Magnetic mesoporous carbon composites incorporating hydrophilic metallic nanoparticles for enrichment of phosphopeptides prior to their determination by MALDI-TOF mass spectrometry

Magnetic mesoporous carbon composites incorporating hydrophilic metallic nanoparticles were synthesized from resol, ZrO(NO 3 ) 2 , ferric acetylacetonate, and triblock copolymer F127. The method involves a multi-component co-assembly strategy associated with direct carbonization. The resulting carbon material is shown to be useful as a metal oxide affinity chromatography (MOAC) material for enrichment of phosphopeptides owing to its large mesoporous (4.8 nm) surface area (442 m 2  g −1 ), large pore volume (0.37 cm 3  g −1 ) and excellent hydrophilicity. The metallic iron and ferric oxide particles modified on the mesoporous carbon exert a magnetic force and, in combination with the metallic zirconia, is a viable MOAC material for enrichment of low-abundance phosphopeptides. Because of metal chelation between metallic nanoparticles and the phosphate groups of phosphopeptides, the zirconia/magnetic mesoporous carbon displays high selectivity even at a phosphopeptide/nonphosphopeptide molar ratio of 1:500. As little as 1.5 fmol of phosphopeptides become detectable. The MOAC was successfully applied to the identification by MALDI-TOF MS of phosphopeptides in human serum and nonfat milk. Magnetic mesoporous carbon composites incorporating hydrophilic metallic nanoparticles were prepared and successfully applied to the enrichment of low-abundance phosphopeptides from human serum and nonfat milk by MALDI-TOF mass spectrometry.