Boronate affinity sorbents based on thiol-functionalized polysiloxane-polymethacrylate composite materials in syringe format for selective extraction of glycopeptides

Abstract In this work, two novel boronate affinity monolithic materials able to extract glycopeptides within a polypropylene syringe are described and compared. The first material was synthesized from glycidyl methacrylate (GMA)-based monoliths modified with poly-3-mercaptopropyl-methylsiloxane (PMPMS) followed by attachment of 4-vinylphenylboronic acid (VPBA) via thiol-ene click reaction. The second material was prepared by using gold nanoparticle (AuNP)-modified monoliths as substrate followed by subsequent attachment of PMPMS and VPBA. The resulting materials were used as sorbents for solid-phase extraction (SPE) to selectively preconcentrate glycopeptides from horseradish peroxidase (HRP) digests. The material that gave the superior performance was that prepared with AuNPs due to the presence of abundant boronic acid groups, being its practical applicability also examined. The hybrid material exhibited a satisfactory efficiency of glycopeptide enrichment (identifying 24 glycopeptides from a total of 27) in mixture of tryptic digests of HRP and bovine serum albumin (BSA) (1:100, w/w) were tested (or as testing sample). The sorbent shows low sensitivity (0.5 fmol/µL), good adsorption capacity (25 mg g-1) and suitable reusability (over 10 times). Moreover, the hybrid monolith was successfully applied to the selective enrichment of glycopeptides from human serum digests, without any pretreatment, in which 85 glycopeptides were identified by nano-LC-MS/MS, suggesting a great potential for application in glycoproteome field.