Design of Two-Dimensional Layered Double Hydroxide Nanosheets Embedded with Fe3O4 for Highly Selective Enrichment and Isotope Labeling of Phosphopeptides

Abstract

Herein, exfoliated Cu/Ga layered double hydroxide (LDH) nanosheets were constructed, over which Fe3O4 nanoparticles were uniformly spread to maintain the two-dimensional (2D) morphology. The prepared Fe3O4-LDH exhibited high adsorption capacity (71.3 μmol g–1 for p-nitrophenylphosphate) and satisfactory enrichment selectivity (β-casein:BSA:ovalbumin ratio of 1:5000:5000). A low detection limit (0.01 fmol) was obtained for β-casein phosphopeptides combined with MALDI-TOF MS determinations, demonstrating that the method was highly sensitive. The recovery of phosphopeptides was determined to be as high as 93.7%. In addition, the composite demonstrated specific capture of phosphopeptides from practical samples, nonfat milk, human saliva, and serum. Fe3O4-LDH also had good performance for quantifying abnormally regulated phosphopeptides in leukemia patients sera by using an isotope labeling method. The material consumedly contributed to MS analysis in phosphoproteome and gave inspirations of using 2D materials...