Selective separation and enrichment of peptides for MS analysis using the microspheres composed of Fe3O4@nSiO2 core...

In this work, we report the development of a novel enrichment protocol for peptides by using the microspheres composed of Fe(3)O(4)@nSiO(2) Core and perpendicularly aligned mesoporous SiO(2) shell (designated Fe(3)O(4)@nSiO(2)@mSiO(2)). The Fe(3)O(4)@nSiO(2)@mSiO(2) microspheres possess useful magnetic responsivity which makes the process of enrichment fast and convenient. The highly ordered nanoscale pores (2 nm) and high-surface areas of the microspheres were demonstrated to have good size-exclusion effect for the adsorption of peptides. An increase of S/N ratio over 100 times could be achieved by using the microspheres to enrich a standard peptide, and the application of the microspheres to enrich universal peptides was performed by using myoglobin tryptic digest solution. The enrichment efficiency of re-used Fe(3)O(4)@nSiO(2)@mSiO(2) microspheres was also studied. Large-scale enrichment of endogenous peptides in rat brain extract was achieved by the microspheres. Automated nano-LC-ESI-MS/MS was applied to analyze the sample after enrichment, and 60 unique peptides were identified in total. The facile and low-cost synthesis as well as the convenient and efficient enrichment process of the novel Fe(3)O(4)@nSiO(2)@mSiO(2) microspheres makes it a promising candidate for selectively isolation and enrichment of endogenous peptides from complex biological samples.