Elution-free ultra-sensitive enrichment for glycopeptides analyses: Using a degradable, post-modified Ce-metal–organic framework

In this work, we presented a facile elution-free method for ultrasensitive enrichment of glycopeptides using two kinds of novel Ce-metal-organic frameworks (Ce-MOF) post-modified with hyaluronic acid (Ce-MOF@HA) and glutamic acid (Ce-MOF@Glu). Both of the synthesized materials remained stable in the loading buffer to enrich glycopeptides selectively and degrade in the eluent to release captured glycopeptides. Due to the dissolution of materials, the elution step of the enrichment process is omitted, resulting in an extremely high sensitivity (detection limit, 0.5 fmol/μL). Meanwhile, Ce-MOF@HA and Ce-MOF@Glu also possessed excellent selectivity with molar ratios of IgG and BSA digests being 1:1000 and 1:500, respectively. Noticeably, the practical applicability of the obtained materials was inspected by analyzing the glycopeptides enriched from human serum (2 μL) by nano-LC-MS, in which 434 N-glycopeptides from 182 N-glycoproteins (by Ce-MOF@HA) and 328 N-glycopeptides from 135 N-glycoproteins (by Ce-MOF@Glu) were detected, respectively. This work provides a new method to simplify the process of glycopeptides enrichment and also paves a novel way for the enrichment of trace targets from complex matrices.