mammalians due to its functionality in nervous system development, immune regulation, and involvements in many diseases . We tested the sensor's classification performance on the most common α2,3 and α2,6 sialic acid linkage . By using various BA receptors, the sensor could achieve 100% accuracy in the classification of sialic acid linkages. In summary, this sensor could work as a user-friendly platform to directly detect glycan profiles in biological samples and intact glycoproteins without timeconsuming glycan purification steps.