Facile synthesis of carboxymethyl-β-cyclodextrin conjugated magnetic nanoparticles for selective enrichment of glycopeptides

Rationale Selective enrichment of glycopeptides prior to mass spectrometry (MS) analysis is essential due to the low abundance of the modified glycopeptides in complex samples, ion suppression effects during MS ionization and detection caused by the co‐presence of non‐glycosylated peptides, etc. Among different enrichment approaches, hydrophilic interaction liquid chromatography (HILIC)‐based magnetic separation has become one of the most popular methods in recent years, due to its high efficiency and selectivity for glycopeptide enrichment. Methods Herein, novel carboxymethyl‐β‐cyclodextrin (CMCD)‐modified magnetic nanoparticles (MNPs) were synthesized via a carbodiimide activation method. CMCD was covalently bonded with the –OH group on the surface of MNPs through carbodiimide, and the proposed procedure provides a rapid and efficient alternative for glycopeptide enrichment due to its stable interaction, time‐saving, and easy operation. Results The prepared absorbents with a mean diameter of 15 nm demonstrated a strong magnetic response to an externally applied magnetic field. The results of thermogravimetric analysis showed the content of bound CMCD was 3 wt%. The outer CMCD layer conjugated on the Fe3O4 core showed high hydrophilic surface property. In the analysis of a complex mouse liver sample, a total of 666 unique N‐glycosylation sites corresponding to 494 glycosylated proteins were identified successfully. Conclusions The study demonstrated an easy‐to‐use CMCD‐modified MNPs‐based approach with high selectivity and high capacity in the enrichment of low‐abundance glycopeptides from complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd.