Efficient separation of phosphopeptides employing a Ti/Nb-functionalized core-shell structure solid-phase extraction nanosphere

A strategy for effectively enriching global phosphopeptides was successfully developed by using ammonia methyl phosphate (APA) as a novel chelating ligand and Ti4+ and Nb5+ as double functional ions (referred to as Fe3O4@mSiO(2)@APA@Ti4+/Nb5+). With the advantage of large specific surface area (151.1 m(2)/g), preeminent immobilized ability for metal ions (about 8% of total atoms), and unbiased enrichment towards phosphopeptides, Fe3O4@mSiO(2)@APA@Ti4+/Nb5+ displays high selectivity (maximum mass ratio beta -casein to BSA is 1:1500), low limit of detection (LOD, as low as 0.05 fmol), good relative standard deviation (RSD, lower than 7%), recovery rate of 87% (O-18 isotope labeling method), outstanding phosphopeptide loading capacity (330 mu g/mg), and at least five times re-use abilities. In the examination of the actual sample, 24 phosphopeptides were successfully detected in saliva and 4 phosphopeptides were also selectively extracted from human serum. All experiments have shown that Fe3O4@mSiO(2)@APA@Ti4+/Nb5+ exhibits exciting potential in view of the challenge of low abundance of phosphopeptides.

Automated summary

The Fe3O4@mSiO(2)@APA@Ti4+/Nb5+ material has shown promising potential in effectively enriching global phosphopeptides, with high selectivity, low detection limit, good reproducibility, and excellent loading capacity.