Preparation of zwitterionic cysteine-modified silica microsphere capillary packed columns for the on-column enrichment and analysis of glycopeptides in human saliva

• Published in: Analytica chimica acta 2020-02, Vol.1096, p.1-8
• Main Authors: Wu, Yonglei, Lin, Haizhu, Xu, Zixing, Li, Yan, Chen, Zongbao, Deng, Chunhui
• Format: Article
• Language: English
• Subjects: Glycopeptides; Hydrophilic enrichment; L-Cysteine; On-column enrichment
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2019.11.032

In this work, for the first time, L-cysteine (L-Cys), a zwitterionic hydrophilic compound containing abundant amino and carboxyl was modified on silica microspheres for the fabrication of SiO2@L-Cys capillary packed column. Since the SiO2@L-Cys capillary packed column possessed great hydrophilicity brought by L-cysteine, they could be utilized to enrich glycopeptides with a low detection limit of 5 fmol μL−1 HRP digests as well as a good selectivity of the mixture of HRP and BSA digests up to a molar ratio of 1:50. The capillary packed column were further applied into the glycosylation analysis of human saliva and 69 glycopeptides were identified from 2 μL human saliva digests. Silica microspheres were functionalized with L-cysteine (L-Cys) which contains amino and carboxyl to obtain hydrophilic microspheres denoted as SiO2@L-Cys. The SiO2@L-Cys microspheres were employed as packing material to fabricate SiO2@L-Cys capillary packed columns for on-column enrichment of glycopeptides, which exhibited great performance. [Display omitted] •SiO2@L-Cys microspheres were first employed as hydrophilic packing material for on-column enrichment of glycopeptides.•The SiO2@L-Cys capillary packed columns exhibited good performance in enriching standard glycopeptides.•The method based on SiO2@L-Cys capillary packed columns was further applied into glycosylation analysis of human saliva. The great results achieved demonstrated its broad application prospect in handling various biological samples. The method also possessed enormous potential of on-line coupling with LC-MS for glycopeptide identification.