Selective enrichment of glycopeptides based on copper tetra(N-carbonylacrylic) aminephthalocyanine and iminodiacetic acid functionalized polymer monolith

Efficient separation and enrichment of low-abundance glycopeptides from complex biological samples is the key to the discovery of disease biomarkers. In this work, a new material was prepared by coating copper tetra(N-carbonylacrylic) aminephthalocyanine and iminodiacetic acid onto poly(glycidyl methacrylate-pentaerythritol triacrylate) monolith. The monolith was applied to polymer monolithic microextraction for specific capture of glycopeptides coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The developed monolith exhibited satisfactory efficiency for glycopeptide enrichment with high selectivity and detection sensitivity. When the tryptic digest of immunoglobulin G was used as the sample, total 24 glycopeptides were identified and the detection limit was determined as 5 fmol. When the approach was applied to the analysis of glycopeptides in the mixture of bovine serum albumin and immunoglobulin G (100:1, m/m) digests, 16 glycopeptides could still be observed. Moreover, the monolith was successfully applied to the selective enrichment of glycopeptides from human serum digests, exhibiting great practicability in identifying low-abundance glycopeptides in complex biological samples.