Selective enrichment of sialylated glycopeptides with a d-allose@SiO₂ matrix

Abnormal sialylation of glycoprotein is associated with different kinds of cancers and neurodegenerative diseases. However, analysis of low abundance sialylated glycopeptides (SGPs) from complex biological samples is still a big challenge. To solve the problem, materials with high SGPs enrichment selectivity should be designed and prepared. Inspired by the saccharide-saccharide interaction in life systems, a d-allose@SiO₂ (ABS) material was prepared and applied in SGPs enrichment under hydrophilic interaction liquid chromatography (HILIC) mode. Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and nitrogen adsorption experiment results proved that the ABS matrix was successfully synthesized. The SGPs enrichment selectivity of ABS matrix was evaluated with Nano Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry (Nano ESI Q-TOF/MS). The results indicated that the SGPs enrichment selectivity was notably higher with the ABS matrix (24 SGPs) than the commercially available Sepharose CL-6B (9 SGPs) and TiO₂ (8 SGPs), taking digests of fetuin/bovine serum albumin (BSA) (1 : 10, w/w) as the test sample. The SGPs enrichment performance of ABS matrix was further validated by the interference, recovery rate, and reproducibility evaluation experiments. In the end, the ABS matrix was applied in the analysis of real biosample (HeLa cell lysates). Totally 301 SGPs with 277 glycosylation sites from 186 glycoprotein were successfully characterized by taking HeLa S3 cell lysate as target sample in two replicated experiments. The results indicated that the ABS matrix had great potential to be applied in the enrichment of SGPs from complex biological samples.