Bi-amino acid functionalized biomimetic honeycomb chitosan membrane as a multifunctional hydrophilic probe for specific capture of N-linked glycopeptides in nasopharyngeal carcinoma's disease patient's serum.

In this work, a novel porous bifunctionalized composite material was synthesized via a simple method. Gold nanoparticles are uniformly dispersed on the surface of the biomimetic honeycomb chitosan membrane through the interaction between amino and Au, and then cysteine and glutathione are successfully grafted onto the surface of the Au by the Au-S bond. The modification of cysteine and glutathione makes this bifunctionalized composite material have significant advantages of superhydrophilicity and small steric hindrance simultaneously. This material manifests excellent property in glycopeptides enrichment, with high selectivity (1:5000), low detection limit (0.1 fmol·μL ), high recovery rate (99.4 ± 0.5%), and good repeatability. In addition, with the help of nano-flow liquid chromatography tandem mass spectrometry, this composite achieved excellent performance in efficiently enriching glycopeptides in the serum of healthy people and nasopharyngeal carcinoma's disease patient. More excitingly, further gene ontology analysis of molecular function and biological process indicated that 41 original glycoproteins of the identified glycopeptides from serum of nasopharyngeal carcinoma's disease patient significantly partake in numerous cancer-associated events, including protease binding, calcium ion binding, enzyme binding, extracellular matrix organization, cellular response to tumor necrosis factor, and inflammatory response.