Polydopamine-mediated immobilization of phenylboronic acid on magnetic microspheres for selective enrichment of glycoproteins and glycopeptides

In this work, we demonstrate for the first time, a method to synthesize phenylboronic acid-Fe3O4@polydopamine (Fe3O4@PDA-PBA) magnetic microspheres via the combination of mussel-inspired polydopamine coating and click chemistry. Uniform-size and core-shell structured Fe3O4@PDA-PBA magnetic microspheres with a core diameter of similar to 240 nm and a shell thickness of similar to 13 nm were obtained as identified by the characterization of the morphology, structure and composition of the synthesized microspheres. We evaluated the selectivity and binding capacity of the Fe3O4@PDA-PBA magnetic microspheres by using standard glycoproteins (ovalbumin, immunoglobulin G and catalase) and nonglycoproteins (human serum albumin, bovine hemoglobin, myoglobin, lysozyme, and ribonuclease A) as model proteins. Adsorption experiments, SDS-PAGE and mass spectrometry analysis demonstrated that the Fe3O4@PDA-PBA magnetic microspheres had much high binding capacity and selectivity for glycoproteins/glycopeptides compared to nonglycoproteins/nonglycopeptides. In addition, the practicability of the Fe3O4@PDA-PBA magnetic microspheres was further assessed by selective capture of glycoproteins from healthy human serum. The good results demonstrated its potential in glycoproteome analysis.