Two-in-One Strategy for Effective Enrichment of Phosphopeptides Using Magnetic Mesoporous γ-Fe2O3 Nanocrystal Clusters

Designed with a two-in-one strategy, the magnetic mesoporous gamma-Fe2O3 nanocrystal clusters (m-gamma-Fe2O3) have been successfully prepared for integrating the functions of effective enrichment and quick separation of phosphopeptides into a single architecture. First, the mesoporous Fe3O4 nanocrystal clusters (mFe(3)O(4)) were synthesized by solvothermal reaction and then were subjected to calcination in air to form m-gamma-Fe2O3. The obtained m-gamma-Fe2O3 have spherical morphology with uniform particle size of about 200 nm and mesoporous structure with the pore diameter of about 9.7 nm; the surface area is as large as 117.8 m(2)/g, and the pore volume is 0.34 cm(3)/g. The m-gamma-Fe2O3 possessed very high magnetic responsiveness (Ms = 78.8 emu/g, magnetic separation time from solution is less than 5 s) and were used for the selective enrichment of phosphopeptides for the first time. The experimental results demonstrated that the m-gamma-Fe2O3 possessed high selectivity for phosphopeptides at a low molar ratio of phosphopeptides/nonphosphopeptides (1:100), high sensitivity (the detection limit was at the fmol level), high enrichment recovery (as high as 89.4%), and excellent speed (the enrichment can be completed in 10 min). Moreover, this material is also quite effective for enrichment of phosphopeptides from the real sample (drinking milk), showing great potential in the practical application.