Fabrication and application of zwitterionic phosphorylcholine functionalized monoliths with different hydrophilic crosslinkers in hydrophilic interaction chromatography

In this study, a series of zwitterionic phosphorylcholine functionalized monolithic columns were fabricated via the thermally initiated co-polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and different hydrophilic crosslinkers, including 1,4-bis(acryloyl)piperazine (PDA), N,N′-methylenebisacrylamide (MBA) and 2-(methacryloyloxy)ethyl-[N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC). The physicochemical and chromatographic properties of these MPC functionalized monoliths, including column morphology, pore size distribution , permeability, column efficiency, retention mechanism and ζ-potential analysis, were systematically compared. Furthermore, the influence of the crosslinker on the chromatographic performance of these MPC functionalized monoliths was evaluated. The chromatographic results indicate that the polarity of MPC functionalized monoliths may be related to the polarity of the crosslinker, which further affects the column selectivity and efficiency. A particularly high column efficiency (88,000 plates/m) was obtained on the novel poly(MPC- co -MMPC) monolith at optimum linear velocity using thiourea as test analyte. Compared to the poly(MPC- co -MBA) and poly(MPC- co -PDA) monoliths, the poly(MPC- co -MMPC) monolith exhibited higher separation selectivity for polar analytes, including nucleobases , nucleosides and benzoic acid derivatives. Moreover, 24  N -glycopeptides could be detected after enrichment with the poly(MPC- co -MMPC) versus 19 and 10  N -glycopeptides with the poly(MPC- co -MBA) and poly(MPC- co -PDA) monoliths, and no N -glycopeptide without enrichment. Therefore, MMPC has a great potential as a new and alternative hydrophilic crosslinker for the development of zwitterionic polymeric monoliths.