LAUSR

Efficient enrichment and identification of phosphopeptides are of great significance in biological applications. Glycocyamine functionalized magnetic layered double hydroxides (Fe3O4@LDH@NH2-GAA) was fabricated through an easy process. The magnetic composite possessed high surface area, good biocompatibility, and fast magnetic response. Fe3O4@LDH@NH2-GAA, combining not only metal ions (Cu2+ and Ga3+) in LDH but also functional guanidyl groups in glycocyamine, offered multiple affinity sites for phosphopeptides enrichment. With these favorable characters, it exhibited high selectivity (β-casein: bovine serum albumin = 1:5000), low detection limit (0.1 fmol), satisfactory enrichment recovery (94.5%), high adsorption capacity (82.4 mg g-1), and good repetitiveness. Moreover, the efficient enrichment of phosphopeptides by Fe3O4@LDH@NH2-GAA from nonfat milk, human saliva, serum, and A549 cell lysates further confirmed its great potential for trace biological detection and proteomic analysis.