Selective enrichment of glycopeptides/phosphopeptides using Fe3O4@Au-B(OH)2@mTiO2 core-shell microspheres

In this work, the bifunctional Fe3O4@Au-B(OH)(2)@mTiO(2) core-shell core-shell microspheres were designed and synthesized for the selective enrichment of glycopeptides/ phosphopeptides. Due to the bifunctional property of the titanium dioxide and the boronic acid group, the microspheres were successfully applied to the enrichment of phosphopeptides and glycopeptides, evaluated by capturing phosphopeptides from tryptic digestion of model phosphoprotein bovine beta-casein diluted to 2.0 mu g gL(-1) (8.0x10(-17) mol mu L-1) and glycopeptides from tryptic digestion of model glycoprotein horseradish peroxidase (HRP) diluted to 80 pg mu L-1 (2.0 x 10(-15) mol mu L-1). The enrichment selectivity of the bifunctional microspheres was evaluated by capturing phosphopeptides from a peptide mixture of beta-casein and bovine serum albumin (BSA) with the molar ratio of 1:1000 (4.2x10(-12) mol of beta-casein and 4.2x10(-9) mol of BSA in 100 mu L) and glycopeptides from a peptide mixture of HRP and BSA up to the ratio of 1:100 (5.0x10(-12) mol of HRP and 5.0x10(-10) mol of BSA in 100 mu L).