ZrO2 doped magnetic mesoporous polyimide for the efficient enrichment of phosphopeptides

FexOy and ZrO2 nanoparticles co-doped layered porous polyimide, polyimide-FexOy-ZrO2 is prepared with a one-step strategy, shortly termed as PI-FexOy-ZrO2. The layered and porous structure of the polymer offers a supported platform for metallic oxide anchoring, exhibiting a mesopore size of 3.93 nm and providing a surface area of 198.47 m(2) g(-1). The metallic oxides were uniformly and highly dispersed in the PI-FexOy-ZrO2 nanocomposite with percentages of 15.81 and 20.53 wt% for Fe and Zr, respectively. The magnetic FexOy provides driving force for rapid separation. The high doping of ZrO2 facilitates effective enrichment of phosphopeptides, even at a very low mass ratio of 1:1000 for tryptic digest of phosphopeptides/non-phosphopeptides, e.g., beta-casein/BSA in this particular case. In addition, the PI-FexOy-ZrO2 nanocomposite exhibits better adsorption performance to phosphopeptides with respect to commercial titanium dioxide nanoparticles. The effectiveness of low-abundant phosphopeptides isolation and enrichment from human serum is further identified and demonstrated by means of MALDI-TOF MS and LC-ESI-MS/MS.